Dual Exhaust: Custom made or do it myself?

[Saskadude]

Sent: 3/6/2008

Want an opinion here.  I'm looking at putting a dual exhaust on 1973 GMC Van chassis class 'C'.  Sadly it's not a Winnebago, but it's plenty old...  I wanted to know if anyone knows of an inexpensive kit available that I could put on myself, or if I should go to a shop and have them custom make one for me.  Trying to do it inexpensively and the "custom" job makes my wallet want to cry...  Cheers!

[ontheroadagain]

Sent: 3/6/2008

I was shopping for a dual setup and here is the best priced set I found http://www.autoanything.com/exhausts-mufflers/61A2904A0A0A2418412.aspx but i'm going to go with a  single system that uses a mid 90's y pipe with the 3in. outlet to a preformance muffler with a 3in. inlet and a 2.5in outlet to save some money and have less pipes to rot and leak

[Saskadude]

Sent: 3/7/2008

The website you listed is a good one, wished it included mufflers though.  I'm going to go to a muffler shop today to see what kind of price they can offer before I make a decision.  I'll post prices (I'm in Canada, so they will be in Canadian currency) when I do a little more research.  A friend told me that PAW is a good option also, going to check them out today.

[ontheroadagain]

Sent: 3/7/2008

magna flow seemed to be the best buy because they are stainless steel and they have a lot of different designs & lifetime warranty just call them 1-800-824-8664 and tell them what you have and they will recommend the best muffler. this link is for the dealer with the lowest prices http://stores.ebay.com/Greyhound-Performance if you don't see the one you need send him a email with the number you need and he will give you a price and set up a listing if you want to buy it

I have a 1980 chevy class c mnnie winne

[Froggy1936]

Sent: 3/15/2008

Hi, I am just getting underway with installation of headers on my Mini Winnie  Class C 1977 Chevrolet powered  I purchased the headers complete new in box with all parts & instructions on E Bay for $ 175.00  incl shipping & handling there were a lot of other sets still available Chev 350   1955 thru 1999  Still have to buy pipes, mufflers & hangers & clamps  I talked with local Monroe muffler shop they said they can make me a R/S tail pipe after i install the rest of system  It looks like the biggest problem is going to be clearance at L/S header with floor of cab right where dog house seats to floor next to accellerator pedal Cly head is very close to floor Modifying floor creates problem with dog house seal I will take some pick for you if you want  Frank

[Saskadude]

Sent: 3/16/2008

Looking forward to seeing the pics.  I have a similar problem with clearance, especially since it doesn't look like long tube headers will work.

[Lefty]

Sent: 3/16/2008

There are numerous prior discussions regarding the installation of headers on Dodge chassis, but little that would relate to a GMC/Chevy van chassis. A van may gain more power from headers/ dual exhaust, but at the cost of increased heat under the doghouse, and also a reduction in low end torque. headers and dual exhaust are primarily for high revving engine applications, where the stock single exhaust may not be able to flow a sufficient amount of exhaust gas. In motor homes, the opposite is usually the case. Many engines rarely, if ever exceed 4,000rpm, and the stock exhaust is quite capable of handling that amount.
The exception would be if you have also upgraded the rest of the engines components to flow more air. Things such as porting the heads, boring the block to a larger size, installing a better flowing intake, using a bigger carb., using a higher lift/longer duration camshaft, installing larger valves,etc... All of these affect how much air the engine can flow, and thus how much exhaust the engine produces. Replacing one component without upgrading the rest to match usually negates any gains that you might see, and is a waste of money. An example would be installing a high lift cam in a 2bbl powered engine, the 2bbl could never flow enough air to feed the engine enough air to take advantage of the cams potential.
The best way is to think in terms of each parts ideal operating range and capabilities, then look for and weaknesses or problem areas. Try to keep all systems as closely matched as possible for the best results and minimum waste of funds.

[Oz]

Sent: 3/16/2008

Excellent, excellent explanation, Lefty.  In a much more basic form, a member once told me, the equation for improved performance is... more air in + more air out = increased performance..  If you don't have what's on both sides of the plus sign, you don't have an equation, or equality.  So, without equality, you suffer on either end of the equation.

Headers are designed with two distinct divisions, one for high RPM and one for low RPM....high being mid-range (which our motor homes rarely, if ever see) and off-idle to mid-rage.  That's what you need to feed your dual exhaust.   And, you need to consider what engine you have.  A 440 takes up nearly all the space in the engine area so, by default, it has little air flow over and around it.  Also, you have to consider the location of vital components in relation to the heat source (headers/exhaust manifold).... FUEL lines... we've had members who's fuel and BRAKE lines have been literally melted through with the use of unshielded headers.

Which brings me to the next point... ceramic headers vs. chrome or unshielded.  This could be disastrous!  Without proper shielding, you will have melted spark plug cables/boots, fuel lines, brake lines and other engine electrical wiring which run near the exhaust... best scenario I've read according a member testimonial... the rig died.  Worst scenario... brakes failed and and engine fire started as well.  Would you take these chances?

A 318 has much more air space around it and the component location of  spark plug & distributor wires are much better to avoid the heat of the exhaust but you stll need to take a detailed look at how everything is routed and make changes and shielding as necessary.

But again, as Lefty said, if you don't feed the intake of the engine with increased fuel/air... adding a more breathable exhaust will have more negative results than  postitive.  Yeah, it'll sound cool, but wait until you hit your first hill!

We had  a member that swore his 3" exhaust was the bomb!  No arguments accepted.  He made no upgrades in his carb, intake or anything else Lefty mentioned.  Surprise, surprise... after his first trip, he made a post wondering why he had no power going up hills...

Ergo, go back and read Lefty's reply again.  You dont' have to be "Mr Mopar" to understand there is a balance between intake and exhaust.  Choosing the proper components to improve both intake and exhaust, and installing the necessary heat protection associated with these upgrades, can maximize your engine's potential.

[denisondc]

Sent: 3/16/2008

If I wanted to spend the time/money to get my Winnie to the peak of its performance, I would do a valve job, put in new piston rings, get the distributor rebuilt, and put on a rebuilt carb. Beyond that I don't think I could improve the original design, for all around countrywide usefulness.
When and If I get to 'restore' mine, the only customizing I would plan, is to make an access lid for the master cylinder reservoir, to have a slight 'crown' to the new roof with a little more insulation up there, and use modern drain valves for the holding tanks - ones that parts are available for.

[Froggy1936]

Sent: 3/16/2008

OK I Will try to keep a cost & pictorial record , Plan to upgrade engine later (still runs well). Has Quadrajet with large open air filter,  I only have a few wires to move to outside of frame (away from heat) I have known problem with starter solenoid that wont operate after short shut down (filling gas tank etc)  I think i will have better air flow at starter area w headers If they do not cure problem next step is a fan directing air across solenoid on a timer upon shut down (as used on Audi Engines) I know i have to add shielding as necc for fuel /brakes/wires/ doghouse , etc Also a few minuets of idling before shut off will help dissipate exhaust heat (headers cool much faster than cast iron manifolds) But as with all modifications there is a learning process.   I think i saw somewhere SOB said he was going to try to collect and separate Chevrolet/ GMG specific info from  Mopar  to make these kind  of projects easier to research (would also be time to separate Ford info) I can see SOB now smacking his head and saying MORE WORK FOR ME !!!   Sorry for mentioning it.    Frank. P. S. You do a fantastic job Congratulations Mark.

[Lefty]

Sent: 3/16/2008

Froggy,
From your response I can point out a couple of things you can do right now, for little cash, that will help.
1: Replace that open element air cleaner that is sucking scalding hot air into your engine with a closed unit ducted to suck cool outside air. Potential gain: 10-30hp
Several members have constructed home buit units from sheet tin, rivets, a couple of furnace floor ducts, and metal dryer vent tubing.
2: Hot soaking of the solenoid on GM vehicles is a common problem, which is why sensible car makers mounted a remote solenoid away from all that heat. Luckily, it is easily cured by installing a heat shield onto the starter to protect the solenoid. You can get them from almost any auto parts store. Another option is to replace it with a newer style high torque starter, which is much smaller and thus has more distance from the exhaust. Just make sure that you get one for the same number of flywheel teeth as yours. There are two different GM teeth counts, 158 and 162 and if different, the starter nose will snap off.

[ZR91]

Sent: 3/18/2008

Lefty,

-You have obviously had some bad experiences with headers, as have I.

-just because a set of headers will physically bolt up to your engine does not guarantee that you will see any improvement.

That is why I suggested Heddman headers. After much online research (and many long distance phone calls) I realized that they do indeed offer custom headers for motor homes with guaranteed results.

So, how did they work for me?

1) They are fairly well made, although I had to spend 1.5 hours die grinding a LOT of welding slag out of the tubes.

2) The collector bolts they supplied snapped in half on our first trip out.-Try finding a hardware store at 11PM ! You should use grade 5  3/8 by 3" SS bolts with NYLOCK nuts if you want them to stay together.

3) The installation instructions were WRONG- the only way to install the passenger side header is up from the bottom-after you lift your MoHo up about 18".

However, beleive it or not I still think it was worth the hassle.

Why?

Better fuel economy-about 1.3 mpg (combined with a true dual exhaust)
Improved acceleration
Much, MUCH cooler engine cover, and a 10 degree drop on the temp gauge.

Is it worth it?
Well, yes and no. If you are a do-it -yourself kind of person with time and tools, sure.

Otherwise if I had to pay someone to do what I had to do, I would just keep the stock exhaust manifolds and then just run a set of true 3" duals....

Jay

[melyash]

Sent: 3/19/2008

My only question would be are you going out each side or dual off one side. The Carbon Monoxide fumes would be best left away from the entrance area, in case you might want to run it for a while to charge batts. Just a thought on safety. Yes a cross wind can carry said exhaust under or around the rig to you, but in general you would be hard pressed to get me to put the exhaust on the right side.

Matt

[Lefty]

Sent: 3/20/2008

I have had Hedmann Headers installed on my 1983 Chevy C-10, with a 383 stroker motor, since I built the engine in 1999. They have not needed to be removed since the original installation. With that set-up, I did use an after market plug wire holder designed to drop each plug wire straight down to the plug. I also used special plug wires designed for headers. And as an added precaution, I used heat sleeve insulation on each plug wire, and heat shields over the boots. I have never had a burned wire. I also used he same heat sleeve on the fuel line going up to the carb. And some over the wiring that goes to the starter. Overkill? Maybe. Cheap? Nope. But I have never had a burned wire, or fuel to boil in the line either. My starter is the original style, which was the big one. Clearance was less than 1" from the header. I used a Mr. Gasket Heat shield on the starter and have never had a hard start problem.
The only issue I have had, is replacing the standard collector gaskets with a set of copper ones about 5yrs ago. It has not leaked anywhere since.

My advice? Use quality parts. Don't take shortcuts, and plan ahead for the worst.
Heat sleeve tubing is available in rolls about 10' long and can be cut to length. Spend a few bucks more and get the matching spark plug boot covers too. Build a custom set of wires yourself, sliding the sleeve over the wire before installing the boots. Use only high-heat racing boots designed for headers. They can be bought individually from Napa. Take care to cut each wire to exactly the length needed with no excess that could hang loose. Use a quality holder that will hold the wires clear of the header tubes. Cover anything like wires of fuel lines that even look like they might get hot. A simple heat shield can be made from plain sheet metal.
Never use header wrapping tape. It does lower the under hood temps, but at the cost of intensely increasing the heat inside the headers. It will drastically shorten the life of the headers and any gaskets, and usually instantly voids any warranty you may have.

[Froggy1936]

Sent: 3/26/2008

Well I got started on the exhaust, Had to move the servo for the cruise control (it was rubbing on the dog house)  When I removed the distributor cap I found my centrifugal weights were rusted in place & vacuum advance was bad (had to overhaul dist)  Cannot see timing marks from any angle at damper. Will have to adj timing on the road . Now to the exhaust of the 6 bolts holding Y pipe to the manifolds 5 snapped off  (had to drive a 1/2 in socket on to rusted 9/16 nuts)  Then had to hammer a 13 MM socket onto manifold bolts (rust again)  Had to use a 1/2 in breaker bar to break bolts loose (more rust) If one  of these snaps it will probably mean removing cly head (no room for drilling) Ah ha   r/s manifold off  That was the easy one.   (had to destroy factory spark plug heat shields)  Impossible to get at bolts with manifold in place And engine in chassis . All bolts were soaked daily with penetrating oil for the last week   (waste of WD40)  Tomorrow  L/S  & try to save L/S tail pipe. & more pics will post them when done.

[MSN Member]

Sent: 3/27/2008

I used to keep a repair kit at my old shop in the 80's and 90's that had a drill bit and plastic bushings to permanently fix this problem.
If you have a GM HEI ignition system your cap and rotor should be replaced every few years.Having the ignition coil sitting in the cap right on top of the rotor tends to be hard on them.
And when the rotor leaks the electricity goes right to ground by way of the advance weights.This makes the 2 pivots wear and rust.

[Froggy1936]

Sent: 4/6/2008

Thanks for the tip, Luckily the kit i purchased contained new weights with the holes enlarged to accept the plastic bushings (incl) with new springs etc and a new coil & cd unit with primary wires and cap & rotor, Now for the L/S manifold I had to loosen both motor mounts & remove L/S mount & bracket to lower engine far enough to make it a straight shot at manifold bolts thru space between frame and fender well (to facilitate driving socket onto bolts) Also Had to remove York A/C compressor & bracket  to allow engine to drop far enough (now as i am half way to replacing water pump (wich i already carried as a spare just in case) I will also do before reinstalling A/C comp. Since i had 1 mount out I replaced all 3 of them at this time. (Tranny mount was separated) YES, all the manifold bolts came out. Then I had to remove the metal fuel line (which ran inside the frame and was actually in the way of the R/S header, besides heat problem )To the outside of the frame. And the weiring on the L/S frame rail from inside to outside. I am also going to relocate (add On) cruise control from above L/S header to O/S of L/S frame rail (heat again) Hope to be able to use original speedo cables. More pics, Till next step.

[Froggy1936]

Sent: 4/17/2008

Update ,To insulate brake line inside of R/S frame rail  I covered the opening with sheet aluminum (pop rivets & hose clamps) the radiator fan blows air through the channel to cool brake line.Starter shield installed, Both headers are installed with copper gaskets, Had plenty of room at floor on L/S header,New water pump finished, A/C compressor reinstalled with modified idler pulley(to stop belt slip A/C on with York compressor at idle) belt now has 60% contact with pulley. Reinstalling spark plugs requires using a box wrench and an open end (cannot get socket on some plugs with headers.) Routing of plug wires next problem, Later Frank

[Froggy1936]

Sent: 4/26/2008

update  2   Plug wires, had to install & route then cut to length then remove and take to vise to install dist end terminal (reuse orig boots HEI) then reinstall wire 8 times  Install asbestos wire protectors at plug end (All parts for this operation From Advance auto parts and Pep Boys )  Removed original dash mounted shifter & cable (Personal decision) Install B&M Z Shifter on floor next to drivers seat. Very nice unit with back up light switch & neutral/park starter switch (Much easier to operate than original) Also easier to protect from header heat than original. Installed transmission temp gauge. and radiator cap with temp gauge on face of cap . Decided to leave cruise control in original position and install heat shield  would cause major problems to relocate. More photos  Now last problem design ant build exhaust system. Later Frank

[Froggy1936]

Sent: 5/10/2008

Update 3 Exhaust completely installed (est 100 hrs) If I knew how much trouble this would be i would not start on it. This is a major job Results not yet known, Decided to make my own R/S tail pipe (used correlated bendable pipe) Ha, its amazing how strong a piece of this stuff is with a large 6 in bench vise & a 8 ft long piece of 2 in steel pipe it was very tough to bend. Another side job (wile veh is raised) was to remove fuel tank to replace suspicious hoses (30 yrs old) Generator feed hose was very bad others were cracked at the ends When fuel tank is installed at the factory there is no body on the frame and workers install all clamps facing up making them impossible to access with tank in place had to jack up body 1/2 in to get pinched filler pipe out from between body & frame (note this is not a 1 person job) reinstalling tank (WARNING make shure tank is completely empty sloshing fuel makes it very difficult to control tank supported by floor jack) Now if it will stop raining & warm up again i will be able to refill tank & check exhaust also finish taking pics which i will post next with total cost Frank

[denisondc]

Sent: 5/10/2008

 I made up my own tail pipe, getting a 10' length of straight 2.5" pipe.  I cut it with a hacksaw at each distance where I wanted a 'bend'.  If I wanted a 10° bend I made the cut at 5° and welded the ends back together with them rotated 180° to each other.   It took about 6 bends - lots of hacksaw work.    That was in 1991, and my homemade tail-pipe is still there; looking pretty rusty now.

[Froggy1936]

Sent: 5/11/2008

Well i fired er up Sweeeeeet now it was worth it!! Cost over $670.00 in parts incl headers That does not incl A/C idler,water pump, motor mounts, transmission mount, floor shifter, fuel tank or distributor repairs. Once you start down this road you cannot go back. If you want to eliminate the original manifolds it gets involved. Also not incl MIG welder (for fabricating pipes). I figure if I drive 960,000 mi i will save that cost Ha Ha Ha Ha . Now if I can attach pics so Motor Arbeau can get an idea of whats involved. Clearance is no problem. Frank