Milling 799 heads
11-04-2016, 09:32 AM
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Milling 799 heads
I have a 4.8 in my truck now and am considering picking up a set of 799 heads. By my research it looks as though I will lose roughly 6-7 cc and a touch of compression but will gain bigger valves and more flow. Will that be enough to over come the compression loss or will I need to mill them to get back that compression. Could I go smaller by milling further or will that cause it's own separate issues. Id really like to build a higher reving motor if all possible. Due to a plan to run a 4.30 gear and a 28-29 inch tall tire.
11-04-2016, 09:51 AM
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The way to look at it I guess is the Gen IV 4.8 is exactly that.... a 4.8 with 243/799 heads on it and the 87 mm gen 4 intake. I think it's 305hp and whatever for torque.... but only 8.8:1 compression. You would need to mill around 0.030" to get back to where you are at now for static compression. Just for efficiencies sake milling to gain that compression back is a good thing, let alone any other long term goals. This question does get asked a lot on here.... and there are a ton of threads where guys have done exactly what you want to do with their results posted. Not being a dick lol... but search is your friend on here.
11-04-2016, 10:27 AM
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That's actually one of the ones I read I geuss my biggest question where if it would cause problems to mill them that much? Like as far as intake alignment or other unforeseen issues. Possibly messing combustion chamber design
11-04-2016, 11:52 AM
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That's what I was just looking at too I wonder if .040 would give piston to valve issues. Does anyone know what comp ratio it would be with .040 milled off I don't mind running 93 but I don't wanna have run 110 octane. The guy that used to build my motors has closed shop and he would usually be the one to tell me if it was a good idea or or a bad one