I started my '39 Ford two door sedan today and noticed during the first few minutes of the cam break-in that the paint was blistering on the right fender and the left fender was really hot. I am running fender well headers that fit a '55 Chevy, I think. Should I wrap them or build shields? From what I've read on here I'm leaning toward shields. I haven't measured the distance from the header to the fender but was surprised to see so much heat transfer.
Use the wrap and you will greatly shorten the life of your headers. Two person experiences here so "Been there and done that". Build the shields and leave an air gap and if possible build them so air will flow through the gap to keep things cool. I have run headers through fiberglass bodies with shields and they work. Dan
Wrap is very effective at reducing heat transfer. I have used it with great success in insulating my pipes from starters and master cylinders. I have used it mainly on aluminized tubing and never had it reduce the life of my pipes; maybe if you used it on plain steel or got them wet frequently.
I have had wrap on my bike for 8 years and still no problems. It is meant to keep the heat in the pipe.
When breaking in a new cam its best to use some junky headers if you have them .The break in process creates some crazy heat and will burn off paint and even high temp coatings.After cam is broken in you probably wont see that extreme heat to that degree.
I've run wrap on a few bikes, never noticed any problems. Some people wet it to keep from getting the itchy stuff on themselves, I could see that process reducing the life of the pipes. I just wear gloves or have a shower after it. I can safely say that the wrap does keep the heat in though, I can sit my bare hand on the header pipes while a bike is running if I want.
Thanks for all the input, guys, very helpful. Is there a "best" metal for shields, stainless or aluminum? Thanks again, Rod
Hey sunbeam, the timing was at about 32 degrees or so and I advanced it just a little. It's a centrifugal advance, no vacuum. I thought that should be about right at 2500 RPM. Sound right?
That should be fine. I was talking 20- 30 degrees retarded. Some times in the rush to get the engine up to speed to break the cam in the timing is not where is should be.