question on expanding the outlet on glasspack

[hawkeyestoob]

I have ordered a TTI 2.5" manifold back exhaust for my 67 Belvedere with a 318. It looks like Cherry Bomb medium offset glasspack mufflers will fit up nicely but I will need to adapt the exit from 2.25" to 2.5". My question is will I be able to use an exhaust pipe expander to open up the 2.25 outlet to mate up with the 2.5 pipe or will I need an adapter of some sort?

 

[68-500]

I would imagine they can be expanded to work with larger tailpipes.
Personally I would look for a muffler that doesn’t neck down to 2.25. You bought 2.5 exhaust, I would do my darnedest to stay that size.

 

[pnora]

I have ordered a TTI 2.5" manifold back exhaust for my 67 Belvedere with a 318. It looks like Cherry Bomb medium offset glasspack mufflers will fit up nicely but I will need to adapt the exit from 2.25" to 2.5". My question is will I be able to use an exhaust pipe expander to open up the 2.25 outlet to mate up with the 2.5 pipe or will I need an adapter of some sort?

View attachment 2004195

That is a big stretch. It depends a lot on the materials the muffler is made from. If the material is soft enough it might stretch. Otherwise it might split. I doubt a cheap expander will open it cleanly. You might have to visit a muffler shop to have it done on a hydraulic machine.

 

[hawkeyestoob]

I would imagine they can be expanded to work with larger tailpipes.
Personally I would look for a muffler that doesn’t neck down to 2.25. You bought 2.5 exhaust, I would do my darnedest to stay that size.

I completely get where you are coming from but I am not seeing any good glasspack options that are offset in 2.5" inlet and outlet. If anyone knows of something please let me know about them. If I was going for ultimate power then I would be far more more concerned about going from 2.5 to 2.25. But for my 318 that has been rebuilt back to stock with the addition of an Edelbrock 1406 carb and Performer manifold I can't imagine that it will make a huge difference.

 

[68-500]

I missed the 318 part. Probably of little concern necked to 2.25.

 

[33 IMP]

I'd put the 2 1/2 tailpipe over the 2 1/4 muffler outlet. If needed, I'd split the tailpipe, and weld it after I had the tailpipe where I want it.

 

[R413]

You have a stock 318 with exhaust manifolds? Your engine doesn't need 2.5" duals, too big.

 

[AR67GTX]

I would do what 33 IMP suggested. You might still have to have the muffler outlet expanded slightly to where it slides inside the tailpipe piece with a reasonably close fit.

 

[1967coronet]

Most all muffler shops or good automotive stores can get you a pre made 2.25 to 2.5 straight piece about 5" long.
You may have to trim a little off the pipe to get it to fit right.

 

[toolmanmike]

Not rocket science. A 2 1/4" od goes inside of a 2 1'4" id pipe. The parts store segmented "expanders" won't actually expand the pipe to the next size. You need something like this or a pipe bender at an exhaust shop. This one is from Harbor Freight and might not be tough enough to last a long time. You have to hammer on that pipe a lot to expand it. These tools will square the pipe so you have to take the expander out and index it to make the pipe round. Exhaust tubing or sheet metal mufflers expand easier than glass pack style mufflers because of the tubing used. Something else that may work for the OP is a band clamp. You can get those in different sizes on both ends to adapt different sizes.

 

[WileE]

I'd put the 2 1/2 tailpipe over the 2 1/4 muffler outlet. If needed, I'd split the tailpipe, and weld it after I had the tailpipe where I want it.

^

 

[hawkeyestoob]

I'd put the 2 1/2 tailpipe over the 2 1/4 muffler outlet. If needed, I'd split the tailpipe, and weld it after I had the tailpipe where I want it.

Thanks for this. I will take a look at how easy-ish this will be once I get everything here and can lay it out for some test fitting.

 

[493 Mike]

Naked glass pack shells are available too. Just weld on the size you want with the angle you need for the offset.
Mike

 

[hawkeyestoob]

Naked glass pack shells are available too. Just weld on the size you want with the angle you need for the offset.
Mike

I had not even considered that as an option but is an excellent idea!

 

[1967coronet]

Thanks for this. I will take a look at how easy-ish this will be once I get everything here and can lay it out for some test fitting.

One more thing is will toss in the mix,
Once you get your glass packs look down the inside. You will see many scoops / flutes that scavenge the flow and route it through the packing. The correct way to reduce the volume is the flutes facing forward, if you want it loud, flip them around.