Alrighty, I've read quite a few archived posts and it's still not clear to me which vacuum port I should be using for distributor advance.

My setup:
67 F100 with 390 and FMX auto tranny. I just finished installing an Edelbrock Performer Carb #1411. The only emissions equipment I have is the PCV valve running from passenger valve cover to PCV valve inlet on front bottom of throttle body. I want to run a single vacuum line from either the timed vacuum or manifold vacuum port to my distributor (a single vacuum advance model, one you would get if you went to Kragen and asked for a distributor for this year truck with this engine), and I can't tell whether I should use timed port or full vacuum port. I think I want to use the timed port because that (I think) would mean no advance at idle, and increasing advance off-idle, which I think is the goal here, but I could have entirely the wrong idea here. Also, do you set base timing with the vacuum line disconnected and the port plugged, or is that not necessary?

On another topic... what do you all think about the kick-down linkage to the auto tranny? Mine has never been hooked up (someone removed it before I ever got the truck) and I haven't really noticed a need for it. Does the kickdown do the same thing as shifting into second when hitting the throttle hard? I've tried this, and I can't say that it's something I would want done automatically for me. It seems like it would be dangerous at high engine rpm's (blowing up the engine).

 

you're right on w/ the vacuum port. i have a an edelbrock performer carb on my 302. my mechanic sez it's best not to have any vacuum at idle. and yes, i always disconnect the vacuum line to set timing.
i never had a kickdown linkage on my truck either. don't know if you need it but i never really missed it but, i'm sure it wouldn't hurt your motor if you had one.

mike

 

[updated:LAST EDITED ON 19-Aug-02 AT 11:34 PM (EST)]okay, that's encouraging.

But out of curiosity, why does the carb come with both connections for the distributor? The instructions with the carb say that the timed port is for "Emission-controlled vehicles" and the full vacuum port is for non-emissions vehicles. Under what conditions would one want to use the full vacuum port? A dual-advance distributor?

Greg
67F100 390 FMX

 

that's a good question greg. i hooked mine up as per the instructions. my mechanic later told me i had too much vacuum at idle and recommended the switch and it ran better. as long as it works, i aint gonna question it

mike