how to tell if distribbuter bushings are worn

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pjc360

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Just wondering if there is an easy way to tell if distributer bushings are worn? I have noticed the tip of my rrotor has a score mark on it from hitting the button o the inside of the cap. And whenever i tried running an echlin rotor they would hit the inside of the cap and destroy them.
I dont know if that was from not having the cap on right or not having the rotor on good enough? I do notice that my distributer would not turn freely when i had it apart and it was hnging up on the pick up assembly some where. I'm not sure weather i should just get a new distributer or try getting a new pick up assembly first. Also i noticed the reuctor is a pain to get back on had to hit it pretty hard with a rubbr tip hammer, are the reluctors normally that had to get on and off? Its the newer mopar distributer that has the adjustable mechanical advance.
 
Offhand, I'd say it needs bushings at the very least!!!
 
I'm thinking about just buying a brand new distributer. Not worth damaging the engine from detonation.... I can order one from don at fbo are 180 bucks and he will custom curve and phase it for ya so when i got it all i'd have to do is drop it in. I'm tired of taking this dam thing apart all the time the reluctor never wants to go back on easily and i think the bushings may be screwed as well because everytime i try and run an echlin cap and rotor the rotor would also be dented and mangled.
 
Are you sure it isn't a problem with the caps? Search on www.slantsix.org for several posts about distributor caps that hit the rotor just like you experienced. Of course, you may have a small block or big block. That info always helps when you ask for advice. The year and model helps too.
 
Small block 360. I just wish i knew more about these distributers and how to tell if the bushings are screwed in them or not. I Can pull the rotor post up and down but been told that is normal.... The advance plate its self is old and look like it could be replaced.
Yesterday when i had the distributer out i shook it and a piece of plastic fell out of it and it was tan brown just like the napa echlin caps are but i cant tell if that was a piece of a bushing or if it was a piece from a cap.
I guess i can try putting a new pick up assembly in it and seeing how it does. I have my mechanical advance set at 18 degrees so i can run 16 degrees of initial timing and 34 total and i just changed from two stage advance curve to a single stage advance curve with the springs that come with the mopar spring kit. I decide to try the two brown springs wich brings all my timing in by 2500 rpm and it starts to come in around 1500 rpm.
I adjusted my vaccume advance can while it was running i ran the engine up untill it stopped advancing with the vaccume advance hooked up to ported vaccume on the carb and i adjusted the vaccume can untill i had 48 degrees total timing with the vaccume advance hooked up. I read in my mopar engines manual and it says for small block engine total timing should be 50 degrees with vaccume advance hooked up so i figured 48 is close enough.
I did notice with my gap set at tthe correct setting wich is .008 that the distributer hung up on the advance plate while rotating the distributer so i took the advance plate ad pick up assemble back out and put it back in and got it to turn without hitting but i dont know if its hitting while its running or not? These things rive me nuts wich is making me think i should just give in and spend the 200 bucks for a brand new distributer plus tell don at fbo whats its going in and have him custom curve and phase it himself so that when i get it i can just drop it and go and be done with taking the distributer in and out.
What do you guys think? Should i try a new advance plate i can buy one from napa or should i just leave it alone and call it good not knowing if my rotor is pahsing or not knowing if my bushings are shot or should i just fork out the dough for a new distributer that will be curved and phased right out of the box and be done with it for a couple years? I hate having to spend money if i dont have to but on the other hand i hate not knowing if my distributer is good or not. And no one in my area knows anything about dodge they are all ford and chevy guys.
 
If the rotor is hitting the cap, it might be the cap is not aligned with the tab on the vacuum advance, and is on cocked. It could also be that the upper part of distributor shaft is bent. Or incorrect parts for cap or rotor.

The bearings can be checked with a dial indicator, or possibly by using a feeler gauge on the reluctor teeth to the pickup. Check the variation in gap from tooth to tooth, this will check if the shaft is bent. Apply finger pressure in and out toward and away from the pickup and see if the gap decreases and increases. If it does that is bearing slop. I do not know the spec, but I would think it should be under 0.001". An example is the gap would vary between 0.008" and 0.009", or 0.007" and 0.008".
 
OK update on whats going on.... I bought a brand new pick up assembly for the distributer this afternoon and a new vaccume advance canister an adjustable one. I threw it in and set my timing at 16 degrees initial and 34 degrees total , i'm running the brown springs wich is a single stage advance curve all in by 2500 rpm starts to come in around 1500 rpm. I took it for a drive and 3000 rpm and above its running better then it ever has since i have been playing with it but 2500 rpm and below i am expierencing some strange issue. When i'm just lighty cruising around there is slight surge and when i go to apply throttle smoothly it surges and surges and surges untill it gets up to about 3000 rpm and it smooths out and runs great. I pulled over and disconnected my vaccume advance and that made it run real crappy it was sluggish of the line, to be hones it sounded like i had just pulled a spark plug wire off of a sprk plug.
Whats up with that? running no vaccume advance makes it run like complete crap and with it plugged in it only runs good at roughly round 2500 to 3000 rpm. I would guess carburetor problem but i know its not the carburetor because when i was running the purple and orange advance spring wich made it a two stage advance curve it never did this, this only started when i changed to the single stage advance curve ( the two brown springs).
Is my timing coming in too soon and its detonation that i'm feeling at those low cruising rpms? Or do i need to turn the vaccume advance up or down? I set the vaccume advance to give 50 degrees total timing including the vaccume advance and i double checked it so i know that vaccume advance canister is adding an additional 16 degrees of timing.
Just trying to figure out if i need to stick to a two stage advance curve? Running these two brown springs brings all the timing in at 2500 rpm and it starts to come in around 1400-1500rpm...
I wanna be able to figure this out myself and save the 200 bucks but i'm really feeling like calling don at fbo telling him what i have and what i do with it and have him phase and curve a brand new disributer for me so i can just bolt it in and be done. I dont know if this probelm i am having is too much timing or not enough or if its coming in to fast or if my rotor is phasing or not? Its got a brand new pick assembly and reluctor. I can pull up on the rotor post and it will move up and down and with the advance plate in if i pull up on the rotor post it will catch on the advance plate so im guessing that it comes up to far and that could be causing this and if so that means i need a new distributer?
I just dont know thats why i'm asking you guys, please be patient with me i'm not trying to be an annoying punk just trying to learn and i'm doing my best to explain whats going on.
 
KitCarlson said:
If the rotor is hitting the cap, it might be the cap is not aligned with the tab on the vacuum advance, and is on cocked. It could also be that the upper part of distributor shaft is bent. Or incorrect parts for cap or rotor.

The bearings can be checked with a dial indicator, or possibly by using a feeler gauge on the reluctor teeth to the pickup. Check the variation in gap from tooth to tooth, this will check if the shaft is bent. Apply finger pressure in and out toward and away from the pickup and see if the gap decreases and increases. If it does that is bearing slop. I do not know the spec, but I would think it should be under 0.001". An example is the gap would vary between 0.008" and 0.009", or 0.007" and 0.008".
Click to expand...



X2....exactly what he said.....First thing you need to do is, You need to take the rotor off and grab the top of the shaft with your fingers and move side to side and watch the distance between reluctor tip and pickup coil.....If it moves more than .001 it needs bushings....Also, as mentioned check the gap on all 8 points of the reluctor to make sure the shaft is not bent..... Also, don't forget to use a brass feeler gauge when setting the .008 gap.... If any of this stuff isn't right you will have problems
 
The gap between the reluctor is .008 checked it with a brass feeler guage. and there is some side to side play but hardly any at all.... I'm thinking about just buying a brand new distributer. If the distributers don sells at fbo are the newer mopar ones with an adjustable mechanical advance i'll get one of them and tell him to set it up for my application it's only 200 bucks and i wouldnt have to mess with it again for a long time just change cap and rotors when needed.
 
what i wanna know most is why does it run like crap when i un hook the vaccume advance? And why does it run awesome at higher rpms but at light cruising speeds i have surging aand when i try to apply gas slowly i just keep getting more surges and more surges untill finally i get above 2500 rpm and it starts to smooth out and does great.
 
Is the advance curve i'm running coming in way to early? All in by 2500 rpm sounded fine to me givin i am running larger tires and only have 3.55 gears but still all in by 2500 rpm and i'm running premium fuel. Didnt think that would be all that early???
 
If you have hardly any side to side play I would say your bushings are good.....Rotor should not hit cap though or there is something wrong with rotor or cap......When you disconnected the vacuum advance did you plug the line??? You should...then take it for a ride and see what it does....too much advance at low engine speed will cause surging....Coming in too quick or too much intial will also do this....Your timing settings sound close to me but try going to 14 intial and put a set of heaviers springs in the distributor and see if it still surges....If it still does maybe a lean carb issue?
 
OK i will turn down the vaccume advance canister. The only time i had a problem with the rotor hitting the cap is when i tried to run an echlin cap and rotor. I went to car quest got a cap and rotor from them and its been fine. I can see where the chrome tab of the rotor has a little black spot on it from where it's been coming in contact with the button that the coil wire plugs into. I didnt plu the vaccume line i just pulled it off the carburetor. And i highly doubht there is a lean condition with the carburetor. In fact i have strugled trying to get it to not run so rich.
If turning down the vaccume advance dont do anything i will take it all apart again and go back to a two stage advance curve. The single stage advance curve that i am running now is the slowest curve out of them all wich is all in by 2500 rpm. Maybe i need that additional timing at lower rpms that a two stage advance curve allows to help the engine along. I m running a high gear ratio and big tires and an overdrive transmission. I plan to get 4.56's put in it once i get the oney to do it... but that may be awhile.
I just couldnt believe how crappy it was running once i un-hooked the vaccume advance it was ver sluggish when taking off. I still think i'm going to call don at fbo on onday he has a distributer machine and can phase a disttributer and set the mechanical advance and put the springs in for me so all i would have to do is drop it and go. The distributer i have is pretty old about 7 or 8 years old.
 
The whole reason i switched to a single stage advance curve ( the to brown springs) is because when i was running a stage two advane curve ( the purple and orange spring) i would get surging while the truck parked and i tried slowly climbing the rpm range. Didnt do it while driving only while at a stand still....
So i switched to a single stage advance curve the two brown springs bout a new pick up assembly and reluctor put it all in and put the two brown springs in and it solved the surging while holding the throttle steady aat 2000 rpm while in park, but it brought this surging on at low rpms. Like if im cruising at like 30 to 35 mph in second gear and go to lighly squeeze into the throttle it will start surging untill i get above 2500 rpm and then it will run like no bodys buissness.
 
Ditto pishta. I bought one from him for my SB and his $20 E-core coil. Haven't installed yet, but looks well-made and even better than the factory one. You get HEI, so no more melted Mopar boxes.

Re shaft play. In the old days with my 69 Dart, a parts guy looked at my distributor just trying to wiggle the shaft side to side, as mentioned, and said it looked fine. I was also worried about the up & down movement, but that is normal. That was points distributor and electronic are pickier, especially the Mopar ones with a single pickup. The linked one has multiple pickup teeth all around, so a little side play shouldn't matter. My SB currently has a Crane optical pickup (axial), where side movement hardly matters (no air gap to a tooth).

As far as surging, several things can cause that. I think with a lean mixture, it wants more advance, so if the engine speed pickups up and the weights advance, it runs better, speeds up more, etc, known as "positive feedback", so it tends to surge at idle. In the Holley Commander 950 manual it talks about programming the advance. You want it to run worse if it speeds up a bit at idle so it holds a stable idle. That must be how all modern programmable spark advance is designed. I wonder if the "vacuum advance" in classic distributors serves a similar purpose.
 
Pull the line of the cannister ( not the carb ) and put a golf tee in the end of the hose....take it for a ride....If it doesn't surge the problem is in the vacuum advance not the springs (mechanical advance).....Understand that the heavier springs hold tighter requiring more centrifical force ( higher rpms) to spread.....In other words, timing will come in later with heavier springs.....It will still come in to the total timing set by the stop bushings....that will not change with the spring weights.....understand
 
yes i fully understand how the advance works in the distributer. What i dont understand is why i am getting surging at light cruising speeds and why it hesitates when i try to squeeze into the throttle from a light cruising speed. I did not plug the hose off i just pulled it off of the carburetor. Why does it need to be plugged off?
So my problem is stemming from ether too much vaccume advance or the centrifical advance is coming in too soon? I cwnt imagine all in by 2500 rppm being too soon. But i will plug the vaccume advance hose off at the vaccume canister end and see what happens if it takes it away i'll turn down the vaccume advance if it doesnt i will tear down the distributer and go back to a two stage advance curve.
 
bbrroowwnn and oklacarcollecto beat me to the part about plugging the vacuum line when you remove it from the advance . It sucks air through it otherwise. Which is a big vacuum leak. This will definitely make it run like crap. you still are causing a vacuum leak if you just remove it from the carb it would have to be seal there then cause you're still sucking air into the engine.
 
Understand the vacuum is coming from the carburator to make the cannister work....not the other way around.....So if you take it off at the carburetor and don't put a cap on the nipple you essentially have a big vacuum leak....(Hence, runs like %$&^%$)
 
First off let me ask this. What would be the best advance curve to run in my application? 360 magnum the one time it was dynoed it put out 319 horse power and 424 ft lbs of torque but that was with a crane cams ignition box same carb and intake tho.
The truck is a half ton short bed 4 inch lift 33/12.50/15 tires on 15x10 wheels.
Transmission is a non lock up A-518 the gears are 3.55's. I know i am way under geared and will adress it soon as i can but for now with what i have is a single stage advance curve better? or is a two stage advance curve better? do i want it all in by 2500 rpm or 2800 rpm or 3000 rpm or even higher?
I found the sweet spot for this engine to be 16 degrees initial timing and 34 total.
it starts on the first turn of the key almost everytime. I know i am really close to having this perfect. The carburetor cant be running lean i have .092 jets in the front .092 jets in the rear running the 7047 metering rods and the orange step up springs. Accelerator pump linkage is in the middle hole. I just dont see the carburetor being the problem, i checked the floats and they were a tad bit lower then 7/16's of an inch wich is what my edelbrock repair manual says they should be at, i took the floats off and bent the tabs to where a could slide a 7/16s drill it under them nd the drill bit barley touches them so i know the float level is good. Fuel pressure is right 5 lbs.
I have a good cap and rotor the premium blue boxed cap and rotor from car quest my plug wires are 7mm borg warner selects they are only a couple months old.
Just trying to give as much info as i can so i can get ball park figures from you guys as far as when to have the timing all in by and wether or not a stage one advance curve would be best or a two stage.
 
OK....i understnd why i need to plug it now sorry that was a huge bain fart on my part
 
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