advice configuring 406 or 427 that will pass California emissions requirements
06-30-2018, 02:15 PM
#1
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advice configuring 406 or 427 that will pass California emissions requirements
I need help. I'm thinking about building a 406 or 427 with DART short block, but it needs to go into my 1978 (will replace L82) that must pass California's emissions. It has AIR system on engine, so I will need to preserve the AIR. I want lots of torque for street driving and don't see RPMs over 6500 RPM.
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
- Found the AFR Street and Race versions of the 195s which are EO certified. Are these just too small for 406 or 427? If it will only compromise high RPM power, it may be okay. Is additional price of the race versions worth it in my case? Any other EO certified options that would be better matched to the 406 or 427?
- Found Hedman 63127 headers (https://www.summitracing.com/oh/parts/hed-63127). Are these better than the standard exhaust manifolds on the L82 or would they be waste of money? Any other options?
- Recommendations for dual plane intake manifold that is EO certified and will also fit under hood? Looks like Edelbrock might have an option.
- Recommendations for EO certified carburetor?
- Recommendations for EO certified cam shaft that would generate sufficient vacuum but still have nice sound?
- What about distributor?
- Any transmission recommendations?
- What other drive line changes would be necessary?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
06-30-2018, 03:17 PM
#2
Instructor
I am wanting to make internal mods to my CA car also so will be interested in what you find out. I don’t think you can run headers at all on it. You will be looking for CARB compliant parts. As far as visual inspection I spend an afternoon every 2 years putting the emission equipment on for the inspection but the rest of the time I have it all off. Really just depends how much work you want to do every two years to bring it back into compliance. I am running everything stock though, minus emission equipment currently.
06-30-2018, 03:34 PM
#3
Check this out. I believe these are the headers I used to have when I had to get smogged checked:
https://www.jegs.com/i/Hedman/500/68301/10002/-1
OR, you might be able to weld these things on those 1.75" headers you want and hope it passes:
https://www.summitracing.com/parts/hed-22830
https://www.jegs.com/i/Hedman/500/68301/10002/-1
OR, you might be able to weld these things on those 1.75" headers you want and hope it passes:
https://www.summitracing.com/parts/hed-22830
I need help. I'm thinking about building a 406 or 427 with DART short block, but it needs to go into my 1978 (will replace L82) that must pass California's emissions. It has AIR system on engine, so I will need to preserve the AIR. I want lots of torque for street driving and don't see RPMs over 6500 RPM.
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
- Found the AFR Street and Race versions of the 195s which are EO certified. Are these just too small for 406 or 427? If it will only compromise high RPM power, it may be okay. Is additional price of the race versions worth it in my case? Any other EO certified options that would be better matched to the 406 or 427?
- Found Hedman 63127 headers (https://www.summitracing.com/oh/parts/hed-63127). Are these better than the standard exhaust manifolds on the L82 or would they be waste of money? Any other options?
- Recommendations for dual plane intake manifold that is EO certified and will also fit under hood? Looks like Edelbrock might have an option.
- Recommendations for EO certified carburetor?
- Recommendations for EO certified cam shaft that would generate sufficient vacuum but still have nice sound?
- What about distributor?
- Any transmission recommendations?
- What other drive line changes would be necessary?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
Last edited by carriljc; 06-30-2018 at 03:36 PM.
06-30-2018, 06:56 PM
#6
Burning Brakes
How are they going to ding for headers when some of them came stock with headers from GM? Aren't you only required to smog for what the requirement was of that year?
I don't know anything about Cali smog 'cept they are stupid, IMO im with Andies.
If they are going with only air sample, then stick a 210 t-stat in it and run it LEEEEEEEEEEAAAAAAAAAAAAAAAAAAN when you go in there and make sure it's at full temp.
I don't know anything about Cali smog 'cept they are stupid, IMO im with Andies.
If they are going with only air sample, then stick a 210 t-stat in it and run it LEEEEEEEEEEAAAAAAAAAAAAAAAAAAN when you go in there and make sure it's at full temp.
Last edited by naramlee; 06-30-2018 at 06:57 PM.
06-30-2018, 08:31 PM
#7
Drifting
I need help. I'm thinking about building a 406 or 427 with DART short block, but it needs to go into my 1978 (will replace L82) that must pass California's emissions. It has AIR system on engine, so I will need to preserve the AIR. I want lots of torque for street driving and don't see RPMs over 6500 RPM.
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
Is it possible to build one that will pass requirements of visual inspection and sniff test for California? My impression after speaking with referee is that the block doesn't matter (they are not concerned with bore, stroke, displacement, etc. inside the block for the visual inspection). If it looks like a 350 SBC block, they will consider it a 350 SBC. That means, you just need to have EO certified 'add ons' for heads, headers, etc. Can anyone confirm this with their experience?
With this in mind, I'm searching for 'EO certified' add ons that would not handicap the DART 406 or 427 short block too severely. Any suggestions?
- Found the AFR Street and Race versions of the 195s which are EO certified. Are these just too small for 406 or 427? If it will only compromise high RPM power, it may be okay. Is additional price of the race versions worth it in my case? Any other EO certified options that would be better matched to the 406 or 427?
- Found Hedman 63127 headers (https://www.summitracing.com/oh/parts/hed-63127). Are these better than the standard exhaust manifolds on the L82 or would they be waste of money? Any other options?
- Recommendations for dual plane intake manifold that is EO certified and will also fit under hood? Looks like Edelbrock might have an option.
- Recommendations for EO certified carburetor?
- Recommendations for EO certified cam shaft that would generate sufficient vacuum but still have nice sound?
- What about distributor?
- Any transmission recommendations?
- What other drive line changes would be necessary?
Is the answer: just stick with 383 stroker and forget about the 406 or 427 because it will be so handicapped by EO certified components that it's waste of money, please let me know.
Thanks,
- Ryan
07-01-2018, 08:38 AM
#8
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07-01-2018, 12:32 PM
#9
Le Mans Master
The 81/82 C3 have a tubular exhaust manifold that is essentially a shorty/block hugger header, instead of ramhorn exhaust manifolds, like all the other C3 years. Here is an example:
https://www.ebay.com/i/263494595832?chn=ps
C3's never came with Long Tube headers.
My 94 Mustang GT has a similiar tubular exhaust manifold/shorty header from the factory. I replaced the same with a BBK shorty header that is the same style with bigger primaries.
07-01-2018, 01:02 PM
#10
Racer
I looked at CARB compliant parts when I was considering buying an '80.
I think that the cat. converter ends up being your biggest performance restriction.
I've been told by some of the smog guys that if the car came with one cat, then that's all you can run. You're not "legally" allowed to run dual-cats.
There are high-flow units out there in 2 1/2" and 3", but after reviewing the EOs, it looks like only the 2 1/2" are allowed on the C3. So whatever approved mods you do to the engine (CI, compression, intake, headers, EFI, cam, etc), you still have to exhaust it all through a single 2 1/2" converter.
If you can find some documentation to the contrary, please let us know, because I'd love to have an '80 or '81 for more of a driver.
Chris
I think that the cat. converter ends up being your biggest performance restriction.
I've been told by some of the smog guys that if the car came with one cat, then that's all you can run. You're not "legally" allowed to run dual-cats.
There are high-flow units out there in 2 1/2" and 3", but after reviewing the EOs, it looks like only the 2 1/2" are allowed on the C3. So whatever approved mods you do to the engine (CI, compression, intake, headers, EFI, cam, etc), you still have to exhaust it all through a single 2 1/2" converter.
If you can find some documentation to the contrary, please let us know, because I'd love to have an '80 or '81 for more of a driver.
Chris
07-01-2018, 01:34 PM
#11
Team Owner
Surely there has to be some avenue for smog testing a vehicle that is not a stock configuration. You need to research the actual stated requirements by going on the web and finding them within the actual testing documents. Businesses/private folks make 'modified' vehicles all the time and CA would not have a "production" configuration to test them against. It wouldn't be legal for CA to just say, "Well, it's not an EPA-approved production automobile, so you can't drive it in Cal-ee-forn-ee-ah."
Do some research on the smog laws; build an engine which will produce relatively low emissions; install CATs needed to clean up the rest AND not be a significant restriction for your exhaust system; and take it to them for testing....along with a copy of the CA.gov documentation which allows testing of 'unique' vehicles.
If you present the vehicle as a specific year/model of Corvette, that's how it will be tested. Change your strategy.
Do some research on the smog laws; build an engine which will produce relatively low emissions; install CATs needed to clean up the rest AND not be a significant restriction for your exhaust system; and take it to them for testing....along with a copy of the CA.gov documentation which allows testing of 'unique' vehicles.
If you present the vehicle as a specific year/model of Corvette, that's how it will be tested. Change your strategy.
Last edited by 7T1vette; 07-01-2018 at 01:37 PM.
07-01-2018, 03:30 PM
#12
Instructor
You can drive them in CA, just can’t register them in CA. If you have family or friends that live in another state you can register it out of state or revert it back every two years for smog check. Pre 1975 is exempt from smog requirements.
07-01-2018, 03:46 PM
#13
Race Director
Here’s what I learned years ago from going down this same road on my 81 in CA. The 81 has both the advantage and disadvantage of having a computer controlled Q-jet in that it will make adjustments to keep the hydrocarbons in check but was very limiting to cam choices.
Heads: From a prictical standpoint, you can do anything you want here. Yes, it’s supposed to be certified but takes an astuteness on the part of the inspector to notice. In my experience, astuteness isn’t common
Same goes for intake. Bore and stroke is a free for all; hard to verify even if they did care, and they don’t.
Exhaust manifold/headers: This one is tough. It’ll be pretty obvious if the smog pump isn’t connected to anything and there were only a couple of choices that I could find in headers that had these, all of which were discontinued. The shorty headers on the 81s and 82s were about the best choices. The 82s were said to be slightly larger in diameter, but I was never able to verify this. There is an aftermarket version but I can’t remember who makes them. Any of these will tend to choke a larger displacement engine but your RPM range will help.
Cam: Tougher than headers. I’d suggest going to a custom grind from Comp or one of the other specialty companies once you have your engine specifics. Tell them what you want and need to achieve and they’ll help. A lot of your goals, like rough idle, will tend to be compromised by emission requirements.
Catalytic converter: Cats are your friend! An efficient aftermarket cat will cover up many of the compromises and shortcomings of your build (from an emissions standpoint) and will allow you to get away with more. They also flow about an order of magnitude better that the stock pancake cat. Also make sure that it’s good and hot before your smog test. Makes it work more efficiently. Set timing to spec too on the more retarded end of the range. You can adjust this back for performance after you pass.
You results may vary
Heads: From a prictical standpoint, you can do anything you want here. Yes, it’s supposed to be certified but takes an astuteness on the part of the inspector to notice. In my experience, astuteness isn’t common
Same goes for intake. Bore and stroke is a free for all; hard to verify even if they did care, and they don’t.Exhaust manifold/headers: This one is tough. It’ll be pretty obvious if the smog pump isn’t connected to anything and there were only a couple of choices that I could find in headers that had these, all of which were discontinued. The shorty headers on the 81s and 82s were about the best choices. The 82s were said to be slightly larger in diameter, but I was never able to verify this. There is an aftermarket version but I can’t remember who makes them. Any of these will tend to choke a larger displacement engine but your RPM range will help.
Cam: Tougher than headers. I’d suggest going to a custom grind from Comp or one of the other specialty companies once you have your engine specifics. Tell them what you want and need to achieve and they’ll help. A lot of your goals, like rough idle, will tend to be compromised by emission requirements.
Catalytic converter: Cats are your friend! An efficient aftermarket cat will cover up many of the compromises and shortcomings of your build (from an emissions standpoint) and will allow you to get away with more. They also flow about an order of magnitude better that the stock pancake cat. Also make sure that it’s good and hot before your smog test. Makes it work more efficiently. Set timing to spec too on the more retarded end of the range. You can adjust this back for performance after you pass.
You results may vary
Last edited by CA-Legal-Vette; 07-01-2018 at 03:50 PM.
07-01-2018, 08:19 PM
#14
These state that they are AIR headers and look to be available. https://www.jegs.com/i/Hedman/500/68301/10002/-1
Also .. eyeball this post where Member Joe Papa installed them: https://www.corvetteforum.com/forums...post1591943994
What year vehicle are you asking about anyway? Read the text in the above link. It has some wishy-washy words but they might be ok to use with your vehicle.
You're lucky it isn't 1985 when nobody knew what they were doing. I even had a thermostatic air cleaner on for smog checking the first time. In about 1990 I was sent to an "approved" shop where they drilled and tapped my headers and installed AIR tubing and a smog pump.
Also .. eyeball this post where Member Joe Papa installed them: https://www.corvetteforum.com/forums...post1591943994
What year vehicle are you asking about anyway? Read the text in the above link. It has some wishy-washy words but they might be ok to use with your vehicle.
You're lucky it isn't 1985 when nobody knew what they were doing. I even had a thermostatic air cleaner on for smog checking the first time. In about 1990 I was sent to an "approved" shop where they drilled and tapped my headers and installed AIR tubing and a smog pump.
Last edited by carriljc; 07-01-2018 at 08:22 PM.
07-01-2018, 08:46 PM
#15
Melting Slicks
07-02-2018, 09:23 AM
#16
Drifting
If your car has the removable auto crossmember buy another crossmemeber and have two exhaust systems. One to pass the test/visual and another to pass a drive by/ on street test and have dual cats. I have an 80 so my exhaust runs under the crossmember so was easy to swap out when they did visual testing here.
07-02-2018, 01:03 PM
#17
Drifting
Let the Referee Decide?
Forum: I remember some time ago someone commenting on this subject.
The smog station guys have no latitude in what does or does not pass.
The referee can check to see that you have the right stuff and give you a pass.
The comment was that it is easier to get a pass from the referee than a test station?
Add on duals w/cats should pass!
Please let us know how it goes.
R
The smog station guys have no latitude in what does or does not pass.
The referee can check to see that you have the right stuff and give you a pass.
The comment was that it is easier to get a pass from the referee than a test station?
Add on duals w/cats should pass!
Please let us know how it goes.
R
07-03-2018, 01:14 AM
#19
Le Mans Master
If it is not stock it better have a CARB number. Carburetor, Intake, heads, headers and air filter housing. Even a replacement cat needs to have an OE Number.
Timing also can only be + or - 2 degrees fro factory.
Transmission, rearend, and exhaust after the cat are not part of the visual.
Timing also can only be + or - 2 degrees fro factory.
Transmission, rearend, and exhaust after the cat are not part of the visual.
07-03-2018, 08:26 AM
#20
Team Owner
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St. Jude Donor '05
The cat configuration has to be exactly as delivered from GM, cant convert a single to dual
The cat must also have the correct CA CARB # stamped on it or they will fail you. Just went through this with my 02 truck a few days ago, no getting around it
The visual is a royal pain. There was no sniffer test but the visual..they checked EVERYthing, checking to see if every hose was attached, not faked, plugged etc.
A good LEGAL high flow cat wont hurt your power. Keep the overlap to a minimum, cant run it too lean or screw with timing they wil check.
It can be done but will take some planning. A good efficient combustion chamber really helps. our smog laws are downright stupid..
Some limits are impossible to achieve. Had to sell my 80s/90s era cars they simply wouldnt pass anymore. My 02 truck was on "the verge", in perfect running order and bone stock.
The cat must also have the correct CA CARB # stamped on it or they will fail you. Just went through this with my 02 truck a few days ago, no getting around it
The visual is a royal pain. There was no sniffer test but the visual..they checked EVERYthing, checking to see if every hose was attached, not faked, plugged etc.
A good LEGAL high flow cat wont hurt your power. Keep the overlap to a minimum, cant run it too lean or screw with timing they wil check.
It can be done but will take some planning. A good efficient combustion chamber really helps. our smog laws are downright stupid..
Some limits are impossible to achieve. Had to sell my 80s/90s era cars they simply wouldnt pass anymore. My 02 truck was on "the verge", in perfect running order and bone stock.