Author Topic: Need advice - new exhaust  (Read 841 times)

Offline Dr_Snooz

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Need advice - new exhaust
« on: June 20, 2024, 09:07:47 AM »
My entire exhaust system needs replacing. I have to pass CA smog when it's over, so yeah. I want to use these smog legal headers:

https://www.summitracing.com/parts/jba-1830s-4js

This cat:

https://www.summitracing.com/parts/mpe-339109/make/chevrolet/model/v2500-suburban/year/1989

This muffler:

https://www.magnaflow.com/products/11229-magnaflow-4-x-9in-oval-straight-through-performance-exhaust-muffler-11229

Stock routing, 2.5" -> 3", unless I can think of something better.

I'll also put in some V-band clamps to let me remove the Y-pipe for transmission work.

All advice is appreciated.
« Last Edit: June 20, 2024, 10:33:51 AM by Dr_Snooz »
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline ehjorten

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Re: Need advice - new exhaust
« Reply #1 on: June 20, 2024, 10:23:39 AM »
Do you not have the SMOG pump?

Sounds like you will either be doing some welding and fabrication, or you will be taking it to a custom exhaust shop.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline Dr_Snooz

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Re: Need advice - new exhaust
« Reply #2 on: June 20, 2024, 10:35:50 AM »
No smog pump. My nephew welds, so I'll be buying him something lovely and making with the nice nice.

 ;D
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Captkaos

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Re: Need advice - new exhaust
« Reply #3 on: June 20, 2024, 11:08:47 AM »
If you have the money I would get stainless piping if you have a welder for that..  and definitely use V-bands for disassembly.

Offline JohnnyPopper

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Re: Need advice - new exhaust
« Reply #4 on: June 20, 2024, 11:47:46 AM »
So your truck did not come with air injection? What year is it?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Mike81K10

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Re: Need advice - new exhaust
« Reply #5 on: June 20, 2024, 12:20:11 PM »
When I first bought my truck (1981 K10 - Colorado Truck) it had a smog pump. Long removed!
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline Dr_Snooz

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Re: Need advice - new exhaust
« Reply #6 on: June 20, 2024, 08:35:38 PM »
It's an '89.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Online bd

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Re: Need advice - new exhaust
« Reply #7 on: June 20, 2024, 09:41:49 PM »
Generally, in California, you must maintain the original exhaust pipe diameter and quantity.  Cats must be specific by application per the pertaining CARB EO.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Dr_Snooz

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Re: Need advice - new exhaust
« Reply #8 on: June 21, 2024, 09:07:43 AM »
Do you think there's a tech who will measure my exhaust diameter?
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Online bd

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Re: Need advice - new exhaust
« Reply #9 on: June 21, 2024, 11:12:39 AM »
They did on my 87 R10 w/TBI.  I suffered weeks long protracted arguments and had to produce a small book of documentation to "prove" that my truck was actually manufactured with a 3" exhaust, before the local CARB office issued an "exception."  All because the state's reference manual indicated the exhaust on my truck should be 2.5".  I won that argument but it was a trying PITA.  In other words, the risk is yours.  But that was years ago and times change.  Based on the direction California has chosen, it is probably worse, now.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline JohnnyPopper

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Re: Need advice - new exhaust
« Reply #10 on: June 21, 2024, 12:23:03 PM »
Mike, nice to be free of your air pump!

Dr, if your rig came with one, per bd et al the CARB zantis will be looking for it!

Jus sayin... 8)
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Dr_Snooz

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Re: Need advice - new exhaust
« Reply #11 on: June 21, 2024, 09:11:05 PM »
They did on my 87 R10 w/TBI. 

I kinda feel like there's more to this story, lol. Anyway, my install is legit. Everything is stock. Everything has an EO number on it. My shop knows that everything I bring them is legit. It may look shabby. It may have quarter million miles, but it always blows clean.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60