Going a little nuts, need help!

[GlenwoodCJ7]

Tuning and idle?

SO I finally got around to deleting the smog junk out of the jeep and rewiring the whole thing due to the PO screwing everything up. Anyhow, I am trying to get it tuned up and a few things are causing my OCD to ramp up. To start with the tuning, I began to go after setting the total timing but found the PO had already set the timing curve on it and installed different springs in the dizzy (Mallory Unilite) and it only has about 10* mechanical advance with the vac unplugged. I have the timing set at 14* BTDC for high elevation but wondering if it needs to be set higher since the mechanical advance can only get it to 24-25* of advance. I have heard 32-34 would be optimum. Would I need to start from square one and remove the springs from the dizzy and check the total timing? I was thinking if there is only 10* of advance I could simply advance it to say 20* BTDC. Is that crazy :???:

Secondly but more important right now is trying to get it to idle properly. I am idling around 700 but it seems like it's stuttering and what is strange is that I can disconnect the IAC and the idle really does not change but the stuttering goes away. I have replaced the IAC and nothing changed. I have check for vacuum leaks and cannot find any. When I removed the smog, I left the EGR valve hooked up along with the PCV valve and the charcoal canister.


Would love any input



The setup

1981 CJ7

AMC 360
Howell TBI
Crane cam (Mild)
Mallory Unilite dizzy
MSD high vibration coil

 

[GlenwoodCJ7]

Ok, figured out part 2 of this equation. Hooked up a test light to the IAC and was only getting power to 2 wires. I disconnected the 32 pin connector from the ECM and keyed on the ignition and tested pins 3,4,5,6 coming out of the ECM itself and am only getting power to pins 3 & 4. I guess it's off to the parts store for a new ECM. I think the one I have is under warranty so hopefully just an exchange.

 

[69jeepcj]

Not sure exactly how you did things, but to check the total "distributer" timing you need to disconnect the vac hose from the advance can and plug it, then rev the motor to around 2500-3000 rpms, this will ensure the weights get flung all the way out and take a timing reading. That will be the total degrees of timing built into the dist, someone may have limited this already going by your post. To check vac advance at the advance can: if you are running full manifold vac to the dist, then you can simply idle the motor take a timing reading at idle and plug the vac hose back into the advance can and your timing and idle should immediately go up, take a timing reading again, the difference between the two is the timing in the advance can. if you are running ported vac to the can, take a timing reading at idle with the hose to the can off and plugged, then plug it in and rev motor to around 1500-2000 rpms, take a timing reading with motor reved, now subtract what the total dist timing earlier was and subtract your idle timing, what is left is the timing in the advance can. THERE IS NO VAC AT WIDE OPEN THROTTLE, OR VERY HEAVY LOAD. this is why you check for timing with vac and with out. Half throttle and cruising the vac advance is in play and as load and rpms increase the vac decreases until it hits 0. so at wide open throttle (or no vac) you should see probably between 28-34*, at part throttle or cruising vac advance is in play and you should see around 46-50*. that would work something like this: initial timig 14* (at the balancer no vac), vac advance can 10*, dist degrees 24*. in that situation you would have a cruize total timing at "cruise, part throttle, vac advance is in play" of 14 + 10 + 24 = 48* which woul be good but at full throttle "no vac in play at full throttle" you would have a total timing of 14+24= 38, that's a bit high for toatal timing (no vac), if you lowered your initial timing at the balancer 2* that would drop it to 36 total, drop it 2* more amd you are at 34* which is good but you wide open also drop to 44* which Is still acceptable. If I read your post right it sounds like you have dist time of 10* and initial timing at the balancer of 14*. I would try to raise the dist to at least 20 and the initial * to 12 that would give you a total with no vac of 32 which is acceptable, and try to get the advance can to between 10-14*, that would give you between 42-46* total cruise timing. (remember vac advance drops out around 2500 rpms, or wide open throttle. I didn't see a figure for your advance can? this was just an example and I don't know how high altitude affects your timing so you settings will vary. Oh and the springs do not limit the dist timing, they just slow or speed up how fast the timing comes in.

 

[69jeepcj]

Not sure exactly how you did things, but to check the total "distributer" timing you need to disconnect the vac hose from the advance can and plug it, then rev the motor to around 2500-3000 rpms, this will ensure the weights get flung all the way out and take a timing reading. That will be the total degrees of timing built into the dist, someone may have limited this already going by your post. To check vac advance at the advance can: if you are running full manifold vac to the dist, then you can simply idle the motor take a timing reading at idle and plug the vac hose back into the advance can and your timing and idle should immediately go up, take a timing reading again, the difference between the two is the timing in the advance can. if you are running ported vac to the can, take a timing reading at idle with the hose to the can off and plugged, then plug it in and rev motor to around 1500-2000 rpms, take a timing reading with motor reved, now subtract what the total dist timing earlier was and subtract your idle timing, what is left is the timing in the advance can. THERE IS NO VAC AT WIDE OPEN THROTTLE, OR VERY HEAVY LOAD. this is why you check for timing with vac and with out. Half throttle and cruising the vac advance is in play and as load and rpms increase the vac decreases until it hits 0. so at wide open throttle (or no vac) you should see probably between 28-34*, at part throttle or cruising vac advance is in play and you should see around 46-50*. that would work something like this: initial timig 14* (at the balancer no vac), vac advance can 10*, dist degrees 24*. in that situation you would have a cruize total timing at "cruise, part throttle, vac advance is in play" of 14 + 10 + 24 = 48* which woul be good but at full throttle "no vac in play at full throttle" you would have a total timing of 14+24= 38, that's a bit high for toatal timing (no vac), if you lowered your initial timing at the balancer 2* that would drop it to 36 total, drop it 2* more amd you are at 34* which is good but you wide open also drop to 44* which Is still acceptable. If I read your post right it sounds like you have dist time of 10* and initial timing at the balancer of 14*. I would try to raise the dist to at least 20 and the initial * to 12 that would give you a total with no vac of 32 which is acceptable, and try to get the advance can to between 10-14*, that would give you between 42-46* total cruise timing. (remember vac advance drops out around 2500 rpms, or wide open throttle. I didn't see a figure for your advance can? this was just an example and I don't know how high altitude affects your timing so you settings will vary. Oh and the springs do not limit the dist timing, they just slow or speed up how fast the timing comes in.

correction on my second sentence. you will need to subtract your initial timing to find out how much timing is in your dist. hope that didn't confuse you. sorry

 

[GlenwoodCJ7]

Not sure exactly how you did things, but to check the total "distributer" timing you need to disconnect the vac hose from the advance can and plug it, then rev the motor to around 2500-3000 rpms, this will ensure the weights get flung all the way out and take a timing reading. That will be the total degrees of timing built into the dist, someone may have limited this already going by your post. To check vac advance at the advance can: if you are running full manifold vac to the dist, then you can simply idle the motor take a timing reading at idle and plug the vac hose back into the advance can and your timing and idle should immediately go up, take a timing reading again, the difference between the two is the timing in the advance can. if you are running ported vac to the can, take a timing reading at idle with the hose to the can off and plugged, then plug it in and rev motor to around 1500-2000 rpms, take a timing reading with motor reved, now subtract what the total dist timing earlier was and subtract your idle timing, what is left is the timing in the advance can. THERE IS NO VAC AT WIDE OPEN THROTTLE, OR VERY HEAVY LOAD. this is why you check for timing with vac and with out. Half throttle and cruising the vac advance is in play and as load and rpms increase the vac decreases until it hits 0. so at wide open throttle (or no vac) you should see probably between 28-34*, at part throttle or cruising vac advance is in play and you should see around 46-50*. that would work something like this: initial timig 14* (at the balancer no vac), vac advance can 10*, dist degrees 24*. in that situation you would have a cruize total timing at "cruise, part throttle, vac advance is in play" of 14 + 10 + 24 = 48* which woul be good but at full throttle "no vac in play at full throttle" you would have a total timing of 14+24= 38, that's a bit high for toatal timing (no vac), if you lowered your initial timing at the balancer 2* that would drop it to 36 total, drop it 2* more amd you are at 34* which is good but you wide open also drop to 44* which Is still acceptable. If I read your post right it sounds like you have dist time of 10* and initial timing at the balancer of 14*. I would try to raise the dist to at least 20 and the initial * to 12 that would give you a total with no vac of 32 which is acceptable, and try to get the advance can to between 10-14*, that would give you between 42-46* total cruise timing. (remember vac advance drops out around 2500 rpms, or wide open throttle. I didn't see a figure for your advance can? this was just an example and I don't know how high altitude affects your timing so you settings will vary. Oh and the springs do not limit the dist timing, they just slow or speed up how fast the timing comes in.

So when I first started to tune the jeep, I disconnected the vacuum from the dizzy and rev'd it to around 3k and found there is only 10* of mechanical advance. Your assumptions of the previous post are correct, I opened up the dizzy and found the PO had changed the springs in it and set the timing curve. So I am assuming that setting my initial advance to 20* BTDC would be fine since there is only 10* of mechanical advance. Am I getting that right? I am also understanding that if I want "TOP" performance I should change the springs to allow for more mechanical advance and lower the initial timing. I guess my question would be this.... Would I get better top end or bottom end performance from changing the springs out? Thanks for the help, been great.

 

[69jeepcj]

so with no vac connected to the advance can you only have 10* mechanical timing in the dist? wow! that is insanely low. The springs will not change the timing, it ONLY allows the set timing to come in faster or slower depending on if you put stiffer or weaker springs on. Bring the timing in too fast and you will get knocking and pinging, too slow and performance suffers. To change the timing in the dist, take off the cap and look closely at the plate the springs ride on, under that plate should be a slot that tabs from the spring plate ride in, that slot limits how far the springs can fling out, the farther the fling out the more your timing advances. Sounds like someone has limited the slot to limit how far the spring plate can fling out. Look there and if there is a bushing on the tab that rides in the slot, take it off. New springs, spring weights, and a bushing, is the normal for a dist recurve kit, so if someone has put springs in there they have probably put the bushing in also, take that bushing off and you should probably have around 20-24* from the dist. bottom end performance is gained from a recurve if done correctly, you can recurve a dist to bring the timing in very slow (heavier springs) or very fast (light springs) The faster you bring in the timing the better performance you will gain, but you can bring it in too fast and get pinging and knocking. If get pinging taking off from a stop, lower the * in the vac advance can by limiting the slot the arm on the can rides in, or adjusting it if you have a adjustable can. If you get pinging accelerating from a cruising speed, lower your initial timing at the balancer 2* at a time until its gone. you really need to find out why you are only getting 10* from the dist, someone has limited it, most all dist get between 20-24* from the factory and most are 24* so something is up with that. It is best to get most of your time at the balancer as long as the starter will allow. set too high and the starter will start to kick back when you start it. A ideal setting would be 16* at the balancer, 20* dist, 10-15* vac advance. Most motors will not allow this. mine is set at 24* dist, 10* balancer, 14* vac advance. I get pinging if I raise the balancer(crank) timing or vac advance can, if I lower my dist timing to 20 I can raise my balancer timing and it should not ping. I should have asked this earlier, WHAT KIND OF DIST IS THIS, HEI? if so, the only way to change the timing in the dist is to change weights NOT LIMIT THE SLOT AS I STATED EARLIER. There are numbers marked on the weights of the hei, those number represent timing *. only way to change it is to change weights, which is why I haven't lower my dist timing, I cant find correct weights. Raising your initial timing to 20* would be good as far as the numbers go, but your starter probably wont allow it, it may though with the dist timing being only 10*. Try it.

 

[69jeepcj]

after thinking about it a minute, I think I would raise my initial to 20* and take it for a ride and see what happens. I think as long as the starter don't kick back you may be fine. Just so we are on the same page with terminology, which I think we are. initial timing=at the crank with timing light,
dist timing= mechanical timing in dist, vac advance= timing in advance can.

 

[GlenwoodCJ7]

Raised it to 20* and seems to run much better. I'm not getting any starter kickback but am stressing over ping since I have some pretty crisp pipes and can't really hear what the engine is telling me when driving it. I might lower it down to 18* to be on the safe side and tackle the dizzy this winter when it's not being driven. I also thought about taking it to a dyno shop and having them recurve it.

 

[GlenwoodCJ7]

Wow, I am ****ed like no other. Looked online for a advanced curve kit for the unilite and could not find one anywhere. Called Mallory and they told me they are no longer making anything for the distributors but are going to bring them back (someday). Arghhhh I really did not want to buy another distributor. Wonder if I could use HEI springs? I would have no idea where to start though since the specs would be completely different.

 

[69jeepcj]

Yes, by all means, if you can afford a dyno tune go for it in my opinion. They will tune it better than both of us. Taking it down to 18* was probably smart, I have the same situation with my pipes. Hard to hear if its pinging, until it pings then its obvious, going up a big hill and giving it a lot of gas about half way up works real good on mine. That's too bad about the recurve kits. I would suppose you could use any spring as long as you map out your curve and its with In range. to map it out, make a graph with RPM on one side and timing * across the other, take a timing reading at every 500 rpm. take one at idle, 1000, 1500, 2000, 2500, 3000 or as close to 3000 as you are comfortable with. make a dot on the graph for each reading, then drawl a line connecting your dots. that will show you the curve as your rpm climbs. make two of them, one with vac, and one without, that way you could use any combination of springs a be sure your not over advancing. Do you have a standard timing light? I dont think the dial backs work well in the upper rpm range. I would buy or make a timing tape and use a regular timing light. Glad its running better!!

 

[69jeepcj]

 

[69jeepcj]

Hey, I put a couple very good articles in the "general chat" section on this subject. They are from a former GM engineer that helped design this system. Should be very helpful for you.

 

[GlenwoodCJ7]

Hey, I put a couple very good articles in the "general chat" section on this subject. They are from a former GM engineer that helped design this system. Should be very helpful for you.

Thanks, will check it out