I am having trouble finding the vacuum line routing. I need to know where to find the thermal vacuum switch (TVS) or where the early fuel evaporation solonoid. The car was messed with and Im having trouble finding its location. Its a 86 z28 with the LG4 305 4-bbl,

 

Does this help at all?

http://www.autozone.com/images/cds/g...3d80163817.gif

 

Thanks, I got that but there seems to be no EFE TVS. I found the TVS purge in manifold and the goose neck has a fan switch and ECM temperature sensor. In a GM shop manual for the car it said it might have a EFE solonoid controlled by the ECM.

Exactly, where should the EFE TVS be, or the EFE solonoid be located? Any help or info would be great.

 

Hi,

On your 86 LG4, the EFE TVS should be located on the thermostat housing (aka waterneck). If you replaced the stock with one of those flashy chrome waternecks that you can buy at AutoZone and the like, chances are it did not have a hole to mount the EFE TVS in... perhaps not even a hole for the Coolant Temperature Sensor, a very vital sensor used by the ECM.

If that's not the case, the EFE TVS should still be on the waterneck. It might have possibly broken off though. My car's EFE TVS and purge TVS pretty much crumpled to peices from just touching it after sitting on the engine for 19 years or so. If that's the case, just go down to AutoZone and pick up another EFE TVS valve. I bought mine for about $20.

If, however, you are looking for the purge TVS (the thermal vacuum switch which controls the time in which the engine purges the charcoal canister's stored fumes; located directly on the intake manifold in front of the carb), good luck because it will be a rather hard part to find. GM has discontinued it and both my local AutoZone and GM dealer do not sell it. I bought a similar sensor to fill its place that used the same size threads and two ports that open based on coolant temperature (pretty much what the original one did). It seems to be working pretty well. If you are looking for this part, have one of the guys at AutoZone look up different valves in their parts book. The valve I bought was in there.

Hope that helps.

 

Thanks very much for all your information but I also have another question. What do you have to do to replace a Q-jet with a aftermarket Holley?

 

?????.....

 

Let me answer that by asking you a question:

Why do you want to switch to an aftermarket Holley?

The stock q-jet flows more than enough air for any mildly-modded 305 (and can be modified to flow up to 750 from what I've read) and will be more economically friendly. Not to mention it'll be difficult to pass inspections if your state has them. Plus, the carb is definately what's holding you back performance wise, if that is why you want to get a new carb. Buying a new aftermarket carb for more performance has a terrible HP-to-$$$ ratio.

I'd recommend you head over to www.thirdgen.org and read the tech article about CCC Quadrajet tuning for performance. It will tell you everything you need to know.

If you still want an aftermarket carb, plan on picking up a non-computer controlled distributor as well.

Hope that helps. Good luck on whatever you plan to do.

 

Well I know the Q-jet is a fantastic carb but it got messed up, not fixable so I have to buy a new one. I havent been able to find a local place that sells them for cheap, a Holley is cheaper so I was just wondering what I would have to do to put one on.

 

Ah, I see.

Well, I'm sorry but I can't offer much help in that respect as I still have my factory quadrajet.

However, I do know you are going to have to do something with the computer to keep it from acting up when getting rid of the carb, and you're also going to need a new non computer controlled distributor.

 

Well a replacement from the junk yard and ride now the car just sounds great, you cant even tell the car is on when its idling. Thanks alot for all your help in getting my engine running smoothly.

 

Glad I could help.