My new Offy .400 heads only have .350 over valve pockets.

My new Offy .400 heads only have .350 over valve pockets.

As the ***le sais this is the situation. Im concerned its going to limit my cam choice and i have no idea what the compresion will be.

Whos had this problem and what should i do about it?

 

How thick is the head gasket? I'm thinkin maybe the compressed thickness is factored in. The last one I saw was pretty thick. Just my guess

 

Well not exactly sure but i did read a few places its .050 so yeah i supose that would make .400. however thats not the impresion i was under when i ordered them.
By the same token i measured my stock heads and they had .325, So my off heads are only .025 over. Im a bit disapointed but i can always re work the valve pockets with a die-grinder.

 

Run em with copper gaskets. Mine ran fine....for alot of hard miles.

 

I wouldnt think you would get a very consistant comp ratio, cylinder to cylinder, with a die grinder job. Why not make a call to whoever you bought them from and ask some questions first?

 

Bought from reds headers, they are calling offy and getting back to me. One thing i noticed is the chamber above to dome is an additional .025 on the offy heads which seems odd, it would lower the compresion and the squeze-turbulence. Thanks pete, but running a thick copper gasket would reduce it again... high dome pistons would sort it but theres a bit of cash there.
Food for thought.

 

I dont really know about offy's quality these days, my dad has a set of v-8 60 heads that were really bad with sand pitting and poor machining

 

Had the same prob with mine.....Offys maching/QC is ****.

Mocked up without head gaskets the cam lift/valves would lift the heads clean off the block on both sides.

Chamber volumes were all over the place.

I modded mine, fly cut, unshrouded the valves and added a nice radius for better flow and had enough clearance with a L100 - .375" lift cam.

My domes/quench were fine - DO NOT run a thicker hea gasket for clearnance, get the heads fly cut. This way as mentioned, you will keep your quench, maximise combustion/flame travel and turbulanece that the FH excels at.

Rat

 

If I remember right Best copper gaskets are 0.057" compressed and their composite gaskets are o.053" thick.

Jim

 

Thanks Rat. Yes as mentioned the dome clearance is .025 more than my stockers so i may look at a .025 cut (ill be claying of course). However as ive mentioned also, the valve pockets are only .025 over my stockers too so that'll bring it right down. Do you have any pictures of what your heads looked like after you re worked them?
One last thing, i see your in OZ, im in NZ, how did you go about getting your L100?

 

Does anyone else have this problem? or ideas/solutions?