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MG MGB GT V8 Factory Originals Technical - Headers

Hi

I have a 74.5 MGB Rover 3.5 with block hugger headers.
When I did the engine conversion I beat up the inner fenders to get the headers to fit. In hindsight I am not sure I had to do that.
However I used bondo to fill it back in and every 2-3 years I have to pull the engine and redo the bondo because it has bubbled from the heat.

My body man wants to cut out the inner panels and weld new ones (from a donor car) back in.

I have discovered a product called ‘lap metal’. http://www.alvinproducts.com/Products/Products.asp?id=2 They have one product which is good to 1000F degrees but requires heat curing of 425F for at least an hour to cure. Or they say I can use Infrared lights to cure it. Getting IR lights for a one off use seems like a waste.
They also have another product which endure heat up to 350F. And it seems to me if the product works as they say it will it will be a whole lot faster/cheaper to repair

So the question is what temperature do the headers get up to? They are ceramic coated and there is at least an inch clearance between the header and the inner fender.

Thanks guys. All the best for the holiday and the New Year


Bruce
Bruce Mills

Know someone with an infrared temperature gun? Easy to find what your headers are running.

I would think that the ceramic coating would be keeping the heat exchange into the engine bay down.
Rick Ingram

Bruce,
Below is another post on this same topic I have done a cut and paste on.
There may be some useful info here but to get it truly accurate the only way is to have yours measured.

"All this high temp and ceramic paint talk has me baffled. Just how hot do you expect these things run??
Here are some temps I did to answer a question last summer.
Jeff

Here are the readings I just took with a contact themocouple, rather than infrared.
1275, at operating temp, idling after a 10 mile drive.
All temps in Fahrenheit, surface temps only.

Top of head at thermostat housing: 163.1*
#2 stud at intake/exhaust manifold: 186.3*
Exterior of exhaust manifold: Front: 289.0*
Center: 290.1*
Rear: 287.0*
Intake Manifold flanges: Front: 163.2*
Rear: 167.4*
Head at rear exhaust manifold mating flange: 220.8*
Head at #3 plug: 158.8* "

Cheers , Pete.
Peter Thomas

Thanks Pete, that is what I was looking for. I didn't know what temperature they would be running at but I would have thought it would be under 350F as you have stated.

With this information I feel confident that I should be able to use the filler rated for 350 with no adverse effects.

Bruce
Bruce Mills

The paint kept peeling off the right-hand inner wing on my factory V8 with tubulars, and the metal was rusting. It was also peeling and rusting in the arch, and eventually pin-holed, which was an MOT fail. I said to the tester 'what about if I cut huge holes and ran the exhaust through them' and he said that would be fine, but a rust hole isn't no matter how small. So I cut and patched, and then fitted a piece of shaped stainless sheet over the repair, larger than the repair, and that reflects the heat away and it hasn't been a problem since.
Paul Hunt

Hi Bruce:
Long time since we've talked! I expect that you've got a season's running on your flares by now.

I didn't reshape my inner fenders but did "replace" some metal. I remember that you did make louvers in your upper rear fenders (I think?) but I went with this solution. Some TIG welding and grinding and they look stock after paint. I happened to have access to some old school lockers.
I'll email soon to catch up.
Regards and Merry Christmas!
Phil

Phil O

Bruce,
Some additional information I have from a mate in the dyno testing business.

This is a cut and past from an ongoing discussion on ceramic coatings...

"just to give you a idea, we did some tests for hi octane ceramic coating a few weeks back..

uncoated 1 3/4 mild steel headers on a VU SS UTE would get to 640deg after 1min of high load.

coated they only got to 310deg.. i couldn't believe it, i always thought the coating was a bit of hit and miss etc...

there was a drop of 100deg while doing a power run as well..."

The vehicle is a GM 5.7 ltre V8.

Hope this helps.

Pete.
Peter Thomas

Bruce, have you considered "lead" filler? Eastwood sells a lead free "lead" filler... the listing says "plastic" range is 428 - 932F Can be powder coated & cured at 400F so should easily handle the under hood temps with ceramic coated headers. Info here... http://eastwood.resultspage.com/search?p=Q&ts=custom&w=lead+free+solder

Rob Ficalora

Once I stripped the paint and filler I ordered used inner fenders. Live and learn. And I continue to learn lots from this car.

Thanks all for the advise


Bruce
Bruce Mills

This thread was discussed between 21/12/2008 and 29/01/2009

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