Exhaust System Replacement

[Tynan918]

Never replaced manifolds, installed headers, or any exhaust parts...removed exhaust manifolds for a engine pull once and wrapped headers before, but that's it when it comes to the exhaust system.

Should I buy the parts and have a shop install them (how much ?) or just install everything myself

Starting with the manifolds first...

Headers or OEM manifolds? If headers, can you give me examples or specs as to what I should be looking for while shopping for headers ?

 

[Tynan918]

I just hope I get better performance when I'm done with this.. all that black on those gaskets look like it was a pretty bad leak and I would assume it took a negative effect on my performance and acceleration and things like that.. especially with those bolts being loose the way they were..

 

[Built6spdMCSS]

Clean the Port surface with a scraper or Wizz wheel on a die grinder. Even a wire brush on a drill works.

Those single piece copper ones work excellent, have had literally the same pair on multiple LS Engines in 3 different vehicles since early 2007. The bevel faces out.

 

[Tynan918]

Ok...good news and bad news...

The good news is I have the driver's side finished successfully and with ease...

The bad news is the passenger side...it started with the exhaust manifold bolt kit hardware, some of the bolts were too short... didn't have this problem with the driver's side. The other thing I noticed (after attempting to use the older longer bolts) was the gasket was too short by a 1/2"-1" making it impossible for all of the holes to line up and tighten everything down.

After looking at the part numbers on both manifolds, I see two different part numbers...

Driver's side said "14094045 LH"
Passenger side said "14094046 RH"

Do I have two different and mismatched SBC manifolds on my engine ?

P.S. I only looked at the driver's side manifold numbers when I was shopping for gaskets...I assumed they were matching manifolds...

 

[SSMonteMan]

You won't notice any difference in performance by using manifolds. Maybe with headers but not manifolds.

The passenger side is always a pain in the *ss. I've considered pulling the AC and inner finder on the passenger side to install headers before, but that's just more work... it'll go in, just make sure you have all the bolts lined up right. The heads are identical left and right, so there's no way the gaskets can't line up on one side but not the other.

 

[79 USA 1]

looking at the pictures the issue is with the gaskets. The manifolds you are using on the right side require the 7th bolt hole. Your gaskets only have 6. You need a gasket that has the 7th hole.

 

[scoti]

I sure did... I've been asking here and I've been asking in a few Facebook groups and the responses wasn't quick enough.. all I knew was that I needed copper gaskets and if I had to pay 60 bucks for these that's what I had to do... But apparently these are high quality and will even seal warped heads and manifolds exhaust ports..

They 'can'..... That's not the same as they 'will'.

 

[Tynan918]

You won't notice any difference in performance by using manifolds. Maybe with headers but not manifolds.

The passenger side is always a pain in the *ss. I've considered pulling the AC and inner finder on the passenger side to install headers before, but that's just more work... it'll go in, just make sure you have all the bolts lined up right. The heads are identical left and right, so there's no way the gaskets can't line up on one side but not the other.

Leaking exhaust manifold don't have a negative effect on performance ?

 

[Tynan918]

Removed the gaskets and mounted the manifolds straight to the heads...what do you all think ?

Sounds better and I don't smell exhaust fumes from the engine bay or in the cab...

 

[SSMonteMan]

Leaking exhaust manifold don't have a negative effect on performance ?

Not in your setup, no. You would see more performance by removing the manifolds completely than by replacing gaskets and making sure it's sealed up right.


I'm pretty sure GM didn't use gaskets from the factory anyways... so you should be just fine as you are now, be sure to re-check torque after a couple drives.

 

[Tynan918]

Not in your setup, no. You would see more performance by removing the manifolds completely than by replacing gaskets and making sure it's sealed up right.


I'm pretty sure GM didn't use gaskets from the factory anyways... so you should be just fine as you are now, be sure to re-check torque after a couple drives.

Two things that I've noticed since I've been driving without the gaskets..

Sometimes I can smell exhaust fumes and it's enough to bring tears to my eyes.. you can't smell it the whole time I'm driving and it doesn't happen all the time if ever but it happens.

My fuel economy is worse.. and I'm using 91 no ethanol which runs my motor great and better than the 87 no ethanol.