MSD/Roller Cam Distributor Gear

Brad Pfeifer · #1 (**permalink**) 11-02-2001, 05:21 PM

Hello all,

I am building a 427 small block (351W) and it has a hydraulic roller cam in it. I got the short block from Probe Racing. I am using a MSD 8578 distributor.

I understand I need to change the distributor gear. That part is simple enough, but trying to get the right part number is almost impossible. I understand I can use either steel or bronze, but bronze will wear at a faster rate.

I need a recommendation on whether to use steel or bronze and an MSD part number for the right gear.

Thanks,

Brad

greenwater · #2 (**permalink**) 11-02-2001, 06:13 PM

Brad,

I can help you with your first question: bronze or steel.....I had to face the same dilemma with my Mallory/roller cam combo. I've opted for a bronze gear as I could not yet find a steel gear for it. (You don't want to go with iron)

My finding with bronze is that they won't hurt your cam but they wear out at a very rapid rate: I had to change a first one after about 1500 miles and my second one with about the same mileage on it now shows somw sign of being worn out wich is irregularities in fire. The comportement of my engine is much better with a fresh gear....I suppose this have to do with the gear "theething" once worned having some gap with the cam's ....I mean one as to see what's left of a bronze gear after 1500-2000 miles!
Sorry I cannot help you with the specific steel gear that will match your dist. but its worth the effort finding it!

DavidWard · #3 (**permalink**) 11-02-2001, 07:53 PM

Don't know the part #, but you can get the steel gear from Ford. It comes un-bored, however, so you will have to get a machine shop to bore it. I'm running the 8582 distributor, which is the same unit that you have except shaft is shorter to fit the 302. MSD sent me two gears, the first was cast, and the second was steel, but wrong diameter. I went with the Ford gear, and it still looks good after 13,000 miles. Ford gear was $11 when I bought mine.

David

Jack21 · #4 (**permalink**) 11-02-2001, 08:46 PM

Dirty little secrets MSD didn't tell you about.

Using same MSD distributor for 351W w/ Comp Cams hydraulic roller.

You can't use a cast iron dist gear on a steel roller cam. Incompatible metals. And you're finding out why bronze isn't such a great idea either. Not to mention where that bronze is going after it departs the dist gear.

For distances measured in 1/4 miles, I guess there's a use for a bronze gear. 1000's of miles, forget it.

The good news is this. The steel gear Ford uses on their 351W roller motors will work just fine on yours. Ford PN: M-12390-F, ~$11 sounds about right. Tap out the dist gear roll pin with a drift punch, the gear should slide off with little persuasion, if new gear is a little tight, warm it up a little. Slide on, reinstall pin, and you're done.

Another dirty little secret. Everything on this dist is adjustable, right? For 200 bucks, it oughta be, right? Wrong again. The vacuum advance isn't adjustable, it's fixed at about 20 deg crank.

So you set your initial lead at 12 deg, centrifugal at 20 deg, for 32 deg total. Add another 20 deg vacuum (not adjustable) and what do you have? Trouble!!!

What does MSD have to say about this? "Oh, you shouldn't be running any more than 8 - 12 deg vacuum for part throttle cruise. But...we don't make an adjustable one...sorry"

However, since the MSD is essentially a GM distributor on a Ford stalk, the pre-HEI GM adjustable vacuum advance from Accel or Crane (and another $30 at your friendly speed shop) will fix the problem. I'll let you know what, if any, hassles it was installing it tomorrow.

mike55 · #5 (**permalink**) 11-03-2001, 03:25 PM

i asked the question some time back on the shop talk forum about which distributor gear to use with my setup - tfs steel cam and msd #8582. all the replies were excellent and pretty consistant; i think the best advise came from the cam manufacturer. tfs tech stated categorically that an iron gear should be used with the cam. using two like metals was not a good idea.

i have yet to fire up the engine and see .............

mike

DavidWard · #6 (**permalink**) 11-03-2001, 04:15 PM

The determining factor here is the cam gear. You don't want both gears made from the same metal. If the cam gear is iron, then you want a steel distributor gear. If the cam gear is steel, then you want a cast iron distributor gear. The roller cams from Ford use a cast gear, so a steel distributor gear is needed. Some of the after-market cams use steel gears.

David

Jack21 · #7 (**permalink**) 11-03-2001, 05:30 PM

All,

There was a card attached to the MSD distributor that I took out of the box. I'm reading it.

It says, (and I quote):

"NOTICE
Read this card before installing this distributor.
This distributor is equipped with a cast iron gear. It should be used ONLY with a cast iron camshaft (hydraulic or solid flat tappet).
All billet steel camshafts (hydraulic roller tappet) must use a steel gear. See MSD catalog."

Questions?

Brad Pfeifer · #8 (**permalink**) 11-03-2001, 06:06 PM

Thanks for all the input guys!

Mike55 and David,

I think you got things confused on your last note. Hydraulic ROLLER cams are made from steel. Standard, or flat tappet cams are nodular iron. You cannot use an iron gear with a steel cam - the cam will chew the iron up. You can also use a bronze gear with a steel cam, the steel chews it up still, but takes smaller bites.

With the steel cam I have, I need to use a steel gear or a bronze gear. I would rather use the steel gear - as I don't want to be changing this thing out every 1000 miles.

David I think you had it right the first time. Jack21 also has the answer. Ford Racing part # M-12390-F is a steel gear, with an inside diameter of 0.531" (page 63, 2001 Catalog) Lists for $29.95.

Brad

greenwater · #9 (**permalink**) 11-03-2001, 07:05 PM

Quote:

Originally posted by Brad Pfeifer
Thanks for all the input guys!

Mike55 and David,

I think you got things confused on your last note. Hydraulic ROLLER cams are made from steel. Standard, or flat tappet cams are nodular iron. You cannot use an iron gear with a steel cam - the cam will chew the iron up. You can also use a bronze gear with a steel cam, the steel chews it up still, but takes smaller bites.

With the steel cam I have, I need to use a steel gear or a bronze gear. I would rather use the steel gear - as I don't want to be changing this thing out every 1000 miles.

David I think you had it right the first time. Jack21 also has the answer. Ford Racing part # M-12390-F is a steel gear, with an inside diameter of 0.531" (page 63, 2001 Catalog) Lists for $29.95.

Brad

Brad,

I'm relief reading this last post of yours as few posts here were getting me doubting my knowledge.....I also agree on the need of same material for the cam and distributor gears:
steel/steel,iron/iron. Mixing iron with steel would be calling for trouble.

I had bought a 12390-B (smaller diam. ) for my 289. It is listed in motorsports catalog as to be used with roller cam.

I haven't put it yet on my dist.here's why:

looking at it my machinist cannot say if this one I have is indeed steel or iron...

I've been told that the right gear (steel) should be carrying an orange touch of spray and mine has a yellow one......

To top it all I read somewhere that a steel billet lunati roller cam (like I have) can be ordered with a pressed-on cast gear.....On that I've sent lunati my grinding number and the guy answered me that cam number cannot fit my 289....oh well that's why I keept running bronze but one day I'll get that steel gear on!

Brad Pfeifer · #10 (**permalink**) 11-04-2001, 09:36 AM

Greenwater,

Greetings from California!

In looking at the 2001 Ford Racing catalog: PN M-12390-B is indeed a steel gear, but it has NO color. The application is for 302's with steel production cam's. It should work on a 289, though the application doesn't say so. (Ford didn't build a 289 roller). Sounds like your cam is in and running so it obviously does work in the 289. That may solve one problem.

PN M-12390-A is for a 289/302 flat tappet cam. It is iron, it is also orange. PN M-12390-C is a Bronze gear, colored bronze.

The gear you need is going to depend on the inside diameter of your distributor. All 289/302/351W use a 1.249" outside diameter gear. There are two different inside diameters (slides over the distributor shaft) 0.467" which are generally for the 289/302's flat or roller, and 0.531" which is for the 302/351 flat and roller cams. Consideration needs to be given to the distributor you have.

Are we all thoroughly confused now?

Brad

greenwater · #11 (**permalink**) 11-04-2001, 11:54 AM

Brad,

Thanks for the infos. Eventually when all parts are to be pasted together I should end up with the complete pict.!

I've just reread my source of infos. few filed e-mail from a seemingly knowledgeable machinist( from cal. incidently) who didn't spare is time and efforts to inform me on this subject.

The only "bogus" left as far I'm concerned is the gear (.467 diam.)I have carry a yellow stripe on its side!Altough I still have its "enveloppe" on wich one can see 12390-B printed on......

...To stir the mixture a bit more, rereading John's (cal. machinist making parts for FFRs) e-mails I am there said that the larger shaft diam. 351's gear should carry that yellow striping.....and that the 289/302 shouldn't have nothing on.....could it be someone at Motorsports goofed ? Wrong cans of spray,wrong gears, bad monday morning?....

I guess I could order another one but here in Canada once taxes,customs service,exchange, ect ect, that 29.95 ends up 105. of our dollars!

If you could tell me where one can read that the 12390-B should not carry any color marking possibly I could go back to my local ford dealer with this on hands, and eventually get an unmarked one.

Thanks.

Brad Pfeifer · #12 (**permalink**) 11-05-2001, 08:30 AM

Greenwater - and anyone else who is interested -

Go to www.fordracing.com you can order a catalog. The cost about $5 (USD), but are a good source of information.

You can also call 1-810-468-1356 which is Ford Racing Parts Technical Hotline.

Brad

scr11 · #13 (**permalink**) 11-11-2001, 07:25 PM

Guys - I need some help choosing the "correct" MSD distributor for my new 393 stroker. It comes down to either the 8578 small diameter pro-billet or the 85805 billet for a 351w with a vic jr. intake. I know I need a steel gear to match my custom hydraulic roller cam. I plan on using ford's steel gear (part # M-12390-f)as it cost about $30 vs. paying msd $60.
(Also, I'm using a 6AL and a blaster 2 coil.)
Any thoughts?
Thanks.
Scott

Jack21 · #14 (**permalink**) 11-11-2001, 08:36 PM

In addition to the above steel gear from Ford, you'll need the MSD #8478 Street Pro Billet distributor (has vacuum advance for street use), and either a Crane or Accel adjustable vacuum advance for a '57 - '72 GM points type distributor. The one that comes with the MSD is not adjustable, supplies too much advance, and will have to be replaced before installing the distributor.

scr11 · #15 (**permalink**) 11-11-2001, 08:42 PM

Jack 21 - I see the 8478 has vacuum advance while the 8578 does not. At the risk of asking a silly question, do I really need vacuum advance? The car will be 80% street and 20% race.
Thanks.
Scott

Jack21 · #16 (**permalink**) 11-11-2001, 09:58 PM

I like a vacuum advance on a street driven car for better part throttle cruise and fuel economy and have always used them. Other hot rodders leave them out and take the economy hit. Some swear there's no difference. The one with the vacuum (the one I used) comes with a lock out adapter if you don't want to use the vacuum. Little plastic piece you screw in. Your option either way.

Brad Pfeifer · #17 (**permalink**) 11-14-2001, 02:10 PM

Scott/Jack,

As noted, I have the 8578. It does not have a vacuum advance, and I did not notice any difference in drivability from when it had the stock Duraspark stuff in it. The 8578 was recommended by Mark Dove of SPF in Ohio, as what they use on the stroker motors they build.

Also recommended was about 36-38 degrees total timing.

Brad