Best catalytic converter recommendations - The 1947 - Present Chevrolet & GMC Truck Message Board Network

KShortell · 02-17-2004, 11:54 AM

Well, the time has finally come. The catalytic converter on my stock '86 350 has finally started to do the "death rattle". It was blowing out the white ceramic pellets a couple of years back, but still passes emissions. Now that I've had the valve stem seals replaced, a new cat has a better chance of doing a good job anyway. I think that the "pro" I had do it didn't do the valve cover gaskests right, though-- the side of my block and oil filter is covered in oil...

It's started to idle lower, roughly, and kinda funny the last few days and the cat has begun to rattle-- the same rattle the cat in the Jeep had when it went bad a couple of years ago. At least that one was still under warranty.

SO, I'm pretty certain I need a new one.

My question is which catalytic converter have y'all had the best luck with? GM, Random Technologies, Catco, etc.? I'm ideally looking for something that will just bolt up and not require new pipes due to a different length.

My exhaust is the standard Y-pipe, 2.5" exhaust, AIR at the manifolds, and single stage (no air injection) catalytic converter. This 2.5" dumps into a Flowmaster 3-chamber Delta Flow with dual 2" outlets.

Thanks for the input!

Kevin

Destructo · 02-17-2004, 12:17 PM

I had 2 catcos on my truck, till my holley ruined them because I let the floats get to high and it melted them. Their still under warranty, but I really doubt I could get away with claiming warranty on them since the comb was completely melted pretty much.

I'll be buying two new ones except i'm going to get the universal 12" ones.

apstguy · 02-17-2004, 02:07 PM

Catcos are cheap and you get what you pay for. Random tech is the best but also the most expensive. OEM pellet style are restrictive and out of date - I don't even think they sell them anymore. I don't know about Hedmans.

**swervin ervin** · 02-17-2004, 02:10 PM

If you want the best, Random Technologies is it. I have one.

Read my user text.

Slonaker · 02-17-2004, 02:28 PM

I know this doesn't help you, but mine are "Charlie Brown" brand. I get a good laugh whenever I see them.

Slonaker

DCRANER · 02-17-2004, 02:57 PM

swervin is right, Random Tech. is the best one. If you have a quality exhaust header / pipe/ muffler system complete it with the best cat.

Also, it is best & most effecient to mount the cat as close to the header as possible, as any cat needs heat / exhaust velocity to really work correctly.

Doug

Matt_305 · 02-17-2004, 04:59 PM

Love livin in Nova Scotia, not necessairy if your car was built before 1991

TIMSPEED · 02-17-2004, 06:09 PM

I always use Carsound. I USED to use Random Tech..but since learning that Carsound's flow JUST as well, and are MUCH cheaper, I wll forever use Carsound.
Also, as a side note, a friend bought a BRAND NEW Catco cat from Summit...turns out, Catco didn't pass smog! (And it said it was a direct replacement!) He installed a Carsound and passed with flying colors.

Grim Reaper · 02-17-2004, 06:24 PM

Mid 90's Tahoe's are supose to have a good free flowing cat.

I looked in mine. No restriction.

8600 GVWR has me exempt to smogging.

Cats are BS. Cats only do somethign when the vehicl is not running right. I had a 79 K5 pas the sniffer 3 years and thye missed the visual to the fact it had no cats. It was cleaner then the 87 FI Merkur we had at the same time.

gchemist · 02-17-2004, 09:49 PM

I use a Catgo. Cheap and easy to hollow! Pass inspection and still have high flow.

Newt408 · 02-19-2004, 09:14 PM

I read in a mag a while back that the GM's off a 96 to 99 truck with the vortec engine flowed better than the aftermarket cats

View Poll Results: Which catalytic converter works best
GM (OEM)	0	0%
Random Technologies	4	57.14%
Catco	3	42.86%
Heddman	0	0%
Other	0	0%
Voters: 7. You may not vote on this poll

02-17-2004, 11:54 AM	#1
KShortell Registered User Join Date: Oct 2003 Location: Chesapeake, VA Posts: 734	Best catalytic converter recommendations Well, the time has finally come. The catalytic converter on my stock '86 350 has finally started to do the "death rattle". It was blowing out the white ceramic pellets a couple of years back, but still passes emissions. Now that I've had the valve stem seals replaced, a new cat has a better chance of doing a good job anyway. I think that the "pro" I had do it didn't do the valve cover gaskests right, though-- the side of my block and oil filter is covered in oil... It's started to idle lower, roughly, and kinda funny the last few days and the cat has begun to rattle-- the same rattle the cat in the Jeep had when it went bad a couple of years ago. At least that one was still under warranty. SO, I'm pretty certain I need a new one. My question is which catalytic converter have y'all had the best luck with? GM, Random Technologies, Catco, etc.? I'm ideally looking for something that will just bolt up and not require new pipes due to a different length. My exhaust is the standard Y-pipe, 2.5" exhaust, AIR at the manifolds, and single stage (no air injection) catalytic converter. This 2.5" dumps into a Flowmaster 3-chamber Delta Flow with dual 2" outlets. Thanks for the input! Kevin __________________ Semper Paratus

02-17-2004, 12:17 PM	#2
Destructo Registered User Join Date: Sep 2003 Location: Lewisville, NC Posts: 1,836	I had 2 catcos on my truck, till my holley ruined them because I let the floats get to high and it melted them. Their still under warranty, but I really doubt I could get away with claiming warranty on them since the comb was completely melted pretty much. I'll be buying two new ones except i'm going to get the universal 12" ones. __________________ 1985 Scottsdale Shortbed 4x4 Stout 350 with some "upgrades"-700r4-33x12.5" Mud Tires, Warn 8274-50 winch. 2005 Chevrolet Colorado Regular Cab 2wd 4-banger, 5 speed, Street Pack with 3.73 axle.

02-17-2004, 02:07 PM	#3
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	Catcos are cheap and you get what you pay for. Random tech is the best but also the most expensive. OEM pellet style are restrictive and out of date - I don't even think they sell them anymore. I don't know about Hedmans. __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

02-17-2004, 02:10 PM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	If you want the best, Random Technologies is it. I have one. Read my user text. __________________ Mike 1985 Chevy C-10

02-17-2004, 02:28 PM	#5
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	I know this doesn't help you, but mine are "Charlie Brown" brand. I get a good laugh whenever I see them. Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

02-17-2004, 02:57 PM	#6
DCRANER Registered User Join Date: Feb 2004 Location: Atlantic Highlands, N.J. Posts: 139	Best Cat? swervin is right, Random Tech. is the best one. If you have a quality exhaust header / pipe/ muffler system complete it with the best cat. Also, it is best & most effecient to mount the cat as close to the header as possible, as any cat needs heat / exhaust velocity to really work correctly. Doug __________________ 86 GMC SWB, DK. BLUE, ZZ430,TH400, 4.11'S, HEADMAN CERAMIC HEADERS, WELD BILLETS, BFG 275 / 60 / 15, 325 / 50 / 15 DRAG RADIALS, FIBERGLASS COWL HOOD, B&M SHIFTER. MSD, MARCH PULLEYS / ALT. / PWR. STEER PUMP, BECOOL RAD., BILLET GRILL & GRANT WHEEL.

02-17-2004, 04:59 PM	#7
Matt_305 Registered User Join Date: Dec 2003 Location: Nova Scotia, Canada Posts: 102	Love livin in Nova Scotia, not necessairy if your car was built before 1991 __________________ 1981 GMC Sierra 1500 4.1L I6 1985 GMC Sierra 1500 5.0L V8 (Parts Truck)

02-17-2004, 06:09 PM	#8
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	I always use Carsound. I USED to use Random Tech..but since learning that Carsound's flow JUST as well, and are MUCH cheaper, I wll forever use Carsound. Also, as a side note, a friend bought a BRAND NEW Catco cat from Summit...turns out, Catco didn't pass smog! (And it said it was a direct replacement!) He installed a Carsound and passed with flying colors. __________________ I have a few cars... See Them Here

02-17-2004, 06:24 PM	#9
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Mid 90's Tahoe's are supose to have a good free flowing cat. I looked in mine. No restriction. 8600 GVWR has me exempt to smogging. Cats are BS. Cats only do somethign when the vehicl is not running right. I had a 79 K5 pas the sniffer 3 years and thye missed the visual to the fact it had no cats. It was cleaner then the 87 FI Merkur we had at the same time. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

02-17-2004, 09:49 PM	#10
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	I use a Catgo. Cheap and easy to hollow! Pass inspection and still have high flow. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

02-19-2004, 09:14 PM	#11
Newt408 Registered User Join Date: Feb 2004 Location: west texas Posts: 71	I read in a mag a while back that the GM's off a 96 to 99 truck with the vortec engine flowed better than the aftermarket cats

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