Piston hitting heads!

[3twinridges]

Finally got the last piston in, even though the EAB heads were NOS, I was still worried about them hitting the egge pistons. Sure enough, they hit.

I foil balled the valves and cylinder with the head torque down with a gasket and it wouldn’t turn over. Basically no clearance with a gasket which means I would have to remove about .05 of material, seems like a lot!

Thoughts on an 8BA head having enough clearance?

JB

[Ken/Alabama]

I ran into this once. It was just on the passenger side. I ran two head gaskets on that side. While not ideal, I ran it for thousands of miles like that.

[petehoovie]

Originally Posted by 3twinridges

Finally got the last piston in, even though the EAB heads were NOS, I was still worried about them hitting the egge pistons. Sure enough, they hit.

I foil balled the valves and cylinder with the head torque down with a gasket and it wouldn’t turn over. Basically no clearance with a gasket which means I would have to remove about .05 of material, seems like a lot!

Thoughts on an 8BA head having enough clearance?

JB

[Mart]

Are they hitting just in the middle of the dome? Some pistons have a constant radius dome. Some pistons have a "pointy" dome. In my experience, French pistons have the pointy dome. I have reduced the point by filing on my lathe and by just filing in situ on one occasion. If this your problem there is normally no problem with removing enough material to achieve the correct clearance.
If it is more general across the dome, maybe the heads have been previously milled and some different heads will do the trick.

[richard crow]

did you install a 4 inch crank.if yes did you use ford pistons. you must use mercury pistons

[chap52]

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I had this happen and used a grinder to grind a bit off the heads and double gaskets did the job. Poor folks. We ain't got much but we do have a shade tree... Lol. Chap

[35fordtn]

I have 14k miles on my 1936 Pickup. It has two headgaskets on each side.

[tubman]

Sounds like a perfect opportunity to get in there and custom fit your heads for optimum "quench".

[GB SISSON]

I made an improvised 'doming head' from old V8 parts on my 276 stroker build a couple of years ago. This did a good job of cleaning up and finishing the somewhat crude hand grinder work I did in sculpting out the bowls with an angle grinder. Not sure how to link parts of an old post into this one, or to interject some of the photos. Therefore until someone smarter than me can do that, go to my build thread '276 stroker from 35 years of parts' and go to page 13 is where the discussion on clearance/squish area/foil balls starts and maybe on page 15 or so I come up with this crazy apparatus. You would need an extra block and a few junk parts to construct one.

[big deuce]

Look into cosmetic head gaskets, they have a wide range of thicknesses. Without a gasket, how much does the piston raise the head?

[petehoovie]

Originally Posted by GB SISSON

I made an improvised 'doming head' from old V8 parts on my 276 stroker build a couple of years ago. This did a good job of cleaning up and finishing the somewhat crude hand grinder work I did in sculpting out the bowls with an angle grinder. Not sure how to link parts of an old post into this one, or to interject some of the photos. Therefore until someone smarter than me can do that, go to my build thread '276 stroker from 35 years of parts' and go to page 13 is where the discussion on clearance/squish area/foil balls starts and maybe on page 15 or so I come up with this crazy apparatus. You would need an extra block and a few junk parts to construct one.

Page 13 > https://www.fordbarn.com/forum/showt...troker&page=13


Page 15 > https://www.fordbarn.com/forum/showt...troker&page=15

[petehoovie]

Originally Posted by big deuce

Look into cosmetic head gaskets, they have a wide range of thicknesses. Without a gasket, how much does the piston raise the head?

COMETIC Head Gaskets > https://www.cometic.com/materials/head-gaskets

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Thickness: .018, .019, .020, .021, .022, .023, .024, .025, .027, .029, .030, .031, .032, .034, .035, .036, .038, .040, .042, .043, .044, .045, .046, .047, .049, .050, .051, .052, .053, .054, .055, .056, .057, .058, .060, .062, .064, .065, .066, .067, .068, .070, .071, .072, .073, .074, .075, .076, .077, .078, .080, .081, .082, .084, .086, .089, .092, .095, .098, .100, .102, .104, .120, .124, .140


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[3twinridges]

Not against two gaskets, I am going to have to do that anyway to get enough clearance to measure how much I need to take off. I am still hitting with one gasket, so at least 0.050 in some places.

I am going to call the shop tomorrow to see if they can redome them. With the piston top profile and the right cutter, and depth to remove seems like you could get pretty close and have a nice uniform combustion chamber. Hopefully they have run into this before.

JB

[vincent]

When putting Edelbrock heads on one of my french motors, I found that the pistons just touch slightly at their peak point. I made a cutter to the shape of the piston and deepened the pockets in the heads. When doing this I found that those 4 pockets were not exactly parallel to the head and of slightly varying depth...
Here is a pic of my cutter. It is just a shaped HSS in the slot so I could make different cutters for other shapes, if needed.

[oldbugger]

Originally Posted by richard crow

did you install a 4 inch crank.if yes did you use ford pistons. you must use mercury pistons

2X ask me how i know

[petehoovie]

Originally Posted by vincent

When putting Edelbrock heads on one of my french motors, I found that the pistons just touch slightly at their peak point. I made a cutter to the shape of the piston and deepened the pockets in the heads. When doing this I found that those 4 pockets were not exactly parallel to the head and of slightly varying depth...
Here is a pic of my cutter. It is just a shaped HSS in the slot so I could make different cutters for other shapes, if needed.

[3twinridges]

Talked to the shop today today and they can redome them, but they were afraid of final head thickness above the piston.

I talked to cometic and they can make a gasket for me, going to go that route. At least in principle it seems like the easiest fix. Going to bolt up a head tonight and get the thickness I need.

[rotorwrench]

The OP states he has NOS EAB heads. I've seen new heads back in the day but I've also seen misrepresented ones too. Make sure the bottoms of the coolant exit ports have a fair clearance to the deck surface. I've seen them shaved all the way down to the coolant port bottoms.

The Ford pistons with a Merc crank as was mentioned, is another problem. The Merc piston pin bores are a good bit lower on the piston to get clearance right for a 4-inch crank.

Block deck height is another thing if they've been shaved too much.

[3twinridges]

Originally Posted by rotorwrench

The OP states he has NOS EAB heads. I've seen new heads back in the day but I've also seen misrepresented ones too. Make sure the bottoms of the coolant exit ports have a fair clearance to the deck surface. I've seen them shaved all the way down to the coolant port bottoms.

The Ford pistons with a Merc crank as was mentioned, is another problem. The Merc piston pin bores are a good bit lower on the piston to get clearance right for a 4-inch crank.

Block deck height is another thing if they've been shaved too much.

They are mercury pistons and I don’t think the heads have been shaved that much. I have a new set of EAB heads still in the crate and they haven’t been touched and they hit. I am going to put two gaskets on tonight to see what I have in clearance. I figure with two gaskets compressed at 50ft/lb I will be at 0.110 gasket height. If I get 0.030 clearance I can run a 0.086 cometic gasket.

JB

[3twinridges]

I was able spend some time on this. I torqued down two gaskets, best I could tell final compressed height of both gaskets came to 0.110 at 50 ft/lbs. Lowest clearing I had with aluminum foil balls was 0.068. So with an ideal 0.050 clearance, I could take 0.018 off 0.110 and run a 0.092 cometic gasket, which they have with a 3.250 bore size. My bore size is 3.2275 so I think that is fine also. Logic sound right?

That is for the passenger side, on to the drivers side.

JB