EGGE pistons hitting EAB heads??

[flatheadernie]

I think the 8cm with thick gasket would be best bet. my first flathead build I domed out to .030 clearence ( ok I was young ! ) and # 7 ticked for first 2 min, cold cranking com 200lbs. thing was a torque monster in its day (54) ran 1/4 in second using 3.54s pulling all the way. ernie n tx

[Jack 34pu]

Thanks for the replys so far.

UPDATE 3 - remeasured everything.

1. The drivers side bank has the tightest fit which indicates it may have been milled before.

2. Using the copper gasket on EAB head, I figure the closest tolerances would be on driver bank:
.035" on piston #5
.042" on piston #6
.038" on piston #7
.036" on piston #8

3. Passinger bank ranges .047 to .055 which I could live with.

OK, how about the experts?? What say?

[Russ/40]

Where on the piston is your tightest tolerances on the drivers side? If it's the dome peak, like I said before, knock .010" off the tops and forget about it.

[Straightpipes]

I used EGGE pistons on a Merc crank with EAB heads. The heads had never been milled. Not enough clearance. I cut the tops of the pistons from the center top (.030 ) to the edge at zero. This matched the radius of the head combustion chamber. With stock gasket I still only had .040 over the piston. I cut the combustion chamber deep enough to get the .050 that I wanted. EGGE 4" pistons have a different radius on the dome.

[Jack 34pu]

I put hard grease on top of all pistons and got an even coat on the heads so they seem to be semetrical. No high spots as far as I can see. I started another string asking for info on thicker head gaskets which may aleive the problem. Copper looks like the way to go for a thicker gasket although I've never used copper.

[Vergil]

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Here is a cut-a-way of an 8ba block and 8ba cylinder head, notice the flat area around the combustion chamber of the cylinder, probably the head has been milled but it is a good place to have piston to head contact also. Does your combustion chamber dish diameter measure the same as the bore?




Vergil

[Flat Ernie]

Originally Posted by Vergil

Here is a cut-a-way of an 8ba block and 8ba cylinder head, notice the flat area around the combustion chamber of the cylinder, probably the head has been milled but it is a good place to have piston to head contact also. Does your combustion chamber dish diameter measure the same as the bore?




Vergil

Stock EAB heads have a similar flat area.

Mart had a similar issue not long ago. But his was due to French pistons, I think (can't recall correctly) - in the end, he went primitive on it & used a grinder, got his clearances, and the engine runs fine.

[37don]

Jack, I;m no expert but I have around 17000 0n my 276 and have .035" head clerance. When Ol Ron built the engine he used copper gaskets and set the head clearance at .050". I changed the gaskets and used kevlar composite gaskets which were thinner than the copper. I talked it over with Ron and we aggreed to give it a try but in Rons words " Don't go over 4000 rpm." I blow out the bugs now and then with no problems. The only thing that will give you greaf is if you go against Rons advise and stretch the rods. I run several hours at a time on the freeways and don't give it a thought.

Don

[Jack 34pu]

Don,

Why did you switch from copper to the composit gaskets? I was thinking of going to thicker copper gaskets to make up the diff to .050". OR just give up on the EAB heads and go with the original 8CM which would still give me a little higher compression because of the higher pistons.

The EAB heads measures 65cc's and the 8CM was 84cc's. I'm guessing that it would be somewhere in the mid 70's cc's.

[Jack 34pu]

To answer Virgil's question, . . . no, the EAB compression dome measures approx 3" (I have 2 sets - so you see that flat spot ring around the edge. The block is bored .080 over.

On the other hand, the 8CM dome nearly matches the bore of the block.

I dont think either set of EAB heads were milled as the 65cc is in the original ballpark.

My block must have been decked earlier or the EGGE pistons don't have the same pin center line to top of piston distance as the originals.

Thanks Virgil

I am learning quite a bit from you fellow Barners and I appreciate your keeping this thread going.

[37don]

Jack, I found dscoloration on the heads when I took them off which was the start of corrosion. After all the used headsd I saw at flea markets with bad corrosion I just decided to go with composite and be done with it. Time will tell but I feel better with the composite.
Don

[barnfind08]

I have EAB gaskets. Aspestos/metal with .068 thickness and copper sandwiched with .075 thickness. Take your choice. Fred

[Russ/40]

Spam alert

[Jack 34pu]

Thanks Fred,

It is the compressed thickness that is important to me. EAB gaskets are probably for smaller bore than mine. The copper may be fine if the compression area measures around 3 1/4" dia. EAB's are probably around 3" dia. which my .080 pistons my hit.

[barnfind08]

The EAB gaskets are 3.280 across, the copper are 3.300 Fred

[barnfind08]

More information. The EAB aspestos EAB gaskets are FOMOCO and the copper gaskets are Fitzgerald or McCord

[GEOFFNZ]

Have had that problem and used bearing blue on pistons to mark high spots on head then die grinder on head to remove repeatedly until just clear with no gasket.The gasket then gave a safe clearance.Most heads I had had been resurfaced more than once.I used 81T heads that gave 70/75 cc when finished.

[Fordestes]

the supplier for the head gasket shims is ,Innovative Machine & supply,1-800-736-1875
49/53 part#HSF0239-7525,HSF0239-7526,
Good Luck,
Fordestes

[Ol' Ron]

If a cylinder head has 70-75 cc's then the CR on a 276 is between 7.2 to 7.5:1. You must add 15cc's to the cylinder head volume to get combustion chamber volume. This is a guesstimate, as gasket thickness and piston to head clearance is another variable. I made an instrument that checks the volume of the chamber to give an accurate measurement of the Cr. is
CR

[Fordestes]

Also try silver seal for the shims , part number should be the same,I don't have a current catalog.
Fordestes,