Bulltear cam gear help

[melton83]

I recently installed a matched set of bulltear distributer gears after my previous cam gear got chewed up immediately after my engine rebuild. It’s been running great, and I’ve put about 200+ miles on the bulltear gears, but now my cam gear is all chewed up again. The Distributor gear looks completely normal! Looking at all the parts through the dizzy hole, and looking at the distributor gear, everything looks like it’s covered in plenty of lube, so I don’t know what the hell to do. Does anyone have any advice? My wife’s gotten so fed up with having to share one car that I’m about to just have it towed into the shop where I had my parts machined and have them fix it. Please, any advice would be greatly appreciated!

[fifesjeep]

Is that the stock timing cover or is it an aftermarket? You could have alignment issues...

[melton83]

It's the stock timing cover. Both of the dowell pins were inserted through the cover into the block too, so it shoudn't be an alignment issue right?

[jeepsr4ever]

Thats very strange. Are you sure you were running both our cam and distributor gear. I would take and try to turn the oil pump with a screw driver down the distributor hole to see if its binding in any way. I would say something major is happening.

[melton83]

Yeah I've tried turning it with a screwdriver, and it's easily done by hand. I'm at my wits end. I'm just going to have it towed to the machine shop today and have them check it out.

[mrtazwrench]

how about the dizzy, stock? aftermarket? any possable issues with it, the HEI's with issues a while back come to mind. :-|

[fifesjeep]

How are the gears meshing? When you put the new gears on toss on some gear die clamp the distributor down and rotate the engine by hand... Pull the distributor and see where the witness marks are... You could have it sitting too high or too low, and if you don't have enough shims between the distributor gear and housing this will cause the Distributor shaft to move up and down cause premature wear... Check this stuff... Also, make sure the distributor is a snug fit in the timing cover (No side wobble).

[melton83]

well I couldnt take it to the shop friday because they were already closed by the time I got out of work.

yes it is an aftermarket HEI distributor. Before installing it though I measured the length from where the dizzy rests on the timing cover to the gear and it was the exact same length as my old dizzy. Also there aren't any shims between the bulltear dizzy gear the the dizzy shaft, because there's no play at all. It's a tight fit. With the dizzy fully seated in the timing cover there is no movement or wobble in the distributor so it seems to be seated right. I going crazy!!

[jeepsr4ever]

What make of HEI unit is it? Their are a couple that dont sit down all the way allowing the oil pump drive gear to be forced into the oil filter adaptor and that can cause distributor gear damage. It may just be that HEI!!

[tufcj]

http://www.bulltear.com/forums/viewtopic.php?t=7679

Bob
tufcj

[76-cj7]

This morning as im pullin into work and my jeep dies......come to find the the gear on my dist is wiped out completely........brand new MSD dist and brand new MSD cam gear. The cam gear looks fine but the dist gear is gone......wut the hell would cause this? Have great oiling.....entire engine was new 5k miles ago along with cam and bearings.... Would cam walk be suspect?

[fifesjeep]

I can't see where cam walk would be an issue with an AMC... Especially with how the cam bearings are situated... If anything, if the cam were to walk wouldn't it walk away from the distributor gear and into the back plate?
I yanked my distributor HEI just to look at the Gear and I can see definite wear on the top of the gear... I have a few extras... I normally go to the yards and pull the Distributor gears and cam gears if they're good... Looks like I'll be replacing here soon.

[tufcj]

The MSD gear may not have been compatible with the cam gear you were running. There are factory and a couple of aftermarket sets out there, each with its own unique gear cut. That's why cam and dizzy gears should always be replaced as a matched set, and never mixed from different sources.

There is only about 1/4" of clearance between the cam bolt and the front cover. The lobes and lifters (and a tight chain) all work to pull the cam toward the rear, so the back of the cam gear rides against the block. The only direction the cam can walk is forward (unless the bolt loosens). Check the inside of the timing cover for damage from the bolt. If it has walked that far forward, there may also be damage to the base of the dizzy housing, and the cam lobes and lifters.

Bob
tufcj

[76-cj7]

well the cam gear was also a brand new MSD so i dont see where matching would be a problem........everything seems fine but come to think of it with the temp being in the teens around here for the past feww weeks and thick oil might be suspect.....

[jeepsr4ever]

MSD definately does not have a good gear set. Many AMC'ers have trashed theirs.

[fifesjeep]

I've ordered a few gears from different companies and I have noticed that some cut the gears too deep as other cut them too shallow... Then others will cut them right-on and when they heat treat the gears their dimension change. I figure if I find a set of gears (Junk yard) that look good and have miles on them without any signs of abnormal wearing then they'll work for my use. (Call me cheap :? ... I've been burned a few times with purchasing new gears). :agrue:

[76-cj7]

Well MC....on that comment about the MSD gears.....i guess i better take advantage of your free shipping....better package me up a set cause im ordering them right now :t:

[melton83]

OK, i just got a call from the machine shop, and they asked if I had my original distributor from before the rebuild. the one in it now is a ProForm HEI. They want to try switching them and seeing how if that fixes the problem. Before installing I measured the distributor shaft lengths and they were both the same, also I had the matched bulltear gears installed. So do you guys think just switching the distributors would really fix the problem. Oh, they also deteremined that there was no oiling issue, the gears were getting plenty.

[melton83]

Sorry for the double post, but I just want to be ready. If I do need to get another distributor, any recomendations. I go offroading maybe once or twice a month, but my AMC 304 1976 CJ7 is my daily driver. Just asking because my old distributor is a Mallory unilite without vacuum advance. I would like one with vacuum advance because it should make city driving smoother. Thank you for all the info!

[fifesjeep]

I don't see how the original is going to help them seeing that both gears were changed... Unless they're going to check the dimensions... How and what did you use to check the distributor dimension(s)?

[melton83]

A tape measure........

[fifesjeep]

:shock: Yeah man, I guess that'll get you close but if you're off even 1/64" (.015") that would matter and make a world of difference... If the gears don't mesh at the correct pitch circle then the gears will chew one another etc... Chances are that's the problem...
check this out.... this shows where the gears should mesh (This is for spur gears) but it's almost the same as helical.
http://shopswarf.orcon.net.nz/gear2.gif
Here is a better site, scroll down and look at the disadvantages of Helical gears...
http://www.agroengineers.com/gears/Helical-Gears.shtml

[melton83]

Thanks for the info fifesjeep. I know there are much more accurate ways to measure things when it comes to mechanics, but the tape measure was all I had at the house. I'm fairly new to this kind of work. Does anyone know the dimensions of an AMC 304 distributor, as far as how long the shaft is supposed to be, so to speak. I no longer have my old distributor.

Just wanted to say thanks again to everyone here with all this great knowledge on AMCs, helping us amateurs keep'em alive.

[ironman_gq]

use gear marking compound

[jeepsr4ever]

OK, i just got a call from the machine shop, and they asked if I had my original distributor from before the rebuild. the one in it now is a ProForm HEI. They want to try switching them and seeing how if that fixes the problem. Before installing I measured the distributor shaft lengths and they were both the same, also I had the matched bulltear gears installed. So do you guys think just switching the distributors would really fix the problem. Oh, they also deteremined that there was no oiling issue, the gears were getting plenty.

If you ruined a set of our Chromoly gears their is no other gear out there that will work. We need to find the root of the problem. I am guessing its either a oiling issue or an alingment issue.

[ironman_gq]

post a picture of the gears if you can. sometimes you can tell what caused them to fail by the wear pattern

[fifesjeep]

OK, i just got a call from the machine shop, and they asked if I had my original distributor from before the rebuild. the one in it now is a ProForm HEI. They want to try switching them and seeing how if that fixes the problem. Before installing I measured the distributor shaft lengths and they were both the same, also I had the matched bulltear gears installed. So do you guys think just switching the distributors would really fix the problem. Oh, they also deteremined that there was no oiling issue, the gears were getting plenty.

If you ruined a set of our Chromoly gears their is no other gear out there that will work. We need to find the root of the problem. I am guessing its either a oiling issue or an alingment issue.
Gear mesh... I'm 99% sure that this is the problem... If you don't have the gears meshing properly then they are eventually going to build heat which will cause expansion (Even if it's minimal) which in-turn will cause more friction... The garage said that you are getting oil to the gears and that's not the issue... You can have plenty of oil getting to those gears... but if they're not meshing correctly one or the other gear will get chewed (I'm beating a dead horse I know). But without the oil that gear would've been toast a long time ago... You need to have that garage find the correct depth in-order to have the proper gear mesh. This will be a trial and error process with that distributor... It's also a good idea to check the gears tooth thickness/circular pitch/addendum/dedendum,whole depth and the list goes on and on etc. It's a good practice to know how to use a gear tooth vernier... In-order to check some of the above. A good engine shop/garage should be able to figure this stuff. I've made plenty of Spur Gears, Helical gears, worm and worm wheels etc... Try making a set of worm gears and a worm wheel and not having the proper height or tooth dimensions #-o and then do a test run with minimal lube... :idea: the gears will basically fuse together (Sort of)

[rustyfloors]

I'm with MC & fifesjeep! If you chewed up a set of chromoly gears it has to be a mesh issue or your oil pump gears are tight!

What was you oil pressure when it ran good? I know this is a different animal but, I had the same problem with a strait 6 ford! It would chew up dizzy gear or shear the roll pin every 50 miles or so! The root of the problem was the oil pump!

Just my .2

[Paul Nance]

I also lost a set of gears with pro comp dist . diz shaft was under size made and replaced bushings &shimeout all but.020 thosands end play replaced gear with one from ebay for after market dizs .had it replace oil & gear drive roll pin with a smaler pin . one that would fit in oil pump drive slot . so far about 3,000 miles every thing still works .migh go ---- tomorrow hope not. good luck building a 360 it will have a new diz with mached gears .i now have 304 ,.060 over &other mis. parts .

[melton83]

I Well I was forced to have the machine shop fix the problem because I'm just not to that level yet to be able to troubleshoot this kind of thing. ( Plus my wife was getting fed up with only having one car). They did a dye test and found that the cam gear was riding to high and had to be lowered down. Well there are two different holes on the end of my HEI dizzy shaft for mounting the dizzy gear, so they droped it down to the lowest hole, and found it was meshing up where it should be so that fixed that. They put on a MSD gear set. They also were aware of the known AMC oiling problems and drilled a hole that would allow more oil to squirt onto the gears. So far so good. I reaaalllly hope this doesn't happen again!!

[fifesjeep]

I Well I was forced to have the machine shop fix the problem because I'm just not to that level yet to be able to troubleshoot this kind of thing. ( Plus my wife was getting fed up with only having one car). They did a dye test and found that the cam gear was riding to high and had to be lowered down. Well there are two different holes on the end of my HEI dizzy shaft for mounting the dizzy gear, so they droped it down to the lowest hole, and found it was meshing up where it should be so that fixed that. They put on a MSD gear set. They also were aware of the known AMC oiling problems and drilled a hole that would allow more oil to squirt onto the gears. So far so good. I reaaalllly hope this doesn't happen again!!
I figured as much... As for drilling a hole for extra oiling... I'm not 100% sure if you actually needed that... They did say that you were getting good oil supply already... and that wasn't the issue... :-| Did they disassemble the block before they drilled it? If not you're going to have fine metal shavings getting into everything... Bearing and journal surfaces,oil pump/filter, lifters, pushrods etc... Chances are it'll settle to the bottom but... Even that, I'd have them yank it, clean it and rebuild it for free...

[Mudrat]

WARNING ENGINEERING CONTENT!! :mrgreen: =D>


:shock: ... if you're off even 1/64" (.015") that would matter and make a world of difference... If the gears don't mesh at the correct pitch circle then the gears will chew one another etc... Chances are that's the problem...
check this out.... this shows where the gears should mesh (This is for spur gears) but it's almost the same as helical.
http://shopswarf.orcon.net.nz/gear2.gif
Here is a better site, scroll down and look at the disadvantages of Helical gears...
http://www.agroengineers.com/gears/Helical-Gears.shtml
You can use the same principle in electric motors too! By making the rotor and stator function like a helical gear, you increase power, the efficiency, and decrease what's called motor slot frequency (noise). Cool stuff though :t:

[fifesjeep]

WARNING ENGINEERING CONTENT!! :mrgreen: =D>


:shock: ... if you're off even 1/64" (.015") that would matter and make a world of difference... If the gears don't mesh at the correct pitch circle then the gears will chew one another etc... Chances are that's the problem...
check this out.... this shows where the gears should mesh (This is for spur gears) but it's almost the same as helical.
http://shopswarf.orcon.net.nz/gear2.gif
Here is a better site, scroll down and look at the disadvantages of Helical gears...
http://www.agroengineers.com/gears/Helical-Gears.shtml
You can use the same principle in electric motors too! By making the rotor and stator function like a helical gear, you increase power, the efficiency, and decrease what's called motor slot frequency (noise). Cool stuff though :t:

By nature the Helical gear is a quieter design due to the gears running mesh... Although the gear efficiency (transfer of energy) isn't as good as the noisey spur gear but then again Helical Gears are stronger than a typical spur gear of the same tooth size... There's pro's and con's to each... Never really gave electric motors any sort of thought... :-| Makes sense though. I actually miss making gears... Well, sort of... The set-up for the most part sucks... It's been a short minute since I made any sort of gear.. about 8 months I think #-o Last gears I made were helical gears... I dislike setting up the gear-train too... You think somebody would make a quick select for a wide range... Bolt it up to the Horizontal Mill, select the needed gear train and go... Oh-well.. I can always wish. :roll:
I'm waiting until the CNC software becomes so easy to operate that a monkey can do it and then they'll start laying these over payed button pushers off 8) Then the pay focus will be back on to the manual machines where the real machinists are :mrgreen: Manual machining is a skilled Art, working a computer that has self check sequences is...????? A skilled button pusher??? :idea:

[maccj5]

ive had the same thing happen 304 in 73 cj5 new omix t cover omix cam gear msd dizz new rebuild 1,500 miles= cam gear junk----- put on new gear went with stock dizz 2,200 miles =cam gear junk, pulled motor havent checked it out yet found great running 401 to put in am building 2 other 401's have several 360's to build going to go with the bull tear gears for future builds and a lot checking on specs its a real pita to keep pulling engines because of these pesky little gears p.s both dizzy gears were ok :(:

[fifesjeep]

Honestly, the stock gears are fine just as long as everything else is correct... Gear mesh, minimal vertical play in the distributor shaft, tight tolerances with distributor and timing cover... alot of things come into play...

[AMX69PHATTY]

It's pretty cool that AMC motors stock from the factory were fine and never known to eat dizzy gears more or less. Stock AMC motors have ran over 100k miles all the time wth stock dizzy gears with no problems. The factory seemed to know what they were doing when it came to dizzy drives.

[fifesjeep]

It's pretty cool that AMC motors stock from the factory were fine and never known to eat dizzy gears more or less. Stock AMC motors have ran over 100k miles all the time wth stock dizzy gears with no problems. The factory seemed to know what they were doing when it came to dizzy drives.
Yup that's what I was basically saying... By putting in the hardened gears all that's going to do is move the problem area... Most likely side load the distributor shaft and wear the Bronze Alloy bushing (Sintered Bronze) at the base of the distributor... Then your dist. gear and shaft will be "doing a little dance, make a little noise... get down tonight"... Ooops, the 70's just came back... :?