221 cu in 1939 Failed No4 Piston 1

[Phil Gillespie]

See a few pics of the reason my No4 Cyl was not showing any compression.
Engine is 221 with 80 thou oversized piston.


The reason for this? These pistons have possibly 9 to 10 thousand miles max.
On the plus side, head, Edelbrock is unmarked, bore on this No4 is also unmarked. Intention to remove piston, identify and just get one and a set of rings and refit. However still running the spit valve guides and thinking of maybe replacing as suspect some oii usage is due to valve guide clearance.
When I got it home after a test run whe this happened, couple of good clouds of smoke into compartment. I took a set of compressions next day when cooled down .
!: 140. 2:135. 3: 132. 4: Zero!! 5: 120. 6:120. 7: 115 *: 100.
So figure to check valves at No4 as well as getting hold of a replacement piston and rings. Hope to do this in place wth engine in car.Should be possible?




You just have to move on and attend to it.
Phil NZ

[Talkwrench]

Ahhh geezus... Better talk to Brian he may have some insight..

[GEOFFNZ]

Hi Phil.That is not good.Any sign of the piston hitting the cylinder head,Geoff

[Phil Gillespie]

Nope Geoff as the cylinder head is in good order.The pic is of that section of cylinder head above No4 piston. Only idea I currently have is this piston No4 & No1 had a problem with spark plug gaps closing up to almost nothing. Hence combustion would not have been good. Maybe some carbon build up.
I eventually ended up putting an extra seal washer on both spark plugs and they then retianed the spark gap and plugs as checked were a nice tan colour. Previously were showing slightly oily dark.
Once i get the piston out will then begin search for a piston and rings.
These type of valves with the split guides will come out complete once valve guide retainer is removed?
Phil NZ

[flatheadmurre]

The guides will come out in one piece...and hopefuly without to much bad language.
A K-D valve guide puller is your best friend for that job.
Since thoose pistons aren´t ford finding a weight matched couple might be a challenge...you can just cut so much weight off and if they are heavy slugs it´s even worse.

[Phil Gillespie]

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Ok so I can remove, hopefully if all is free, the complete valve and spring, and retainer, by just removal of the horseshoe and then dismantle valve out of engine. These being split guide with mushroom at valve stem? Yes.?
Phil NZ

[Ggmac]

Did a spark plug electrode let go ?

[51 MERC-CT]

Don't remember ever seeing registration marks on top of the pistons that big and deep. Look almost big and deep enough to alter the compression ratio.

[Ggmac]

Ok , how much nitrous did you use ?

[tubman]

This may be completely unrelated, but the last time I saw something like that was on a snowmobile we were racing. The leaner you get 'em, the faster they'll go until something like this would happen.

[flatford8]

There doesn’t look like enough carbon to cause a plug gap to change. ( If I read the post correctly)....:Mark

[marko39]

if valve and guide wont come out as an assembly, pry up spring and remove retainer and then spring. lift valve and tap out guides with a thin punch. take care not to bend spring too much unless you have a spare.

[Admiral]

Sorry to hear what happened! I wonder what the culprit could be, as everything is pretty spotless in there. Carbon buildup wouldn't be my guess.

[JSeery]

If it was me, I would be looking for a set of 8 new pistons.

[Mart]

Would I be completely off base by thinking, if it were me, If I could find a piston, I'd reuse the existing rings? In my mind, the rings are bedded to that bore equally as well as the other 7 piston/ring/bore sets.

It does beg the question, though, why did that one let go? If due to lean mixture, there should be 3 other pistons that might have been getting fuel and air from the same side of the carb. (Assuming single carb). If it is a defective piston, what is to say the others are not on the verge of letting go?

If you can find one piston, all well and good, cross your fingers and carry on. If not it might be worth going with a new set of pistons and rings and a freshen up of the bores with a hone to seat the new rings, or go .100 over on all 8 with a new overbore.

Personally I'm a chancer and would just change the 1 if a replacement could be found, but that might be the clincher. You might not be able to find just 1 and be able to weight match it to the rest.

Good luck with it, though.

Re the valves, you should be able to pull the guide(s) down with the correct tool and withdraw the whole assembly in one go. Remember on the inlets it is often easier to push the guide down with a suitable lever.

You push the guides down just a bit to get the horseshoe clips out.

Mart.

[alanwoodieman]

if the gaps on the plugs are closing then- too long on the reach of the spark plugs--exam the sparkplug thread area- have they been counterboared? we have used double seal rings on several spark plugs used with aluminum heads to correct this reach

[40 Deluxe]

Could be #4 went lean. check the intake gasket. If it's an aluminum intake, check the exhaust crossover passage for burn through. I'm not sure which cylinder(s) this would affect, but worth checking. A closed-up plug gap wouldn't cause this. A weak or no spark would make that cylinder run cooler, and this is an excessive heat problem.
Also, could two plug wires have been crossed? This could cause extremely advanced timing in #4, resulting in detonation.

[JSeery]

Very hard to tell much from photos, but that piston and cylinder head doesn't look like it has been that hot. That coupled with the overall look of the pistons (they look like low quality, but again based on a photo!), I would suspect piston failure. It could have been a detonation issue, but the piston seems thin in the failed area. The amount of work involved finding a piston and getting it to match weight wise, etc, it would be simpler to just replace the lot. But then, that is what I would do.

[Phil Gillespie]

Yes Alanwoodieman that was the case with these Edelbrock heads the 2 plugs in 1 & 4 wennt too far into the head. These were new heads with this finish! Made offshore and not as would expect. That was why i fitted extra washer at those 2 cylinders to reduce distance into combustion space.

[Seth Swoboda]

His pistons look like mine. Mine are Egge. I would assume Egge has a good quality piston.

[Phil Gillespie]

Appreciate as always all advice as offered. Will get the piston out and have a better look. Then it may be a new set.
Initially thinking of trying for a replacement piston, will probably remove another onne for a correct weight measurement etc and see how it goes. Perhaps even have the piston checked further.
Phil NZ

[Phil Gillespie]

Yes Seth you are correct they are Egge pistons which I purchased from Chassis Engineering as i had a bit of trouble to get these 80 thou over pistons.
Maybe will contact Egge and see what they think?
Phil NZ

[JSeery]

Originally Posted by Seth Swoboda

His pistons look like mine. Mine are Egge. I would assume Egge has a good quality piston.

They do not look the same to me (maybe similar), but I'm sure not a piston ID expert. The OP pistons appear to have an additional machined area around the outer edge of the piston. And the failed piston seems very thin in the failed area. Anyway, I'm not attempting to tell anyone what to do or determine a piston failure based on photos, just saying I would replace all of them while I was at it.

Updated, they are Egge pistons! Maybe just that piston was weak in the failed area? I've never used Egge pistons, but I know a lot of people do.

[Seth Swoboda]

Originally Posted by JSeery

They do not look the same to me (maybe similar), but I'm sure not a piston ID expert. The OP pistons appear to have an additional machined area around the outer edge of the piston. And the failed piston seems very thin in the failed area. Anyway, I'm not attempting to tell anyone what to do or determine a piston failure based on photos, just saying I would replace all of them while I was at it.

Updated, they are Egge pistons! Maybe just that piston was weak in the failed area? I've never used Egge pistons, but I know a lot of people do.

I agree I would replace them all and have them balanced if it were mine. Pistons ain't cheap.

[19Fordy]

Wonder what quality aluminum Egge uses?

Here's the answer and how they are made.
https://www.youtube.com/watch?v=owgcK0TswBM

[Seth Swoboda]

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I'd say he had an engine condition that caused the hole other than a bad piston. Anything is possible though. I do believe he said the spark plug electrode was too long. I wonder what plug he was using? He also has aftermarket aluminum heads.

[flatheadmurre]

If they are Egge gettting 2 replacements isn´t a problem just call them.
Get a good one out and have it weighed then order 2 spares.
If it was me i would take a look at the rest first to make sure they are ok

[flatford8]

The length of the plug reach has been mentioned a few times. If that was so,wouldn’t that BREAK a hole in the piston? To me, it looks like the hole in his has been MELTED. If I’m missing something that everyone sees as obvious, I’ll take getting yelled at by anybody who wants to......Mark

[Cecil/WV]

As already stated, if there is no definite cause for this piston failure, I would replace the whole set. Another piston may give up as soon as you start it up the next time.

[Ggmac]

I'm wondering if part of the plug dropped in , a piece of porcelain ? I guess it'd be in the pan when removed .

[40 Deluxe]

Originally Posted by flatford8

The length of the plug reach has been mentioned a few times. If that was so,wouldn’t that BREAK a hole in the piston? To me, it looks like the hole in his has been MELTED. If I’m missing something that everyone sees as obvious, I’ll take getting yelled at by anybody who wants to......Mark

You are absolutely right Mark! Any time a foreign object or broken plug piece gets in the cylinder it beats the snot out of the combustion chamber and piston top before it exits! As you say, this hole was melted.
If the piston top was too thin from the get-go, it would have shown up when it was weighed at Egge (or the balance shop). It would have been noticeably lighter than the rest of the set and would stick out like a sore thumb!

[JSeery]

Originally Posted by flatford8

The length of the plug reach has been mentioned a few times. If that was so,wouldn’t that BREAK a hole in the piston? Mark

Depends on what you are referring to. The plugs are over the valves, not the pistons. A broken piece of a plug could cause damage, but there is no indication of a foreign object hitting the piston or the head.

[flatheadmurre]

Hard to tell from the pictures if the cause for the hole is detonation...
Usually you hear something if it´s bad enough to melt pistons.

[Seth Swoboda]

I'd be interesting to see the rest of the piston once it is removed.

[Ol' Ron]

I have bored several of these to 3 5/16, with no problem. I think they have the same casting as the standard 59 block.

[Phil Gillespie]

Appreciate as always all assistance given.
The heads when fitted were fitted with the longer reach plugs as recommended by Edelbrock. The two plugs which were sitting too far into the combustion space were closed up only to around 2 thou by the interference of the valves. Nothing was broken off these plugs and nil sign of anything loose hammering in head area.
If the gap is closed up to this extent combustion would not be so good?
This was corrected with the extra seal washer and plugs have maintainned their set gap of 26 thou since fitting.
Once I get this piston out I will go from there.After a good check out. May take it to have it checked out.
Thinking at this stage for 2 spare pistons and rings. As suggested by Mart,
Fit existing rings to new piston and refit after checking both valves.


The removal of sump with engine still in place I understand may require front of engine to be slightly lifted and crank turned to ensure pistons 1 & 5 are towards to top of cylinder?
At least here in NZ weather is still warm now tail end of summer.
Phil NZ

[Pete F]

Is that piston as thin as it looks in the picture.
Can you take a closer picture because maybe the casting was off and the top of the piston was thin so it melted.
I would change them all .


Sent from my iPhone using Tapatalk

[Marv]

Originally Posted by JSeery

If it was me, I would be looking for a set of 8 new pistons.

I second that, and a different brand.

[Kurt in NJ]

Using a washer changes the heat range of the plugs, overheated plugs can cause such problems as holes burned in pistons

[Phil Gillespie]

Today got the No4 piston out along with No3for comparrison and weight check.
The line on top at hole is another area cracked ready to let go. The underside is almost suggesting it lrt go from here?
The thickness in the failed area is 7 to 8 mm.
Intact piston weight 400 grams. Damaged is 395 grams. The damaged area as it sits in the bore is on the side where spark plug is fitted. But nil sign of any contact. again the bore is in good order and unmarked as is cylinder head.


Phil NZ

[Phil Gillespie]

Drop
Droping the sump off was fun!! The first error forgetting the set bolt at top area by starter motor. Then had to drop the wishbone down to clear but with patience did get it.
The tops of pistons 1,2,& 3 look good. Will probably take the other head off and check.
Just checked and have only arond 9000mls on this since rebuild.
Need also to check clearances above piston and aim for the magic 5o thou.
Phil NZ

[Lawrie]

Phill , we mistakenly ran our dragster engine with only .013 on one side,it went the fastest up till then but there was a head in print on 4 pistons.
Lawrie

[flatheadmurre]

Check the piston at the crack...a mechanical crack is sharper...if it´s heat involved you can usually see that the dome has collapsed inwards and edges is rounder...this is tiny differences. A surface on the piston top that looks like it´s been blasted with something is a sign to.

[Mart]

Phil:

Have you found the broken piece or pieces?

That slightly brighter ring around the centre drilling on the good piston. Is that the result of you cleaning it up, or was it always bright like that?

I'm trying to rule in or out contact with the head. Hence my previous suggestion to do a clearance check. The circular mark in the middle of the head dome - is that slightly raised? Any sign of it kissing the piston?

Mart.

Oh yeah, forgot to ask: You any good at Ally welding?

[DocJohn]

There looks like a crack at the bottom of the register groove as well. Is that so, or is it just a dirty mark? This failure looks a lot like cracks driven by a big thermal cycle. Something getting the piston crown very hot and then being quenched repeatedly.

[Kurt in NJ]

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It's not to easy to see in the picture, but it looks like on the undamaged piston that the skirt wear is uneven --on one side at the bottom, then at angle to other side at top---when a piston skirt shows angled wear it is a sign that the rod may not be straight causing the piston to be crooked in the bore ---of course it could be a shadow in the picture too

[Phil Gillespie]

Have had contact with Egge whoc say it looks like one of their E120 pistons but has been modified? Still await a reply from Reds Headers who i purchased the pistons and rings from Their invoice only gives their part No for the pistons with no name?
Whereas the rings are Grant as on invoice?


Egge confirm heat is the problem and also confirmed with scuffing at top .
So it will be a process to work through. But problably to go with a new set of pistons and rings.


The ring set on these are a 4 ring set. Being top 2 compression rings, 3rd oil control ring and lower ring an oil scraper ring. The top ring on these sets has a chamfer on one internal edge. Does this go to top or bottom in piston ring groove/


Also the new 3 ring sets what is the function of these 3 rings. Is there no oil scraper ring with these?


My 4 ring pistons were brought in 2012.
Thanks Phil NZ

[KiWinUS]

The standard for this Phil is if the chamfer is in it goes up , if it is out it goes down.
Good luck!
Cheers
Tony

[flatheadmurre]

Originally Posted by Phil Gillespie

Have had contact with Egge whoc say it looks like one of their E120 pistons but has been modified? Still await a reply from Reds Headers who i purchased the pistons and rings from Their invoice only gives their part No for the pistons with no name?
Whereas the rings are Grant as on invoice?


Egge confirm heat is the problem and also confirmed with scuffing at top .
So it will be a process to work through. But problably to go with a new set of pistons and rings.


The ring set on these are a 4 ring set. Being top 2 compression rings, 3rd oil control ring and lower ring an oil scraper ring. The top ring on these sets has a chamfer on one internal edge. Does this go to top or bottom in piston ring groove/


Also the new 3 ring sets what is the function of these 3 rings. Is there no oil scraper ring with these?


My 4 ring pistons were brought in 2012.
Thanks Phil NZ

With modern pistons and rings you don´t have the oil control issues that was the reason for the forth ring.
So a modern piston with a 3 ring setup only needs one oil ring to work fine.

[B-O-B]

Which is it CE or reds?
They are Egge pistons which I purchased from Chassis Engineering.
Reds Headers who i purchased the pistons and rings from.

Looks to my untrained eye that something punched a hole from the top of the piston. What does the matching area of the head look like?

[JSeery]

BOB, he posted a photo of the head in his first post.

[Phil Gillespie]

Pistons are confirmed as Egge Pistons and Grant rings as purchased from Reds Headers.They have confirmed this with me. The hole as from Egge tech is heat related.
Need to remove all pistons for check. One I have with me now is ex No3 and there is signs of a circle on the top of this piston as observed by one of the guys here.
The key could be the piston to head clearance from rebuild 2012.
To my knowledge piston to head clearances were not taken or recorded.
So need to kinda start again with the pistons, rods and bottom end bearings.
This engine previously had had deck machined and was fitted with a regular head one side and a truck head the other side. perhaps to conpensate for deck machining.


I again thank all input and advice and suggestions.
Phil NZ

[Mart]

Phil, I had a french motor with Offenhauser heads. The French pistons have a different shape dome than normal Ford pistons, the dome is slightly "pointy" for want of a better term. I fired it up and it ran fine but I became aware of a noise as the revs came up. It turned out the central part of the dome was "kissing" the heads. I have heard that the Egge pistons can be a little "pointy" but have not been able to judge that from your pics.

Of course decking the block would make this more likely to happen.

I looked again at your first set of pics and can see a circular mark in the middle of the dome of the head. I can see bright metal around the centre drilling of the piston.

I cannot conclude anything from this far away just by pics. I need to be there with the parts in my hand.

If you can do a foil ball and grease clearance check on the remaining pistons on that side and maybe some on the other side it may tell us something.

Do some digging and let us know what you find.

Mart.

[Phil Gillespie]

Mart, intend now to remove all pistons and take them in to be checked along with conrods. Depending upon out come will be a part replacement or full replacement of pistons, bottom end bearings etc as required. Egge are able to supply 2 pistons if required. But a foil check is a good idea before removal.
Eventually will remove engine for assembly etc. And depends on nunber of pistons to be replaced. Will only hone cylinders to be fitted with new rings etc.
Now have an excuse to purchase an engine hoist.
Phil NZ.

[Phil Gillespie]

So today before removing pistons 1&2 I checked the head to piston clearance.
Used head joint from that side it measured up at 50 thou. Put foil balls in both and one at the centre of the piston . Pulled head down not torqued but firm.
No1 came in around 68 thou. And No2 at 76 thou. The centre point on both came in at 85 thou, so profile of dome of these pistons seems compatible with the Edelbrock heads.
Checked spark plug fitted and from back of electrode to head was: 1: .172. 2: .240 3: .245. 4: 205. Thats with the extra seal washers at Nos 1 &4 spark plugs.
Have pulled pistons from other bank and look ok as does the head. Slight scoffing on pistons on fore & aft positions. All cylinders look good as do bottom emd brgs.
Now will have all pistons, brgs and rods checked by local Engine Rebuilders and take it from there. I am confident now to see whats good and replace pistons accordingly.


Appreciate all assistance and advice. Engine still in car but will remove for the reassemlby.
Phil NZ

[Mart]

Thanks for the measurements, Phil, at least that rules out the "pointy dome head kissing" theory.

Mart.

[Phil Gillespie]

Yes good o progress through in an orderly way as it rules that one out. The pull down to around 50 thou is standard for the composite gasket. These aluminium Edelbrock heads are torqued less than normal CI heads?
Phil NZ

[Charlie ny]

The post on #40 showing the underside of the failed piston shows a border area around the hole. This border area could indicate a bad pour during the casting process. omho.
Charlie ny

[Bored&Stroked]

It sure looks like something got into that cylinder and punched the top out of that piston. With that said, usually the REST of the piston crown will show marks from being beat up - before one section lets go.

Those crowns looks pretty thin - might have been an issue in how they were cast and machined - or maybe they're always that way (I've never ran or inspected Egge pistons). Personally - I don't like the looks of them one bit (but hey, the last cast pistons I ran in a flathead were Jahns - and 40 years ago!). I also don't like the uneven scuffing/wear marks on the sides - am wondering why that occured?? There has to be a reason - and it may have to do with how the pistons were made . . . or it could be the cylinders . . . or it could be the rod . . . something is not right in my mind.

If it were mine, I'd replace all 8 pistons and I'd do a slight hone and re-ring the cylinders. It makes no sense to re-use the same rings - just replace them. You've had a situation where a bunch of raw fuel was washing that one cylinder down - which removes oil and also could have caused some of the scuffing on the piston sides.

Lastly, as some have mentioned . . . I've seen pistons where the crowns were machined with multiple radius values - three different ones. The result can be a pointed area in the center. Those newer Edelbrock heads have a consistent radius pattern for the crown (like Ross forged pistons, old ForgedTrue, Jahns, etc) - so you want pistons with a consistent radius crown - makes sure whatever you get is as such. Then, setup your squish height to be around .040 to .050 max - and it should be pretty consistent across the whole top of the piston (if the crown shapes match the chambers). Having a tight squish area is critical for flathead performance - so tune the chambers as such.

I'm not picking on Egge, but the quality of those cast pistons would make me nervous in anything other than a stock engine . . . I'd buy something else.

Okay - enough coffee for me! Good luck!

B&S

[Bored&Stroked]

Here are some pictures that will give you an idea of how a consistent radius dome compares to a multiple radius (pointy) dome.

I made 3D CAD models of both of these variants - such that I can CNC the domes of heads to match pistons. On a recent build, I had to take a brand new set of Edelbrock heads (like the one from this post) and CNC the domes to match the 3-radius piston design that the engines Jahn's 4-ring pistons had - otherwise they would touch in the middle crown area of the Edelbrock heads. Also, I wanted a consistent squish area of .040 above the piston - so a new chamber was needed.

Edelbrock Standard Dome - Matches Ross Pistons:

3DSectionView-RossEdelbrock-Dome.jpg

Multiple Radius Dome - Matches a lot of cast pistons:

3DSectionView-Ford-Egge-Dome.jpg

Sketch - Edelbrock Standard Dome - Ross Pistons (based on a .1875 crown height and 3 5/16 pistons):

Sketch-RossEdelbrock-Dome.jpg

Sketch - Multiple Radius Dome - 3 5/16 cast pistons (4 ring Jahns):

Sketch-Ford-Egge-Dome.jpg

Note: On some of the early 4-ring Jahn's pistons, they used the multiple radius dome . . . on the 3-ring versions that a lot of the racers used, they had a consistent radius dome.

Hope this helps you all visualize the differences.

B&S

[Phil Gillespie]

Originally Posted by Charlie ny

The post on #40 showing the underside of the failed piston shows a border area around the hole. This border area could indicate a bad pour during the casting process. omho.
Charlie ny

Charlie I noted this also the border area around the hole and had similar thoughts.
When i sent a couple of pics to Egge their comments were the piston was like theirs but had been modified??? These were Egge pistons from Reds Headers. Having all pistons and rods and bearings checked.


What alternatives for pistons for a 3 1/16 plus 80 thou. Any recommendations?
Thanks
Phil

[Phil Gillespie]

Originally Posted by Charlie ny

The post on #40 showing the underside of the failed piston shows a border area around the hole. This border area could indicate a bad pour during the casting process. omho.
Charlie ny

Originally Posted by Bored&Stroked

Here are some pictures that will give you an idea of how a consistent radius dome compares to a multiple radius (pointy) dome.

I made 3D CAD models of both of these variants - such that I can CNC the domes of heads to match pistons. On a recent build, I had to take a brand new set of Edelbrock heads (like the one from this post) and CNC the domes to match the 3-radius piston design that the engines Jahn's 4-ring pistons had - otherwise they would touch in the middle crown area of the Edelbrock heads. Also, I wanted a consistent squish area of .040 above the piston - so a new chamber was needed.

Edelbrock Standard Dome - Matches Ross Pistons:

Attachment 354457

Multiple Radius Dome - Matches a lot of cast pistons:

Attachment 354456

Sketch - Edelbrock Standard Dome - Ross Pistons (based on a .1875 crown height and 3 5/16 pistons):

Attachment 354459

Sketch - Multiple Radius Dome - 3 5/16 cast pistons (4 ring Jahns):

Attachment 354458

Note: On some of the early 4-ring Jahn's pistons, they used the multiple radius dome . . . on the 3-ring versions that a lot of the racers used, they had a consistent radius dome.

Hope this helps you all visualize the differences.

B&S

Yes I can visulise the difference for sure as you really want the profile of piston crown and head profile to match to give consistent clearance between surfaces.
Thank yu for your time to put this together.
Phil NZ

[Mart]

Were they prepared to say in which way they were modified??

Mart.

[JSeery]

I have never dealt with Egge, but there would be no reason for Reds to modify Egge pistons (just added cost if nothing else) and that does not look like heat damage to me. There is a second crack partly through the piston to the side of the hole in the top! Might contact Reds and see what they have to say.

[Brian]

I think the 'modification' refers to what appears to be a chamfer machined around the outer top edge of pistons, possibly to clear a head gasket protruding over edge of cylinder?
Compare with Seth's photo...

[Phil Gillespie]

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Originally Posted by Brian

I think the 'modification' refers to what appears to be a chamfer machined around the outer top edge of pistons, possibly to clear a head gasket protruding over edge of cylinder?
Compare with Seth's photo...

Was not aware this had been done, but would not the answer to have gone to the larger bore sized gasket?
Phil NZ

[flatjack9]

I have seen pistons with that exact same top. They were not in the original box so I don't know their history.

[Phil Gillespie]

Just did some measuring for Con Rods:
Con Rod Bore Less Brg: 2.215. Brg OD: 2.222. Brg ID: 1.958. C/Shaft dia: 1.955.
Wrist Pin dia .744. Wrist Pin bush: .748.
From these measurements this would be a 40 thou over sized brg for bottom end?
All pistons are showing scuffing at L to R locations on pistons. Presume my rods are 21A. See pic. no castle nuts with pins, no self locking nuts??

[Phil Gillespie]

Some more pics for above post. Cant see how these pistons have been modified as per Egge comment.
Phil NZ

[40 Deluxe]

Do you have any photos of piston pieces that ended up in the pan?

[flatheadmurre]

Originally Posted by Phil Gillespie

Was not aware this had been done, but would not the answer to have gone to the larger bore sized gasket?
Phil NZ

When dealing with 21 stud engines there´s no big bore stuff available so that is perhaps why they modified the pistons.

[Lawrie]

That looks like detonation to me,
Lawrie

[Phil Gillespie]

Originally Posted by flatheadmurre

When dealing with 21 stud engines there´s no big bore stuff available so that is perhaps why they modified the pistons.

This is a 24 stud engine and checked out when removed heads and plenty of clearance from observation.
Phil NZ

[Phil Gillespie]

Originally Posted by Lawrie

That looks like detonation to me,
Lawrie

This will occur in just one cylinder like this? A single stromberg 97 with 45 jets and 65 pv should not be leaning out surely. Plus am using 95 octane.
Distributor recently rebuilt and set up as per machine.
Phil NZ

[JSeery]

Originally Posted by Phil Gillespie

This will occur in just one cylinder like this? A single stromberg 97 with 45 jets and 65 pv should not be leaning out surely. Plus am using 95 octane.
Distributor recently rebuilt and set up as per machine.
Phil NZ

Well, if anyone would be familiar with detonation in a flathead, my guess is it would be Lawrie! This should be a more common occurrence in a high performance engine.

Could a couple of mixed up plug wires be the cause, firing that cylinder early?

[Charlie ny]

Casting flaw, casting flaw, casting flaw........I'll bet insiders at EGGE know it too !
Charlie ny

[B-O-B]

Had the heads on my f-500 6 cylinder milled & torqued back on. I was pulling a grade with a load of gravel when there was a puff of white smoke. Yep it burned a hole right thru the top of one of the pistons. The exhaust was pretty loud & I didn't hear it pinging for help. Piston kinda looked like yours with a hole in the top.

[DocJohn]

Whilst the crack in the piston might have started at a small casting flaw, that's not the root cause of the failure. Those cracks are driven by a stress perpendicular to the plane of the crack - so a radial stress in the piston crown in this case. The most likely cause is a severe hot/cold cycle so that the centre of the crown gets very hot then is trying to cool faster than the outer rim and is restrained, setting up a radial tensile stress. The region around the hole has clearly been very hot, looking at the surfce condition.

Cause of the hot/cold cycle? Air leak into the No 4 port somewhere - runs lean and hot especially under load, and repeated quenched by the incoming cool mixture off load?

Of course, it's not helped by a thin crown or internal casting defects, but all the pistons will have those so the question comes down to the origins of the excess stress cycle.

[Phil Gillespie]

Originally Posted by B-O-B

Had the heads on my f-500 6 cylinder milled & torqued back on. I was pulling a grade with a load of gravel when there was a puff of white smoke. Yep it burned a hole right thru the top of one of the pistons. The exhaust was pretty loud & I didn't hear it pinging for help. Piston kinda looked like yours with a hole in the top.

Yes kinda like it happened with me the puff of smoke.
Do you find a cause or just a replacement piston?
Phil NZ

[Phil Gillespie]

Originally Posted by DocJohn

Whilst the crack in the piston might have started at a small casting flaw, that's not the root cause of the failure. Those cracks are driven by a stress perpendicular to the plane of the crack - so a radial stress in the piston crown in this case. The most likely cause is a severe hot/cold cycle so that the centre of the crown gets very hot then is trying to cool faster than the outer rim and is restrained, setting up a radial tensile stress. The region around the hole has clearly been very hot, looking at the surfce condition.

Cause of the hot/cold cycle? Air leak into the No 4 port somewhere - runs lean and hot especially under load, and repeated quenched by the incoming cool mixture off load?

Of course, it's not helped by a thin crown or internal casting defects, but all the pistons will have those so the question comes down to the origins of the excess stress cycle.

Thanks for your insight. The cause of the hot/cold cycle? Could this be a fault perhaps in inlet manifold. Although in saying that it had a good steady idle vaccum of 20 inches.
Phil NZ

[GOSFAST]

Personally based on the photos it does appear to be "old-fashioned" detonation!

Having that small "indentation" in the center makes that area of the piston a sort of "weak" point?

Most lower level pistons have that "dadum" point to help with the final machining on them. Actually most "cast" pieces usually contain them also! You won't find them on a forged Ross type piston.

Thanks, Gary in N.Y.

P.S. Also by looking closely at the "top" rod brg on the piston with the hole may give a better indication of what happened! On detonated pistons you'll normally find the "upper" inserts down to the "copper" more so than the others that haven't experienced it.

[DocJohn]

Yes, that's the mystery! I'm presuming that you couldn't measure the vacuum on individual cylinders so the 20 inches is the overall vacuum below the carb. Something very close to the port perhaps? Gasket problem? Damage to the manifold face? Has anyone drilled a vacuum port? What did the plugs look like? Did No 4 look as though it had been hotter than the others?
Sorry, this doesn't really help!
John UK

[Kurt in NJ]

Fix your spark plug spacing problem, the xtra washer changes the heat range, the plug could overheat and cause the mixture to fire without spark, and at wrong time

[Phil Gillespie]

Originally Posted by GOSFAST

Personally based on the photos it does appear to be "old-fashioned" detonation!

Having that small "indentation" in the center makes that area of the piston a sort of "weak" point?

Most lower level pistons have that "dadum" point to help with the final machining on them. Actually most "cast" pieces usually contain them also! You won't find them on a forged Ross type piston.

Thanks, Gary in N.Y.

P.S. Also by looking closely at the "top" rod brg on the piston with the hole may give a better indication of what happened! On detonated pistons you'll normally find the "upper" inserts down to the "copper" more so than the others that haven't experienced it.

Thanks also for your assistance gary. will check the top rod brg.
Can you recommend a piston for me as all pistons as removed have scuffing L to R sides of piston in varying degrees.
221cu in 3 1/16 bore 80 thou over.
Phil NZ

[Phil Gillespie]

Originally Posted by Lawrie

That looks like detonation to me,
Lawrie

Lawrie you were correct detonation it was comfirmed by MS Coombes a very long standing engine rebuilders and machinests in Christchurch.
However the cause was not as you may suspect running too lean.


From their observations the following contributed:
The Edelbrock heads(1125 64cc,) the use of dome top pistons and the distributor with too much advance. It would seem these 3 items were the contributors and of late fitting an 11A distributor gave it a little more advance again.
Also noted the scuffing caused by too rich and washing off oil.
So again on a positive note will be taking in block to have bores checked and measured amd proceed from there.
Then once correct bore size is reached after measure & hone can get pistons etc.
Again I thank you all for comments and observations.
Phil NZ

[JSeery]

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Good feedback Phil!

[Lawrie]

Good feed back
Lawrie

[Bored&Stroked]

I agree on detonation - those last pictures you posted (very clear) show signs of heat and detonation on the area around the hole. Given how thin the crowns of the pistons are, it probably didn't take much detonation and probably not for long. I'm not necessarily going to jump on the too rich conclusion as of yet - especially in that cylinder as once there was a hole, there was raw gas washing the cylinder and rings from that point forward.

Questions:
1) Do the other pistons have the same amount of scuffing?

2) Do you know your total advance?

3) Any signs of detonation on the other cylinders?

[Phil Gillespie]

Originally Posted by Bored&Stroked

I agree on detonation - those last pictures you posted (very clear) show signs of heat and detonation on the area around the hole. Given how thin the crowns of the pistons are, it probably didn't take much detonation and probably not for long. I'm not necessarily going to jump on the too rich conclusion as of yet - especially in that cylinder as once there was a hole, there was raw gas washing the cylinder and rings from that point forward.

Questions:
1) Do the other pistons have the same amount of scuffing?

2) Do you know your total advance?

3) Any signs of detonation on the other cylinders?

All pistons had similar amount of scuffing. No piston without scuffing.


Running an 11A divers helmet distributor with Initial timing of 4 degree
and full Mech Advance of 12 degree. Total being 28 degrees.


No signs of detonation at other pistons but the guy at the engine builders said that there would be small radial cracks going out from the centre "hole" at centre of piston crown.


The rich mixture was shown to be at the edge of the rings a sharp edge, and on top top able to detect a ridge with thumb at outter edge. He also commented that ring wear was greater than normal with ring in groove.
I am postive now to move forward with this and with care and attention a good runner back in the 39 Coupe.
Bottom end brgs all look good as do the top wrist pin brgs.
Of note the con rods in use have the tangs at one side for the shell brgs.
But will stick with the existing brg set up. These are 40 thiu oversize, or undersize depends how you want it.
Thanks again to all.
Phil NZ

[Talkwrench]

Ok someone may have to school me on this one .. Normally for detonation issues its a lean condition with a lots of advance [to blow a hole in a piston].. for your situation was the car running ok ..? Im thinking for it to do whats its done didn't you feel something wasn't right.. ? And as far as being rich... for any issues surely the plugs would show much much darker for any issues of 'wash'..?
Just thinkin'...

[cas3]

i had a chain saw once that would "pop" every now and then, and then go rite back to work. i found out later each pop was a piece of the piston blowing off due to lean mix. top of piston had specs missing all over, and one hole. good story phil, hope you get it all good

[john in illinois]

too hot a plug can contribute to detonation. Do any of the plugs have melted edges on center electrode under magnification? As Kurt said spacer rings could add heat.

John

[flatheadmurre]

Check the porcelain on the sparkplugs, if you see any signs of aluminum or black particles fused to the insulator you have detonation issues.

[48fordnut]

This has been a good tutorial from a lot of good guys. Just read the whole blog. Received a set of pistons from speedway today. I think the add said Offenhauser. 3 5/16x4 for a 49 mercury block. Any comments?
thanks,
jim

[Fordors]

I can tell you that they were not manufactured by Offenhauser. Speedway paid Offenhauser for rights to use the name on some of the products they market.

[quickchange34]

After looking at that pistonI would have to say it was a casting flaw . I have seen it before with egge pistons . I would not put them in a lawn mower.

[flatjack9]

I may be jinxing myself, but I have used Egge pistons in many builds without a problem.

[Phil Gillespie]

All plugs looked ok. Definately no sign of heat etc. Once all sorted will go with the plugs where tip does not protrude out so far, thread length is same. Cant remember the name. hope to drop block off early next week for the measure up, final hone and sizing for pistons. These Edelbrock heads with their 64cc do alter the combustion a little and other items as advance etc have now to be match up for that ideal combustion process.
All compressions taken after the mishap were good. Valve clearances checked were also good a couple of exhausts at 0.018 a couple above the 0.016 but will probably settle with that as lifters in use are non adjustable.
Phil NZ

[Phil Gillespie]

Originally Posted by flatjack9

I may be jinxing myself, but I have used Egge pistons in many builds without a problem.

At this stage also I will be using the Egge pistons with Grant rings again. Looking at 0.083 O/sized set. The 0.080 once honed will finish up at 0.083 as Egge have pistons at this size.
Phil NZ

[40cpe]

So judging from your post about ignition advance, can I assume you have the engine back running?

[Phil Gillespie]

Originally Posted by 40cpe

So judging from your post about ignition advance, can I assume you have the engine back running?

I wish. Nope that is another engine an 8ba in a 38 PU.


Engine is awaiting measurement and bore honing before pistons are ordered.
Also have opted for a NOS rods as my rods are already 0.008 and require resize. Getting hard to get bearings as cranks are 40 under.
Also will have flywheel clutch assembly balanced.
This engine will get there eventually along with distributor set up, as now have the timing light to check advance through the rev range to avoid this again. I hope!!
Phil NZ

[flatjack9]

Do not hone until you have the pistons.

[Phil Gillespie]

Originally Posted by flatjack9

Do not hone until you have the pistons.

Why not to hone until I have the pistons? There must be a logical reason for this.
Phil NZ

[flatjack9]

You want to actually measure the pistons before honing. No good machinist would hone without having the pistons in hand.

[Phil Gillespie]

Originally Posted by flatjack9

You want to actually measure the pistons before honing. No good machinist would hone without having the pistons in hand.

Ok of course you are correct with that. Knew there was a logical reason.
Pistons are plus 80 but there are also some plus 83. Measure up prior to honing then get pistons check them and final hone.
Phil NZ

[Phil Gillespie]

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Update:
Sometimes things continue to go backwards. Centre main bearing cap cracked in 3 places. At least it was still intact at dismantle.Plan to check out several caps and select one with least off set. Who knows could get lucky. Then progress from there.Probable line bore. Noted for this block, 81A could not locate a part number for this bearing cap in the Green Bible, did not see this year listed!!
Phil NZ

[tubman]

My oft-told old story : Back in the day, I broke a center main cap in my '51. Went to the junkyard and brought home a bucket full of caps I had removed from various similar engines and some "Plasti-gage". Long story short, the first one I tried fit perfectly. I put it back together using the same bearing insert and it ran great, had good oil pressure, and was still running when I sold the car three years later. The moral of this story is that Ford machining tolerances back in the day must have been very, very good.

[flatheadmurre]

Usually i come real close after picking through a bunch of main caps...and it doesn´t matter if the centre main cap come from a later model as long as the bore is same.

[Phil Gillespie]

Encouraging to know that I could get lucky. Heres hoping.
Phil NZ

[flatjack9]

I have done that more than once. If I ever junk a block, I keep all the main caps.