C3 Dual Exhaust
01-03-2002, 05:44 PM
#1
Le Mans Master
Thread Starter
C3 Dual Exhaust
Hey yall,
I have true duals on my Vette, but it is getting hard to pass emissions, so I want to go back to the y-pipe set up. I have a dual exhaust crossmemeber, was this an option? Will the y-pipe set up fit? Please advise.
I have true duals on my Vette, but it is getting hard to pass emissions, so I want to go back to the y-pipe set up. I have a dual exhaust crossmemeber, was this an option? Will the y-pipe set up fit? Please advise.
01-03-2002, 05:48 PM
#2
Melting Slicks
Re: C3 Dual Exhaust (VetteBoy1979)
I believe in 1979, they were still using the same frame from previous years that had legally installed duals. So yes, the stock Y-pipe set up should install without any modifications, as the "dual" crossmember was stock.
01-03-2002, 05:55 PM
#3
Team Owner
Re: C3 Dual Exhaust (79MakoL82)
Cat-butt-trophic converters were installed first in '75 and for a cou;le of years or so, the frames were same...2 holes for exhaust....
in '78 they only had ONE exhaust hole....I worked on a friend's 78....
now that exact year/date of change, I"m not sure....
GENE
in '78 they only had ONE exhaust hole....I worked on a friend's 78....
now that exact year/date of change, I"m not sure....
GENE
01-03-2002, 06:01 PM
#4
Team Owner
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St. Jude Donor '11, '16-'17
Re: C3 Dual Exhaust (VetteBoy1979)
Too bad you're not in Oregon. I have the stock exhuast on my '79 and don't need to pass emissions. I would be happy to trade. My crossmember does have two holes as well.
01-03-2002, 06:06 PM
#5
Le Mans Master
Re: C3 Dual Exhaust (VetteBoy1979)
Too bad we're not closer either, I have front and rear stainless steel y-pipes that are cluttering my garage. Two Flowmaster Delta 50 series mufflers still clamped on the rear y-pipe. If anyone in the Chciago area needs or want them, let me know. I've got a pair of Dynomax Corvette ceramic coated headers as well
01-03-2002, 08:26 PM
#7
Melting Slicks
Re: C3 Dual Exhaust (mrvette)
Cat-butt-trophic converters were installed first in '75 and for a cou;le of years or so, the frames were same...2 holes for exhaust....
in '78 they only had ONE exhaust hole....I worked on a friend's 78....
now that exact year/date of change, I"m not sure....
GENE
in '78 they only had ONE exhaust hole....I worked on a friend's 78....
now that exact year/date of change, I"m not sure....
GENE
[Modified by 79MakoL82, 6:27 PM 1/3/2002]
01-03-2002, 09:18 PM
#10
Race Director
Re: C3 Dual Exhaust (VetteBoy1979)
Vetteboy: You only have to worry about emissions 2 more times. You'll be exempt in 2004. I think you should be able to sneak by 2 more times??? Most inspection stations don't have a clue as to what to look for. You can pass the idle sniffer easily without a cat.
01-04-2002, 12:35 AM
#11
Le Mans Master
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St. Jude Donor '08-'09
Re: C3 Dual Exhaust (zwede)
Perhaps you could add 2 converters. Then have the exhaust shop make two "converter-sized" piece of pipe... for off-road use only, of course. :lol:
01-04-2002, 02:14 AM
#14
Burning Brakes
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Re: C3 Dual Exhaust (VetteBoy1979)
I am in Houston as well and have duals on my '79 with no problem on the emissions test. They allow 600 ppm hydrocarbon for our model and I have run 250-300 for the past 4 years. Before going to the test center I always change my oil, plugs and air filter and insure that the car is at operating temperature. Give it a try and see if it helps.
01-04-2002, 04:30 AM
#16
Drifting
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Re: C3 Dual Exhaust (mrvette)
Nope, my 78 has a 2-hole crossmember. I had duals installed a few months ago. Luckily in Oklahoma there aren't as many restrictions. In fact as of last fall we have no state inspection whatsoever.
01-04-2002, 06:26 AM
#17
Melting Slicks
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Re: C3 Dual Exhaust (VetteBoy1979)
My 79 had 2 holes too. Two pipes and 2 cats should be "bluffable" especially with 2 factory holes in the frame for the pipes. Are they questioning the duals; or, is the smog out the tail pipes getting close to the maximum limit?
If you have to go back to the Y pipe I would suggest using 3" pipe to help offset the loss. One 3" pipe is almost equal in flow area to two 2.25" pipes. I doubt that they would check for original pipe diameter even if they do demand the original configuration.
Chuck
If you have to go back to the Y pipe I would suggest using 3" pipe to help offset the loss. One 3" pipe is almost equal in flow area to two 2.25" pipes. I doubt that they would check for original pipe diameter even if they do demand the original configuration.
Chuck
01-04-2002, 10:51 AM
#18
Drifting
Re: C3 Dual Exhaust (VetteBoy1979)
My 79 has the 2 hole crossmember and I have true duals.I have headers w/ dual cats out of monza mufflers sounds great.I just passed inspection.
01-04-2002, 11:02 AM
#19
Melting Slicks
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Re: C3 Dual Exhaust (vettes)
my '79 has the two hole crossmember...
no inspection here either....gotta love it....but i bet i would pass...high performance engines are usually burning much more efficiently and pass these tests easily...i have some friends that have to pass them in different county..
we change oil, plugs, wires, and dump 93 octane with a fuel additive in it.
they pass everytime with no cats...
I have dynomax headers to duals, crossover, out twin dual-tip monza mufflers.
no inspection here either....gotta love it....but i bet i would pass...high performance engines are usually burning much more efficiently and pass these tests easily...i have some friends that have to pass them in different county..
we change oil, plugs, wires, and dump 93 octane with a fuel additive in it.
they pass everytime with no cats...
I have dynomax headers to duals, crossover, out twin dual-tip monza mufflers.
