Quote:
Originally Posted by Tony455
So some of the info I'll give is known but alot is assumed.
The block is a .060 over 455 with forged rods and -15cc dished icon pistons.
The cam is a melling spc-8 cam (041) and I have Rhoades lifters.
The heads are 6x-4 heads with 1.5 roller tip rockers.
I'm fairly certain the deck height is stock and I don't believe the heads have been milled. If I pull the heads I will check these things.
But assuming a .016 piston to deck height and 94cc for the heads with a .039 gasket. The basic calculators put me right around 8.9:1 compression.
If I were to pull the heads and mill them to say 84cc which would put me around 9.6 unless the block happens to be zero decked then I would be closer to 9.9 but with good quench. And I'd clearance them for 1.65 full roller rockers.
What could I expect for a power gain? Obviously that's alot of assumed specs but If those were the numbers would the gain be worth the time and money? And how much of the gain be from the rockers and how much from the compression? Is it worth just doing one?
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I'm guessing 20-30 horsepower gain with the head milling and 1.65 rockers. You will feel an improvement, get better mileage and see a difference on the time slip if you race your car. I'd also adjust the deck height with a thinner gasket if the piston isn't even with the deck.
Is it worth the work, depends how much the performance difference means to you. You'll need to mill the manifold or manifold side of the heads. To do the job right you should leave a step at the bottom of the intake side of the head (assuming you choose to mill the manifold side if the head which is usually the better way) for the valley pan to seal and you might need shorter pushrods.