CTO Question?

[Powerstroked]

My vac. line to dist has vac all the time. 12-13in. hot or cold. I set timing to proper spec and adjust curb idle but when i hook line up idle goes way up. Is it the CTO or possibly water temp not reaching 160 deg? Temp gauge goes about 1/4 way into green. Thanks

[Max Power]

I hope this is not a stupid question, but shouldn't you keep the vacuum line connected to the dist while setting the timing/idle? I was under the impression that the vacuum line was only there to help more quickly increase the engine speed during acceleration. Someone please correct me if I am wrong.

thx,
R

[letank]

Seems like a bad CTO, you can test the various port with a vac pump and another vac gauge. So you can connect direct from ported vac to distributor after timing is done..... until you replace CTO

Robert: one port helps for morning cold start and is connected to manifold vaccum... which is high at idle and very low at open throttle and when the engine is warm enough as per CTO specs... it switch to ported vaccum... which vaccum does increase with rpm.....

Michel
74 wag

[Max Power]

Helloooo DSPO,

After reading Michels post (and the TSM) I think I understand. But My distributors vacuum unit is plugged directly into the base of the carb...

I think that this means that I am not getting any benefit from manifold vacuum after startup, but after the choke opens, the vacuum advance works properly. Any thoughts??

Is this correct? and am I hurting anything by leaving it this way? she runs fine summer or winter.

thanks for the info michel.

[Bob Barry]

You probably have it hooked up to straight manifold vacuum; good for when the engine is too cold or too hot.

For best operation, you want it to be running off ported vacuum, which only provides a vacuum signal when the throttle is opened.

What the CTO's do is switch back and forth between manifold and ported vacuum, depending on engine temp.

Find a port that only provides vacuum when the throttle is opened, and hook the distributor up to that.

You can add CTO's in-line if you like, to aid in cold-weather driveability and to delay overheating.