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1975 barth 454 headers install
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I have an exhaust manifold leak and am thinking about installing a set of headers.
Has anyone else done this?
Posts: 2 | Location: Ontario Canada  | Member Since: 02-27-2023Reply With QuoteReport This Post
Glassnose Aficionado
Supporting Member of 2/09
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I put Doug Thorley headers on my 78 and had a 2 1/2 inch exhaust fabricated. Cost wise having the manifold shaved and a new gasket is much cheaper, but for performance the headers are the way to go.

79 Barth Classic
Posts: 3482 | Location: Venice Fl. | Member Since: 07-12-2004Reply With QuoteReport This Post
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"you get what you pay for" is especially true with headers. The cheap ones use a 1/4" cheap steel for the cylinder head flange. More expensive ones use a 3/8" higher quality steel. Thicker and higher quality means that the seal with the head will be better and is more likely to last forever.

Headers will give better performance, but you also need to know that you might need to speak a bit louder inside the RV.

happy motoring!

1987 Barth 27' P32 Chassis
Former State Police Command Post
Chevrolet 454
Weiand Manifold, Crane Cam, Gibson Exhaust
Posts: 531 | Location: Massachusetts | Member Since: 07-28-2006Reply With QuoteReport This Post
Official Barth Junkie
Supporting Member of 1/24
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I put Thorley headers on my 86 and reinstalled the dual exhaust system. 2 1/2 inch back to mufflers, 3 inch stainless behind the mufflers. Engine ran smooother at idle. Better performance. No regrets. I did not notice an increase in noise.

Here is a link to the headers:

Dual exhaust:

Getting rid of those heavy red hot manifolds will allow the engine bay to cool down faster after shutdown.

"98" Monarch 37
Spartan MM, 6 spd Allison
Cummins 8.3 325+ hp
Posts: 5197 | Location: Kalkaska, MI | Member Since: 02-04-2011Reply With QuoteReport This Post
Supporting Member of 8/11
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Matt is right, the thicker the better, you truly do get what you pay for. I was a motorhome specific mechanic for over thirty years and installed both Thorley and Banks with great success. The Banks units feature a 5/8” Blanchard ground flange that is a metal to metal fit, the gaskets are the number one failure point on header installations. Of course that only works if the exhaust manifold surface on the head is still smooth. If you must use a gasket due to deformities, use one composed of extended graphite.

The 454’s are not prone to breaking manifold to cylinder head bolts but if some do, don’t panic! I can help there too.

Good luck
Billy T

Billy & Helen Thibodeaux

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