My question is about my 1985 GMC S15 with the LR2 2.8 and varajet carb. (non-CCC). I'm hoping someone on here has similar experience with their 2.8 Camaro/Firebird. I'm removing/replacing my rotted and missing vacuum hoses, and need to know where to hook them up to the carb. I have included 2 pics with the ports labeled just like they are on the carb. Port E is to the PCV valve, Port A goes to the primary vacuum break, port G goes to secondary vacuum break (I think), port F is the bowl vent. Ports B,C,and D i'm not sure about, but I think port B is ported vacuum, where I need to connect my vacuum advance and TCC pressure switch.



After researching different vacuum diagrams, I think I have figured out the minimum vacuum hoses for my truck to have and still run. I think I can hook them up like this.


Port A - primary vacuum break
Port B - Ported vacuum? Vacuum advance and low vacuum switch (for lock up converter)
Port C - capped
Port D - capped
Port E - PCV valve
Port F - bowl vent
Port G - secondary vacuum break (I think)

My truck has had the charcoal cannister and AIR pump removed, as well as the decel valve and EGR, so I don't have to hook them to anything.

 

nothing personal, but I'm going to be closing this thread on 4/19/2008 if there are no truely helpful responses. Since the vacuum diagrams and routing for the trucks is not the same for the F-bodies, this is a non-f-body thread. Sorry...

Any issues, please feel free to PM me

 

I'm afraid the guys on the Carb forum deal more with V8 systems.

Perhaps the V6 guys could help you.

 

Amusingly enough, this thread was already closed when he cross-posted. -_-

 

After communicating with ericknight about this thread, I have decided to reopen it for the time being in hopes that he finds at least something that he is looking for. I will be closing this thread if nothing deemed useful is posted here by 4/19/2008.

 

Well I did some searching and found some vacuum diagrams that helped in this thread.

https://www.thirdgen.org/forums/tech...m-diagram.html

That was a good idea to make the lines different colors, those black lines on most diagrams tend to run together.

 

I have a 85 s10 blazer with the same engine, on mine the vacuum advance runs off port B on your picture. The choke doesn't go to any ports on the carb it goes to the air cleaner. As for the TCC I can't say for sure cause my blazer is a 4 speed but I think it might also run off of port B with a T but don't quote me on this. Hope this helps if you need to know anything else let me know I can check.

 

Thanks for the info, that's how I have it hooked up. I put a tee on port B and ran one line to the vacuum advance and one to the TCC switch. I capped ports C and D, I think they controlled EGR, and connected port F to the vent line coming from the fuel tank. The line from the secondary vacuum break originally ran through a sensor on the air cleaner, but I hooked it directly to port G with no ill effects, that's where it received it's vacuum to start with. I can tell when the torque converter locks up now, I don't think it was locking up before with all the cracked vacuum hoses. I've drove it a couple hundred miles since getting it back together, and it runs good, for a 2.8 anyway. I have slight detonation on hard acceleration, but I think I can adjust my timing to compensate for having no EGR and correct that.

 

No issue with this POV and this policy... This is a 3rd Gen site not an S10 site...

But we often miss opportunities with this POV... Many on this forum forget that almost all early carburated Canadian Third gens (82-86), be they 305 V8s or 2.8s had emissions systems based on trucks. If someone were to post the vacuum diagram for this S15 and for a Canadian 2.8L V6. You will find they are pretty darn close...if not identical.

The trucks are also a great source of info for getting lock up TCCs to lock up with out a computer etc... Lots of Americans love to ditch the CCC system and as above most Canadian cars didn't have them... The FSM assumes that all cars are CCC based... They aren't... If you are working on a Canadian car you need the FSM from an S10 (for the 2.8) or the full size trucks (for the 305)...