Vaccum line Hell !!!!

[jeepgj]

I have a 77 CJ 7 W/ 232, stock 1bbl carb and distrib. My questions are the vaccum line coming from the intake to the CTO valve and then to the dist. Is that neccessary? Can the CTO be bypassed and go straight from the carb to the vaccum advance on the dist. Same question for the other side. What exactly does the CTO valves do ? I'm new to the Jeep family. I'm rebiulding the carb right now and am just confused with all the vaccum line running around in there. Is it worth switching to the Weber and upgrading to the DUI dist. ? Thanks in advance for any replys.

[jadams68]

CTO (Coolant Temperature Override) switch. It's a valve that opens after the engine reaches a certain temperature. I believe it provides more vacuum to the distributor and the EGR valve.

[Penguin]

It is a switch that shuts off and opens lines for uses at different temps. Your EGR valve doesn't need to be open after the motor warms up. Also for some years it controled things for a cleaner burning engine.

[Jodean]

Just take all the vacuum lines off....well....except the vacuum advance......

[John Strenk]

It is a switch that shuts off and opens lines for uses at different temps. Your EGR valve doesn't need to be open after the motor warms up. Also for some years it controled things for a cleaner burning engine.

Well actually it's quite the opposite. The EGR valve should not open until the engine reaches the right temperature. Otherwise it will lean out the mixture too much for cold conditions. The EGR is also only open at mid throttle positions, at idle or at WOT the valve should be close. You may have mixed that up with the heatriser vlave that doesn't need to be operating when the engine is warm. On a 1bbl, heat riser is operated with a spring.



Just take all the vacuum lines off....well....except the vacuum advance......

Well do leave the EGR also connected. IT doesn't rob any power and reduces the cumbustion temperature so you dont ping and lowers emmision.

[Penguin]

That is interesting, the FSM has it opening at lower temps and closing at higer temps. Even the test say it should have vacuum at low engine temps and none at higer.
So are you sayinng this is the reason I cannot get my engine to run right? Is this causing my no power in 5th gear?

[Hill, Bill E]

I'm having the same problems in 4th, my top gear. Glad this was brought up.

[Penguin]

Ok, I just did a google and your information was right. Could it be that jeep had some ERG that when it had vacuum it was closed and open when it didn't?

[John Strenk]

I don't know all the CTO/EGR variations but there could of been.

As for no power in 5th gear, it may be something as stupid as a btoken vacuum motor in the Air Cleaner housing keeping the door shut to some mixture/ignition problem or even tire /ratio incompatablities were you don't generate enough HP at the slower RPMs.
If you have the O2 sensr still in the manifold you can get an idea of the mixture by measuring the voltage generated. I put some bad plugs into my engine one day and couldn't get the jeep up to highway speeds.