LMC exhaust kits - will it work? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MrC1 · 02-11-2009, 04:35 PM

I've got a '72 C20 with a 402, but I'm considering getting one of the LMC standard exhaust kits, which has 2 1/4" pipes (mandrel bent). I assume this would flow about the same as 2.5" crimp-bent system. Since I don't spin more than 5000 RPM, this should work great.

Here's the thing. LMC advertises the kit as for smallblocks only. I can't understand the difference, especially since I'll be running headers. Since I have headers, can't I use this kit? Anybody know? I figure the bolt-up to the stock manifolds is the issue causing it to be a smallblock kit. Sound right?

68gmsee · 02-11-2009, 04:55 PM

FYI: I ordered the 6 cylinder kit from them since it looked simple enough. Parts were of real good quality, fitment was not.

The parts were not the same as advertised but I was able to make them work with a lot of effort.

71 super · 02-11-2009, 05:15 PM

If you are using headers there should not be an issue with it working. The factory exhaust was 2.5 on bb with a 2 inch tailpipe. The 2.25 should work with no problems. If using with manifold there is considerable difference in manifold exits and some fab work would have to be done to make work.

Stock72c10 · 02-11-2009, 06:21 PM

Just remember that a 2.5" pipe is ~20% larger than a 2.25" pipe.

tcb-1 · 02-11-2009, 07:06 PM

take my advise, go to a quality custom exhaust shop. spend the extra dough and have something that fits..... and it will keep you off the crawler for hours.

MrC1 · 02-12-2009, 10:40 AM

Quote:

Originally Posted by Stock72c10

Just remember that a 2.5" pipe is ~20% larger than a 2.25" pipe.

Yes, but doesn't the mandrel bending make up for it? Those crimps squeeze down at least 1/2" or more.

MrC1 · 02-12-2009, 10:43 AM

Quote:

Originally Posted by tcb-1

take my advise, go to a quality custom exhaust shop. spend the extra dough and have something that fits..... and it will keep you off the crawler for hours.

What kind of fitment probs did you have? I would obviously have a muff shop cut and weld in the front portion since I'll be running headers, but I figured I'd bolt the rest of the system in place and let it hang there on the way to the shop for the finishing touches.

Would this technique make it easier since I'm not tied down to the location of the front hook-up position? I figure all I have to do is make the back of it fit and the shop will make the front fit.

fnoblitt · 02-12-2009, 01:26 PM

i had a muffler shop fab me up a custom system, 2 1/2 pipes with flowmasters for my small block . and it runs and sounds great

tcb-1 · 02-12-2009, 01:37 PM

I have never installed one of thier kits, but the "ready made" exhaust kits in a box are notorious for needing tweaks. I would just have a muffler shop fab you a 2.5" aluminized manifold back system. that way, you can have your choice of mufflers, exits, etc.

MrC1 · 02-12-2009, 02:42 PM

I guess it's the $220 price that's getting me. I couldn;t get a custom system for that much, especially if I went with mandrel bends.

tcb-1 · 02-12-2009, 04:15 PM

had my 2.5 custom bent, turboflow, duals, with all new mounts for $250. drive in, drive out. no headaches.

check around D town, I bet you can find good deals out there!!

dieselarmy13 · 02-12-2009, 04:47 PM

Quote:

Originally Posted by tcb-1

had my 2.5 custom bent, turboflow, duals, with all new mounts for $250. drive in, drive out. no headaches.

check around D town, I bet you can find good deals out there!!

Same here. Mine was about $250 with Flowmasters, but it ends before the axle. I've done a couple of 'bolt-on' systems in my day. A Borla on my Ranger, and a Flow on my T-bird. Never again.

Longhorn Man · 02-12-2009, 04:57 PM

some areas will RAPE you on exhaust work.
I have the kit you are asking about, and while most ppl say it fits pretty OK, I was unable to make it all work.
HOWEVER... I was asking for trouble. I installed it on a leaf spring truck, with a caddy big block, and 133 inch wheel base.
So don't go by my words... a lotta ppl on here have used it with much better results.

LUV2XCLR8 · 02-12-2009, 05:01 PM

Not that matters, but i used to work PT doing this stuff and this
chart (Taken out of the Flowmaster Dealer Catalog) might help.

02-11-2009, 04:35 PM	#1
MrC1 Dork For Days Join Date: Aug 2005 Location: Dallas Posts: 407	LMC exhaust kits - will it work? I've got a '72 C20 with a 402, but I'm considering getting one of the LMC standard exhaust kits, which has 2 1/4" pipes (mandrel bent). I assume this would flow about the same as 2.5" crimp-bent system. Since I don't spin more than 5000 RPM, this should work great. Here's the thing. LMC advertises the kit as for smallblocks only. I can't understand the difference, especially since I'll be running headers. Since I have headers, can't I use this kit? Anybody know? I figure the bolt-up to the stock manifolds is the issue causing it to be a smallblock kit. Sound right? __________________ 1972 C20, 402/700R4 - My first classic truck, bought in September 2005. 85% transformed from "Farm" to "Cool" status! 1970 Dodge Challenger 440, 4sp (my other toy) 12.67 @ 117 MPH, with a pathetic 2.022 60' 2007 Dodge Charger SRT-8 2008 Cadillac CTS All-American garage, baby! Last edited by MrC1; 02-11-2009 at 04:36 PM.

02-11-2009, 04:55 PM	#2
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: LMC exhaust kits - will it work? FYI: I ordered the 6 cylinder kit from them since it looked simple enough. Parts were of real good quality, fitment was not. The parts were not the same as advertised but I was able to make them work with a lot of effort.

02-11-2009, 05:15 PM	#3
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,079	Re: LMC exhaust kits - will it work? If you are using headers there should not be an issue with it working. The factory exhaust was 2.5 on bb with a 2 inch tailpipe. The 2.25 should work with no problems. If using with manifold there is considerable difference in manifold exits and some fab work would have to be done to make work. __________________ 67 blue step side- bb 68 gold and white swb cst anniversary 68 custom swb hot rod Ls swap 69 swb cst 6 cylinder/ overdrive 69 black/black cst bb swb 70 orange and white cst Canada built truck swb bb 71 black and white super swb bb 71 red and white super swb 72 green and white super swb 4x4 62 nova wagon 400 series Ls swapped 68 Camaro 327/4 speed- 1 owner, original paint 66 Volkswagen bettle 69 auto stick Volkswagen Beetle

02-11-2009, 06:21 PM	#4
Stock72c10 classic=of recognized value Join Date: Sep 2008 Location: Wichita, KS Posts: 317	Re: LMC exhaust kits - will it work? Just remember that a 2.5" pipe is ~20% larger than a 2.25" pipe.

02-11-2009, 07:06 PM	#5
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: LMC exhaust kits - will it work? take my advise, go to a quality custom exhaust shop. spend the extra dough and have something that fits..... and it will keep you off the crawler for hours. __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

02-12-2009, 01:26 PM	#8
fnoblitt Registered User Join Date: Mar 2002 Location: southern calif.,usa Posts: 200	Re: LMC exhaust kits - will it work? i had a muffler shop fab me up a custom system, 2 1/2 pipes with flowmasters for my small block . and it runs and sounds great __________________ 70 c10 stepside ,350v8, m-20 4 speed

02-12-2009, 01:37 PM	#9
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: LMC exhaust kits - will it work? I have never installed one of thier kits, but the "ready made" exhaust kits in a box are notorious for needing tweaks. I would just have a muffler shop fab you a 2.5" aluminized manifold back system. that way, you can have your choice of mufflers, exits, etc. __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

02-12-2009, 02:42 PM	#10
MrC1 Dork For Days Join Date: Aug 2005 Location: Dallas Posts: 407	Re: LMC exhaust kits - will it work? I guess it's the $220 price that's getting me. I couldn;t get a custom system for that much, especially if I went with mandrel bends. __________________ 1972 C20, 402/700R4 - My first classic truck, bought in September 2005. 85% transformed from "Farm" to "Cool" status! 1970 Dodge Challenger 440, 4sp (my other toy) 12.67 @ 117 MPH, with a pathetic 2.022 60' 2007 Dodge Charger SRT-8 2008 Cadillac CTS All-American garage, baby!

02-12-2009, 04:15 PM	#11
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: LMC exhaust kits - will it work? had my 2.5 custom bent, turboflow, duals, with all new mounts for $250. drive in, drive out. no headaches. check around D town, I bet you can find good deals out there!! __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

02-12-2009, 04:57 PM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: LMC exhaust kits - will it work? some areas will RAPE you on exhaust work. I have the kit you are asking about, and while most ppl say it fits pretty OK, I was unable to make it all work. HOWEVER... I was asking for trouble. I installed it on a leaf spring truck, with a caddy big block, and 133 inch wheel base. So don't go by my words... a lotta ppl on here have used it with much better results.

02-12-2009, 05:01 PM	#14
LUV2XCLR8 The LuvShack Garage Join Date: Jan 2004 Location: Maple Grove, TN (West Side) Posts: 30,476	Re: LMC exhaust kits - will it work? Not that matters, but i used to work PT doing this stuff and this chart (Taken out of the Flowmaster Dealer Catalog) might help. Attached Images __________________ Owner/Op: "TN Classic Transport Carriers" The Toy: "Square Vette" 72 Hybrid Blazer Toy Barn: "LuvShack" 40 x 60 x 20 Shop Tow Piggy:"Maddy" 88 Silverado 3500 Hauler: "Feathers" 14 Aluma 8218T



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.