Oldsmobile 350 Dual Exhausts in a 80 G Body El Cam!no

Chuck Cole

Chuck Cole

Not-quite-so-new-guy
May 10, 2017
45
40
18
Granite Falls, WA
#1
As I read more of the blogs here and there in this site, I get a feeling sometimes that though G-Body's are similar or almost the same, they are not identical twins in every respect. My mind is a few weeks in front of the build, and while the Olds 350 engine is being finished up and before I wedge it into a 1980 El Camino, I would love to hear from anyone, some of the things I need to watch out for in running duals from the factory cast iron headers to the back bumper. First of all tube headers were eliminated because of so many clearance issues. Like some, there is an exact limit of my budget, and needing to buy different starters or collectors, tinging the pipes in several locations just doesn't seem the best way. Allso U have had a lifetime of failed header gaskets and collector gaskets. Welding sounds so much better!

I can see that it is tight from front to rear and that it may be difficult to have true dual exhausts noting that the G Body duals from the factory came after the Cat Converter. I have spent hours searching for a bolt on system and mostly what I find is cat-back pipes, and some from tube headers. I will probably have to have a muffler shop fabricate mine (There goes the budget!) Any information with a source would be really great! BTW...SBC duals do not fit a 350 OLDS. I would love to hear from Cutlass folks if there is a difference between the El Camino routing and a Cutlass. My idea is to see if I can find some of the parts at a recycler, like crossmembers etc.

I read about the cross member for dual exhaust which is not large enough. That seems odd when you spend so much to have dual exhausts smaller dia than recommended. I will be removing the Catalytic Converter, o2 sensor, and large muffler after the differential. I have in mind 2.5" pipes and factory spec turbo mufflers on each pipe, and I have the 442 Bell Tips just to give a hint that this is not a Chevy.

Anyway...as I pull the 3.8 Buick I plan to make room in as many ways as i can. I'm not a welder or a fabricator, but I know it can be done with the right info. I bolted on the entire dual exhaust system on my 77 CS, but I am sure I will not be so lucky on this one.

80 Cutlass Supreme is just like a 80 El Camino or no?
 
spicercars

spicercars

Apprentice
Jan 7, 2019
99
50
18
Saginaw MN
#2
I bought a g force cross member for my Diablo and it fits great with lots of room for 2.25 pipe. After hours of researching for a bolt on exhaust I found it cheaper to have it done at the muffler shop.
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,088
1,915
113
Melville,Saskatchewan
#3
I had the custom 2" duals off my 70S Cutlass with manifolds, off a 260 on my 88 Cutlass. I actually had an all 2.5" custom downpipes into a compact X pipe, in place of the Y pipe, into a Hooker G body cat back system, all through the passenger side hump. It was with Sanderson shorty headers but manifolds have similar placement. I actually have it off in my shop, so I can take pics. I put the 2" duals and manifolds back on the Olds 350 in my 70S. The 2.5" was droning and blah on the 70 Cutlass, sounded amazing on my 88, which is why it is going back on. Plus it made a big difference in the higher rpms on the Olds 260 in my 88 Cutlass. You could try the Ramair Restorations 2.5" downpipes with manifolds, work with A and F bodies. A G body is tighter by the A arms and nearly everywhere else. Good luck.
 
Chuck Cole

Chuck Cole

Not-quite-so-new-guy
May 10, 2017
45
40
18
Granite Falls, WA
#6
I bought a g force cross member for my Diablo and it fits great with lots of room for 2.25 pipe. After hours of researching for a bolt on exhaust I found it cheaper to have it done at the muffler shop.
Good to know thank you. I agree bolt ons seldom simply bolt on...a few degrees of bend can make them almost impossible to fit
 
Chuck Cole

Chuck Cole

Not-quite-so-new-guy
May 10, 2017
45
40
18
Granite Falls, WA
#8
I had the custom 2" duals off my 70S Cutlass with manifolds, off a 260 on my 88 Cutlass. I actually had an all 2.5" custom downpipes into a compact X pipe, in place of the Y pipe, into a Hooker G body cat back system, all through the passenger side hump. It was with Sanderson shorty headers but manifolds have similar placement. I actually have it off in my shop, so I can take pics. I put the 2" duals and manifolds back on the Olds 350 in my 70S. The 2.5" was droning and blah on the 70 Cutlass, sounded amazing on my 88, which is why it is going back on. Plus it made a big difference in the higher rpms on the Olds 260 in my 88 Cutlass. You could try the Ramair Restorations 2.5" downpipes with manifolds, work with A and F bodies. A G body is tighter by the A arms and nearly everywhere else. Good luck.
I would like to see the pics when you can. Thanks...I live 20 miles from a shop so I have to fashion something to get me there without ruining the engine. I was thinking downpipes long enough to tun under the car would sort of act like collectors. They can toss them if they have a better way.
 
Daca214

Daca214

Master Mechanic
Dec 1, 2017
416
453
63
Jupiter, FL
#9
I had mine custom made for $500 on my regal. I have the thorton 350 jrs on my 350
Custom pipes look awesome also

I had bought that jegs gbody system and its sitting in my garage. Im trying to sell it right now. Night and day from custom pipes
 

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