276 Cu in " Head Clearance

[34 FORDOR]

Hi guys, I would appreciate some advice. I am building a 276 ( mainly street use ) with Ross pistons and Navarro heads.I checked the piston and valve to head clearance with no head casket, using aluminium balls. Top of piston =.075 , outer edge = .045 , valves = .075. Was going to take .040 off heads to tighten up head to piston to head clearance but will this make the valves to tight and affect the breathing ? Do I need to do some work here? or should I leave things as they are.

[Pete]

For a street engine, run what you have.

[flatjack9]

Take the .040 off. With the gasket you would have a minimum of .055 over the piston and plenty over the valves.

[36tudordeluxe]

I have a 276 also, Ross pistons but OFFENHAUSER heads. Milled the heads .020" but recut valve pockets back to .425" depth, wound up with .049 at piston edge and .094 at center and .090 over the valves, these clearances are not ideal for max. performance but suitable for street engine. Am using copper head gaskets, composites would have been a little tighter. With "flame paths" ground in the heads & spark plug holes countersunk and all of the above ended up with compression ratio of 8.7:1, not ideal either but okay. The Navarro heads of course would be different than the OFFENHAUSER.

[40cpe]

That is beautiful work. A while back someone posted a picture of an original cut-a-way cylinder, piston, and head. I seem to remember the tightest area was mid-way between the top and edge of the piston. I don't know how it looks with after market parts, but maybe prudent to measure there, too.

[36tudordeluxe]

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Originally Posted by 40cpe

That is beautiful work. A while back someone posted a picture of an original cut-a-way cylinder, piston, and head. I seem to remember the tightest area was mid-way between the top and edge of the piston. I don't know how it looks with after market parts, but maybe prudent to measure there, too.

At midpoint between edge and top I have .074" Thanks for the compliment.

[40cpe]

Originally Posted by 36tudordeluxe

At midpoint between edge and top I have .074" Thanks for the compliment.

Good on you!

[Ol' Ron]

I'm glad to see people doing this. Unfortunately the piston and cylinder head manufactures can't decide what radius the pistons should be and thus we don't get optimum performance doing this. I have a domoing tool that I made for the Ross pistons, the Egges seem to be closer to the head manufactures. Having ,045 around the edge is the plan, be nice if it could continue further to the center, bur run it.


It's the journey, not the destination

[Pete]

Originally Posted by Ol' Ron

I'm glad to see people doing this. Unfortunately the piston and cylinder head manufactures can't decide what radius the pistons should be and thus we don't get optimum performance doing this. I have a domoing tool that I made for the Ross pistons, the Egges seem to be closer to the head manufactures. Having ,045 around the edge is the plan, be nice if it could continue further to the center, bur run it.
It's the journey, not the destination

It would be nice if there were industry standards for street type
piston domes and head domes so they would match. It's not likely
to happen though.
For one off jobs it is fairly easy to do but for street engines
most people won't pay for all the little things that need to be done
even if they can afford them.
It's the little things that make people say after you have taken
them for a ride, "holy cow, what did you do to this thing, my 276
sure doesn't go like this one".

[Ol' Ron]

I love riding in a car with a properly built engine. I have a friend with a 296 that must have 30K on it and when he stands on it it moves. Warms the cockles of my heart.
It's the journey, not the destination.

[34 FORDOR]

Thanks for all the replies, good to hear from you guys with a wealth of experience. Will have to sleep on it and decide, sweet dreams, leave as is ? or remove .040? Do those "Flame paths " help or is it all snake oil ? There was a story in "Secrets of speed" ( 4 bangers mag) about a guy in India doing some trials and it sounded fairly convincing.

[JWL]

If you read my book you will see how I angle mill heads to achieve the most desirable squish condition within the limits of the "as-received" components.

[awelker]

I found with my last engine build that the Ross piston domes matched very nicely with the new Edelbrock heads. With the Offenhauser heads they were as others described, no where close to matching.