Fresh air inlet plenum

[Keith R.]

How can you tell whether a fresh air inlet is plastic or fiberglass? Is there matting evident in the surface? Also, is there a way to distinquish an original from a reproduction?

[Don H.]

Re: Fresh air inlet plenum

I am not sure what part you are asking about, you used the 58-60 icon. Don H.

[Keith R.]

Re: Fresh air inlet plenum

The JG describes it as a heater fresh air plenum. It's that rectangular piece on the upper right hand side of the firewall that the fresh air hose connects to. There's also a bowden cable that controls the round flapper valve inside the snout.

[John H.]

Re: Fresh air inlet plenum

How can you tell whether a fresh air inlet is plastic or fiberglass? Is there matting evident in the surface? Also, is there a way to distinquish an original from a reproduction?

Keith -

That part is fiberglass, natural/unpainted, with some level of visible fibers in the surface texture.

[Keith R.]

Re: Fresh air inlet plenum

Thanks John.

I bought a used one from Mary Jo and for the life of me, I can't tell if it's plastic or fiberglass. I understand from previous posts that the piece was natural fiberglass but they must have used a colored resin to produce the charcoal gray color as the color goes all the way through the material. There is a casting number and some letters on the inside but I don't know if they distinquish an original from a reproduction. The one from Mary Jo and the one I currently have on the car don't show any signs of fiberglass fibers and I've lost judging points in the past because the Chassis judges thought it was plastic.

[Roger W.]

Re: Fresh air inlet plenum

I could swear that the part that the fresh air hose connects to on my 59 is either plastic or bakealite. There is a small piece broken off and I don't see any fibers like when other fiberglass parts break. I will have to take a much closer look this weekend.

[Mike M.]

Re: Fresh air inlet plenum

they're fiberglass. i suspect the resin to fiberglass cloth ratio is greater than that of a typical c-1 fiberglass body panel. mike

[Keith R.]

Re: Fresh air inlet plenum

That would make sense Mike, I agree. If they used a greater ratio of resin vs. fiberglass material, then the fibers may not be evident. If the pieces were formed from plastic then the surface would be uniformly smooth from the casting mold but in my case and in others I've seen like the used one I bought from Mary Jo had a waviness to the surface which suggests fiberglass even though the fibers are not evident. It would be nice to hear from someone who knows how these were produced.