I am attempting to install Flowmaster 15802 2.5 in tailpipes on my 69 Cutlass. I have researched several threads here on the forum but am still in need of a little help.

The mufflers on the car are offset inlet and offset outlet which I believe should suit the 15802's. When placing the tailpipes into a loose fit position they do not line up as I had hoped.

The main problem seems to be when I move the tailpipe to a position which would allow it pass through the bumper cutout the tailpipe comes in contact with the inner wheel housing which was replaced during reconstruction. So I lowered the tailpipe to where it passes under the inner wheel housing to check alignment. If I cut the inner wheelhouse it in fact would line up with the bumper cutout but would leave about an inch clearance ( prior to tightening) from the tire.

Is cutting of the inner wheelhouse a normal and acceptable part of tailpipe installation ? Or is bending the tailpipes a smarter option ? What clearance from the tire is best ?

Any help much appreciated.

 

You should not have to cut the inner fender wells. You may have the wrong pipes, or may need to rebend them some. May sound like bad question, but sure you have them on the right sides, pipes or mufflers?

 

The first pic is my 69 Cutlass Vert notice the notch in the inner wheelhouse, the second pic is my 69 Cutlass Coupe which I am trying to fit the flowmaster tailpipes to.

I'm not sure which configuration is correct to run the tailpipes out through the bumper cutouts.

 

I'm thinking that if you have the correct pipes for your car, there should be no surgery needed to install them.

 

You got me wandering, so I went and looked at my 70, I know it may be different than 69, but not that much. Mine is notched, and I can see by your photo, that it would not work without notching.

 

Also mine is 2 1/2 inch, and the pipes are very close to the tires.

 

I am wondering if the 442 or other factory models that used the cutouts in the rear bumper came with the notch in the inner wheelhouse. And I'm with you 442Harv I don't see this working without the notch.

Do you know or does it appear that the notch in yours is factory ? Thanks for checking yours,

 

Flowmasters new in the box marked GM A body incl Cutlass

 

I,m a old man and my car is backed up in the garage, had to use a light, not good one, but the cut does not look real clean. Will have to move the car to take a better look. Also my car under neight, is not real clean, will have to check in better light, and can't do till Tuesday, OK?

 

That sounds like a lot of work for you so please don't bother. Thanks for your help and offering though,.

 

Your problem is that whoever replaced the inner wheelhouses didn't install them in the correct position, or didn't trim the bottoms. The pipes are not the problem.

 

Joe,. So the first pic is the correct profile with the notch.in it. I just wanted to be sure before I started cutting Were they all notched that way or just they ones that used the cutouts in the bumper ?

 

The stock inner wheel houses don't extend below the trunk floor.

 

Ok, so then both pics show an incorrect profile and I have some cutting to do on both . Joe are you able to mark on either pic what would be correct ? I think I know now where to cut but just want to be sure. Thanks

 

Factory mufflers and rear hangers are designed for offset inlet and center outlet mufflers. You say you have offset/offset mufflers. That could be a problem.

 

That may be A problem but it isn't the cause of THIS problem. Note how the bottom edge of the inner wheelhouse is much higher than the bottom edge of the trunk dropoff. Now note the location of that edge in the second photo. THAT'S why the tail pipes don't clear. That inner wheelhouse should be cut back almost even with the top of the frame rail.

 

Thanks Joe, got it. and thanks to all those who have responded

 

Most of the time when I see a good tailpipe installation it's performed by someone in-the-know. Each piece may need a little trim/weld to get the tailpipe to tuck up close to the trunk floor. To include as mentioned your wheel well.

You shouldn't see much of the pipe when looking at the car from the side if its properly tucked.
A custom muffler/pipe shop may have the know-how. The bends in the pipes may need a little tweak here n there.

Here is what the trumpets should measure for a factory fit on 68/69s. The picture is a reference. But 70-72 should look the same.
Note the beginning of the flare is about parallel with the outer edge of the bumper lip or 2.5" from bumper to tip.
With about a 1/2" gap. A 1/4" drive craftsman 3/8" socket will just fit in the gap. The OD of the socket is .530 so .030 larger than 1/2".

I've seen this installation to one or the other extreme on numerous cars.

Good:


Bad:

worse: Yes no cut-out bumper here. At least I hope not. For example only.

 

My car was easy to access so I snapped a picture of the drivers side wheelhouse.

 

Great pic thanks

 

Thanks for this as I plan to add tips and needed the clearances as well