MSD Distributor Gear.

[brainbugnj]

There have been multiple threads on the MSD distributor gear replacement. I just ordered a MSD distributor and a Edelbrock RPM cam...... should I also order the steel gear and replace?

Why would they send with a gear that needs to be replaced on an aftermarket distributor which 9/10s of the time you will be using with an aftermarket cam?

can anyone shed some light for me?

Thanks in advance!
Steve

[Hotfingrs]

A lot of aftermarket cams don't have a cast gear on them....so it's much easier to replace a dist gear than a cam gear. I always order my cams with a cast gear, but then you have to wait much longer for delivery, and I'm talking months wait....

[brainbugnj]

i am a tard, but I don't understand. What do you mean a cast gear on the cam...i guess the question is why doesn't MSD send the distrib with the steel gear?

[deadwood1584]

check out the new NASCAR style polymer gears! Will work on cast or steel cams

[TonyMadrid]

I recently ordered an MSD Distributor and when I opened the box there was a memo saying that I would have to get a different gear and have a machine shop press it on. I called MSD Tech and they told me that th egear that came with the dist was fine to use as is.

[brainbugnj]

Tony what kind of cam was it with?

[Hotfingrs]

Cast gear means the gear is cast on the cam when it is made..instead of being pressed on and made of alloy at a later date. With the alloy cam gear, the dist gear has to be made of a softer metal, so that it wears and not the cam gear.....thus my saying it's easier to replace a dist gear than a cam gear. With the cast gear you can use a steel dist gear and never have to worry about changing the gears

[zipzip]

Check out the butcher - he's lived through this and has it well documented....


www.cobralads.com

It appears the critical thing with an MSD distributor is the distance from the mounting plate to the bottom of the gear (as well as the material).

[TonyMadrid]

The cam was made by a guy on the West Coast and it has a cast gear.

[Mr.Fixit]

A cast dist gear is fine, unless you have a roller cam, then you need a steel or bronze dist gear. With a tappet cam, they have cast cam gear, so run a cast dist gear as well.

the polymer gears I don't think are recomended for engines that still use the factory oil pump, I think you need a dry sump or there will be too much load on the gear (I think, may be wrong)

[brainbugnj]

So what I am hearing from you guys is that a cast gear is fine with a non-roller cam/tappets...

Mine is not, standard hydraulic lifters.....RPM Performer Cam.....if I am correct from all of you I should be ok with the standard cast gear then?

....only need the steel gear if you have a roller cam/tappets or a cast cam gear...

[Jack21]

MSD ships its distributors with cast iron cam gear and is intended for use with cast iron hydraulic (or solid) lifter camshafts. The dist usually (mine did) has a tag on it warning the end user to change the distributor gear to a steel gear if the engine has a roller cam which is made out of steel, not cast iron.

If you have a roller cam specially made with a cast iron cam gear, than use a cast iron distributor gear. Don't know of any Ford roller camshafts that can be made with cast iron gear.

[Ray R]

I built a 408 stroker with a Comp Cams roller camshaft that had a hardened cast iron gear. I used a MSD distributor that had a hardened cast iron gear. Unfortunately, the distributor's cast gear had a rockwell hardness that was less than the cam, and when we were breaking in the engine on a dyno (thank goodness I chose to find the flaws of a new engine on the dyno rather than in the car!), the distributor gear disintegrated in 10 minutes. The good thing about most engine dyno's is that they are usually equipped with an oil filter system that removes even the smallest particulates for analysis...at least this one did.

Anyway, according to MSD, when you replace the gear, you press on the new one and drill for the new pin. This obviously limits the number of times you can replace a gear! So, I had the machinist hone a bronze gear and we used the original pin position. After about 15 minutes on the dyno, the bronze gear showed signs of wear as well, although nowhere near what happened with the cast gear. We estimated that the bronze gear would last about 10k miles, then need replacing.

We then tried a steel gear from Comp Cams, and it's worked flawlessly ever since.

One item of real frustration: We made repeated phone calls to Comp Cams and MSD to try to get them to recommend the proper gear type. Each time we called, we got a different person and a different answer.

I guess my point here is that it's really difficult to answer your question without knowing all of the facts and specs. Folks that say use a cast distributor gear with a cast cam gear could be leading you down the same path that I started...remember the rockwell hardness issue?

But my opinion would be that since you're using a non-roller cam, your cast distributor gear should be ok.

[jopper]

My last engine had a Crower steel roller cam. I used a bronze gear on the MSD distributor and had 10K miles on it when I pulled the engine to replace it. The gear had a good amount of wear but was still working fine.

My new engine has a Comp cams roller cam. I haven't fired it yet, but I have had the same response as Ray R from Comp cams. The last guy I talked to said I should be fine with the cast gear on the MSD because my cam is cast. The cam is supposed to be austempered which is a hardening process used with cast cams to harden it for roller profiles. But I'll bet it's harder than the cast distributor gear.

I was going to break the engine in with the cast gear, and keep an eye on it, I has no idea it would go south so fast, but thanks to Ray's post I now will go with a steel gear on the distributor.

[Lowell W]

Why is cam/distributor gear wear such an issue on (some of?)these motors when the stock motors routinely go 100,000+ miles without problems?

I wanted to check the amount of wear/slop in my distributor after 9500 miles but didn't want to pull the distributor. I also wanted an easily repeatable method of checking and measuring the amount of wear from time to time without having to go through setting the timing, etc. I mounted a dial indicator to the distributor housing with the plunger bearing on one of the pivot pins for the advance weights. At this point, I measured .025" of rotational play. Since this is approximately one inch from the center of the shaft, it seems to me that this is reasonable but the best way to tell will be to check periodically to see whether this measurement increases and, if so, by how much how fast. This is a Comp hydraulic roller cam with a steel gear on the MSD distributor.

Anyone have any similar experience? Comments?

Thanks,

Lowell

[Ray R]

The best way to tell if your gears are wearing is to pull the distributor and look. Probably the second best way is to check the timing. If the timing is changing, you're probably wearing the gears.

I don't think that cam/distributor gear wear is an issue on these engines....as long as you start with the right combination. Bronze gears just wear faster. It's the nature of the metal. Usually, bronze is for race engines, and they get replaced often. Sure, stock combinations go forever. But stock engines generally don't have hardened cast iron roller rocker camshafts. We're animals. We upgrade. It's our nature.

If you have the comp cams hydraulic roller with a steel gear, I'm betting you'll be fine for a long time....

Happy motoring!

[Lowell W]

Ray,

Thanks. The timing hasn't changed and, perhaps more to the point, when I shine the timing light on the damper, the markings are sharp and easy to read. I think it's in good shape.

[Jack21]

Factory engines do go 100k+ miles without distributor gear problems, but the gears and cams are matched at the factory. Aftermarket hydraulic roller cams for street motors is when this distributor gear construction became an issue. Ford 302's began using hydraulic rollers in '85, and in 351W's in '93. Used the factory steel distributor gear for a roller motor and have had little trouble.

After 14,000 miles, the gear is showing more than normal wear, so I'm replacing it anyway and check it once a year.

Do like your idea of honing out gear so that it's a slight interference fit rather than a press fit, and use same pin hole, and that's how I'll do replacement.

The initial swap, I heated gear on stove, put distributor in freezer, slid the gear on quickly and it worked.

[RACER X #99]

After reading everything the Butcher had to write about MSD dist. gears, I decided to try and find out why my dist. gears are wearing prematurly.
The numbers that MSD gives you on locating the new dist.gears seems to be wrong and I concur with the Butcher. The pink sheet says 4.005 max and 3.996 min on base of dist. flange to bottom of gear. I tried a brand new gear with those min . 3.996 numbers and when I bolted down the dist. (cam removed) I could not turn the dist shaft. I moved the gear to 3.970( the exact dimension of a Ford dist. I removed from another 351W) Now when bolted in the dist. shaft spins freely and after reinstalling the cam the teeth mesh is correctly centered.

This seems like a lot of trouble to go thru to just install a new dist. But I only had 200 Miles on my new engine when the dist. and cam gear were both wiped out. Steel gear on billet roller cam and crane steel gear on dist. The initial installation I went strictly by the dist. gear instruction (pink) sheet.

It seems to me whomever you buy parts from always puts the blame for something going wrong on the other guy. The amount of questions and problems regarding premature dist. gear wear leads me to beleive that some of the big name manufacturers are not doing their homework.

The only advise that I can give is do not assume that the printed instructions are 100 % correct. Do your own measuring and fitting and if you are not sure how to do it ask somebody who is.

The best place to find the correct specifications are from Engine manufacturers manuals.

Hope this helps somebody,
RD

[djseed]

You can always use the Crane roller combination. I used the Crane hydraulic roller cam and the Crane steel distributor gear on the MSD distributor. You need to make sure of compatibilty issues if you mix manufacturers.

http://www.cranecams.com/master/stdrvgear.htm