Roller Block: Pushrods Rubbing Against Head

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MOPAROFFICIAL said:
If the heads havent been opened up , deep gasket match, then just drill them 9/16 and run it. Simple as that. It 90 bucks at rhe shop. Did this near same combo before.
'88 roller 360, used 974 casting heads from '74 . Runs a lunati. 585 hyd roller with mopar replacement rollers and spider.
All early casting heads need modifications to the push rod holes to run a roller cam.
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Hi. This is a late reply. But I am basically running the exact same block and heads (well my block is an 89). I have my heads at the machine shop right now, and am trying to figure out my best move before I pick them up. This thread is very useful for sure, as I think a lot more people will be looking at this type of setup deliberately. Why? La heads flow better than the 308 heads, (Probably get some pushback for that) ;-) and people will be seeking out the roller block as a way to avoid flat tappet issues. I think the set up is a great idea, it'd be nice if there is a simple solution that is agreed upon by people who have tried different solutions.

So it seems there are two ways to fix this before assembling the motor. 1: Oblong the push rod holes to accommodate the needed clearance. or 2: Drill out the pushrod holes to 9/16.
Now my question to you, how did the 9/16 holes work out? I am worried about getting to close to the intake port, and will there be enough room to do any machining to the intake port for say gasket matching etc.? The gasket matching isn't a big issue for my build as I am not looking for a high HP build, but others will definitely be.

I am thinking of asking the machine shop to drill holes to 9/16 except for the intake pushrod holes and using a die grinder to oblong those ones (just in case I decide to use these heads for something different in the future ie; future considerations). Also what length pushrods did you end up using?

Thanks
 
Old thread. I sure hope no one tried sticking a carbide burr down in a hole thinking it wouldn't chatter itself to death. Use a drill. (or the right parts)
 
I had that issue with an 88 d100 (318)
My first encounter with '302 heads, I swapped them out with a set of older (probably late 70s) 318 heads since I found out that the original 302s were cracked. This was about 30 years ago.
Just by a head swap I went from an engine with fantastic oil pressure to "none". When I put the heads on I just dropped the pushrods in, put the rockers on, and then the valve covers. When I discovered I had lost oil pressure I went back in to figure out why. At the time my guess was that the rubbing pushrods lost contact with the lifters and that was where I was losing my oil pressure.
I ended up rebuilding the whole thing, and I went to the junkyard and got another set of '302 heads, and had them gone thru. I paid $400 back in '94/95 at a junkyard for the replacement set of 302s, plus I paid for the trip they took thru the machine shop.
 
toolmanmike said:
Old thread. I sure hope no one tried sticking a carbide burr down in a hole thinking it wouldn't chatter itself to death. Use a drill. (or the right parts)
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So drilling the holes shouldn't cause an issue with any intrusion into the intake ports?
 
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