A-block head milling

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68cuda

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The 302 heads are finally in the machine shop. I'm considering having .020 milled off the block surface of the head. Per the Mopar engine book the intake surface also has to be milled .0095 for each .010 taken off the block mating surface. No problem.

However they also state that the front and rear intake rails of the block need to be milled .0144 for each .010 taken off the head block mating surface.

My question is this: if I have the head milled on both the block and intake surfaces, with the rail surfaces of the block not being milled, will the intake rail gaskets take up the difference? I'm trying to make the heads "plug and play" without modifying the block.

I'm also putting in 360 valves and am concerned about piston to valve clearance. I know this has been done - what's the best way to go about this?
 
.0144" put in perspective is not quite fourteen and a half thousandnths of an inch. I don't think you'll have a problem.
 
For just .020 off you might be ok without doing the intake side of the heads. For sure the block will be ok, unless you were going to use those dumb cork gaskets between the block and intake. Why everybody uses RTV but dumb Mopar, ha ha
 
Yeah, don't use the end seals and just use a thick bead of grey or black RTV. In regard to the valve diameters... You need to be running a serious cam to get near the pistons of a normal 318 or 360. What cam and rockers are you using?
 
Moper
Mild cam - Edelbrock Performer with 0.42 lift, stock stamped rockers 1.5:1.0. Stock flat top 318 pistons, using 360 valves in the head and .020 milled off the head; and ideally a thin .020 head gasket (that would get the compression up to about 9.0:1.0)

Just went down to the machine shop to talk this over and they also recommended the RTV instead of the rail seals. They also didn't think the valve to piston clearance would be an issue - the owner even offered to come out to my place on his own time and check it with a dial indicator once the heads were done (one of the reasons I use the shop - excellent service).
 
Do you have the EARLY TRUE flat top pistons or do they have a slight dish? I don't think it'll be a problem even with the early pistons, but it never hurts to check. Especially if the shop is willing to go the extra mile. I'd do it just cause.
 
For every .010 removed from the head surface, .012 will need to be trimmed from the intake to keep correct intake manifold alignment.
 
the only way to know wether you'll be a-ok on the intake lining up is to 1st set the heads and intake on the block [with gaskets] and see if they line up NOW before any milling, if it's boarder line then you better mill .010 off of each intake face of the head.

and just use some black RTV on the front and rear rail, skip the cork end seals.

jmo
 
Thackdaddy said:
For every .010 removed from the head surface, .012 will need to be trimmed from the intake to keep correct intake manifold alignment.
Click to expand...

For every .010 from the head suface you should remove .0095 from the intake side of the head. That way you don't have to touch the intake.

(My question is this: if I have the head milled on both the block and intake surfaces, with the rail surfaces of the block not being milled, will the intake rail gaskets take up the difference? I'm trying to make the heads "plug and play" without modifying the block.)

I typically mill .040 off my heads and have never milled the block ends. As others have said, you should be fine, but it always pays to check before you final bolt it together.
 
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