Building a 71 Cutlass convertible. Factory air car. Just installed a 455 and stainless headers. Today I started to install my air/heater box on the cowl and I can see it is super tight to the headers. I can just run a piece of paper thru the gap. I am guessing this is not right. The air/heater box is made of plastic and will melt once the headers heat up.

I'm sure I can dent the header a 1/4 inch or so but that will still be really close to the box.

Anyone run into this issue? What is the solution? I have a non air unit I can install but was hoping to keep the air conditioning.

thx

 

What brand and model of header? Were they advertised as fitting a car with A/C?

 

I don't know either answer. The headers came with the 455 when I bought it. Is there ac and non-ac headers?

 

Some companies might make a header model which doesn't care if the car has A/C or not. Others might optimize a header model for, say, racing and expect that the car does not have A/C.

 

Remove the evaporator case, and install a VintageAir system!


Went through all kinds of crap, trying to get decent headers on my 455. Going to VintageAir would have made it a lot simpler, and cost less in the long run.

 

I don't think your set has equal length tubes. You may need to take a small piece out of the vertical section of that header tube. Heat and bent the horizontal section down and reweld it. Then polish them back up.

 

If I was in your shoes and judging by the high quality headers you have I would try and modify the AC box instead of the headers. Since the headers are stainless, you would have to get a shop to re-weld them with a TIG welder.
Cut-out the area and glass-in an inward relief to clear the exhaust? Your box does not look installed yet so try that. You could also bond in a metal heat shield on top of the relief you made. Wrapping the header is not a first option, but will work OK with stainless (after you make the relief).
Upgrading to Vintage Air is the ultimate best fix but at $1500...............I want do it next year on mine.

 

It must be the brand of headers, or wrong ones for that car. I had 70 with AC, and I did not have that problem. They were Doug Headers. Could it be you have the wrong motor mounts? Setting to high?

 

Does this motor and frame mount look correct?

 

The convertible is based on the Supreme and everybody knows that headers won't fit on a Supreme. Just kidding, I thought I'd bring up the old rumor. I think it is the brand of headers. They look like the stainless steel headers that is selling for $144 with free shipping. Your either going to have to "massage" them then wrap that area or get another brand or do something with the AC box, or get a set of WZ manifolds. I'd massage them. I'm planning on buying a set for a 1972 Supreme myself. I won't have your problem because my box is gone. There's another thread about these Chinese Stainless steel headers or check them out on Ebay. Good luck

 

That engine mount looks cracked. Engine is also shifted upwards possibly causing your problem.

 

Hit the gas real hard once and you won't have to worry about the gap anymore, it will get bigger on it's own :O if the car had a 350 in it before get 350 motor mounts for the 455. Or get the hammer out and create some HP if not worried about the finish.

 

Well, I spliced out 1.5 inches and beat the snot out of it and tigged it back together. She ain't pretty but this should do the trick.

Before I could only slide a piece of paper between the header and air box. Now I can fit my fat fingers in there.

 

Sometimes ya gotta do what ya gotta do. They make stainless clamps similar to tiewraps that maybe a bit prettier.

 

Looks pretty dam good to me. You'll both be breathing much better after beatin' the snot out of it lol.
Put-r-ther good job.

Eric