Emmisions help please. . . . - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*racedvl* · 11-20-2002, 11:46 PM

Well, here is the low down. I have my 86 GMC. It has a 305, and headers. Also, my truck used to be a 4.3L. Well, I bought 2 universal cats, and 2 turbo mufflers. Should be cool, right? WRONG.

It is against the law to run a true dual exhaust on a vechile that was only a single, becuase of the cat situation. If the truck only had one cat, you can't have 2. None of the shops around here will touch it.

Now, one guy would do it "after hours" for a reasonable fee, but my problem is if it would have to go in for emmisions, and they fail it for it, I will have to get another system put on it. Have to pay for it twice.

Now they will also be willing to make a "Y" pipe after the headders, and make it a single system. But to do so, it's a little expensive. Or should I get factory manifolds and get a factory system? Also, it is technecly against the law to have a v8 in place of a v6, but they are pretty leanlent about that, at least they were with my 69. As long as the v8 passes the 6 cylinder specs. Should I get the duals, and take the chance? Should i get some $$$ together and have them make a "y" pipe and run a single system? I feel as if i am between a rock and a hard place. Any ideas? Thanks. BTW, I live in IL.

**swervin ervin** · 11-21-2002, 12:13 AM

I feel your pain. I tried my best to get someone to let me run true dual exhaust, but as you have said, it must be the way it came from the factory, i.e. with a y-pipe and single cat. After the cat, I can do anything I want. They are real strict in my state/county and go by the book to the letter. Reason is because of the money they make off this stuff. It's 30 bucks now for a inspection and I think the state gets around 10 of it.

I can't tell you what to do because I'm not sure what is involved for you to pass and if you can get it done without much trouble. But, I played by the rules. Didn't have much choice, unless I wanted to change exhaust every year it came time for inspections.

I run Edelbrock TES headers, which have a y-pipe and the A.I.R. tubes. I run these into a single Random Technology 3" in/out cat. Every bit of emissions stuff on my truck works and is hooked up. My truck is far from stock, and passes the tests with flying colors.

I know some will chime in and say register it in another county where it will pass. This is not for me though. Besides, the counties around mine are going to emission tests in a year of so.

I know this isn't much help, but I don't have anything to tell you but do what you feel is best and less trouble.

If it were me, I'd go with a y-pipe and single cat and not worry about it. Believe me, it can be made to look good and flow good this way. As far as the engine swapping, from what I understand, it's legal to swap engines as long as the engine you are installing was an option in the truck. But, as my state does, they use your VIN to go by. So, the tests will need to pass what's legal for the old engine. Not a big deal, since they are fairly easy to pass, if the emissions stuff works. Personally, I don't think the inspectors really care what engine is in it, as long as it looks legal.

TooMany2count · 11-21-2002, 03:34 PM

1st thing is you "NEVER EVER" tell them you have a V8 in the truck cause they really dont want to know this as long as it passes. The exhaust I would question only because I have several friends who live here in ILL. also & they have duals on their trucks & they all have passed the test. what I would do is this, rather thank buy a dual exhaust if your worried about it, buy a CATBACK system that has a 3"exhaust ran through it w/headers & it will be emissions LEGAL & if you still worried about not passing just pull your PCV out of you valve cover & let it suck in some extra clean air & IT WILL PASS then, hope this helps...joe

low 84 · 11-21-2002, 05:39 PM

i would get a dual in/dual out cat. that way your really only using one cat but its still pretty much dual exhaust you can take it to you two seperate mufflers after the cat.

**swervin ervin** · 11-21-2002, 06:13 PM

I doubt a dual in/dual out would be any better than a single 3" in/out. Besides, they probably won't let him do this anyway. If his state is like mine, they clearly say, it must be like it was from the factory. I'm afraid none of our trucks came with a dual in/out cat.

*racedvl* · 11-21-2002, 09:15 PM

The only trucks that came factory with a dual exhaust is deisels.

Like said, to be "legal" it has to be like it was from the factory. Also, I know about the hush, hush on the v8, had to do that with the 69.

**GMCPaul** · 11-22-2002, 05:14 AM

Swervin's steering you right, snatch a set of headers with Y pipe, 1- 3" hi-flo cat, and single 3" to muffler with dual outlets. We run this exact set-up on our 1988 GMC with a Eldelbrock multi-port injection system and it lays us back in the seat nicely on acceleration, while maintaining a nice quite cab interior but with a real *****in sound out the rear.
GMCPaul

*racedvl* · 11-22-2002, 09:16 AM

Hhhmmm... Well, I really don't need the 3" stuff. It's a tired 22 year old 305.

Plus i already have the 2 1/4 " stuff already. 2 mufflers, and 2 cats. I dunno, I might just get the "y" pipe made, but $275?!? I only paid $500 for the truck!

benwantland · 11-27-2002, 04:03 AM

Quote:

Originally posted by racedvl
I dunno, I might just get the "y" pipe made, but $275?!?

What is that $275 including? Everything, or just the y-pipe? Here is a cheap flowmaster y-pipe: http://www.jegs.com/cgi-bin/ncommerc...14&prmenbr=361 If you got one of those and could return your mufflers and cats, you could probably run a single 3" system cheaper than your dual 2.25" anyway.

SCOTI · 11-27-2002, 02:43 PM

Sometimes I just don't get the government. Case in point: My 78 elcamino w/tired 305. All original, all correct emission equipment. I added a single hi-flow cat & dual flowmaster exhaust because that's what was 'technically' correct. Fast forward: New 350, crane cam w/L-82 specs, 4-barrel holley emissions carb for L-82 vette, performer intake, + headers. I wanted to run a true dual exhaust w/cats (so I wouldn't be disabling the emission aspect)but it's technically illegal because of 2 cats. I decided that since 2 cats are illegal (it's not any more illegal than none at all & none at all is cheaper), I left them off & pieced together a 2.5" system. Comparing both emissions analysis from one year to the next, WITHOUT cats & with a 4-barrel & performance cam it RAN CLEANER than the stock 305 w/all correct equipment. Just like you, I want cleaner air but technically my combo was illegal even though it burned cleaner. I say stick the probe in the tailpipe to check for a clean burning engine & leave the hood shut. Just so you know, I wouldn't have driven it if it wasn't equal to or better than what was legally required. My 2 cents.

*racedvl* · 11-27-2002, 09:34 PM

Well, I already have all the parts to do the job. So going to a 3" is not really an option. Also, yes, $275 included everything. But... I only paid $500 for the truck, and is by no means something I'm gonna keep forever. I really want a 4x4, and I can't get that $275 back out of the truck, come time to sell it. I dunno what to do.

Longhorn Man · 12-01-2002, 02:32 PM

Jason...FED law says you can have a larger engine in there, as long as it was an angine available in that vehicle make/model when new. We all know a 305 was available in these trucks so it should be ok onless your local gov has added to the laws like Cali does.
While true, your pipes are not legal, I'd imagine once you fix them, you should be ok as long as the engine passes for 305 standards.

*racedvl* · 12-01-2002, 05:44 PM

Nah Andy, when I brought in my 69 for testing, I told the guy it had a V8, and he told me it was illegal! If it was a 6 cly, it has to be still a 6 cly, not a 8. I'm thinking of just getting the pipes done, I am tired of the exhaust dumping under my seat.

11-20-2002, 11:46 PM	#1
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Emmisions help please. . . . Well, here is the low down. I have my 86 GMC. It has a 305, and headers. Also, my truck used to be a 4.3L. Well, I bought 2 universal cats, and 2 turbo mufflers. Should be cool, right? WRONG. It is against the law to run a true dual exhaust on a vechile that was only a single, becuase of the cat situation. If the truck only had one cat, you can't have 2. None of the shops around here will touch it. Now, one guy would do it "after hours" for a reasonable fee, but my problem is if it would have to go in for emmisions, and they fail it for it, I will have to get another system put on it. Have to pay for it twice. Now they will also be willing to make a "Y" pipe after the headders, and make it a single system. But to do so, it's a little expensive. Or should I get factory manifolds and get a factory system? Also, it is technecly against the law to have a v8 in place of a v6, but they are pretty leanlent about that, at least they were with my 69. As long as the v8 passes the 6 cylinder specs. Should I get the duals, and take the chance? Should i get some $$$ together and have them make a "y" pipe and run a single system? I feel as if i am between a rock and a hard place. Any ideas? Thanks. BTW, I live in IL.

11-21-2002, 12:13 AM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I feel your pain. I tried my best to get someone to let me run true dual exhaust, but as you have said, it must be the way it came from the factory, i.e. with a y-pipe and single cat. After the cat, I can do anything I want. They are real strict in my state/county and go by the book to the letter. Reason is because of the money they make off this stuff. It's 30 bucks now for a inspection and I think the state gets around 10 of it. I can't tell you what to do because I'm not sure what is involved for you to pass and if you can get it done without much trouble. But, I played by the rules. Didn't have much choice, unless I wanted to change exhaust every year it came time for inspections. I run Edelbrock TES headers, which have a y-pipe and the A.I.R. tubes. I run these into a single Random Technology 3" in/out cat. Every bit of emissions stuff on my truck works and is hooked up. My truck is far from stock, and passes the tests with flying colors. I know some will chime in and say register it in another county where it will pass. This is not for me though. Besides, the counties around mine are going to emission tests in a year of so. I know this isn't much help, but I don't have anything to tell you but do what you feel is best and less trouble. If it were me, I'd go with a y-pipe and single cat and not worry about it. Believe me, it can be made to look good and flow good this way. As far as the engine swapping, from what I understand, it's legal to swap engines as long as the engine you are installing was an option in the truck. But, as my state does, they use your VIN to go by. So, the tests will need to pass what's legal for the old engine. Not a big deal, since they are fairly easy to pass, if the emissions stuff works. Personally, I don't think the inspectors really care what engine is in it, as long as it looks legal. __________________ Mike 1985 Chevy C-10

11-21-2002, 03:34 PM	#3
TooMany2count Who's in CHARGE?????????? Join Date: Nov 2002 Location: Cahokia, IL Posts: 455	1st thing is you "NEVER EVER" tell them you have a V8 in the truck cause they really dont want to know this as long as it passes. The exhaust I would question only because I have several friends who live here in ILL. also & they have duals on their trucks & they all have passed the test. what I would do is this, rather thank buy a dual exhaust if your worried about it, buy a CATBACK system that has a 3"exhaust ran through it w/headers & it will be emissions LEGAL & if you still worried about not passing just pull your PCV out of you valve cover & let it suck in some extra clean air & IT WILL PASS then, hope this helps...joe __________________ Send a card to a soldier in Iraq My Music PlayList Large Marge Donate Blood,Plasma,Platelets & sign your DONORS CARD & SAVE a LIFE

11-21-2002, 05:39 PM	#4
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	i would get a dual in/dual out cat. that way your really only using one cat but its still pretty much dual exhaust you can take it to you two seperate mufflers after the cat. __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

11-22-2002, 05:14 AM	#7
GMCPaul Senior Member Join Date: Mar 2000 Location: Rockville,In. USA Posts: 3,718	Swervin's steering you right, snatch a set of headers with Y pipe, 1- 3" hi-flo cat, and single 3" to muffler with dual outlets. We run this exact set-up on our 1988 GMC with a Eldelbrock multi-port injection system and it lays us back in the seat nicely on acceleration, while maintaining a nice quite cab interior but with a real *****in sound out the rear. GMCPaul __________________ Secure Online Catalog for-GMCPauls Truck Parts Email- GMCPAULS@GMAIL.COM

11-21-2002, 06:13 PM	#5
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I doubt a dual in/dual out would be any better than a single 3" in/out. Besides, they probably won't let him do this anyway. If his state is like mine, they clearly say, it must be like it was from the factory. I'm afraid none of our trucks came with a dual in/out cat.

11-21-2002, 09:15 PM	#6
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	The only trucks that came factory with a dual exhaust is deisels. Like said, to be "legal" it has to be like it was from the factory. Also, I know about the hush, hush on the v8, had to do that with the 69.

11-22-2002, 09:16 AM	#8
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Hhhmmm... Well, I really don't need the 3" stuff. It's a tired 22 year old 305. Plus i already have the 2 1/4 " stuff already. 2 mufflers, and 2 cats. I dunno, I might just get the "y" pipe made, but $275?!? I only paid $500 for the truck!

11-27-2002, 02:43 PM	#10
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 21,943	Sometimes I just don't get the government. Case in point: My 78 elcamino w/tired 305. All original, all correct emission equipment. I added a single hi-flow cat & dual flowmaster exhaust because that's what was 'technically' correct. Fast forward: New 350, crane cam w/L-82 specs, 4-barrel holley emissions carb for L-82 vette, performer intake, + headers. I wanted to run a true dual exhaust w/cats (so I wouldn't be disabling the emission aspect)but it's technically illegal because of 2 cats. I decided that since 2 cats are illegal (it's not any more illegal than none at all & none at all is cheaper), I left them off & pieced together a 2.5" system. Comparing both emissions analysis from one year to the next, WITHOUT cats & with a 4-barrel & performance cam it RAN CLEANER than the stock 305 w/all correct equipment. Just like you, I want cleaner air but technically my combo was illegal even though it burned cleaner. I say stick the probe in the tailpipe to check for a clean burning engine & leave the hood shut. Just so you know, I wouldn't have driven it if it wasn't equal to or better than what was legally required. My 2 cents. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

11-27-2002, 09:34 PM	#11
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Well, I already have all the parts to do the job. So going to a 3" is not really an option. Also, yes, $275 included everything. But... I only paid $500 for the truck, and is by no means something I'm gonna keep forever. I really want a 4x4, and I can't get that $275 back out of the truck, come time to sell it. I dunno what to do.

12-01-2002, 02:32 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Jason...FED law says you can have a larger engine in there, as long as it was an angine available in that vehicle make/model when new. We all know a 305 was available in these trucks so it should be ok onless your local gov has added to the laws like Cali does. While true, your pipes are not legal, I'd imagine once you fix them, you should be ok as long as the engine passes for 305 standards.

12-01-2002, 05:44 PM	#13
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Nah Andy, when I brought in my 69 for testing, I told the guy it had a V8, and he told me it was illegal! If it was a 6 cly, it has to be still a 6 cly, not a 8. I'm thinking of just getting the pipes done, I am tired of the exhaust dumping under my seat.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.