Ported Intake Gasket Woes

[gbmidyear66]

Thanks for the questions and suggestion Jerry, Lee.

OK - The last 2 times I attached the gaskets to the Plenum using contact cement - maybe that was not such a good idea.

The plenum seems to have good planarity (see pic), I can't get a sheet of paper under the level. The IH are not quite as planar, I can get a sheet of paper under - but just (see pic).

Something I did notice is that my plenum overhangs my IH on BOTH sides by about 1/32 - so I loose a little bit of gasket mating surface. I guess the IH has some play when it is attached - I didn't pay attention to this when I re-installed them after porting.

Ran the car up to temp (it now idles nicely again at about 700) - let it cool and re-torqued. I'll re-check torque after I put some miles on.

Hope this is the end of my aggravation with this....

Glenn

[gbmidyear66]

Jerry, read your questions more carefully. Your observation that the inboard gasket material is pushed out is interesting. I was focused on the vacuum leak - the outboard area pulled in - which I assumed was caused by vacuum. But that would not explain why the inboard is pushed out.

The gasket was bound in place as you see it - took an hour to scrape it off the plenum last night - but obviously I never mounted it like that.

Somehow it seems to have become distorted - I tightened the plenum down from the center working out towards the ends. I can only think that the gasket may have been slightly misaligned relative to the bolt holes and under stress - and what we see is the result?

By NOT attaching the gasket this time - it pretty much had to go on without any stress in the X-Y plane - hope this does it.

[XfireZ51]

Did u follow the torquing sequence outlined in the FSM?

[gbmidyear66]

Yup, per FSM - sequence and Torque. I believe Marc H uses a different sequence - but I used FSM sequence. #4 and #6 Torque may be a bit off because my socket wont fit between the runners - so I use an Allen key and do those by feel.