I have a 406 with stock rods and speedpro flattop pistons and was wanting to know if I could run 58cc aluminum heads and still use pump gas without pinging? I can change my cam to compensate if needed, I need a new cam anyway. I can get a good deal on them is why I am asking

 

You gotta look up the part # of your pistons to see what the ratio is between diff. cc heads.

I'm running -18cc dished pistons with 5.7 rods on my 408 and I'm right around 9.5:1...so I guess it depends. Aluminum heads help though.

 

was it decked? what pistons..if there the cheapo speedpro ones they're sitting lower in the cylinder anyway. If thats the case i wouldnt worry about knock.

If the block wasnt decked and your using cheap pistons, depending on your current heads your compression is probably very low already. Then the 58cc heads would be a nice addition.

 

the block was not decked and I bought the engine assembled and don't know the part number but I am sure they are the cheap speed pros cause the guy also put a wieand x-celerator intake and stock heads that were shaved 20 thousandths they are 997 heads.

 

well i dont know if this will help at all but i had my 406 zero decked with flat top pistons and run iron 72cc heads.
I have to run high grade gas otherwise i get ping,
this is at 10.7 to 1.
My cam spec is 250@.050

 

Yes the motor will ping on low octane gas. No a big cam will not compensate. Most aluminum heads have plenty of meat so you can open up the combustion chambers lowering the compression and gaining flow as well.
Without exact measurement of your motor's piston deck clearance the actual cr with a 58cc head is hard to tell.

You could easily take 10cc's from each combustion chamber with a die grinder.

Assuming a .025" deck height and opening up your aluminum heads to 68cc you'd be at 10.5:1.

Use a cam with about 230-240deg@.050" but don't expect miracles from over camming it. go easy on the ignition timing.

 

Depends on your timing also. You will have more probability of pining w/ more timing etc. I am running Speed Pro Flattops w/ the deck zero decked, heads are 64 cc chambers and w/ the head gasket I am running the numbers come out right at 10.2:1. I have no issues w/ the timing, and its still the stock table...

 

You may want to look into this too.

Do a search. Type in "quench".

 

Match the cam and compression....If you run to much for the cam. You will have to much cylinder pressure, and it will ping like a bitch on pump gas. If you try to run whats considered the norm for timing.