78 Smog parts for CA truck ?

[darren509]

Fixin up a 79 c10 custom deluxe for a buddy of mine, last time he tried to smog it they said they wont because the vaccum has been modified ? My question is what all is needed for smog equipment and also does anyone have any pics they can show for routing vaccum lines etc ?

[Stepper562]

OH jesus forget about about it bro...the only way our trucks will pass the smog here in CA is if the motor is fresh and all the smog equip is almost brand new which will cost you right arou d 700 bucks for all the equipment. Just make it pass hehehe..

[406 Q-ship]

Originally Posted by Stepper562

OH jesus forget about about it bro...the only way our trucks will pass the smog here in CA is if the motor is fresh and all the smog equip is almost brand new which will cost you right arou d 700 bucks for all the equipment. Just make it pass hehehe..

That is not necessarily true, it depends on how much of the smog equipment is missing. There should be at a minimum, EGR, A.I.R., Catalytic Converter (depends on the GVW), OEM closed element air cleaner w/heat riser, Original carb (or a smog legal replacement Edelbrock carbs), and all the thermo switches (vacuum switches in the water neck). The engine needs to be healthy but not fresh. There are plenty of older vehicles that manage to get through bi-annual smog inspection in Cali and I doubt that they all have fresh built engines every 2 years.

[dugvera@gmail.com]

I have never had issues with my 76. All I do is put the proper air cleaner on and set the timming to about 3 degrees and it passes no problem.
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[darren509]

Thermo switches ? Have any pictures of those possibly so I can check if they are there ?

[SSC's76]

Originally Posted by darren509

Thermo switches ? Have any pictures of those possibly so I can check if they are there ?

Not sure on the 78 my 76 was a CA truck glad we moved to CO. The thermo switch mine had was on the t stat housing.

[beamn7]

What engine do you have? 250,292,305,350,400,454?

[dugvera@gmail.com]

In California there is the referee. I have never been down that raod but I hear they will help you with whats needed as far as smog goes.
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[1LowToy]

These trucks really are not complicated. If your just missing hoses that's really not that big of a deal on a 78. I have a 80 six cylinder so chances are the hose routing is different but the same princible applies. If your smog man knows they are wrong he must know whats right. See how much he wants to fix it. There should be an emissions lable under the hood to follow, If not I can take a pic of mine but it is a six cylinder. But with as much experience as this group has we should be putting a serious smog forum. Not one with jungle juice additives or bypasses. California is just a start of what several other states will be following.

This forum if adopted needs to be able to be edited for corrections and additions. Are you hearing me moderators?

[Malo83]

This is the routing on my 83


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[darren509]

Thanks. I will be looking at the truck this weekend to see for myself what is missing or modified.

[beamn7]

Here is the schematic for a 1978 350 with Calif Light duty emissions. Right out of GM's 1978 service manual.... "G only" means van only. Not c/k truck. Hope this helps.

[1LowToy]

The to air cleaner is to the thermal valve on the air cleaner housing and from there to the flap to take in warm air from the exhaust manifold stove instead of fresh air. Other than that it look like spegetti noodles when your done lol.

Set timing properly set idle speed an lean out the air mixture screws. Should be good to go uless your missing more noodles

[beamn7]

correct, just takes it from different source depending on if it's a G van or C/K.... (back of carb vs front)
3 complete turns out on the idle mixture screws for base setting. Then dial in with a vaccum gauge. Like 1lowtoy said, be sure base timing is set proper as well.

[darren509]

well so much for that. He sold the truck and bought a 68 el camino. Anyone have any pictures of that year for the shift linkage that goes from the column down to the trans ? Its missing, all there is looks like a bracket on the side of the th350 but nothing else ? Sorry for this not being relevant to this forum or post.

[charlieatthedisco]

Does anyone know the OEM part number or can direct me to the correct part of the EFE TVS? I think it it also known as the vacuum switch, the one off the truck that broke off ws blue in color and basically just snapped off in my hand when i touched it. Thnanks, this is the last piece I need to complete a new smog system for a CA truck
Charlie

[rfmaster]

Originally Posted by charlieatthedisco

Does anyone know the OEM part number or can direct me to the correct part of the EFE TVS? I think it it also known as the vacuum switch, the one off the truck that broke off ws blue in color and basically just snapped off in my hand when i touched it. Thnanks, this is the last piece I need to complete a new smog system for a CA truck
Charlie

You should start a new thread with your question and post detailed info regarding your truck. However, if your TVS EFE switch screws into into thermostat housing and has NPT 1/2-14 threads a 1979 to 84 service replacement would probably work OK. Look for for GM OE #14007803 or AC-Delco 212-72 (Group 3.140). In grand scheme of things EFE valve is forced closed when engine coolant is below a set point (TVS set point) and forces exhaust gases from passenger side exhaust through the intake manifold passage heating engine faster during cold start. EFE valves are also known to rust through and cause chattering noise when the spot welds that hold a flapper to the shaft break. As long as you have everything connected you should be fine during smog check. This is the level of technology they had back in the 70's before EFI came to the rescue!

//RF

[charlieatthedisco]

Sorry about that the only
Reason why I posted in this thread is because it is the same truck. The tvs I am looking for is the one that's on the intake manifold itself and has a vacuum line to the egr and one that goes back into the carb. I replaced the one on the coolant housing and it was so rusted on there I ended up having to replace the entire housing! Thanks for your help
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[rfmaster]

Yep, been there - do not like that 70's smog crud!

The thermostat housing is available from most auto parts stores new (AL casting) and much nicer to work with. Thermostats housing are available from FOUR SEASONS # 84899 and have two ports - 1/2" and 3/8" NPT which is perfect for TVS switches!

As for EGR TVS the best closest equivalent I can find is GM OE# 373510, AC-Delco 21232, SMP PVS27. Interchange shows TVS EGR vacuum switch used on C10 PICKUP (1976 - 1986) and has thread Size - NPT: 3/8" - 18. By the looks of it it screws into the intake manifold as most manifolds used 3/8" NPT for water jacket ports. But there are some that use 1/2" NPT. So pay close attention to your intake manifold water jacket ports.

IMHO, you can pop both EFE and EGR TVS vacuum switches into the thermostat hosing and route vacuum lines as required. Years ago, I owned '76 Chevy Malibu 305 and it had that TVS arrangement. I could only wish that I took photographs 25 years ago, darn.

Good luck with the project - I feel your pain!

//RF

[charlieatthedisco]

Originally Posted by rfmaster

Yep, been there - do not like that 70's smog crud!

The thermostat housing is available from most auto parts stores new (AL casting) and much nicer to work with. Thermostats housing are available from FOUR SEASONS # 84899 and have two ports - 1/2" and 3/8" NPT which is perfect for TVS switches!

As for EGR TVS the best closest equivalent I can find is GM OE# 373510, AC-Delco 21232, SMP PVS27. Interchange shows TVS EGR vacuum switch used on C10 PICKUP (1976 - 1986) and has thread Size - NPT: 3/8" - 18. By the looks of it it screws into the intake manifold as most manifolds used 3/8" NPT for water jacket ports. But there are some that use 1/2" NPT. So pay close attention to your intake manifold water jacket ports.

IMHO, you can pop both EFE and EGR TVS vacuum switches into the thermostat hosing and route vacuum lines as required. Years ago, I owned '76 Chevy Malibu 305 and it had that TVS arrangement. I could only wish that I took photographs 25 years ago, darn.

Good luck with the project - I feel your pain!

//RF

Very good information! Thank you