My old exhaust system just broke in half and the muffler is shot . I'm just going to take it over to the muffler shop and have him make up a new pipe and muffler from the downpipes on back Question is ... it has a cat or at least the shell of one underneath where it comes together from the downpipes . Its going away , as its not required here in this part of AZ . Should I just have him put in a Y there , or would there be any advantage to having him make up an expansion chamber ( thats not the term I'm looking for but you get the idea , a collector box the size of the catalyst ) where it now lives ? Also the original pipe is 1 7/8 " OD . What size should I go to ? 2 1/8 or 2 1/4 perhaps . EA81 engine with a single carb , 4 speed and hi/lo range transfer . Its just a driver and a toy but I'd like to try to get the exhaust as efficiant as I can for what it is . I doubt if I 'll ever get around to changing out the carb , but you never know on down the line .

 

Probably splitting hairs but thought I'd ask those of you that have been through this before .

 

Thanks ,

 

Bob

Y it together and run 2 1/4 (-+) id back from there, no need for expansion chamber due to the bank fire that our cars have.

 

Just make sure your muffler guy notches the tubing correctly, somtimes they will just beat the pipe to a shape and booger weld it on there... that makes for terrible flow.

 

Also if you want a little more performance, go with a free flowing muffler, like a straight through or simi straight through. Dont bother with no-names, get a cherry bomb or similar.

Yes - don't change the diameter of the tubing from the heads to the collector. After that it doesn't matter but 1-7/8" or 2" would be more than sufficient if you aren't running a cat. Get a muffler that can flow easily.

 

GD

Hey thanks guys ... that was exactly the answers I was looking for .

 

The pipe rotted in half about 2 feet behind the catalyst , and it sure sounds sweet when I run it up through the gears ! Not really that loud either , so a Cherry Bomb shouldnt attract the local Gestapo . Speaking of Cherry Bombs I figured they were long out of business ..... We used to put them on our cars when I was in high school , and I'm an old geezer now . And they really were red too .

 

 

Bob

They are still red, and they still rock. I have a TOPSPEED PRO1 exhaust pipe on mine and it sounds sweet without having a whole lot of resonance, I really like it.