Exhausting day at the Y

Guys:

I've spent the past couple months reviving the '74 Valiant in my sig. Yes, just like the one you scrapped a while back, except much nicer.

I had a huge exhaust leak repaired recently, pretty much the entire pipe from the y back to the muffler. Well, after getting it done it was discovered that was only HALF of the huge leak.

The other half is at the top of the crossover directly underneath the oil pan. Never seen one rot there. The superheated exhaust gases are scorching the oil pan and it can't be good for the oil temp either.

So quick question: Will a y-pipe from an M-body, specifically about an '85 Fifth Avenue, fit on there? I know some of you can't remember or mentally blocked out what stock 318 manifolds look like:mrgreen: so I'll describe:

The passenger is the one looks like a very shallow w with a center dump. The driver side is upswept along the valve cover, then dips down past the back corner of the head. Like a 340 manifold that didn't quite get there.

An M-body is the only V8-powered passenger car in the yards around here, at least the self-service ones I go to. There may be one A-body show up a year, that's it. Used to be you could buy replacement y-pipes but that's been a while. I could possibly have one constructed, but that is severely testing the capabilities of the muffler shops in this area, and they'll certainly charge me for the effort.

And...not being rude, but not doing duals, headers, anything else..period. I already have a modified A-body that has that stuff.

I posted a want ad for a used y-pipe but I doubt I'll get a response, I never do.


Thanks for any help.

Might be better off havin an exhaust shop makin a new one and connecting on to your old exhaust right after the end of the y in it now

If you try it, grab the manifolds too. It might work!! You'll need the manifolds to get the Ypipe connections correct.

Robbie2734 said:

If you try it, grab the manifolds too. It might work!! You'll need the manifolds to get the Ypipe connections correct.

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That's a very good idea except that I'm scared to mess with those manifolds. They don't use gaskets and I have NEVER gotten a "transplanted" set to not leak. They take a set or something over the years. Even with gaskets they leak.

TylerW said:

I posted a want ad for a used y-pipe but I doubt I'll get a response, I never do.

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That's like looking for a needle in a haystack for a used one. I bet most of them are in the scrap yard, that's where mine went.

Mid 80's M bodies have two small cats on each side up near the manifolds in addition to the one farther down under the floor pan so I don't think the Y pipe is going to fit an A body.

That's a pretty interesting driver's side manifold. I wonder what size it is? I have a set from an '88 Gran Fury, but the drivers side dropped down instead of upswept. I wanted to use them on my Duster cause they were a lot larger than the stock 318 manifolds I had. Unfortunately the drivers side wouldn't fit with the PS gearbox.
I am with '74 Swinger on this, probably a lot less hassle and all to get a good exhaust shop fab it up.
C

clhyer said:

That's a pretty interesting driver's side manifold. I wonder what size it is? I have a set from an '88 Gran Fury, but the drivers side dropped down instead of upswept. I wanted to use them on my Duster cause they were a lot larger than the stock 318 manifolds I had. Unfortunately the drivers side wouldn't fit with the PS gearbox.
I am with '74 Swinger on this, probably a lot less hassle and all to get a good exhaust shop fab it up.
C

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You guys are probably right. The biggest problem is finding a GOOD exhaust shop here.

I think that manifold has a 2" outlet. Pretty much standard issue from at least '70-76

Check our local NAPA they do sell new y-pipes reasonable.