78 pace car mods to pass smog
09-08-2016, 05:05 PM
#1
Advanced
Thread Starter
78 pace car mods to pass smog
I have a 1978 corvette pace car with a 350 and an automatic. I live is Sothern California and I want to try and get my car as close to 350 hp while still being able to pass smog. I know about carb aproved parts and stuff but I want to hear about others experiences with mods or engine swaps who'll still pass smog. Any input would be great.
09-08-2016, 08:07 PM
#2
Melting Slicks
You might check with Your States Emission standards in many States a 78 is old enough that there are no more Emissions tests. This doesn't mean that the Sky is the limit and that You can remove anything you want. If the car catch's the attention of an officer he may mandate a vehicle inspection. In Washington State if a car is 25 years old or built in 2009 and newer it doesn't do emissions anymore. This is because most older cars aren't worth enough to fix when they don't pass, and new cars don't fail. So the big cash cow the state has been making is drying up, and they are cutting there losses. The Emissions Testing facility's are private contractors, and they are now going out of business.
09-08-2016, 11:56 PM
#3
Race Director
451hp/485lb-ft torque and passed emissions, visual and otherwise.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
09-08-2016, 11:57 PM
#4
Race Director
BTW, if you are ever up in the San Jose area I'll gladly take you for a ride.
Mine's a 78 pace car too, BTW. Is yours an L-48 or L-82? If L-48, federal or CA emissions?
Mine's a 78 pace car too, BTW. Is yours an L-48 or L-82? If L-48, federal or CA emissions?
Last edited by Shark Racer; 09-08-2016 at 11:57 PM.
09-12-2016, 03:31 PM
#6
Advanced
Thread Starter
451hp/485lb-ft torque and passed emissions, visual and otherwise.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
09-12-2016, 04:39 PM
#7
Burning Brakes
>>> Never mind - I think I found them....(helps to open my eyes sometimes!
)Thanks!
Last edited by bradleyb66; 09-12-2016 at 10:08 PM.
09-13-2016, 01:43 PM
#8
Race Director
Other than that, in the engine bay there isn't much. You may end up having to re-route plug wires to avoid burns, and you'll need to hook the heat riser valve up differently.
The header collectors will need to be welded into your exhaust system as they dump about half a foot down and one foot further back then the manifolds. Probably obvious when you look at the two side-by-side, but not everyone is used to header swaps.
I assume this clears the stock hood ok?
Thanks!
Thanks!
09-13-2016, 08:22 PM
#10
Race Director
I've used all of the ones I've mentioned and they each work fine with a stock style EGR valve. Depending on your valve covers you may need a spacer.
That said, I'm referring to a 75-81 EGR Valve, triangular base with 2 bolts:
I used the Edelbrock EGR adapter to move it away from the valve cover with my EDL-3701. With the ZZ4 manifold, no adapter needed. The Weiand would have required a different adapter (more like a straight spacer) for my setup, but I switched manifolds to the ZZ4 manifold after a couple weeks with the Weiand so never got EGR set up.
That said, I'm referring to a 75-81 EGR Valve, triangular base with 2 bolts:
I used the Edelbrock EGR adapter to move it away from the valve cover with my EDL-3701. With the ZZ4 manifold, no adapter needed. The Weiand would have required a different adapter (more like a straight spacer) for my setup, but I switched manifolds to the ZZ4 manifold after a couple weeks with the Weiand so never got EGR set up.
Last edited by Shark Racer; 09-13-2016 at 08:23 PM.
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shok (09-13-2016)
09-13-2016, 11:16 PM
#11
Team Owner
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St. Jude Donor '05
Good info from Shark Racer
Machine doesnt recognize CI
Watch the overlap on the cam, build for sheer torque.
"Its a 350"...if you have to see the BAR ref its not such a bad thing if all is in order oughta be able to get a sticker.
Cant get away with what we could 10 yrs ago the limits have really tightened up but can still make one run decent. They do check the timing, have a fresh GOOD quality cat on there that has the Ca stamp no generics. The high flow cats are overrated
I dont know if Gov brown signed off on this latest smog bill but IF it did pass you still have to do the visual but can pay 200 to dmv to forgo the emissions end of it up to 1980?81?
Something to look into.
The requirements are beyond rediculous but having smog and egr stuff on your car isnt going to hamper your performance like everyone thought it did 20 yrs ago. stealthy actually
Machine doesnt recognize CI
Watch the overlap on the cam, build for sheer torque.
"Its a 350"...if you have to see the BAR ref its not such a bad thing if all is in order oughta be able to get a sticker.
Cant get away with what we could 10 yrs ago the limits have really tightened up but can still make one run decent. They do check the timing, have a fresh GOOD quality cat on there that has the Ca stamp no generics. The high flow cats are overrated
I dont know if Gov brown signed off on this latest smog bill but IF it did pass you still have to do the visual but can pay 200 to dmv to forgo the emissions end of it up to 1980?81?
Something to look into.
The requirements are beyond rediculous but having smog and egr stuff on your car isnt going to hamper your performance like everyone thought it did 20 yrs ago. stealthy actually
Last edited by cv67; 09-13-2016 at 11:26 PM.
09-14-2016, 12:43 AM
#12
Advanced
Thread Starter
Yes, the EDL-3701, Weiand 7525 (no longer produced, single plane manifold) and ZZ4 intake (GM 10185063) all clear the stock hood without issue, running a QuadraJet with 1/4" base gasket. I'm sure any other manufacturer's EGR manifold would fit fine as well, given that they all are low rise that I've found.
09-14-2016, 03:06 AM
#13
Race Director
I ultimately built a Q-Jet for it following one of the recipes in Cliff Ruggles's book on high performance Q-Jets.
Last edited by Shark Racer; 09-14-2016 at 03:06 AM.
09-14-2016, 07:43 AM
#14
Le Mans Master
451hp/485lb-ft torque and passed emissions, visual and otherwise.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
Hedman 68301 headers, there are a few other legal hedmans depending on whether or not you have AIR tubes.
Crane sells EO'd cams, and you can spec a roller cam with similar characteristics that will do fine on emissions.
Intakes are limited to those that support EGR. Edel 3701 is pretty much the best option available.
AFR 195s. Don't bother with the competition ported variety; the intake ports are taller than the intake manifold. Won't seal.
Compression ratio ~10-10.5:1.
My recipe is close to this, passed smog easily, drives great, surprises lots of people. Being limited to a low-rise dual plane really hampers what you can do with a small-block chevy though.
IMO, this is pretty much the limit of what you can do with a gen 1 smallblock. If you want bigger power numbers, an LS will do it for the same price, more reliably, and with even better emissions. You'll have to go the BAR route and get the engine swap stickered, though.
HTH.
09-14-2016, 11:30 AM
#15
Race Director
09-14-2016, 01:14 PM
#16
Le Mans Master
Awesome!
Your setup is similar to mine with AFR 180's, 10.2:1 compression, 1.5 roller tipped rockers, L-82 OEM aluminum intake (EGR blocked), Howards Roller Cam (.525/.525 lift, duration 219/225, LSA 110, operating range 1,500-5,600 RPM). I have always guessed about 425+ HP once I get the 1 3/4 inch primary LTH's on,,,maybe more!
The 485 ft-lbs torque is at what rpm and how broad?...that is a ton of torque and certainly BB like numbers being close to 500 ft-lbs. My L-82 355's torque is very linear from 2,000-5,000 rpm....
Your setup is similar to mine with AFR 180's, 10.2:1 compression, 1.5 roller tipped rockers, L-82 OEM aluminum intake (EGR blocked), Howards Roller Cam (.525/.525 lift, duration 219/225, LSA 110, operating range 1,500-5,600 RPM). I have always guessed about 425+ HP once I get the 1 3/4 inch primary LTH's on,,,maybe more!
The 485 ft-lbs torque is at what rpm and how broad?...that is a ton of torque and certainly BB like numbers being close to 500 ft-lbs. My L-82 355's torque is very linear from 2,000-5,000 rpm....
Last edited by jb78L-82; 09-14-2016 at 01:18 PM.
09-14-2016, 01:34 PM
#18
Race Director
Awesome!
Your setup is similar to mine with AFR 180's, 10.2:1 compression, 1.5 roller tipped rockers, L-82 OEM aluminum intake (EGR blocked), Howards Roller Cam (.525/.525 lift, duration 219/225, LSA 110, operating range 1,500-5,600 RPM). I have always guessed about 425+ HP once I get the 1 3/4 inch primary LTH's on,,,maybe more!
The 485 ft-lbs torque is at what rpm and how broad?...that is a ton of torque and certainly BB like numbers being close to 500 ft-lbs. My L-82 355's torque is very linear from 2,000-5,000 rpm....
Your setup is similar to mine with AFR 180's, 10.2:1 compression, 1.5 roller tipped rockers, L-82 OEM aluminum intake (EGR blocked), Howards Roller Cam (.525/.525 lift, duration 219/225, LSA 110, operating range 1,500-5,600 RPM). I have always guessed about 425+ HP once I get the 1 3/4 inch primary LTH's on,,,maybe more!
The 485 ft-lbs torque is at what rpm and how broad?...that is a ton of torque and certainly BB like numbers being close to 500 ft-lbs. My L-82 355's torque is very linear from 2,000-5,000 rpm....
451hp@5100, 484@4400, with >470lbft from 3100-5000. (looks like I was off by a lb-ft
)I suspect if I could get away with a high rise dual plane I could improve mid-range torque and the torque fall off at 5000, maybe even touch the 500lb-ft magic number. Of course, that's crank dyno. I haven't done an in-car one yet.
I know people have installed twin EO'd cats and had success, but it's not by-the-books legal. The VC explicitly prevents you from changing the number of cats on a car (whether removing or adding).
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Snoopysvet (09-14-2016)
09-14-2016, 02:44 PM
#20
Le Mans Master
The only 100% legal way to configure these cars is 2-1-2, seems like you could do a 2.5" cat as there are CA certified options for the 78 model year.
I know people have installed twin EO'd cats and had success, but it's not by-the-books legal. The VC explicitly prevents you from changing the number of cats on a car (whether removing or adding).
or make a Large 2-1-2 exhaust
But make sure I keep the original exhaust setup ready to swap for testing!