shaving stock flathead heads

I have an 8ba with the stock heads, i have stock merc heads that i want to put on. Since the merc heads have less compression than the ford heads i was wondering how much I could shave off the merc heads to raise the compression to above the stock 6.8 to 1 that the ford 8ba heads bring. Is it worth doing?

thanks

 

they probably will have less crossover, so on equal compression they will have less performance, Just my thoughts

 

Other than the 8CM label on the heads, why would you want to do this?

 

Just shave the 8ba heads. I took .100 off a set once, with a stock EAB cam. You'll want to clay the valves and see how much clearance you have now, then mill accordingly.

 

The best stock heads are EAB heads. Shave any stock heads to have about .050" clearance above the pistons.

 

I took about .080 off a set of stockers, and got .045 over the pistons . there was still heaps of clearance over the valves. these were 81 heads..not worth the trouble? ah well..it made me feel like a poor young rodder doing what he could with what he had!

 

Just a quick note, no matter how much you take off, make sure you test everything, I had to releive the heads a bit on mine so the valves didn't hit.

My setup was a little different, using Canadian only aluminum heads and milling just over 0.100 off and going 0.125 over slugs. I bolted it together and the slugs still hit the plugs, just enough to close the gap. Just had to run a shorter thread plug.

All I'm saying is make sure you double check everything.