[FreeSafety]

5 hours spent on trying to fit the plenum duct [mounts right under the glove box] It just does not fit.

The mounting pad where the two holes are for installing it on the dash brace, are just too thick. Have any of you installed this new reproduction duct?

I tried my original GM duct and fit in no time. Problem is the holes are, as usual, cracked. This is preventing me from completing the dash end of the restoration.

Here is the part I am referring to:

https://www.firebirdcentral.com/1970...p/duc-2015.htm

[78w72]

the holes are too thick, meaning the screws are not long enough? or is there another issue with installing the screws. if its just a thickness issue for the screws... get longer screws. but if theres another issue with fitment it will need modified, pics will help see what the issue is. or its possibly defective if it doesnt fit right.

[FreeSafety]

The longer screws will not solve the problem. The thicker mounting pad results in the smaller inlet that connect on the bi-level outlet duct right under the glove box, not to line up by about quarter of an inch. This in turn results in the main inlet [the large squarish inlet that mates with the HVAC plenum] not to line up, leaving a 0.5 inch gap towards the top instead of a total seal.

On that note, that main inlet area is totally flat whereas the GM original has a 15 degree [approximate] tilt so that it matches the same amount of tilt on the plenum. Basically, the reproduction duct is a fail. I don't know how these parts are made without quality assuring fitment.

I managed to buy a GM original that is in mint condition and will install it to move the restoration forward. Lesson for others: When you buy a reproduction part, install it as soon as possible. Do not assume it will fit. I installed the reproduction part within 3 days of receiving it and was rewarded with the realization that it will never fit hence I can return the part.

[78w72]

unfortunately thats the case with many repro'd parts. hope you can return it.

[gtospieg]

You may be able to repair the original with this stuff...Polyvance. I watched an interesting you tube vide of a guy repairing a steering wheel with this stuff. It looked impressive so I googled it. It looks legit.

[FreeSafety]

Originally Posted by gtospieg

You may be able to repair the original with this stuff...Polyvance. I watched an interesting you tube vide of a guy repairing a steering wheel with this stuff. It looked impressive so I googled it. It looks legit.

I bought a GM original in used/mint condition.