Old Rugged Crosser
I posted the following once befor and received no answers. Would someone kindly answer?
I have the heads (291-C) off of my engine at the present. Just ported and polished out the exhausts and port matched the intakes with a little cleanup on the inside radius. Getting ready to have chevy ss valves installed as I have to do the guides anyway, so the smaller stems do not cause me any problem. I would really like to try this communication grove (Sighn grove) while I am into this area anyhow. If any of you guys do the experiment would you please post it as soon as possible. I too will be using a die grinder to make the grove.
Also I would like to mill the heads to raise the compression. The pistons are the stock dished tops. The gross lift on my cam is .520 & .523. How much could I take off the heads before running into a piston height problem? I will plasti-gauge it just to be sure of my clearances before I mill. What should the piston to deck height be? What are your idea's?
One more thing: The stock leingth of a amc valve is 4.90 the chev. valve starts at 5.80 I believe. Is this a problem?
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ironman_gq
If you mill the heads they arent going to get closer to your pistons only your valves will. as for how much you can take off, you need to put a piece of clay on top of your piston at TDC bolt your head on and run the engine around to see how much clearance is between the valves and the piston as if the engine were running. For piston to head clearance or quench/squish you want around .045" which is what the typical head gasket usually measures so set you pistons flush with the deck of the block. Not sure about the valves but im sure if you use the search function someone you will probably find all the info you can handle
tarior
The last set of heads I had done, I think the machinst used sbc +.100" length valves. Your machinist should be able to look in his valve catalog and motor manuals and come up with something that will work.
BB Mopar valves are the same length as AMC, but the tip length is different, so the spring seats need cut a little. I don't remember off the top of my head what we did to make the SBC valves work, but it seems like it was a similar deal.
As to the grooves in the heads, I'm not really sold on that one. Your machinist should be able to answer your head to piston and valve to piston questions. If not, find another shop.
