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ALANSD 03-01-2002 09:05 AM

What type exhaust configuration do you have on your motorhome? Mine is dual exhaust, and seems to have a free-flow muffler on each. Just curious, as to what was stock if we can tell at this point.

rdm 03-01-2002 10:40 AM

Our 325 has dual exhaust I believe this was standard. The system could likely benifit from a fresh air intake system and K&N air filter plus the addition of high flow mufflers. this likely remove some of the retained heat from the big block 454.

ALANSD 03-02-2002 02:29 PM

Thanks for your info. I just received my "Tornado" from Camping World..I stated my skepticism elsewhere, but having done some research I am going to try it and see if it will aid the engine breathing.
Any ideas on exhaust changes? Banks looks great but is quite expensive. I know there are a lot of options for the 454.

PeterH-Airstreamer 03-03-2002 08:13 AM

The stock exhaust manifolds on the 454 are constant source of trouble, especially when they get older. Besides that they restrict the exhaust by design. Eventually, I would like to put some headers on there, any input other than banks would be appreciated.
Right now, I have a leak on the drivers side, which goes away after the engine gets warm. But I have to fix it soon, since it will get worse.
The problem is that one of the bolts is frozen to the head. I guess, I will have to use a blow torch to heat it up. But it's right next to one of the power steering hoses. Any suggestions?

ALANSD 03-04-2002 10:17 AM

I used to soak a bolt like that with CRC (similiar to WD40) and let it sit overnight, soak it again sometimes and let it sit again, trying to inch it out a bit at a time. Its painstaking, but might loosen it.

thenewkid64 03-04-2002 07:43 PM

Exaust Systems
The prior owner of my MH said he replaced the factory exaust manifolds with Headman headers. I cannot be sure as they have no paint or markings left on them. It also looks like he replaced the rest of the exaust system with oversized pipes. Prior owner was a hod rod nut.

I will tell you this, the amount of power I have at my disposal is AMAZING!:D When I picked up the rig my wife followed me home in the car and she had problems keeping up with me as I merged onto the tollway from our breaks.

From what I can tell the carb has been rebuilt but not modified and I am running a stock airfilter.

Have only driven it home after purchasing but the 200+ mile trip was great.


PeterH-Airstreamer 03-10-2002 04:26 PM

I finally got the frozen manifold bolt out. Warmed the engine up to operating temperature and use pure force. Must be the first time this manifold came off, since it didn't have a gasket.
Had to pull the plugs and was pleased to see the nice light grey color. Jacobs energy pak is doing its job, no more wet looking plugs.

ALANSD 03-11-2002 06:48 AM

I need to take a peek at Brett's setup. My rig has decent power, and I see receipts for redone headers, but I think they are still stock spec. My "tornado" got to me , and was the wrong size...for a later model 454. They are sending me a replacement.
Meanwhile cleaning the carb seems to have made a nice difference in idle, it always seemed to high, I think my choke was sticking.

thenewkid64 03-11-2002 08:03 AM


Why did you go with the Jacobs system?

Did it improve your performance? Mileage?


PeterH-Airstreamer 03-11-2002 05:20 PM

Jacobs system
The performance increase is remarkable. I am getting 8 plus mpg, mostly city/country road driving. I hoping to see closer to 10 for Interstate driving.
I have known about their RV energy pak for some time and almost put it on my previous RV.
I was looking at their porcelan spark plug boots and decided to give the entire system a try.
No more fouled plugs and entire new sense of power.

PeterH-Airstreamer 03-12-2002 06:56 PM

gasket or no gasket
Had to get a new exhaust manifold, the old one was leaking on three cylinders. After resurfacing and putting in new studs, I would have spend half the money for a new one from the dealer. (wholesale)
The big question, should I use a gasket or not?
Dealer says no, book says yes?
The surface of the cylinder head is in good shape.

FrankR 03-12-2002 07:34 PM

GM Big block exhaust manifolds
The motorhome I had before our bus was a GMC front wheel drive. Power was extracted from a 455 Olds. Yum yum, lots of power, but the exhaust manifolds were problematic. After much testing and trying, I made some changes in the factory exhaust. The stock exhaust was replaced with Jardine headers. Very heavy flanges and pipe size. The 2 inch dualls were removed and a single 3 inch pipe installed with Borla turbo muffler. The headers were wrapped with cloth heat material and retained with stainless .062 wire. No catalytic muffler and the exhaust pipe came out side of coach to have very few bends. The pipe between headers was 2.5 with flanges for any repair. The inner fender water splash panels were removed, with scoop fashioned under front sheetmetal. The hood was opened to allow hot air to escape. Transmission did not share radiator for cooling, seperate stacked plate cooler with radiator fans on switch and seperate t-stat control. The timing was adjustable from driver's seat. Frank

FrankR 03-12-2002 07:40 PM

More on temp control.
The front scoop, inner panel removal, and hood vents are to have lots of outside cool air carry away the engine compartment heat. The air cleaner was also enlarged and connected to the front for a ram effect. Engine compartment air is very poor for combustion, milage and performance. Every little improvement helps. A trans temp gage are very important as well as a trans shift kit. It is of great value to have a tachometer to know when to pick a new gear in high demand situations........Frank

FrankR 03-12-2002 10:14 PM

exhaust manifolds
I use gaskets as they help take up some clearance as the manifolds are cycling. The manifolds must be flat and straight. There are very special exhaust and intake manifold bolts. In some applications, as in boats, the block is heli-coiled and studs are used instead of bolts. Most bolts are grade 8 and are colored green. Enough......... Frank

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