Just got my engine back together after head, intake, header swap and I had/have a pretty bad vacuum leak where the runners bolt up to the plenum. Plenum has been siamesed pretty heavily, as have the SLP runners and I originally thought I may have went "too big" and had a mismatch on the gasket or something. I have the Mr. Gasket #146 (which Summit just jacked up another 2 bucks BTW), and trimmed them to fit my runners.

After plenum removal I can see that the lower part of the plenum to runner gasket is not being compressed since there was no impression when I disassembled it. The rest of the same gasket looks fine. I went ahead and lightly coated the gasket with some Ultra Black rtv and the idle is 90% better, but I think I may just go ahead and "make" some slightly thicker gaskets out of gasket paper, using the Mr. Gasket ones as a template.

Has anyone else had a sealing issue when modding their TPI "stock style" intakes???

FWIW, Edelbrock 3860 base was brand new, as were the SLP runners. I have roughly 1/8" gap between the plenum and runners before tightening bolts up. Is that normal? I ask only because this is my first TPI car...

On the brightside, the Summit 170 heads, Crane 1.6 roller rockers, Hedman Elite longtubes, new fabbed 2-1/2" Y pipe, ported Edelbrock base, Ported and Siamesed runner/plenum combo runs fantastic at WOT. Just need to get the idle "bugs" worked out. Where the car used to labor to rev from 4500 to 5000, it nows cleanly and strongly pulls to 5400 or so. The added compression seems to help out as well. I went from 76cc iron heads with an .021" steel shim head gasket, to a 62cc aluminum head and a .015" head gasket.

This thing is much LOUDER now...lol...

Maybe even too loud....maybe.....

 

i had something of the same problem with my AS&M runners. i also used some RTV to fix it. did you do a cam swap?

and btw pcmforless said that they JUST stoped bruning proms for 85s

 

Please don't take this as insult. Especially since I can't see your parts. Some have installed the SLP runners on the wrong sides. Might as well check all possibilites.

 

Well, that sucks...

as for the cam, I decided to stick with the stocker and 1.6's.
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Fair question, and no insult taken.
Mine has the 9th injector, so mixing them up wasn't an issue.

I think I may make some thicker plenum to runner gaskets just to be safe.