vacuum at idle

[clavin001]

Been having a heck of a time starting my truck in cold weather (below 20degf). Po disconnected all vacuum lines, but had them in a bag when I got the vehicle (who knows why I didn't just toss them). Reconnected the tco's and non-linear valve to the vacuum advance. With engine warm and at idle, getting 5 to 10 inHg at the dist. Shouldn't this be 0 inHg? Tested both Tco's and working properly. Also, engine is now pinging under load which didn't start happening until I reconnected these parts.

[coolram]

Try connecting your dist vac directly to the ported car source and see if you spak knock(pinging)goes away.Right now youv'e got manifold vaccuum going to the carb,but then this is correct for the CTO to do until the motor warms up to the CTO's set temp.

[clavin001]

The dist was connected to the egr vacuum port on the carb when I got it. Now the cto is connected to the dist port (side of carb). Tried running with hose coming directly from the port and still had pinging. How different is the vacuum curv on the side port versus the front (egr) port?

[maxrad]

Coolram is correct, as usual.

The factory distributer hook-up to the carb is through a CTO then to full vacuum.

One of the first things I did is to reverse this effect and plug to the TIMED port of the carb. This change improved everything.

I think that one of your current problems is your vacuum setup itself. You may have faulty CTO's, vac lines, dump valve, non-linear valves, delay valves, etc. or just hooked-up wrong. EGR may also be bad or the air cleaner trap doors may also be faulty. Etc. etc.

The PO may have bypassed all this stuff because he couldn't put his finger on what exactly was at fault.

I would do a search on here for a simpler (earlier) vacuum diagram and put on only the NECESSARY lines. I, myself, have deleated all but the EGR and vac advance system. Now my Jeep works better in both warm and cold climates. Just a thought, more people here (like coolram) are smarter than I.

[clavin001]

Both ctos are functioning properly. I don't really know if the non-linear valve is working properly, but it is having no effect at idle with the engine fully warm because the spark cto does not allow the signal to pass to the dist. Besides, I eliminated the ctos and non-linear valve when I connected the vacuum advance directly to the side port of the carb. I replaced all vacuum hoses. The egr is not connected, but I didn't have the pinging problem before with the egr disconnected.

[ January 19, 2003, 12:57 PM: Message edited by: clavin001 ]

[maxrad]

Clavin, are you SURE the lines are on the CTO's correctly?

If they are backwards it would change your settings. Did you do the hotwater test with the CTO's to verify they work?

Actually you only need one (two line, not three) to function properly. I once had a small bag of used CTO's and tested all only finding two that worked.

[clavin001]

I am ABSOLUTELY positive the hoses are correct. The ctos are working properly, besides; I bypassed the ctos and provided vacuum DIRECTLY from the side port on the carb and still had pinging. Why am I not getting 0 inHg at idle from the side port on the carb? How is the vacuum port on the front of the carb (egr) different from the port on the side of the carb (dist)?