i just swapped the 350 into my car and its running and idling just gotta get the timing perfect. but, ive got one problem, the vacuum advance for the distributor came from a fitting in my old carb (original q-jet) but the new carb (rebuilt q-jet, slightly older) dosent have this fitting for the vaccum. so where can i get some vacuum?

this is the old motor and the vacuum line is the one in the water neck (NOT the blue one) and another quick question what are those two things connected to the water neck and what do they do? they are already gone im just curious lol

 

Looks like the TVS (thermal vacuum switch) was hooked into two vacuum sources on the carb.

Have a pic of the "new" carb?

 

as far as i know the carb is from a 79 1 ton chevy pickup theres also no where to put the kickdown cable even tho the motor was mated to an auto tranny. what does the tvs thing do? am i ok to leave it off? sorry for the quality its a cellphone pic

 

From a thread on the FAQ forum:

https://www.thirdgen.org/forums/atta...agrams-ubl.gif

 

thanks for the pic it helps alot, but my question still stands: where can i get vacuum? can i delete/relocate the tvs?


ive been sizing up the diagram and i was wondering if i can get rid of the hose at "j" since the egr is no longer functional and hasent been for sometime and plug the tvs for vac retard delay into the spot for the egr tvs? can it be done right? or am i totally out to lunch cuz im getting kinda desperate

 

"J" is manifold vacuum, while "H" and "K" are "timed" or "ported" vacuum. You can use "J", just be aware that your vacuum advance will get vacuum all the time, which it wasn't "calibrated" for, and may cause idle or part-throttle issues. I never had a problem using timed with q-jets.

Personally, I wouldn't bother using the TVS. The EGR and EFE TVS's don't work the same way as the distributor TVS does, so either use the distributor TVS or don't use it at all. The purpose of the distributor TVS is to limit ignition advance while the engine is cold (an emissions thing). The other TVS's put vacuum to their respective devices only when the engine is cold - the opposite operation. Since you've defeated the major emissions controls devices, not using the distributor TVS is a relatively minor offense.

 

are "H" and "K" "timed" the same? would it be possible to use a T fitting in "k" and get vacuum from there? and is the vac retard delay switch just the same thing as the tvs? sorry for all the questions i just want to get the car running good

 

My mistake, "K" is the bowl vent vapor line going to the vapor canister.

Again, personally I'd just use the manifold (full) vacuum port and tune accordingly. I don't think I've ever seen a q-jet without the "H" port.

Out of curiosity, did you consider rebuilding the original carb? It's probably the better piece of the two, unless it's been FUBAR'd.

 

Both "J" and "B" are manifold vacuum, by the way.

 

well its pretty rough and the other one just cost me a hundred bucks to rebuild so i was hopin to use it but i may have to get the original one rebuilt if i cant get this right is it possible that the fitting for "H" fell off or something?ill have to look harder

 

Can't tell from your photo. If you could get a clearer one, perhaps.

 

ok heres the plan for tomorrow. swap throttle bodies. should fix both my problems, vacuum and kickdown cable mount. ill post if it works or not

 

I'd guess there's less than a 50% chance they're interchangeable.

 

well they did swap but the "timed" vacuum port isnt on the throttle body according to some searching on the internet the egr is also a ported vacuum source so can i hook my vac advance into there?

 

Right, the timed vacuum ports are only on the main body.

You can use the EGR port for the vacuum advance.

 

thanks for all your help im gonna try it tomorrow if i can get a chance.