Have an 84' camaro automatic with a 350 swap and 600cfm Holly carburetor. The car still has the EVAP canister, and there are fuel lines connected at the bottom, but no hoses going out of it at the top. I heard you could cut some hose and feed it back into the valve cover port on the drivers side. So I tried it out. Noticed very quickly that the car seemed to be running better, but the RPM's, idle and in gear, were really high ( TACH doesn't work, but I could tell by listening to it. Also, when putting it in gear from park, just taking my foot off the brake it traveled at 5mph, and would resist when trying to brake). Also, a couple of times when I shut the engine off, it shook the car violently and made a clunking noise as it was shutting off. So I disconnected that. My questions are as follows. 1. If the car still needs the EVAP canister, where should I hook it up to? 2. Was the high RPMs the cause of the violent shaking and lound clunking noise? I'm pretty new to engines, so plain language if possible. Thanks

 

Did you connect the gas vent to engine vacuum? Are you bringing combustible gas fumes into the motor?

 

Yes. I was informed recently that it's called "Dieseling" and is left over fumes combusting as the engine shuts off. Very bad for the engine. However, is there a way to still have the vacuum connected and this NOT happen? Lean out the carburetor by tightening the idle mixture screws?

 

The dieseling might be an issue with ignition timing.

 

The reason for the run-on and excessive pull at idle is probably just that the idle speed is set too high. Try backing it off.

 

I will look into ways on fixing ignition timing, as it just did the same thing just now when the EVAP canister was not connected. I will also turn the idle down, my only hesitation in doing so, is that a higher idle helps keep it running (one of the only gauges that works is my oil pressure gauge, and as soon as that drops below half way, engine shake usually occurs and/or hard to start/engine gets really quiet, whereas before it was loud and full of life) I plan to reconnect the EVAP, but I will tune down the idle mixture and the idle RPM.

 

Leave the "timing" alone. ABOVE ALL, do NOT retard it, until you have no other choice.

Back off the idle speed.

If the engine runs rough, it needs spark plugs, plug wires, and/or dist cap & rotor. Might be a good idea to launch a preemptive first strike against those offenders.

 

I'll turn down the idle speed, as I do imagine it may be running the engine harder than it needs to. I did check all the spark plugs a couple months ago, but I'll be sure to check them again, as I've read that they can lead to cylinder misfires.

 

I'll be sure to get the wires/dist cap and rotor looked at as well. Thank you