84 k10 custom exhaust

[focoloco5667]

pretty new here, tried searching for a thread with the same question as me but to no avail.

i have an 84 k10 with a 5.7 350 swap that i just got a few months ago. the dude i bought it from lived outside the zone that requires an emissions test so he was running 3.5" straight pipes from the newish headers he put in that are somewhere between 3"-3.5" in diameter (havent had time to pull off the straight pipes and look).

now i live inside the emissions zone so i have a few options. 1-put the second exhaust the dude gave to me on and pray the truck will pass emissions or 2- build a custom one of my own that will stay on there full time and still pass emissions.

so my questions are

• what was the factory exhaust on an 84 with a 5.7 and a 5.0? (not sure if they will go off the vin or the motor that in there)
• will i even come close to passing with the factory exhaust?
• what have you all done in terms of a custom exhaust?

if i go custom i would want it to be loud (duh) but not over the top obnoxious. would i need catalytic converters to pass emissions? what would stepping up the pipe diameter (say from 3 to 3.5 from the cats and 3.5 to 4 or even 4.5 from the muffler) do to sound, mpg, power, and will i pass emissions?? do i want to offset the mufflers/cats entry and exit pipes? is there a way to still have true dual exhaust but use one cat? would longer tailpipes have any effect on emissions? is there anything else i can add to the exhaust that will reduce emissions but not take away from the sound or the power?

i could also potentially have two setups; a straight pipe everyday driver, and a 'gota pass emissions' setup but the latter would have to be dirt cheap.

anything helps here guys, this is my first truck and i know little to nothing about exhaust systems and emissions.

 

[CSFJ]

If part of the test is a visual inspection, you may be screwed unless you have all the factory pieces, or can locate them. I'm not in a state that tests, (luckily for me), but from what I've read on here, they can get quite picky about not having all the factory equipment present. I'm sure one of the others on here that deal with this regularly, can provide more details.

 

[MadOgre]

pretty new here, tried searching for a thread with the same question as me but to no avail.

i have an 84 k10 with a 5.7 350 swap that i just got a few months ago. the dude i bought it from lived outside the zone that requires an emissions test so he was running 3.5" straight pipes from the newish headers he put in that are somewhere between 3"-3.5" in diameter (havent had time to pull off the straight pipes and look).

now i live inside the emissions zone so i have a few options. 1-put the second exhaust the dude gave to me on and pray the truck will pass emissions or 2- build a custom one of my own that will stay on there full time and still pass emissions.

so my questions are

• what was the factory exhaust on an 84 with a 5.7 and a 5.0? (not sure if they will go off the vin or the motor that in there)
• will i even come close to passing with the factory exhaust?
• what have you all done in terms of a custom exhaust?

if i go custom i would want it to be loud (duh) but not over the top obnoxious. would i need catalytic converters to pass emissions? what would stepping up the pipe diameter (say from 3 to 3.5 from the cats and 3.5 to 4 or even 4.5 from the muffler) do to sound, mpg, power, and will i pass emissions?? do i want to offset the mufflers/cats entry and exit pipes? is there a way to still have true dual exhaust but use one cat? would longer tailpipes have any effect on emissions? is there anything else i can add to the exhaust that will reduce emissions but not take away from the sound or the power?

i could also potentially have two setups; a straight pipe everyday driver, and a 'gota pass emissions' setup but the latter would have to be dirt cheap.

anything helps here guys, this is my first truck and i know little to nothing about exhaust systems and emissions.

IMO a single exhaust system with one cat( ? ) and one muffler would be the way to go and just put it on for inspections only. Then run what everf else you want the rest of the year. You would be sure to pass inspections related to exhaust components for the life of the vehicle. Just a real PITA

 

[focoloco5667]

If part of the test is a visual inspection, you may be screwed unless you have all the factory pieces, or can locate them. I'm not in a state that tests, (luckily for me), but from what I've read on here, they can get quite picky about not having all the factory equipment present. I'm sure one of the others on here that deal with this regularly, can provide more details.

there is a visual inspection but its to make sure everything looks ok. as in brackets ok, no holes in the muffler, ect.

 

[Georgeb]

If your inspection requires a cat be installed I would run two of them attached as close to the headers as possible. Then run 2.5" dual with a cross over pipe for scavaging the rest of the way back. As far as mufflers it's your choice from there. The cats would do a bit of muffling so it may sound good to you without mufflers but I think I would try running some nice long glass packs or dynomax super turbos to act as resonators and take the sharpness out of the tone. If the system is made from quality heavy wall pipe not cheap aftermarket exhaust crap it would last a long time

 

[68post]

3" duals are GIANT for even a hi-perf smallblock. Exhaust can also be sized smaller by the time you get to the tailpipes without effecting HP. 2&1/4" from the headers back are plenty for a stock smallblock.

A BIG bigblock with nitrous can use 3&1/2" dual exhaust.

Do tell what your truck setup is - engine and drivetrain wise ?

I've built my exhausts for 37 yrs, I used a large ( 3&1/2") hi-flow single exhaust on our stockcar for example .