Quote:
Originally Posted by chiphead
What is the typical cause of a RPM intake not sealing off on a '69 head?
Had something super strange happen today. I went to do the cam break-in on that 69 400 I did a cam swap on. So I roll the car outside and fill the 750 double pumper with gas. Somehow when I put gas into the secondary bowl vent, all the gas came out the boosters and filled the intake with about 4oz of gas. That's most of what I put in, so it all went right down the intake. A subject for another thread I guess.
But the weird thing is that gas started to show up on the valley pan and run down the front of the engine block. WTF? Close investigation found the intake runner for cyls 2&4 were not sealed to the head, at the bottom of the port. So the gas runs down the runner and leaked out of the bottom of the port. Needless to say I didn't try to fire it off.
I pulled the intake off and didn't find anything super obvious, other than the impression from the intake on the gasket was faint, basically sucked. Bolts were tight, the intake wasn't hitting the valley pan, the gaskets are the fel-pro 9980. The intake came with the motor and there was skin coat of sealer on both sides of the gaskets that came out. The valley pan is new from Butler and I clearanced it for the intake.
The orange alignment plugs were in place, but were mashed to chit. Can they hold the intake off that badly? Is the RPM supposed to have a relief machined for them? What likely happened?
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For what it’s worth I never leave those orange guides in the gasket, I don’t feel like they squash down all the way, not saying it will have a problem every single time but the only reason I use those for scribing my lines for port matching, but sounds like the heads might not have been milled perfectly slat leaving a slight Lee bigger gap at the bottom of your intake gasket than the top, or manufacturer error