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Header collectors - wrap or heat shields?

Jonk67

Jonk67

Well-Known Member
Getting close to finishing the tweaks to my MAC long tube headers to fit around my AOD, they still come within an inch of the pan as I see a lot of LT headers do and I'd like to shield the trans from some of that heat. What would be better:
1. header wrap around the collector/pipes that are near the trans.
2. make my own heat shields out of 18-22ga.?
3. do both?

I've never used header wrap, is it best to pick the one with the highest heat rating? I take it 2" wide vs. 1" wide will give me more overlap coverage and be better for the large collector section? Any brands to avoid? Fiberglass or other material better?

The headers I will be wrapping, probably just the horizontal section:
IMG_0272.jpg


Thanks, Jon
 
I've always heard to avoid wrapping headers like the plague. That it will rust out the headers due to trapping condensation.

But with that said, I had wrapped one tube of my 351W conversion headers with no problems. During the summers here there's not alot of humidity in the air (normally single digit), so I wasn't too worried about it cooling down and condensing. And the fastback didn't get driven a whole lot on the street with that motor...it was a little radical for the street.

Can't tell from the pic, but are the headers coated or just painted?
 
I vote for a heat shield. You can get an aluminized heat shield from a junk yard from any OEM vehicle, or you can also get the stuff they use on NASCAR vehicles on Ebay. Bending some sheet metal may help some, but it doesn't have any insulation properties to prevent it from heating up.
 
The headers are just painted, if they work well I may pull them off in a year and get them ceramic coated.

So I need to look for aluminized metal to fab heat shields from I take it. I'll look for the fleabay NASCAR stuff.
Thanks, Jon

Edit: Ok, looked at the aluminized heat shield but it can't come in contact with the heat source so it's more designed to be wrapped around a starter or the trans. which would be difficult as the collectors end up right next to the pan flange so I'd have to wrap around the entire pan mounting area.

When I mentioned heat shield I was thinking more of bending some thin steel to stand off the collectors between them and the trans. to block radiant heat like the ones you see on a stock cat. conv. between it and the floor pan. I take it the shield should attach to the header and not the trans to keep from heat soaking what it's attached to.

66GT350, I had forgot about the soaking and rusting issue, anyone had this happen. I won't be wrapping them fully, just the horizontal section at the bottom but still if they got soaked (car will be driven in rain) I guess they'd hold moisture and cause rust eventually.
Jon
 
Personally, I think you're over thinking the whole thing. I had to notch the driver's side collector on my '66 to get clearance from the collector to the pan, that's how close my Flowtech Terminator long tubes come to the AOD. It's been like this for 10 years, and the car was my daily driver for 7 of them. Never had a problem, at all.

If you're worried about the heat, send those headers off to Jet Hot and get them ceramic coated (my headers are ceramic coated from the mfg.). Anything else, to me, would just be a hack job that probably won't be very effective, or cause more damage than good.
 
Ok so an inch from the pan isn't too close for painted headers I take it and the moving air will keep it cool enough then. I may go ceramic later but want to make sure the headers fit/work like I want them to before doing ceramic in case I have to tweak more.
Jon
 
"Jonk67" said:
Ok so an inch from the pan isn't too close for painted headers I take it and the moving air will keep it cool enough then. I may go ceramic later but want to make sure the headers fit/work like I want them to before doing ceramic in case I have to tweak more.
Jon
Click to expand...

An inch is about 3/4" more than you need for comfort. I wouldn't worry for a second about an inch clearance!
 
I agree with WaldoPro.

As far as the wrap, I know a guy that uses wrap religiously on his high-performance turbo stuff and it hasn't caused him any rot/problems, but I'm still not a fan because I know it has caused others all kinds of grief.
 
Thanks guys, I'll leave all as is for install and probably get a trans temp gauge mounted temp or perm. and see where I'm at then.
Jon
 
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