hey ya'll i got a 92 z28 and i am trying to put on the edelbrock highflow manifold and tpi high flow runners, but i have a vaccum leak on the both sides of the runners where they connect to the intake manifold, i used all new gaskets and all that crap and dont know how this happened i have taken it all apart and re did it with my father in law and still the same thing dont know if edelbrock messed up and sent me jacked up parts or if anybody else has had this problem and has a hint or something!!thanks!!

 

Are you using the Edelbrock supplied gaskets?

 

yeah i did at first but then when i redid it i used the gaskets you can buy at pep boys! why is there a big difference in them?

 

Probably. Overlay the gaskets on the runners. Look at either the EGR or PCV machining area. Edelbrock machines this area lower than the factory for some unkown reason. The factory style gaskets will not cover the hole. Hence a big air leak.

 

It's been decades since I did my manifold base. IIRC, I bolted the runners to the base and plenum loose, lining everything up. Then tightened up the runner to base bolts and then the plenum bolts

I can't recall if there's a tightening pattern that you need to follow for the runnerto base bolts, but your service manual should provide this info as required.

BTW I'm just curious.....did you have to mod the coil bracket to make it fit? Was there a accessory boss that was too high and not drilled and tapped deep enough?

 

no the coil bracket fit just fine, i heard there was a recall on the edelbrock manifold and runners has anybody heard that also?
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the gaskets line up just fine and cover what they should, we are maybe thinking that the fuel rail is stopping the runner from being totally flush, it looks like the runners and rail are touching?

 

we got it working, thanks ya'll

 

Just to close the loop, what was the problem? It might be helpful to others to know what the fix was.

 

lol it was a stupid mistake, we had the wrong gasket on wrong side on the egr hole!! they look almost the same but there is a slight difference.

 

Just curious, I have a 92 z28 as well. I'm looking to do the same upgrade soon, do you really see a big difference in power with this upgrade?

 

well i havent had my car on the dyno to see the change nor ran it down the track to see the time either but i have driven it but i also threw on hooker headers and new aluminum pulleys and a few other things at the same time as the intake manifold so i felt a huge difference.

 

Yes, you must either use Edelbrock gaskets for their runners, and they are specific per side, or you must modify the runners to use aftermarket gaskets on them, Edelbrock machines the EGR passages different than stock, and the runner diameters are also much larger than stock, so using stock or stock-sized gaskets will choke off performance and leak by the passenger side EGR port.

TA

 

I am in the process of building a 350 TPI and have the edelbrock runners on a factory TPI intake. I doublechecked and did not see a problem. I am nervous now and think I might have to tear this back down. Does it make a difference if using the factory intake vrs the edelbrock? Thanks!