Sears suburban 18/6 rebuild w/ Predator 420 swap

Pulled the stock muffler off the predator, removed the spark arrestor and then removed muffler from the "header". I ended up drilling a couple 1/4" holes or so straight into baffle then into outlet pipe maybe allowing a little more flow. Also port matched the header to muffler a little, I could see an exhaust ring where they didn't match up. May not help, but makes me feel like it does haha. It really didn't make it louder at idle or fixed rpm, but it is louder when quick revving and will pop a little, sounds kind of cool. I think I'm going to cut and just move the muffler once I get hood ready to go on.
@MFDAC may need some pointers on how you did yours.
Hopefully this will give enough extra flow to compensate for air filter and larger jet.

I also bought a new brass bushing for clutch idler, the pulley tilts sideways a little when engaged, hopefully this will line it back up.
 
TAHOE said:
Pulled the stock muffler off the predator, removed the spark arrestor and then removed muffler from the "header". I ended up drilling a couple 1/4" holes or so straight into baffle then into outlet pipe maybe allowing a little more flow. Also port matched the header to muffler a little, I could see an exhaust ring where they didn't match up. May not help, but makes me feel like it does haha. It really didn't make it louder at idle or fixed rpm, but it is louder when quick revving and will pop a little, sounds kind of cool. I think I'm going to cut and just move the muffler once I get hood ready to go on.
@MFDAC may need some pointers on how you did yours.
Hopefully this will give enough extra flow to compensate for air filter and larger jet.

I also bought a new brass bushing for clutch idler, the pulley tilts sideways a little when engaged, hopefully this will line it back up.
Click to expand...

I think I took some pics of modifying the exhaust manifold if that is what you are referring to, Marty? I wanted mine quiet as possible so there was no substantial modification to the muffler, just the pipe and the grill surround notch.

I don't have time tonight, but sure will find what I can tomorrow night after work!

DAC
 
MFDAC said:
I think I took some pics of modifying the exhaust manifold if that is what you are referring to, Marty? I wanted mine quiet as possible so there was no substantial modification to the muffler, just the pipe and the grill surround notch.

I don't have time tonight, but sure will find what I can tomorrow night after work!

DAC
Click to expand...
I remember seeing pics on GTT, I can go back if you don't have time to find any.
Whay type of pipe did you use to extend? I guess this is just steel? Grinds like it is.
 
TAHOE said:
I remember seeing pics on GTT, I can go back if you don't have time to find any.
Whay type of pipe did you use to extend? I guess this is just steel? Grinds like it is.
Click to expand...

Hey Marty, it took me a bit to remember what I was seeing in the few pictures I took. Memory sucks sometimes. I did have a pretty lengthy post on GTT about doing this repower and there were several attempts and changes along the way.

It looks like I cut the Honda clone exhaust , added a black pipe 90* elbow and welded it back together. Probably not "port matched" very well like you are trying to achive---LOL! Originally the muffler stuck straight up and I wanted it sticking out the side so I wouldn't have to chop up the hood. Here's a couple pictures.

Exhaust before being cut. Muffler removed.
Engine swap 004.jpg

This pic is after cutting welding and fitting. I oriented the muffler mount flange so the discharge points straight down.
Engine swap exhaust 005.jpg

I know that welding cast is more of a process than I did but it seems to be working for 3 years now.
Ignore the pipe on the left, I didn't use it.
Engine swap exhaust.jpg

Finished product
getting ready for snow 001.jpg

Hope this may help, Marty.

DAC
 
MFDAC said:
Hey Marty, it took me a bit to remember what I was seeing in the few pictures I took. Memory sucks sometimes. I did have a pretty lengthy post on GTT about doing this repower and there were several attempts and changes along the way.

It looks like I cut the Honda clone exhaust , added a black pipe 90* elbow and welded it back together. Probably not "port matched" very well like you are trying to achive---LOL! Originally the muffler stuck straight up and I wanted it sticking out the side so I wouldn't have to chop up the hood. Here's a couple pictures.

Exhaust before being cut. Muffler removed.
View attachment 21378

This pic is after cutting welding and fitting. I oriented the muffler mount flange so the discharge points straight down.
View attachment 21379

I know that welding cast is more of a process than I did but it seems to be working for 3 years now.
Ignore the pipe on the left, I didn't use it.
View attachment 21380

Finished product
View attachment 21381

Hope this may help, Marty.

DAC
Click to expand...
Yep, that gives me ideas, thanks
 
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