I have a '90 IROC 305 TPI with stock exhaust system and bought a Magnaflow 16450 Y-Pipe to replace the stock Y-Pipe. It lines up pretty good but the passenger side down pipe to the Y portion of the pipe is about 3" short from where it needs to connect to the stock exhaust manifold. The rest of the setup is fine, just that portion.

Anyone else use this MagnaFlow pipe and have any issues with it?

Bruce

 

may have to get a shop to splice in a small piece of pipe. requires cutting the new ypipe and re-welding. Almost positive anything other than the stock ypipe requires cutting/welding.

 

thats why with our cars, anytime u get headers you almost always,need a matching ypipe from the same company.

 

This has me a bit confused?

The compatability chart indiactes that this pipe will fit my year/engine setup, but from what you state here implies that this is not normally the case? If MagnaFlow states this should fit, why should it not do so? Do I have a different exhaust manifold than other '87-'92 IROC V8's? Is there an extension that is missing off my exhaust manifold to fill the 3" gap?

Just trying to understand why this does not fit. As you state, a piece could be welded to it to lengthen it or some other fabrication method, but doing that takaes away a tremendous amount of having a piece of original manufactured equipment from somenone like MagnaFlow.

 

you are using donut gaskets right? they fit into the ypipe

 

most of the time, it requires fabrication. Like when you buy headers,sure they say they fit,but they will not bolt up to your ypipe.

 

Hi BASSr,

If you have stock exhaust manifolds on your car, then there should be an exhuast flange piece that fits between the y-pipe flange and the exhaust manifold. I can't find a picture of it right now, but when I do I will post it!

I have the same y-pipe bolted up to my IROC and there is absolutely no need to modify anything.

My only advice is to get all the bolts started then tighten the passenger side first for a complete seal.

 

On the passenger side exhaust manifold, the studs come out short so there is no exhaust flapper/flange assembly like some of the others, just a metal donut that is flat on one side that mates up to the bottom side of the exhaust manifold then the other side of the dount is curved to meet the down pipe of the passenger side of the y-pipe.

So you are indicating that there should be a flapper/flange assemly on the passenger side? That presents another issue for me as the exhaust manifold studs would not be long enough. Now I don't even want to think about changing those! Take the manifold off, if I am going to do that, then I might as well do headers. Not in my plans right now.

I just think that there is something wrong with this Y-Pipe.

 

I installed this Magnaflow 16450 a few months ago. It fits right in with no bending or cutting.

The passenger side uses that short little spacer on the bottom of the manifold you describe - flat on one side, rounded on the other. Driver's side Y pipe bolts right on the manifold. No need for donuts or any other type of gasket anywhere.

 

I know it's cramped quarters in there but pics of your setup could help with identifying how your exhaust is different than stock.

If you have some sort of modified exhaust manifold with different length flange bolts, NAPA sells the stock replacements,and might possibly have the stock passenger side exhaust extension piece, but in all honesty if I had to do that much when I was installing my magnaflow y-pipe I would have just bought headers and put those on!

 

I must be missing the exhaust flange? That is what seems to be missing.


Does anyone have one they want to sell?

Bruce

 

I dont think you are missing the flange. How were you bolting it up before? The flange should be on the ypipe with 2 holes for your bolts to go through. The ypipe should have donut gaskets after each flange.

 

There is a spacer ebtween the flange and the exhaust manifold. Sorry, that is what I am missing.

The Y-Pipe that was there before the Magnaflow one I am trying to put in had a metal donut (donut on one side, flat on the other side that mated up to the exhaust manifold). I need the spacer, but seems like the spacer needs to be about 2" in depth.

Got one?

 

Carbureted cars had the EFE valve in that spot. Fuel injected cars had a simple spacer.

 

That is what I am missing, the spacer. I do not know what this Y-Pipe is that I pulled off, but it does not need one. It is not custom made either, it is a factory made pipe.

Anyone have one of the spacers available?

 

OK, got the spacer, cleaned it up, installed longer studs, and just tried the MagnaFlow Y-Pipe again.

It just does not want to fit correctly. The passenger side pipe going up to the exhaust manifold is off by about an inch in alignment. pushing it as far as it can go, the pipe coming over from the driver side hits to oil pan. It just looks like this particular pipe was not bent quite right. Otherwise a few corrections to the pipe and it would fit like a glove!

Anyone else run into this?

Bruce

 

just take it in to a muffler shop man. That is why i said there is almost always fabrication involved unless you buy matching headers and ypipe

 

double check your part number? might have gotten a 4th gen pipe??

 

Sorry to hear that your pipe still won't fit after you got the passenger side spacer! Are you thinking about returning it to get another one, or taking it to a shop? The cost to return it might be more than taking it to a shop to have them fit it!

 

No, just going to return it. I don't want to fool wtht it any more right now and the car is up on my lift that I need to use to do other work on another car right now.

Put the stock one back on for now. I think there was something wrong with this particular y-pipe. It was close but no cigar!

 

Well, sorry to hear that... that just means you have a good reason to get some headers with matching y-pipe

 

Interesting note I came across today from a local guy who seems to know quite a bit about 3rd gen's.

Apparently there is a difference in the 5.7 versus 5.0 exhaust manifolds where they line of the Y-Pipe tubes going down would be just off a bit. This is why this MagnaFlow 16450 Y-Pipe will not fit my 5.0 TPI setup.

I guess I could get some 5.7 exhaust manifolds, but does anyone else confirm this difference in the 5.7 versus the 5.0 exhaust manifolds?

 

I have 350 and 305 manifolds and they look the same to me..
all my stuff is 88 and up..
the pipe could have been dropped or something during shipping

 

For anyone using this y pipe, it is a great piece, fit great as well on '89 Trans Am GTA 5speed. Only thing I did was cut the slip end that goes into the cat by about 1" or so. All else was great. Used copper exhaust gasket maker (thinly) on each side and between the spacer and manifold for a nice fit. Get SS for same cost that local shop wanted to fab up aluminized steel replacement ...and no where near as pretty as this magnaflow piece.

 

It's not a 305 vs 350 manifold problem, it's a HO vs non-HO manifold problem. The passenger's manifold dumps at a different angle and length on cars with HO manifolds. The Magnaflow 16450 is for cars with HO manifolds. The car in OP's signature (90 Iroc convertible with an automatic) would have non-HO manifolds and the V6/TBI catback, thus the Magnaflow 16450 won't bolt up.

 

This is where I'm at now. The pipe lines up perfectly, but with the spacer in there the studs that come off the exhaust manifold are barely not long enough for me to get a nut threaded on the passenger side. Not sure if it's because of the length of the studs or the thickness of the flange on the y-pipe. I'm talking about 1/8" would make all the difference. So frustrating!