My car has the dual cats. Im trying to find a y-pipe without cats. I tried Walker 40579, but the fit was just a little off. Got me thinking: is there a difference in the exhaust manifolds of the dual/single cat cars? I thought they were the same.

 

From TransamGTA350:

There were only 2 different manifolds for the V8's throughout the years, but they were different depending on what motor and gearing package they came on. Here is the breakdown.

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

 

I read somewhere on here that one set of manifolds was longer than the other set. The ypipe I tried was too short, so mabey it was for the longer style manifolds. If i read correctly those ones were more restrictive or for tbi or sumthin. I have the h.o. 305 so probably the better manifolds. Mabey the other walker pipe with 3" outlet will fit. Its supposed to be for 350's

 

I've never heard that there was a shorter/longer difference--only that the outlet size was different.

JamesC

 

I dont doubt you. Just sumthinI read on a search. People on here are often wrong...quite often . I'll find out tomarrow. Love livin 45min from Summit

 

well, to me it seems all TPI motors share the same driver side exhaust manifold, but the dual cat cars have a different passenger side manifold. Looks like the outlet is shorter requiring longer y-pipe tubing for just the pass side. Looks like I might be pulling the motor to install headers...just what I didnt want to do at this time to my daily driver.

 

There is a spacer between the pass side manifold and the Y-pipe, which is not present on the driver's side.

JamesC

 

you mean the donut gasket?

 

Nope, there is a flange that allows a round steel piece press into a flared exhaust inlet. It's really hard to explain without pictures. Basically, if you don't have this flange you need to dig it up from a junkyard or make something custom.




As for your Y-pipe issue - apparently this is common. I bought my car with shorties on it. I wanted to put factory manifolds on. I put the factory manifolds on and bought a y-pipe for my year/make/model/submodel. Finding an aftermarket piece that is exactly to spec. is pretty much out of the picture. You will have to add an inch or so to make it work.

 

Hopefully I can weld the pass side piping from the factory dual cat pipe to the aftermarket single pipe. But probably wont....