221 cu in 1939 Failed No4 Piston 1

[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