PRC 220cc 5.3L Stage 2.5
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As much research and searching I have done, I cannot seem to find solid answers. I have a set of PRC heads from TSP and I am trying to do my home work before I start the install
I currently have a Cam Motion 239/244 .61193 intake lift and .61267 exhaust lift and I am hoping to not have to flycut the pistons.
In searching I found alot of people running MS3 cams and some even MS4 without flycutting.
MS3= 237/242 .603/.609 lift clears these heads
MS4= 239/242 .649/.609 lift has cleared for some, others not
Can I use a thicker gasket possibly to help out?
I currently have a Cam Motion 239/244 .61193 intake lift and .61267 exhaust lift and I am hoping to not have to flycut the pistons.
In searching I found alot of people running MS3 cams and some even MS4 without flycutting.
MS3= 237/242 .603/.609 lift clears these heads
MS4= 239/242 .649/.609 lift has cleared for some, others not
Can I use a thicker gasket possibly to help out?
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LSA and advance will also affect PTV and the OP never stated that. It might or might not clear but it would be so close I wouldn't risk it. It could easily come back to bite you in the a$$ later...
As far as I know the GM MLS at .052 compressed is the thickest off the shelf gasket and besides I would get a slightly smaller cam before I would lower compression, Unmilled those heads will yield about 10.7-1 SCR.
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LSA is 114 and the cam card says Camshaft Data= 4 Crank Degree, is this what the advance would be?
I'm also running a 175 shot, so flycutting worries me. I think I'd rather swap the cam to an MS3 before I flycut.
I'm also running a 175 shot, so flycutting worries me. I think I'd rather swap the cam to an MS3 before I flycut.
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OP: You really need to check clearance on that one. It's a very aggressive camshaft and without flycutting the pistons, it's going to be tight enough that you want to check it!
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Take a small piece of modeling clay ( about the size of a gum ball) smash it pretty much flat on piston covering the area where the valves come down toward the pistons....
Bolt the head down with the gasket.
Turn engine over atleast twice by hand with your 1/2"ratchet
Pull your head back off
Measure the depth of the clay where the valves left their imprint.
You need a minimum of .080" intake and .100" exhaust
If you have less than either you need to flycut enough to get these clearances
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Mine were cc'ed and flowed after they came off the car by a buddy who works at a machine shop just because he wanted to do it for the heck of it. The chamber work you guys do basically opens them up to optimize the larger 3.898 bore it looks like....
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Yes sir, that is correct
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