1) Does anyone have a readable vacuum hose diagram for an '85?

2) Which vacuum lines/hoses/ports can be blocked/capped off?

3) Which sensors can be bypassed?

I want to make my 85 TPI as clean and un-cluttered as possible and still make it drivable. Anyone have any first hand knowledge or experience?

Thanks

 

I run an '85 at the track. Just exactly what are you trying to do here?

I would be very careful about removing anything. There's no performance gain in most of the things you've mentioned and there could be a tremendous downside.

If you're driving the car on the street I would just clean everything really well. If it were my car I would do an NCRS type of detailing.

Even though I have no AIR pump and no A/c I don't advocate this for a car that's street driven.

A really nice cleaning and maybe a little polishing will make things look good and keep you from having drivability problems.

Richard Newton

101 Projects for Your Corvette 1984-1996

Ultimate Garage Handbook

 

I don't have a vacuum diagram for you, but here's what I'd suggest to meet your goals (in order of ease v. impact):

1) eliminate smog pump - you can eliminate all the hoses/pipes for the air injection system. You can either leave the pump in place with nothing connected to it or get one of the bypass pullies and remove the pump itself, too. This gets rid of a lot of hosery with no ill effect on the engine other than slightly dirtier emissions during warmup.

2) throttle body coolant bypass - there's a set of coolant hoses that run to/from the bottom plate of your throttle body to prevent it from icing during warmup in extremely cold environments. You can remove these hoses and cap the sources.

3) cold start valve delete - this is the "9th injector" that sits between the intake runners on the driver's side of the motor. You can get a block-off kit and remove it and it's associated piping. Removing it may make your car a little harder to start when cold (kind of performs the function of the choke on a carb), or you can add the cold-start enrichment in the chip like the later cars have that came from the factory w/o the cold-start valve.

4) eliminate EGR - this won't help clean up the engine bay as much on an '85 as it will the later cars since on an '85 it's pretty much self-contained. On the later cars, the exhaust riser comes off the exhaust manifold and over the valve cover rather than through the head on the itron-headed cars (outta sight outta mind). Either way, you can get the EGR blockoff plates and remove and cap the associated vacuum lines. You'll want to take EGR out of the chip, though, or you may get slight knock and/or trouble codes. This obviously will impact part-throttle emissions.

5) eliminate A/C - I belive the '84-'87 cars can use the widely available F-body A/C bypass pulley. Replace the compressor with the bypass pulley and remove even more hoses from your engine bay. Unfortunately, all C4's came with ac, so I don't believe there's a non-ac firewall box that would open up more space if you remove the condensor, too.

You'll want to leave the rest of the sensors, etc., in place as they do a lot to keep the engine running smoothly and efficiently.