AMC Eagle Den Forum

The Mighty 258 => Engine Electrical Systems. => Topic started by: sammuel on February 29, 2012, 10:45:01 AM

Title: timing
Post by: sammuel on February 29, 2012, 10:45:01 AM
so question I have my wagon timed to 10 BTDC but when I hook my vac. line to the distributor after finishing it immediately jumps up to 19-20 BTDC is it supposed to do this? my idle is set at 650 rpm while this is going on
Title: Re: timing
Post by: doc65 on February 29, 2012, 10:52:47 AM
Not normally, sounds like too much vac, or a bad/failed/failing spring in the vac adv. canister(on the dizzy)

Doc
Title: Re: timing
Post by: kajsdf on February 29, 2012, 10:53:50 AM
you will need to adjust a set screw inside the vac port on the distributor. you will have to do a bit of trial and error to get it right. there are distributor advance curves in the eaglepedia.

you shouldn't have any vac advance until your mechanical runs out.
Title: Re: timing
Post by: kajsdf on February 29, 2012, 10:55:54 AM
unless you just put in the mc21xx? curves will be slightly different...i found some on a jeep forum after some googleage
Title: Re: timing
Post by: mudkicker715 on February 29, 2012, 11:24:18 AM
Sounds like you hooked up your distributor to manifold vacuum and not ported vacuum.
Title: Re: timing
Post by: sammuel on February 29, 2012, 11:25:05 AM
dur sorry forgot to mention that, I just finished my motorcraft 2150 install, never checked it before so I dont know if its a new thing will look that up tho
Title: Re: timing
Post by: sammuel on February 29, 2012, 11:26:53 AM
its hooked up to a port that is on the front pass. side of the motorcraft carb and at idle I cant feel any vacuum thats why I was confused
Title: Re: timing
Post by: mudkicker715 on February 29, 2012, 11:32:10 AM
So what changes it when hooked up to the distributor to make it produce vacuum and advance the distributor.
Title: Re: timing
Post by: carnuck on February 29, 2012, 01:01:05 PM
It builds up slowly. The dist should be hooked up next to the choke.
Title: Re: timing
Post by: mudkicker715 on February 29, 2012, 01:15:22 PM
Quote from: carnuck on February 29, 2012, 01:01:05 PM
It builds up slowly. The dist should be hooked up next to the choke.


Sammuel said immediately. Not slowly
Title: Re: timing
Post by: shaggimo on February 29, 2012, 01:22:34 PM
OP: Do you have, or have access to a vac guage? If not they are cheap, and a very valuable tool for working on the carb, vac, ignition systems, I'd start there, and see exactly what the port you're hooked to actually does.
Title: Re: timing
Post by: carnuck on February 29, 2012, 01:50:17 PM
Quote from: mudkicker715 on February 29, 2012, 01:15:22 PM
Quote from: carnuck on February 29, 2012, 01:01:05 PM
It builds up slowly. The dist should be hooked up next to the choke.


Sammuel said immediately. Not slowly

Right, but it takes a minute to build up. That's the port for the EGR. If there is no vacuum to the touch, it takes a bit to build up so it's a smaller port.
Title: Re: timing
Post by: GRONK on February 29, 2012, 02:17:52 PM
Make sure the choke is fully open and the fast idle cam has dropped.  If you are on your fast idle circuit, the timing jump is normal, there should be ZERO vac advance at idle.  If there is advancement at idle you need to back out your curb idle screw and advance your base timing.
Title: Re: timing
Post by: sammuel on February 29, 2012, 03:19:33 PM
k just checked the port there is about 1 in. of vac. at 650 rpms this is the port in front of the choke and just below it, it points straight out from the carb toward the pass side of the vehicle
Title: Re: timing
Post by: GRONK on February 29, 2012, 03:36:50 PM
1hg isn't too bad but you still need 0hg at idle.  Back out the curb idle screw just a hair more and adjust so everything is where it should be.  You will have to bump up your timing just a hair.
Title: Re: timing
Post by: sammuel on February 29, 2012, 03:47:26 PM
so should i set my timing while it is idling at 500 rpm? if so what should it be set to