Header wrap and valve noise

[703MGB]

I have on my B a Peco big Bore system with the matching header. Before I installed it last year I had it coated with ceramic inside and outside to reduce the temperature and move the exhaust gas faster.

This worked fine except that I would hear the valves all the time resonating in the header. So last week since the engine was coming out for my new Overdrive transmission I had the mechanic wrap the header with header wrap.

What a huge and fantastic difference. I do NOT hear my valves anymore

 

[Steve_S]

Be careful. I've heard of problems with trapping all that heat inside the head rather than letting it escape through the walls of the header as intended!

 

[dklawson]

Trapping heat in the head by wrapping the exhaust sounds like an urban legend to me. It's not like you're somehow trapping exhaust gasses in there.

That said, I have heard from a number of people who used wrap that it shortened the life of their header. That said, it didn't stop me from doing it. However, I've never heard of wrapping an already coated header. Be sure to let us know how it works out after a year or so.

 

[Steve_S]

The guy I heard it from said that head temperature was increased overall due to the wrap preventing heat from escaping through the header walls. The gasses weren't trapped but heat dissipation was comprimised. An aluminum head would probably be one solution. But for normal street use it probably doesn't much make a difference.

 

[703MGB]

The purpose of wrapping and coating of headers is to accelerate the exhaust gas in the tubes away as fast as possible from the combustion chamber.

I had mine coated with a ceramic coating. The coating MUST be applied inside the header, it can also be applied to the exterior.

Once done you see a huge difference whereby the header is much cooler that the regular cast iron manifold.

Now wrapping used to serve the same purpose in the past but coating was found to be much more effective.

In my case I had the header also wrapped not because of temperature regulation (already done with the coating) but for noise insulation from the valve clatter.

 

[dklawson]

I still find the mechanic's comments about raising the head temperature suspect. I'd seek advice from the racers on this board and elsewhere to see what they have to say on the subject of coating/wrapping increasing head temperature. The exhaust gasses are in the "thousands" of degree range and the pipes don't represent a lot of mass to store, carry away, or radiate that heat away from the head. The head is only going to get slightly warmer than the temperature your cooling system and lubrication system will allow anyway.

Please let us know if you find out any additional information about this.

 

[Steve_S]

Actually it was a racer who I heard this from, but he is the only person I've heard comment on it. I don't remember the specifics but he was having a hard time with something which turned out to be related to excess heat. He removed the insulation and the problem was reduced. I believe the original idea was to lower underbonnet temps and keep the carbs cooler.

 

[Bugeye58]

I have all my headers and exhaust pipes ceramic coated inside and out, with no problems regarding the cylinder head at all. Underhood temps are reduced significantly, and, as my exhaust runs inside the transmission tunnel, the benefit there is noticeable.
An uncoated header that is wrapped will usually start to corrode as the result of condensation under the wrap.
I can live with valve noise, but an aluminum valve cover will dampen out much of that.
There are materials available to insulate the carbs from the heat, such as Felpro ceramic.
Jeff

 

[dklawson]

It sounds like the person who told you about the head temperature issue was using it to explain problems on his particular engine, problems that may have come from other sources.

See:
https://www.techlinecoatings.com/faq.html
Scan down to the Q/A about temperature changes.