milling heads for comp ratio increase
Well I have heard of 5-8% power increases with a one point CR increase. And it is not that expensive - it is actually the cheapest option I have. Around $120-$150 per head (Aust dollars). Compared to the other things you are thinking of - different pistons (plus then needs a rebore) $1000+. Different new cam: means new lifters also $600. New stainless valves as I already mentioned, means getting the seats recut...$650++...Getting the heads ported - big $$$ in Australia in my city $350 per head. So you can see that milling the heads is the best option - since I feel that a 9.5:1 CR will better suit the cam and 4BBL and M1 intake and headers I am using. It is only a budget rebuild, not wanting huge gains. I feel I should get a rating of 250-270 HP easily.
The bottom end is already built. I had a small solid cam lying around for years so that was no cost. I had the solid lifters refaced years ago - Heads have had four valve guides done, that's all it needed plus those seats recut to suit. Then a good lap in and all valves seat and seal well.
Thanks
You will take some heat for the 5-8% comment regards power, but sometimes the overall flavor of the combination changes by having more compression, and that allowing things to work better and make more power.
My current car/ combination is a perfect example. Stock 360, pistons 028 in the hole, 50 thou head gasket, comp 292 cam, stock eddie heads..... single plane Mopar intake..... car ran 12.17 best with 4.10 gear and 8 inch 4500 flash convertor.
Replaced cam to 260/264 Howards cam( similar lift), dual plane intake, took heads off, had them mildly ported, setup up with new springs, etc, for new cam, milled them to 57cc( about 45 thou) and reinstalled with 28 thou head gasket. No other changes.... cam, intake, mildly port heads, mill for compression, thinner head gasket...... car ran 11.26
This in spite of the fact the cam i installed i am aware is probably one step too big for what i have( i was in a hurry and it was on the shelf when i made these changes)....... a bandaid would be more convertor and maybe gear, convertor change is in the works as we speak
So here we have a decent bump in compression allowing a motor to be able to make more power( lots more) with just a couple easy changes. I suspect this thing will get in the 10’s yet, its gonna love the convertor swap with that big cam
