Distributor Gear

[BOBOCobra]

All, Last year I did the conversion on my 521 crate from a solid roller to a hydraulic roller and have been pleased. However, I ate thru the brass distributor gear in about 1000 miles. installed a comp cam (I don't have the specs with me but nothing out of ordinary) and I am running the HV oil pump. I am wondering if that is what is eating the gear. Prior to cam change I changed out after 2500 miles and still had some room. Ideas?

[spdbrake]

The 1000 miles is not that extreme on the wear out. My last gear was knife edged at 950 miles giving me lots-o-timing backlash...
Since mine is a Billet solid roller from Comp Cams I'm stuck with Bronze or Composite. My next one may well be the Comp Cams Composite gear @ $115 VS $50 Bronze. Not like they're hard to change though.
I'd call Comp with your new Cam PN & get their recommendation on the gear you should run.

[Dar73]

Your current gear is probably bronze. The little I know about gear mating to the cam, I don't think you could go wrong with a Composite gear, I believe that is what Comp would recommend, otherwise a hardened steel gear would hold up better than the bronze.

[blykins]

You wore the bronze gear out quickly because bronze gears don't belong in street cars.

Billet steel camshafts should get nothing but steel distributor gears.

Cast iron camshafts should get nothing but cast iron distributor gears.

No polymer. No composite.

If you can't find a steel gear for a steel camshaft, get a hold of me. That's what belongs on it and I have them. Just because Comp Cams doesn't carry them doesn't mean they don't exist.....they are around $65.

[BOBOCobra]

Isn't the whole idea behind a bronze gear is that it wears the dist gear and not the cam gear and you don't have bits of iron or steel floating around in the lower end? My concern is if the chews up the bronze gear that fast how long before I have to pull the cam if I put a hardened dist gear in there?

[blykins]

You won't.

The bronze gears are too soft in comparison to the billet core camshafts.

Always make sure that the gear is located in the correct spot on the distributor shaft (there's a spec for it), but this is *normal* behavior for a bronze gear.

Stick a steel gear on it and watch it go for miles....and miles....and miles....and miles..........

[keezling]

(hint) HV oil pump+inadequate bearing clearance will wipe out distributor gears pronto as well...

[LG57]

Listen to Blykins advise. This is an on going question across several engine forums. The steel gear for a steel cam is the correct thing to do. You won't have to worry about metal bits flying around in the engine because there won't be any if the gear is installed to the correct dimension on the distributor shaft.

[Gaz64]

That's why transmissions run steel gears, how long would a bronze gear last in there?

I learn't the hard way once, no bronze ever again for me.

Gary

[BOBOCobra]

Thanks for the input and I do listen to Blykins, he is why I decided to change my cam in the first place and had good feedback for me. My concern was the "lack" of direct oiling of the gear and in my pea brain if I'm eating bronze gears then steel is just buying more time, but still eating metal. I do have very good oil pressure, 65-70 at cruise, 40 at idle, and I had read somewhere that the higher pressures will eat gears. I put the bronze back in but will pull later this year and look at it.

[blykins]

Couple of things to mention to help with distributor gear life:

1. Gear material must match cam material.
2. Gear must be installed to spec on shaft. There is a Ford spec, and there is an MSD spec and it depends on if the thrust clearance is taken out of the gear before measuring on which one you use. If this spec is not held when installing a new gear, you will have wear.
3. You absolutely can not just put a new gear back in the same spot so that the pin holes line up and call it good. Different gears will have different dowel pin holes. You have to measure each and every time and if necessary, drill another hole.

I don't have distributor wear issues, even with a high volume/high pressure oil pump and whatever bearing clearances I'm running at the time.

[Paul Kane]

1. On the 385 Series engine, the builder must set proper Distributor Thrust Boss Clearance. If not set correctly you will either be A) chewing up the block and/or distributor and cam gear, or, B) you will be shearing distributor gear pins. I’ve posted extensive details about this on countless discussion forums and it blows my mind how many engine builders are unfamiliar with this critical setting. Use Google and do a search for details and charts.

2. The bronze gear is an intended wear item. Welcome to the world of high performance/high maintenance engines—accept the necessary maintenance and live with it. Better the dizzy gear than the cam gear.

3. I have customers whom have executed the High Flow Dynamics Distributor Gear Oiling Mod, and they claim over 25,000 miles on their bronze gears (your results may vary). It’s very safe to assume their Distributor Thrust Boss Clearance is spot-on as well.

4. HV pumps do not prematurely wear distributor gears, nor do they “pump the pan dry.” Both erroneous beliefs are regurgitated internet rhetoric from “internet engine builders.” Fact is the oil flow pumping rate through these engines is primarily dictated by the bleed-off rate (ie, clearances) in the engine itself. Further, both the standard volume and high volume Melling pumps use the exact same bypass spring (ie, same bypass pressure/and therefore basically the same drive load). Therefore, the HV pump moves essentially no more engine oil through a given engine but simply bypasses more oil (and thereby has more oil available should engine vitals require more oil for some reason).