Pontiac 6X-head problem

[COPO_Anders]

I´m having a problem with the 6X-heads I have on a 400 engine. I want to use an aftermarket aluminum intake-manifold but the used one I bought doesn´t fit. And the gasket can´t be used either.
Is there an easy fix for this problem ? Please point me to the correct manifold, if there is any.

Thanks
Anders

[John Brown]

I don't think that open hole goes anywhere. I think it is only an air space, but since I'm not a Pontiac guy, I may be wrong.

[StealthBird]

Anders, you need to get the Fel-Pro 1233 set.



The "hole" is the heat crossover. You need to make sure it seals, or you'll have a heck of an exhaust leak.

Most of the Pontiac guys use thin metal block off plates, which come with the Mr. Gasket intake set, not the Fel-Pro set. The Fel-Pro gaskets are higher quality.

Blocking off the heat crossover is sort of standard thing all Pontiac guys do, it allows for a cooler, denser air charge by keeping heat away from the plenum floor. But if you don't want to block it off, make sure you get the Fel-Pro set.

Also, if you haven't worked on a Pontiac before, make sure you use the rubber o-ring at the front of the intake to water pump, and use some silicone to seal it. Lots of guys forget that, or don't use silicone/gasket sealer along with the o-ring, and they end up with a puddle of anti-freeze on their valley pan cover.

[njsteve]

Anders,

You do not have any problem with that setup whatsoever. That upper open area is just an open air chamber that does not connect to the heat crossover. Maybe it was Pontiac's version of an air-cooled engine? [img]<<GRAEMLIN_URL>>/hmmm.gif[/img] Or it might have been a way to isolate the very hot cast iron above the exhaust riser passage from the oil that would be spraying on it from the rockers. Maybe a way to eliminate cooking the oil and creating a sludge problem? [img]<<GRAEMLIN_URL>>/hmmm.gif[/img]

Here are the 6X heads on my Gramma's 75 Firebird with a 1972 4bbl intake bolted up. As you can see, there is no leakage (since the paint is still intact and no soot is showing). No exhaust leaks either. [img]<<GRAEMLIN_URL>>/grin.gif[/img]

[njsteve]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: StealthBird</div><div class="ubbcode-body">Also, if you haven't worked on a Pontiac before, make sure you use the rubber o-ring at the front of the intake to water pump, and use some silicone to seal it. Lots of guys forget that, or don't use silicone/gasket sealer along with the o-ring, and they end up with a puddle of anti-freeze on their valley pan cover. </div></div>

Quite right! And make sure you install the timing cover/waterpump housing before you install the intake. The correct procedure is to have that timing cover in place, then put the rubber O-ring on the front of the intake. Then set the intake in place. And this is the important part: The first bolt you tighten is that really long, horizontal timing cover-to-intake bolt that pulls the intake up to the timing cover and compresses the O-ring. Then you can tighten up the intake mounting bolts. [img]<<GRAEMLIN_URL>>/scholar.gif[/img]

Welcome to the wonderful world of Pontiacs. So what's it going in????

[tjs44]

be carefull not to pull it too tight as you will crack the intake or timing cover.I have found to hand tighten the rear intake bolts and then pull the intake to the timing cover.This will keep the rear of the intake from lifting and causing miss match of the intake to the cover.Tom

[COPO_Anders]

Thank you guys ! I know we had a leakage problem (exhaust gases) with the castiron manifold after putting the 6X-heads on the engine. So I thought it was a manifold problem since the intake was older than the heads and I assumed the aluminum intake would cover that &quot;hole&quot;.
It´s going into the 1971 Le Mans that we have, the one that had a RAII engine in it when we bought it. It´s in &quot;members rides&quot; long ago.
Thanks again for your input guys !

[img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img] [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

[Jim Ferron]

I seem to remember I had to 'fill' that crossover with devcon on a set of 4X heads I had...they always leaked exhaust...I got rid of them...