I have an '85 Z28 with the LG4. I'm interested in installing the Magnaflow 16450 Y-pipe and 3" cat-back exhaust (I want to keep the stock manifolds). I see this Y-pipe is listed for 86-91 models and I also see a few cat-back systems that are only applicable to 86-91 models.

Does anyone know if the Y-pipe will fit an '85? And what the differences are between 85 and 86 models?

Thank you.

 

They used a couple of different connections at the back of the cat over the years. Not sure what years or any of that but that's the only difference. Everything else is the same.

Might want to look at the direct replacement cats for those 2 years for further info.

 

The Magnaflow 16450 Y-pipe is a direct fit for 1986 L69 5.0L H.O. cars & 1986 to 1989 LB9 & L98 Tuned Port Injection cars with a single cat convertor exhaust system.

The Magnaflow 16450 Y-pipe won't fit the cast iron exhaust manifolds and EFE valve on a LG4 engine. The outlet diameter of the LG4 manifolds and EFE valve is too small and located in the wrong place to mate up with the Magnaflow 16450 Y-pipe.

You can keep factory cast iron manifolds & passenger side EFE valve but you will have to swap to the ones that came on 1983 to 1986 L69 5.0L H.O. car or the cast iron exhaust manifolds and passenger side spacer that takes the place of the EFE valve on 1985 to 1989 TPI cars. You can also use the cast iron manifolds and passenger side spacer used on 1990 to 1992 TPI cars but only the ones that came with the N10 high flow dual cat exhaust system.

It's probably going to be easier to find the correct TPI manifolds and passenger side exhaust manifold spacer than it is to find the correct L69 5.0L H.O. manifolds and H.O. EFE valve and the odds of the vacuum diaphragm in the actuator for the EFE valve being good on a 40 year part ain't too good. I would do away with the EFE system. It's for cold start emissions and drivability issues when the engine is stone cold.

The part numbers for the correct TPI exhaust manifold are driver side 14094063 LH & passenger side 14094064 RH. These part numbers are cast into the manifolds and you need to be 100% sure the ones you buy have these numbers cast into them.

I'm doing the same thing you are wanting to do but on a 1992 L03 TBI Firebird. These 87 TPI manifolds and passenger side spacer are what I got to use with the Magnaflow system.

California (SOLD) OEM Exhaust Manifold - Third Generation F-Body Message Boards

This place has the Magnaflow parts for 20% off MSRP with FREE shipping in the USA and Canada after promo code.

Magnaflow 16450 | 1986-1989 5.0L, 5.7L Chevrolet Camaro , Pontiac Firebird | Stainless Mandrel Bent Front Y-Pipe

Magnaflow 93441 | 1986-1989 5.0L, 5.7L Chevrolet Camaro , Pontiac Firebird | Catalytic Converter-Direct Fit | Standard Grade EPA

Magnaflow 16829 | 1982-1992 | Chevrolet Camaro, Pontiac Firebird | Stainless Cat-Back Performance Exhaust System

 

If you're swapping to a 3" cat-back, then it's likely to have a slip-fit joint at the cat. Your existing cat bolts on with flanges; it's not slip-fit, and it's too small for a 3" cat-back. The y-pipe also has a slip-fit, and your cat is too small for it too. Swapping to an appropriate 3" cat would solve fitment between the y-pipe and cat-back. Or delete the cat, if you're not concerned about not having one.

That y-pipe is also going to be too large for the LG4 manifolds, and it may or may not line up with them either, so if you want manifolds, then swap to HO/L98/(LB9) manifolds.

@blacksunshine'91 did that all of that about a year ago: y-pipe, manifolds and 3" exhaust.

 

Last year I installed the "H.O." manifolds (p/n: 14094063 and 14094064), along with the Magnaflow 16450 Y-pipe, a 3" cat, and 3" cat back on my '92 T/A convertible. That exhaust spacer is critical. Everything lined up pretty good and didn't have too much difficulty. Only issues I encountered was that the flange on the y-pipe was too thick for the original bolts on the stock manifolds to reach through (bolts were too short) and getting the cat tucked up far enough to not scrape on the ground with the inner SFCs, but the exhaust shop took care of those problems without any issues.

Airwolfe, not sure if I read your comments correctly about this y-pipe not fitting the '92 with an auto, but I didn't have any problems.

 

I was dead tired when I wrote my comment and several times I looked at it and thought it was clear as mud, but I posted it anyways.

I'll go back and look it over and edit it to be more clear.

EDIT: Now that I look at it I see it is about as clear as mud. I'm going to delete it and start over and tailor it just to his question about his 1985 LG4 car.

 

Hey Airwolfe, Sorry to do this this way, but i was trying to message or reply to your distributor thread but it wont let me only on that page. I'm Interested in purchasing one, but i cant even PM you. Anyway we can get in touch? Thanks!

 

New members aren't allowed to PM other members or post in the Classified section of the website until they have some minimum number of posts or threads they have started to show they aren't an AI, bot, or scammer. A Moderator can also remove the restrictions. I'll tag @JT and maybe he can remove the restrictions from you account.

Hang tight because it's the weekend and the Moderators might be busy. Feel free to constructive replies in other threads or start a thread asking some questions you might want answered and the restrictions will fall away by themselves I believe.

The OP of this thread is a Canadian so maybe he won't be upset with a fellow Canadian seeking help in his thread. Weird is the last few new members that couldn't contact me and wanted to order a distributor were also Canadian. Just shipped 2 distributors out to Ontario

 

Not upset at all! I'm happy my thread was able to help some people connect Thanks to everyone for their helpful input!

 

Thanks Airwolfe, this was super helpful. Do you know if that spacer for the passenger side is available aftermarket? Or is a guy limited to trying to find a used one?

Thanks!

 

Thanks Airwolfe, this was super helpful. Do you know if that spacer for the passenger side is available aftermarket? Or is a guy limited to trying to find a used one?

Thanks!

 

Done

 

Thank you.

 

I sent you a PM.

 

I don't think anyone makes it. Seems a long time ago a member here on the forum machined some up and sold some. But I think that dried up long ago.

You just have to make sure when you buy the correct L69 H.O. or TPI H.O. cast iron manifolds that they come with the correct H.O. EFE valve or passenger side spacer.