1990 305 TPI 5.0 L
(lb9)


I want to go back to stock exhaust manifolds for now. I have a leak in my Edelbrock shorties before the o2 sensor and don't want to fight with emissions all summer.

Just wanted to know what years will fit on the bird.

Thanks.

 

From TransamGTA350:

2" outlet manifolds with single 2 1/4" y-pipe
82-87 305 LG4 (VIN H)
88-92 305 L03 (VIN E)
82-83 305 Crossfire
90-92 305 LB9 w/o G92 axle (VIN F)

2 1/4" outlet manifolds with single 3" y-pipe
83-86 305 L69 (VIN G)
85-89 305 LB9 (VIN F)
88 350 L98 (VIN 8)
89 350 L98 w/o G92 axle (VIN 8)

2 1/4" outlet manifolds with dual 2 1/4" cats
89 350 L98 w/G92 axle (VIN 8)
90-92 350 L98 (VIN 8)
89 305 LB9 w/G92 Axle (VIN F)
90-92 305 LB9 w/G92 (Vin F)

JamesC

 

So someone is giving me exhaust manifolds from an 87 camaro TPI, I believe it's a 350.

2" outlet manifolds with single 2 1/4" y-pipe
82-87 305 LG4 (VIN H)
88-92 305 L03 (VIN E)
82-83 305 Crossfire
90-92 305 LB9 w/o G92 axle (VIN F) (Not sure what a G92 axle is, but this seems to be the only match for me)


And I guess what he has would have to be anything below this

2 1/4" outlet manifolds with single 3" y-pipe
83-86 305 L69 (VIN G)
85-89 305 LB9 (VIN F)
88 350 L98 (VIN 8)
89 350 L98 w/o G92 axle (VIN 8)

2 1/4" outlet manifolds with dual 2 1/4" cats
89 350 L98 w/G92 axle (VIN 8)
90-92 350 L98 (VIN 8)
89 305 LB9 w/G92 Axle (VIN F)
90-92 305 LB9 w/G92 (Vin F)

As far as I can tell from looking at this, the manifolds will not be the same. It should be possible with adapters though, right?

 

G92 is Rear Axle, performance ratio. In a 90 Bird that would have been 3.42's for a manual and 3.23's for the auto (according to the Firebird tech data).

If the Y-pipe was designed for Edelbrock headers, fabbing something up to mate the OE manifolds with the after market Y will be an issue.

JamesC

 

you cant have the crack welded in the headers?

 

I'm going to return the Y-pipe for the Edelbrocks and get the stock Y-pipe from Napa or rockauto, I was just wondering what vehicle I'd search for to get the right size pipe.

UnderCover89, the crack is in the area where all of the pipes collect so welding would be very hard if not impossible to do.

 

OKAY, I got the exhaust manifolds. I think the Y-pipe to the exhaust manifold fit is pretty much universal. I think the outlet of the Y-pipe to the inlet of the CAT & number of CAT's (I have one) is what determines the Y-pipe you need.

The outside diameter of the outlet for the Y-pipe I have now is about 2.25". The inlet to my converter is about 2.5" O.D. and the Y-pipe outlet slips inside of the converter's inlet.

Here is where I need help:My options for Y-pipes are 3", 2.25", and 2.5" (assuming it's talking about inside diamter) vs. my options for cats which are 2.25" and 3" inlet (know it's talking about inside diameter).

Do I...
Get both a 2.25" Y-pipe and 2.25" cat?
Get a 2.25" Y-pipe and hope it fits in the converter I have now - don't see why it wouldn't considering mine is about that size now.

Thing is, the cat I have now may have to be replaced so this is why I'm considering New cat vs. new y pipe sizes.


Any input is greatly appreciated.