replacing exhaust system ('85 GMC Jimmy)
Question:
I have a 78 GMC K15 stepside. I have redone my exhaust on it using T-440 Stainless and Flowmaster 3 chamber mufflers…A very distinctive sound and race quality durability are what I found. Its a bit more expensive than any bolt on kit. (paid 125 a piece for the mufflers alone) but the throttle response came way up the fuel economy came a little up…laffs What is MPG with a 350 4bolt and a 750 double pumper, but it does sound nice…(by the way…my truck came factory without a cat. so it was a bit easier, but a hi flow cat for you should do the trick. – Hide quoted text — Show quoted text – > Sometime this spring I am putting a new 350 in my ‘85 Jimmy. I’d also like to > replace my exhaust system as the entire thing from manifold to exhaust tip is > rusted to hell, has holes in it etc. > I’ve never done such a job before, so I just have some super general > questions. First, I want to use headers…but it’d be nice if they didn’t > suffer the same fate as my manifold (RUST!). I’ve seen plenty of headers > advertised with all kinds of different coatings, but which of them actually > works (as far as rust resistance and durability goes)??? What sort of > price range should I expect on a good set of headers? Also, I’d like a dual > exhaust setup…in general, do most dual exhaust systems use just one > catalytic converter and then go on to seperate mufflers etc? How much of an > advantage is it to go with larger pipes (eg 2.5" vs 3")?? Lastly, assuming I > amasse a decent amount of general info about exhaust systems, what are the > pros/cons of replacing it myself vs paying to have it done? > Any input would be appreciated, thanks much,
Response:
Most of the time it is more cost effective to have a reputable muffler shop do the job as they are equipt to handle the rust and bend the pipes in the right directions….my 79 has stock manifolds with single 2 1/4 to the cat and a single 2 1/4 in and out flowmaster…granted living in AZ i don’t have the rust to contend with but this is my point of view. One problem associated with headers besides making it hard to change plugs is the full lenght headers actaully get pretty darn close to the frot spring rear shackles making bushing replacement a problem and contact can occur. JBA makes a shorty header that you can get in coated form…still hard to get at plugs but well worth the hastle in trade for the performance they add. A set of JBA headers will set you back around $500 if i remember corectly. Since you are a K5/ Jimmy owner please stop by and check out www.coloradok5.com…lots of K5 and Jimmy owners there to share ideas with and answer questions. AZBLAZER – Hide quoted text — Show quoted text – > Sometime this spring I am putting a new 350 in my ‘85 Jimmy. I’d also like to > replace my exhaust system as the entire thing from manifold to exhaust tip is > rusted to hell, has holes in it etc. > I’ve never done such a job before, so I just have some super general > questions. First, I want to use headers…but it’d be nice if they didn’t > suffer the same fate as my manifold (RUST!). I’ve seen plenty of headers > advertised with all kinds of different coatings, but which of them actually > works (as far as rust resistance and durability goes)??? What sort of > price range should I expect on a good set of headers? Also, I’d like a dual > exhaust setup…in general, do most dual exhaust systems use just one > catalytic converter and then go on to seperate mufflers etc? How much of an > advantage is it to go with larger pipes (eg 2.5" vs 3")?? Lastly, assuming I > amasse a decent amount of general info about exhaust systems, what are the > pros/cons of replacing it myself vs paying to have it done? > Any input would be appreciated, thanks much,
azblazer.vcf
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Response:
i’ve got Cyclone headers on my chevelle. they’re ceramic coated inside and out and have a lifetime warranty. i paid $250. they’re made by dynomax, i think. i only have about 5,000 miles on them but they’re approx. 3 years old. no problems with rust or excessive engine compartment heat. they haven’t stayed as pretty looking as i thought they would, but definitely no severe corrosion problems. for a 350 in a truck, i wouldn’t go over 2.5" duals, preferably 2.25". a 3" single would be okay, and it would only require 1 muffler and cat. remember, in a truck you want to maintain your low end torque, and going to too-big pipes will reduce that in favor of high rpm horsepower–which you’re less likely to need and your engine is less likely to be capable of producing anyway. -rob – Hide quoted text — Show quoted text – >Sometime this spring I am putting a new 350 in my ‘85 Jimmy. I’d also like to >replace my exhaust system as the entire thing from manifold to exhaust tip is >rusted to hell, has holes in it etc. >I’ve never done such a job before, so I just have some super general >questions. First, I want to use headers…but it’d be nice if they didn’t >suffer the same fate as my manifold (RUST!). I’ve seen plenty of headers >advertised with all kinds of different coatings, but which of them actually >works (as far as rust resistance and durability goes)??? What sort of >price range should I expect on a good set of headers? Also, I’d like a dual >exhaust setup…in general, do most dual exhaust systems use just one >catalytic converter and then go on to seperate mufflers etc? How much of an >advantage is it to go with larger pipes (eg 2.5" vs 3")?? Lastly, assuming I >amasse a decent amount of general info about exhaust systems, what are the >pros/cons of replacing it myself vs paying to have it done? >Any input would be appreciated, thanks much,
Response:
Sometime this spring I am putting a new 350 in my ‘85 Jimmy. I’d also like to replace my exhaust system as the entire thing from manifold to exhaust tip is rusted to hell, has holes in it etc. I’ve never done such a job before, so I just have some super general questions. First, I want to use headers…but it’d be nice if they didn’t suffer the same fate as my manifold (RUST!). I’ve seen plenty of headers advertised with all kinds of different coatings, but which of them actually works (as far as rust resistance and durability goes)??? What sort of price range should I expect on a good set of headers? Also, I’d like a dual exhaust setup…in general, do most dual exhaust systems use just one catalytic converter and then go on to seperate mufflers etc? How much of an advantage is it to go with larger pipes (eg 2.5" vs 3")?? Lastly, assuming I amasse a decent amount of general info about exhaust systems, what are the pros/cons of replacing it myself vs paying to have it done? Any input would be appreciated, thanks much,
Response:
My personal experience says that it isn’t all that expensive to have exhaust work done, especially not if you have already done a lot of the prep work (you can remove the old stuff, and put in the new headers yourself) When you get there, they should be able to do it pretty quickly, and in whatever fashion you want. If you want dual exhaust, they can do it. Dual certainly costs more, especially if you are going with two cats. As for the size of the pipe itself, bigger is better, but that is not an absolute. You do have to maintain a certain backpressure (different from vehicle to vehicle) for the motor to operate most efficiently. Again, a shop should know about this and be able to set you up correctly. Doesn’t mean you can’t do it yourself, but……One of the things I’ve learned about exhaust work is: It’s faster and easier to pay someone else to do it. I dislike exhaust work (especially rusty old stuff) because you are under the vehicle (usually not on a lift if you do it yourself) and all the dirt, rust, road grime falls down on you (ABSOLUTELY WEAR EYE PROTECTION). In the eyes, mouth, ears, and up the nose. The rust stains your clothes, and the sharp pieces of broken exhaust can be dangerous. Where with it on a lift, thing are so much easier and quicker. I’ve done it in a pinch (did a cat back on a 75 Impala in a driveway while on vacation once) but I try not to do it unless I have to. Chris
