Mopar Muscle Association UK

So, 2 x bronze (oil pump/dizzy) gears have now been eaten away and neither lasted more than a few hundred miles. First symptom I noticed both times was a drop off in performance due to timing having backed itself off as the gear has worn....much worse and I'd have ended up low/no oil pressure pretty soon afterwards!

Is this just what you have to suffer with mechanical roller cams, or can I get away with fitting a steel gear? The cam is a Crower 'street roller' 32412 in a 512 stroker motor. I asked Crower, but they didn't respond.

https://www.crower.com/camshafts/mopar- ... illet.html

bronze gears are sacrificial to save the cam, only they don't seem to last any mileage. the oil pump is what puts the load on it.

fit the steel gears and keep an eye on the wear for the initial few hundred miles, if all ok then leave alone after that.

(did the same with a Chevy engine years ago. no wear with the steel gear so bronze gear seemed pointless?)

Are these engines set up the same way as a Rover V8 in that the distributor drive also drives the oil pump?

Only mention it as a pal of mine kept having similar issues and we determined that it was the high volume oil pump generating too much resistance and therefore adding extra stress on the drive gear. Regular oil pump fitted, no more stripped gears.

@Boz - yes, think I'm going to do that. Was wondering whether there might be gears made out something tougher than bronze but less tough than steel, but doesn't look like there is, apart from some I see referred to as coated? Wouldn't want to be relying on a coating.

@Sloth - Yes, that's the setup - the gear actually fits onto the oil pump driveshaft

Actually Super Sloth, I am running a HV oil pump....might be the issue. Given that it's not recommended to fit a steel gear on a used cam I might fit another bronze one and swap out the pump for a regular one.

also bear in mind that the bits of both (so far) bronze gears are now in the sump with the oil pickup and could therefore find their way into the oilways (if they don't block the pickup first) which is never good.
regards, neil.

mygasser wrote: ↑Sun May 12, 19 11:11 am also bear in mind that the bits of both (so far) bronze gears are now in the sump with the oil pickup and could therefore find their way into the oilways (if they don't block the pickup first) which is never good.
regards, neil.

Thanks for cheering me up Neil..lol!!

David Murray wrote: ↑Sun May 12, 19 12:26 pm

mygasser wrote: ↑Sun May 12, 19 11:11 am also bear in mind that the bits of both (so far) bronze gears are now in the sump with the oil pickup and could therefore find their way into the oilways (if they don't block the pickup first) which is never good.
regards, neil.

Thanks for cheering me up Neil..lol!!

i aim to please

Hi david.have you got a cam button on front of cam up against timing cover(preferable aluminium timing cover),this stops the cam moving forward and backwards,and will stop it eating gears.
If its a street engine you would be better with a solid lat tappet or hydraulic flat tappet,less valve spring pressure etc

DaveB wrote: ↑Sun May 19, 19 8:43 am Hi david.have you got a cam button on front of cam up against timing cover(preferable aluminium timing cover),this stops the cam moving forward and backwards,and will stop it eating gears.
If its a street engine you would be better with a solid lat tappet or hydraulic flat tappet,less valve spring pressure etc

Good suggestion

yeah that will help

i stuffed a nice bit of nylon up the middle of my 3 bolt cam in my new ish motor
i left a few thou clearance with the cover

i have not razor edged my oil pump drive gear or busted a nylon dizzy gear or indeed smashed an oil pump off its delicate mounts....
my original/old motor with single row chain wore a hole in the timing cover the cam slap was b A A Ad
and the oil pump and dizzy gears were horrible. it was fixed in OZ as described below

the delicate balance between spring pressure the slope on the cam lobe the dome to the lifters and the force needed to turn the oil pump and dizzy gears was quickly lost once the motors got 50K + on them the cam rode back and forth in the block stretching the single row chain wareing the front face and the cover and chrysler oz started getting warranty claims and bad press

chrysler australia's patented bodge for the Hemi 6 below, it assumes a pressed steel cover. new ally ones, if you can find one, come with the bodge already installed saves paying summit for a cam button.

The following is an extract of a Chrysler Australia Service Bulletin dated September, 1976.
1. Remove radiator, fan, vibration damper and timing cover.
2. Locate on the timing cover the centreline of the camshaft. (Refer to figure 1.) your timing cover is different as this was for a hemi 6 the hemi 6 picture was all corrupted so i didn't lift it for here, most have a flat circle in the middle of the strengthening flutes


Drill a 5/16" hole through the timing cover to align with the centreline of the camshaft. Braze a 5/16 U.N.F. nut to the outer side of the timing cover (it is recommended that a 5/16" U.N.F. bolt and nut be used to positively locate the nut being brazed to the outer side in the timing cover, to ensure correct alignment with the centreline of the camshaft.)
4. Modify a 5/16" x 2" U.N.F. setscrew, by drilling the centre of the bolt sufficiently to accommodate a 1/4" diameter steel ball bearing. (Refer to figure 2.)




5. Refit timing cover to engine.
6. Screw lock nut (5/16" U.N.F.) over full length of setscrew, then thread setscrew with ball bearing positioned (smeared with grease to temporarily secure) through nut brazed to timing cover. Ensure steel ball bearing does not dislodge from counter bored setscrew.
7. Adjust setscrew to eliminate end float of camshaft, then back off 1/4 turn. Lock up setscrew with lock nut. (Refer to figure 3 for assembly condition).



8. Refit vibration damper, fan and radiator, refill cooling system.
9. Road test vehicle, ensure there are no oil or cooling system leaks. IMPORTANT: Ensure that the end float adjustment screw is backed off 1/4 turn minimum, and that there is sufficient clearance between setscrew and fan belt.


no..... they actually published a service bulletin suggesting this to their dealers

my current motor has a nylon button (nylon rod and a bloke with a lathe)...no problems
the previous one was repaired in this way (as in the bulletin) with a new cover and timing set...it went much better with a chain that was not half a mile stretched


more on how to australian-ise your car here http://www.geocities.ws/drhemi.geo/techpage.html

Interesting and thank you Dave's. Not sure whether I have a cam button fitted...I suspect not, but will check with my 'chief mechanic'! Along with switching back to a stock oil pump, this may make the difference. Don't really want to drop back to a flat tappet cam as performance with my current setup is great.

Mancini racing site shows a coated steel distributor drive for roller cams and shows oil pump recommendation too.
https://www.manciniracing.com/hughesadd1.html
Must be a Hughes Engines part, judging by the product reference.
Chris

Birdman wrote: ↑Tue May 21, 19 2:22 pm Mancini racing site shows a coated steel distributor drive for roller cams and shows oil pump recommendation too.
https://www.manciniracing.com/hughesadd1.html
Must be a Hughes Engines part, judging by the product reference.
Chris

Looks a good upgrade, especially for plentiful street driving. That said, the Cam button will help to reduce thrust load on the gear from the cam, which can only be a benefit for either gear option.