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Old 10-15-2018, 11:58 AM   #1
G_Don
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Default Honing Cylinders

Hey Guys,

I have a B motor which was supposedly rebuilt (no receipts, but looks clean with oil pan removed and head off), which was experiencing blow by out of the oil filler tube and would get hot after only running it for a minute or less.

I removed the head, pulled the pan and removed the first and second pistons. Attached is a picture of the piston #1. Piston #1 has wear in both the front and back of the piston like that where the rings are melted to the piston. Piston 1's rings were not equidistant apart and the ring seams were only about 15 degrees off of each other. Was this a result of the overheating issue or the cause of the overheating/blowby issue? I heard rings being spaced like this allows for gas to escape, but is it the same for oil? Piston 1 was also quite difficult to remove from the cylinder, and I ended up using a wooden dowel to lightly tap it up and out of block.

Piston #2 which isn't shown but is similar has wear on only the front of the piston. The rings are set at more of a distance, probably 120 degrees off. Piston 2 was much easier to remove than piston 1, although I still needed to lightly tap it with a hammer.

The block was supposedly bored 0.080" over from the etching on the pistons. I measured all 4 cylinders using a telescope gage and 3-4" mic. They were consistently 3.954". But 0.080" overbore on 3.875" cylinders should theoretically be 3.955".

The pistons measured 3.931" and have 3 rings on each piston including the oil ring. There is a slight buildup on the cylinders of what I'm assuming is melted aluminum from the pistons.

Im curious as to whether or not the cylinder bore was not honed enough (there was cross-hatching) seeing as it measure 0.001" small, which caused it to overheat, or if it was the rings being set improperly in the first cylinder that cause the engine to overheat. I did measure with a telescope gauge which admittedly isn't the most accurate way to measure the cylinders but did measure them multiple times at degrees.

Would it be ok to go ahead and use a 4" flex hone to remove this aluminum buildup (what I think it is) and buy a new set of pistons and rings, properly set the rings this time and then run the engine?

Thanks in advance!
Gordo
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Old 10-15-2018, 12:54 PM   #2
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Default Re: Honing Cylinders

Quote:
Originally Posted by G_Don View Post
Hey Guys,

I have a B motor which was supposedly rebuilt (no receipts, but looks clean with oil pan removed and head off), which was experiencing blow by out of the oil filler tube and would get hot after only running it for a minute or less.

I removed the head, pulled the pan and removed the first and second pistons. Attached is a picture of the piston #1. Piston #1 has wear in both the front and back of the piston like that where the rings are melted to the piston. Piston 1's rings were not equidistant apart and the ring seams were only about 15 degrees off of each other. Was this a result of the overheating issue or the cause of the overheating/blowby issue? I heard rings being spaced like this allows for gas to escape, but is it the same for oil? Piston 1 was also quite difficult to remove from the cylinder, and I ended up using a wooden dowel to lightly tap it up and out of block.

Piston #2 which isn't shown but is similar has wear on only the front of the piston. The rings are set at more of a distance, probably 120 degrees off. Piston 2 was much easier to remove than piston 1, although I still needed to lightly tap it with a hammer.

The block was supposedly bored 0.080" over from the etching on the pistons. I measured all 4 cylinders using a telescope gage and 3-4" mic. They were consistently 3.954". But 0.080" overbore on 3.875" cylinders should theoretically be 3.955".

The pistons measured 3.931" and have 3 rings on each piston including the oil ring. There is a slight buildup on the cylinders of what I'm assuming is melted aluminum from the pistons.

Im curious as to whether or not the cylinder bore was not honed enough (there was cross-hatching) seeing as it measure 0.001" small, which caused it to overheat, or if it was the rings being set improperly in the first cylinder that cause the engine to overheat. I did measure with a telescope gauge which admittedly isn't the most accurate way to measure the cylinders but did measure them multiple times at degrees.

Would it be ok to go ahead and use a 4" flex hone to remove this aluminum buildup (what I think it is) and buy a new set of pistons and rings, properly set the rings this time and then run the engine?

Thanks in advance!
Gordo
Get a new set of pistons FIRST. Then, have a shop that knows what they are doing, hone the block to fit the pistons to the manufacturers' specification for clearance.
Be sure they clean the block after machining. There will be all of the old piston residue throughout the block.

Rings rotate when running so where the end gaps are at tear down is usually of no consequence.
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Old 10-15-2018, 01:19 PM   #3
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Default Re: Honing Cylinders

I think the piston condition is a symptom, not a cause. Check the exhaust system for blockage.

I'd hone the cylinders in place, protect the crank races from the dust. I think the hone would remove the aluminum rather easily. If not, then maybe machining would be required.

If you're a cheapskate like me, I'd try to salvage the pistons with a ring groove cutter/cleaner, maybe flat file on the sides. But new rings are a must.
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Old 10-15-2018, 01:20 PM   #4
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Default Re: Honing Cylinders

You have .023" clearance ?

Where were you taking the piston measurements ? It should be taken on the thrust surfaces.

Piston makers have their own clearance recommendations.

Generally .001"/ inch of bore is kinda the accepted value, but, like with most things in life is subject to change. [ I like a little more than that]
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Old 10-15-2018, 02:51 PM   #5
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Default Re: Honing Cylinders

Gordo,
The piston you show looks like it started seizing in the cylinder. Many piston manufacturers suggest .002 to .003" clearance and for a solid skirt piston, that is too tight. I usually hone to .0035" for a street engine and .004" for a performance engine that will be worked hard.

If your clearance is down around .002", you will have problems.

I am sure some others will chime in on this subject.
Good Day!

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Old 10-15-2018, 03:43 PM   #6
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Default Re: Honing Cylinders

That piston has been on the verge of seizing in the bore. The first place they grab is exactly as you show in the photo - at the gudgeon ends (wrist pin to you guys). With the rings jammed in the groove like that, they might as well not be there. You will get LOTS of blowby. As has been said, 0.001" per inch of bore is the minimum clearence you should have. The piston manufacturer will give their recommendations. Observe them!
I'd go with the suggestion to buy a new set of pistons and hone the cylinders to suit. There are some who will say they don't like this method but it works. Use the appropriate feeler gauge between the piston and bore at the thrust side of the piston.
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Last edited by Synchro909; 10-16-2018 at 05:18 PM.
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Old 10-15-2018, 03:46 PM   #7
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Default Re: Honing Cylinders

what I am having a time to understand is why the piston seized on the top of the piston, typically, the piston is smaller in diameter (relieved) than the skirts.
The skirt dimension is what stabilizes the piston in the bore to control rock-over at the ends of the stroke.
If the rods are bent, typically the piston will show wear on the top on one side and the bottom of the other. If the crank is out of alignment fore and aft far enough to ride on the pistons, this would also cause wear as shown.
Whatever is causing this, it is pretty major and will likely not be fixed by just honing the bores.
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Old 10-15-2018, 04:59 PM   #8
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Default Re: Honing Cylinders

Quote:
Originally Posted by G_Don View Post
Hey Guys,

I have a B motor which was supposedly rebuilt (no receipts, but looks clean with oil pan removed and head off), which was experiencing blow by out of the oil filler tube and would get hot after only running it for a minute or less.

I removed the head, pulled the pan and removed the first and second pistons. Attached is a picture of the piston #1. Piston #1 has wear in both the front and back of the piston like that where the rings are melted to the piston. Piston 1's rings were not equidistant apart and the ring seams were only about 15 degrees off of each other. Was this a result of the overheating issue or the cause of the overheating/blowby issue? I heard rings being spaced like this allows for gas to escape, but is it the same for oil? Piston 1 was also quite difficult to remove from the cylinder, and I ended up using a wooden dowel to lightly tap it up and out of block.

Piston #2 which isn't shown but is similar has wear on only the front of the piston. The rings are set at more of a distance, probably 120 degrees off. Piston 2 was much easier to remove than piston 1, although I still needed to lightly tap it with a hammer.

The block was supposedly bored 0.080" over from the etching on the pistons. I measured all 4 cylinders using a telescope gage and 3-4" mic. They were consistently 3.954". But 0.080" overbore on 3.875" cylinders should theoretically be 3.955".

The pistons measured 3.931" and have 3 rings on each piston including the oil ring. There is a slight buildup on the cylinders of what I'm assuming is melted aluminum from the pistons.

Im curious as to whether or not the cylinder bore was not honed enough (there was cross-hatching) seeing as it measure 0.001" small, which caused it to overheat, or if it was the rings being set improperly in the first cylinder that cause the engine to overheat.

Thanks in advance!
Gordo
Rest assured that your problems were NOT caused by the location of the ring gaps. As already mentioned, rings rotate in their grooves when the engine is running so the gap locations are always changing and will not affect how the engine runs in any way, shape, or form! This ring gap myth is just a lot of malarkey, blarney, baloney and hot air!
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Old 10-15-2018, 06:23 PM   #9
Tom Wesenberg
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Default Re: Honing Cylinders

The top of the piston runs the hottest, and has the least amount of oil, so I'm not surprised at your piston scuffing.
Did the engine ping?
Did the engine overheat?
I saw a good running engine wipe out the pistons like that in a couple miles of pinging.
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Old 10-16-2018, 10:56 AM   #10
Jim Brierley
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Default Re: Honing Cylinders

As John says, it is unusual for pistons to seize at the top, and as Dave says, you need more piston-to-wall clearance. Start with a new set of pistons, bore or hone cylinders and start fresh. I bore a stock engine to .003" clearance, then hone another .0005", more on performance pistons. You can safely bore to 4" if you want. Back in the day Ford said .002" maximum, that is way too tight with today's pistons.
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Old 10-16-2018, 11:18 AM   #11
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Default Re: Honing Cylinders

Quote:
Originally Posted by Patrick L. View Post
You have .023" clearance ?

Where were you taking the piston measurements ? It should be taken on the thrust surfaces.
I took the measuremnets at the top of the piston right above the top ring. I'm assuming this is not the thrust surface. Where is the thrust surface? I tried googling it, but it was still unclear. I will be sure to re-measure the piston when I get home from work.

Quote:
Originally Posted by Dave in MN View Post
Gordo,
The piston you show looks like it started seizing in the cylinder. Many piston manufacturers suggest .002 to .003" clearance and for a solid skirt piston, that is too tight. I usually hone to .0035" for a street engine and .004" for a performance engine that will be worked hard.
Thanks for the link! Good stuff on there! I heard 0.0035" from a guy I know. He said to get the pistons and then hone them accordingly, and that I could have a little more clearance than what is typically recommended.

Quote:
Originally Posted by Tom Wesenberg View Post
The top of the piston runs the hottest, and has the least amount of oil, so I'm not surprised at your piston scuffing.
Did the engine ping?
Did the engine overheat?
I saw a good running engine wipe out the pistons like that in a couple miles of pinging.
The engine definitely had a higher pitched, irregular noise when I would run it. It had no rhythm in relation to the engine, kind of sporadically Id hear a "ping". The engine overheating and smoking while driving was the initial start of this whole problem.

Quote:
Originally Posted by Jim Brierley View Post
As John says, it is unusual for pistons to seize at the top, and as Dave says, you need more piston-to-wall clearance. Start with a new set of pistons, bore or hone cylinders and start fresh. I bore a stock engine to .003" clearance, then hone another .0005", more on performance pistons. You can safely bore to 4" if you want. Back in the day Ford said .002" maximum, that is way too tight with today's pistons.
Would it be best to purchase a new set of pistons that are 0.080" and hone it or just go to 0.100" and have it bored. I guess it couldn't hurt anything, other than my wallet to get 0.080" pistons and hone the cylinders, and if anything goes wrong, have a professional bore the cylinders to 0.100".

I was consistently getting cylinder measurements under 3.955", roughly 3.953" to 3.954" with the telescope gauge and mic. Would it make sense that the cylinders were too small, and the pistons (with 0.080" etched on top) were 3.955" and wouldn't have enough clearance in the cylinder?

I did hear that boring to 0.100" gets really tricky, i.e. the cylinders' walls are too thin.


Thanks so much for the help guys.
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Old 10-16-2018, 11:48 AM   #12
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Default Re: Honing Cylinders

You asked about Flex hone. There are 2 types the ones that support and drive the stones and wipers with flat springy sheet metal strips. The other one is "dingle ball " hone also known as Brush hone. The first example is basically useless and the second one is good for re-establishing the cross hatch pattern when bore is perfect but the rings are being replaced and the walls are glazed. The machine shop would use a third kind of hone known as a rigid hone. These are way more expensive and are usually machine driven. A rigid hone can remove taper but without increasing diameter. By the look of the pistons I say the walls are shot but there is no picture. Take it all to the machine shop and let them advise you.
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Old 10-16-2018, 12:06 PM   #13
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Default Re: Honing Cylinders

Quote:
Originally Posted by Jim Brierley View Post
As John says, it is unusual for pistons to seize at the top, and as Dave says, you need more piston-to-wall clearance. Start with a new set of pistons, bore or hone cylinders and start fresh. I bore a stock engine to .003" clearance, then hone another .0005", more on performance pistons. You can safely bore to 4" if you want. Back in the day Ford said .002" maximum, that is way too tight with today's pistons.
I agree with Jim regarding it is okay to bore to 4".
I intentionally bored my Phaeton to 4" (.125" oversize) when I installed inserts in it and 98,000 miles later, it is still running strong. Update: Normal use will not require a high capacity radiator as Jim points out below.

Good Day!

Last edited by Dave in MN; 10-17-2018 at 01:53 PM.
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Old 10-16-2018, 04:08 PM   #14
Patrick L.
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Default Re: Honing Cylinders

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Originally Posted by G_Don View Post
I took the measuremnets at the top of the piston right above the top ring. I'm assuming this is not the thrust surface. Where is the thrust surface? I tried googling it, but it was still unclear. I will be sure to re-measure the piston when I get home from work.



Thanks for the link! Good stuff on there! I heard 0.0035" from a guy I know. He said to get the pistons and then hone them accordingly, and that I could have a little more clearance than what is typically recommended.



The engine definitely had a higher pitched, irregular noise when I would run it. It had no rhythm in relation to the engine, kind of sporadically Id hear a "ping". The engine overheating and smoking while driving was the initial start of this whole problem.



Would it be best to purchase a new set of pistons that are 0.080" and hone it or just go to 0.100" and have it bored. I guess it couldn't hurt anything, other than my wallet to get 0.080" pistons and hone the cylinders, and if anything goes wrong, have a professional bore the cylinders to 0.100".

I was consistently getting cylinder measurements under 3.955", roughly 3.953" to 3.954" with the telescope gauge and mic. Would it make sense that the cylinders were too small, and the pistons (with 0.080" etched on top) were 3.955" and wouldn't have enough clearance in the cylinder?

I did hear that boring to 0.100" gets really tricky, i.e. the cylinders' walls are too thin.


Thanks so much for the help guys.




The thrust surface is the 'fattest' part of the piston which is the area 90 to the wrist pin. If you can find who made those pistons, give them a call to see what they like for clearance. I like to add a bit to that. I'd rather run them a bit loose rather than too tight. Take several readings to see if the pistons are tapered and the correct size.

Last edited by Patrick L.; 10-17-2018 at 05:33 AM.
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Old 10-17-2018, 10:34 AM   #15
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Default Re: Honing Cylinders

The rigid hones are best, they remove any high spots in the cylinder. You may be able to rent one? Hone first to see if bores are good. Boring to 4" does not require any trick stuff, there is enough metal in the block to do this. In the old days racers bored to 4.060" but had to shift the center-lines in order to have the gasket seal well. 4" does not require a heavy duty radiator.
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Old 10-17-2018, 04:12 PM   #16
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Default Re: Honing Cylinders

I repeat, check for exhaust blockage. Instant overheat, blow-by on a recent engine - yeah.

Check block/head/manifold mating surfaces for warpage. i'd expect some.
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Old 10-18-2018, 03:45 PM   #17
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Default Re: Honing Cylinders

So I was able to borrow a mic from work again today and measured the pistons on the correct thrust surface. I got 3.9515" to 3.952".

Seeing as my measurements for the cylinders were 3.954" to 3.955" that'd give me roughly 0.003" clearance. I feel like this should be ample clearance to not cause any problems.

Ive attached some pictures of the cylinders below. The first two pictures are of cylinder 1. The third picture is of cylinder 3. I believe that crud to be melted aluminum, as you can still very easily see the cross-hatch in each of the cylinders.

I'm wondering if as BadPuppy said, it was caused by an overheating issue? I was pushing the engine decently hard when it started smoking, because of a Big Dodge truck on my ass, so maybe that caused the issue?

I noticed my radiator only holds 2.5 gallons of water. I read on the mafca website that the 2.5 gallon radiators are sears repops from the 60s which were notorious for causing overheating issues. Is that correct? Is there any distinguishing marks on the sears radiators that would tell me for sure if it is one of these notorious radiators?

At this point I'm thinking Im going to purchase a 3 stone hone, order new pistons and rings ; when I get the pistons, measure them all and hone the cylinders to 0.004" over what each individual piston is, order the radiator from snyders, check the exhaust for blockage, and then try it out.

Is there a recommended piston to order? Are the ones from snyders that are $95 a set a good option?

I am curious as to what the best way to cover the crank is while honing the cylinders? Do I just have to cover the bearing surfaces of the crank?

Thanks so much for all the help.
Attached Images
File Type: jpg cylinder1.jpg (37.0 KB, 84 views)
File Type: jpg cylinder2.jpg (34.1 KB, 83 views)
File Type: jpg cylinder3.jpg (27.2 KB, 78 views)
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Old 10-18-2018, 04:46 PM   #18
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Default Re: Honing Cylinders

Quote:
Originally Posted by G_Don View Post

I am curious as to what the best way to cover the crank is while honing the cylinders? Do I just have to cover the bearing surfaces of the crank?

Thanks so much for all the help.

Do as you like, but IMHO you will do more damage than good trying to hone that in the car with a flex hone. The issue you have is the stones will jump over the galled area (because that aluminum has been hot and is harder now) however the stones will likely remove material on either side. Eventually what you will have is an egg-shaped cylinder. You really need to use a rigid hone in this scenario.


Also, just an FYI, most quality piston manufacturers size their piston to the nominal size, and then grind their piston undersize to account for thermal expansion for the alloy they are manufacturing the piston from. As you mentioned earlier, by you now telling me/us the bores are 3.954+, that tells me that you are tight because the nominal size for an 0.080" piston is going to be a minimum of 3.955. In this situation, I would use a bore dial indicator that is set at zero with the same micrometer that you are measuring the pistons with. That way you will know exactly what the differential is. Also with a dial bore gauge, you can measure in intervals at 90 from each other and at different heights in the bore. Very probably that someone used a flex hone on it during the rebuild and the walls could be tapered or egg-shaped.




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Old 10-19-2018, 01:49 AM   #19
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Default Re: Honing Cylinders

I'd start by using a sharp knife to see if you can peel away that aluminum from the walls, then rigid hone it to size. Be sure to turn the crank throw down for each cylinder, so you don't catch the hone on it. Cover the crank with a rag, then when you are done, use a syphon sprayer to clean it to be sure all grit is out. I also use the syphon sprayer while honing to keep the walls wet.
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Old 10-19-2018, 07:37 AM   #20
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Default Re: Honing Cylinders

Tom has it right, cut the aluminum with a sharp knife before honing. In my opinion I think you had a timing problem.
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