Exhaust

[Astrodokk]

I have noticed that alot of MH's have their pipes exiting in front of the rear wheels. I have dual exhaust that have pipes exiting behind the rear wheels, which caused a big problem at CW when I had the shocks done. They wanted to charge extra for removing the hangers so that the shocks could be replaced. While I am thinking about redoing the exhaust system to a banks or gibson or just plane ol headers, where should I have the tailpipes exit?
By the way, where is the spare tire on these things?

[thenewkid64]

I think it was 83 before they factory put an intergrated spare tire carrier on the MH. My 76 has a PO installed spare carrier, but my 78 has NO SPARE! and no provision for carrying one at this time. I am trying to find the space underneath for the spare.

I have looked at the Gibson exaust, but it is spendy. Banks is too. I know it has a lifetime warranty, but I can get 2 or 3 full systems if I use regular headers for the same bucks!

I am looking into the ceramic coated headers. The kind that have the coating on the inside and the outside. The coating is supposed to reduce under hood temps and also protect the metal from the excessive heat that the exaust system produces. The Ceramic is supposed to also help exaust flow due to the smooth finish in the tube and it is said that the engine runs cooler and quieter than other headers due to the heat being pushed out the muffler. I have read all this, I have no real world experience yet.

Headers 139.00
Coating inside and out 239.00
2 free flow mufllers (Dynomax) 100.00
Pipe, clamps, hangers. gaskets 150.00

628.00 for the nuts and bolts, maybe 200 to get it all bolted on and I am still 200+ less than the Gibson stuff from CW that the chome will flake off of before I leave the lot.

I think I would save the 200+ and take my chances that in 10 years I might need to do it again. Don't forget to add an extra 60 bucks if you want chrome tips!

Any of you gearheads want to chime in and correct my assumptions please do!

[74Argosy24MH]

Spare

I have the same quandry with the spare. There is not a lot of space/clearance underneath, and it is not a convenient location. They are fairly heavy and get pretty nasty after a couple of years when bottom mounted. OTOH, short of the rear bumper mount that is the only other area I have been able to come up with. The rear mount covers my generator opening and means a flip mount and some type of cover.

Exhaust

I would spend a few more bucks on the headers. Most of the $139 ones don't fit that well and are thinner tube and flange metal. The price will double for decent ones but with ceramic coating they will be pretty much lifetime.

One thing I did was put in an H pipe, it helps low end torque. If you are thinking about OD, make sure it is out of the way. I ran it just behind the tranny crossmember and had to flatten the top about 1/2" when I installed the OD. Not going to hurt anything, just meant pulling the whole exhaust when I wouldn't have had to if it were 8" further back.

John

[PeterH-350LE]

When I had new mufflers installed, I had them move both exhaust pipes to the street side forward of the rear wheels.
It really helps keeping the exhaust fumes away from the open door during warm up and those times you are messing around. After all the gennys exhaust already exits curbside.

[torin knorr]

I have a 85 270 MH 454 that I bought from the orginal owner. It had the orginal exhaust and it was in bad shape. After taking a trip with my brother in his 30' Bounder and watching him pass me by on gentle hills, I did some research and had CW install a Bank power exhaust system.
What a difference, exceleration on to freeways is awsome, no longer do I watch my brother pass me by, but now I pass him with easy. Improved gas mileage, engine runs @ lower rpms.
I just came back from a trip to Santa Barbara and there is a grade north of San Luis Obispo that has claimed many a RV. As I approached the grade, 3 or 4 RVs pasted me trying to get as much speed as possible, half way up I was in the fast lane saying BYE BYE.. Regarding CW, I was in for a new hot water heater, they noticed a small leak in the right exhaust and took care of it .. Service is everything.

We have a saying " It's only expensive if it doesn't work."

[fangthorpe]

Our '92 300LE picked up 2 1/2 MPG ( 65 mph = 10 mpg) by installing Thorley headers and a 3" Flowmaster series 70. Had several bad headstuds that needed drilling and tapping...nasty. The Thorleys come with a Y-pipe with a 3" out that heads into the Flowmaster and then the original cat. Single 3" down the driver's side and out in front of the rear wheels. We have Jacobs wires and a stock ignition. I left the inner panels off, meaning to bleed the brakes, but a couple of trips later, I'm seriously considering leaving them off, due to the improved airflow through the doghouse. Power is good solo, but I'm trying to choose between a 502 tow motor and a Whipple supercharger so I can pull the racetrailer.

[Astrodokk]

The idea of putting both pipes out the street side forward of the rear wheels is good. It's true that while the engine is running, i get that darn exhaust through he door! Now I have to figure out brand names.
Just a thought for California dudes buying from out of state. I just went to DMV to get title and license registration. 7.5% TAX!!! Plus, they said it has to pass smog. So Monday it's going to get what as someone recommended, a pre-smog. If it doesn't pa$$, they'll fix it $o it will. Then i can smog it real like. Double the cost, double the plea$ure! This rig, which was 13K, just went up to 16K fast.

[zachc]

I am considering buying a 1989 class A 28 ft RV with a 454 in it. I have been trying to get it checked out. My mechanic said this. The exhaust pipes are red hot. He said no one (and the seller cannot be depended on) could figure out how long the seller had been driving it in this condition. Thus the intake or exhaust valves could have been at risk for burning. Even doing a compression test may not show the fact that this vehicle may have serious existing damage. Could someone please explain this stuff to me. Its all very new and complicated to me and I coudl reward whoever helps me with a shredded memory foam pillow like a tempurpedic as that is my business.

For further clarifiction. apparently the engine block runs hot and gets the manifolds hot, now the manifolds or something is made of stainless steel, which apparently makes them less likely to warp or easier to fix if they do warp.

I guess a real danger is that its 'running lean' . Please somebody help me understand whether it is a terrible mistake to buy this RV.
Please call 775 746 1355 or 1 877 212 8951
zanvibar@hotmail.com
Thanks!!!

[ALANSD]

the 454 manifolds get very hot, that is a common issue that can create some other problems, like burnt wires, and such. The statement "red hot" though may not be the reality of it...they just may be HOT!!
So onto the next question...does the motorhome run strong? Is the water temperature in the 160-200 or so range when up to speed? Does it have adequate power? Does it start easily? Is the trans shifting smoothly? What shape is the body and interior in? Do the other systems work...like a/c/ generator, heater, water system, and so on, we could go on for awhile on this stuff....

There is a lot more to worry about than engine heat.
If you know absolutely nothing about the mechanical stuff and really don't want to learn I would suggest staying away from the vintage Motorhomes. However, if you are ready to tackle some projects and not afraid to turn a wrench...then read on, in these forums you will find out all you need to know to do a whole lot of self restoration and maintenance.
Of course if you have a trusty RV mechanic and a pocket full of money to burn, its a different story.

[swebster]

OK...I'm getting paid on the completion of a freelance gig and will have about $750 to spend on the Airstream. Is laundering money from the budgetary goddess against the law?

As much as I want to plow all of this into remodelling the inside of our baby I know I still have some things left on the "mechanicals" list. The big one being the replacement of this goofy exhaust system the PO installed. It's gotton to be downright embarrasing at stop lights. (rattles, squeaks, leaks and putters.)

Still can't afford a Banks so I'd like to go with a Thorley, Dynomax setup but can't seem to find good information on specific parts, compatibility, where to buy pipes, etc. Can you buy a bolt up setup or is cutting and welding required? What about the crossover?

Also wondering what to do with the air pump and hardware on the existing manifolds. Kentucky just abolished state emissions testing so maybe this can find its way out of the doghouse?

Any and all advice, sources, opinions, etc is appreciated. I'd like to buy a "kit" if that is possible but realize that sourcing each component on it's own might be cheaper.

(I wanted to add that I phase two would include a replacement intake manifold, carb, ignition and distributor. So I want to make sure everything will work together)

[Astrodokk]

Apparently both my exhaust manifolds were cracked, causing not only pollution in and out of the MH, but that chug chug chug sound at the lights too. After much reading and website searches, I chose the Doug Thorley headers with H crossover pipes behind the tranny (told them to leave space for a Gear Vendor...doesn't look like it though), Flowmaster 70 mufflers (no catalytic converter on this model), and had the pipes come out the driver side in front of the rear wheels. Sounds like a darn race home now, but I like it. Supposedly low end torque will be better...I'll find out next week going over the Grant's Pass in Oregon. BTW, do I need chains in these in snow?

I had previously replaced my carb with an Edelbrock electric choke, although now I think I would have kept the hot air choke stock if I did it again. It has spacers apparently for cooling?

Anyway, I didn't have the $$$ to get a new efficient intake manifold, but it all works fine.

With the money you get from that job you mentioned, I think you can get some of the parts you want. I paid people to do the labor for me, and it was quite a bit. If I had done the labor myself, the parts alone would have been well over the $750. range. Then, I still would have had to pay for someone to fix what I had done afterwards

[87MH]

"Advice and Sources Wanted
OK...I'm getting paid on the completion of a freelance gig and will have about $750 to spend on the Airstream. Is laundering money from the budgetary goddess against the law?


Also wondering what to do with the air pump and hardware on the existing manifolds. Kentucky just abolished state emissions testing so maybe this can find its way out of the doghouse?

Any and all advice, sources, opinions, etc is appreciated. I'd like to buy a "kit" if that is possible but realize that sourcing each component on it's own might be cheaper.

(I wanted to add that I phase two would include a replacement intake manifold, carb, ignition and distributor. So I want to make sure everything will work together)"


Steve

re Budgetary Goddess

Don't Ask, Don't Tell

Works for just about everything

As for as the mods on the engine.

It's very important that you do it once, and do it right.

To ensure that you have the practical experience, I hereby volunteer my unit so that you can practice on removing the engine jewelry and find the right combination of carb, electronics, etc.

Just come on down any time with your tools and you can get started.

Thanksgiving weekend works for you?
__________________

[swebster]

Dennis,
You are truly a noble and generous man. If you lived a little closer I'd be happy to oblige.

Astrodokk,
I'm using some numbers from one of Brett's replies earlier in this post. I'll be doing all the work myself (if no welding is required) because I'm cheap and twisted enough to actually enjoy cutting rusty tubing under a vehicle in November (mostly cause I'm cheap) so hopefully I can source parts myself and install in phases. Phase one - exhaust replacement (i like the curbside output idea a lot) and phase two - change intake side and ignition (this phase is not funded yet)

I'm getting 8.4 - 8.7 mpg (hwy) now so I'm hoping this will repair what is broken and have the added benefit of adding some torque and fuel economy. Shooting for the magic 10 mpg number!

[87MH]

FWIW, I would LOVE to get to 8.0 mpg.

Got close to 8 earlier this year, but then the trip to the Rockies I experienced as little as 4-5.

Lately I've gotten 6-7.5, but I really cannot explain the differences in mpg.

Consistent driving patterns at 60-63 mph, same load (all water tanks empty), and not towing anything.

With the infra-red thermometer, I can check for dragging brakes, but a new distributor and ignition system might be getting higher on the "wish" list.

Haven't ruled out breathing problems, yet, the intake air routing plenum is crimped just in front of the metal intake horn on the air cleaner assembly, and I might bypass, or find an alternate feed, for a trial tank or two to evaluate if that is a problem.

[87MH]

"Phase one - exhaust replacement (i like the curbside output idea a lot)"

FWIW, I would think drivers side exhaust would be preferable.

The few times I've stopped and left the main engine running, the exhaust was "right there" when I exited the coach.

On the other hand, having personally spent a good deal of my time on my back underneath the chassis, I cannot recall a "good" place to cross the exhaust over.

The times that the curb side exhaust was a problem (so far) would (do) not tempt me to fabricate a drivers side exhaust for both manifold banks.

BTW, my unit does not have a crossover (except internal to the engine)

[Astrodokk]

Yeah, I think that's what he probably meant, the 'Driver's Side', aka Street Side. I've been thinking of moving that little pipe coming off the generator to the street side too. I've stopped at times and had the genny on, and although it's propane, I still smell something and don't like the idea of it coming in on a breeze as my door is open. Happy Thanksgiving everyone!

[overlander63]

Originally posted by 87MH
FWIW, I would LOVE to get to 8.0 mpg.

Got close to 8 earlier this year, but then the trip to the Rockies I experienced as little as 4-5.

Lately I've gotten 6-7.5, but I really cannot explain the differences in mpg.

Consistent driving patterns at 60-63 mph, same load (all water tanks empty), and not towing anything.

With the infra-red thermometer, I can check for dragging brakes, but a new distributor and ignition system might be getting higher on the "wish" list.

Haven't ruled out breathing problems, yet, the intake air routing plenum is crimped just in front of the metal intake horn on the air cleaner assembly, and I might bypass, or find an alternate feed, for a trial tank or two to evaluate if that is a problem.

Recently on our vacation, I noticed something. When I drove 55-60, I got 10.4 MPG. I then speeded up a little, and drove 60-65, and got 9.9. I then drove 65-70, and got 9.0...Like the little anti-speeding signs say, how fast can you afford to go?
Terry

[swebster]

Dennis,
You are right about driver's side exit (also this is what I meant). I'm not sure how to cross the driveshaft "gracefully". Figuring this out would put both engine exhausts and the genset exhausts on the driver's side AWAY from the door.

I've always had decent mileage. Put a new cap, rotor, wires and plugs in right away. The worst I got was 7.8 in the mountains on I-40 in Tennesee.

Something is definately amiss on your powerplant. If you are not towing a toad and running with the holding tanks dry you should be getting better than 4 or 5 mpg.

[overlander63]

Dennis, you might want to take the MH to a garage and have the carburator adjusted. It sounds like it may be on its way out, which they can also check by putting the exhaust into a four-gas analyzer.
The absolute worst I personally think you should get is around 8, and better with the A/C off.
Hmm... Do you run your generator while driving? If you do, and the generator runs off the same tank as the engine, that would make a huge difference with mileage. Some people do this to run the roof A/C and refrigerator while driving.
If it is not full electronic, you may want to check the vacuum advance on the distributor, and make sure it is working. If it is not, that will cost you mpg also.

Terry

[PeterH-350LE]

Originally posted by 87MH
FWIW, I would LOVE to get to 8.0 mpg.

Got close to 8 earlier this year, but then the trip to the Rockies I experienced as little as 4-5.

Lately I've gotten 6-7.5, but I really cannot explain the differences in mpg.
....

4-5 sounds right for Rocky mountain driving.
6-7.5 is better than the average MH gets sporting a 454
8 is under optimal driving condition, no head wind, flat land and going 60 mph max.
We often underestimate the weight of the "stuff' we gradually pack.
A full gas tank adds 500 pounds.
Carbs have to go really bad to cause a dramatic decrease in fuel economy, which usually results in black smoke, black oil and fouled plugs.
"Hot" aftermarket ignition systems do make a difference.