[Cliff R]

I've had some issues early on and here is what I do to prevent them.

Before installing any billet roller cam I do a visual inspection of the drive gear for the distributor. Using a small jewelers file I'll remove any sharp edges or rought spots, tooling marks, etc. Then it goes to the bead blaster and gets smoothed with ulta-fine glass beads. Another quick inspection to make sure it's baby butt smooth and it's good to go.

If you fail to do this there is a chance that you'll wipe out a BOP or polymer gear very quickly. I ran a BOP gear in my first roller cammed 455 for years and it was mint condition when removed. It went into a second 455 with a different roller cam that I didn't "prep" first and it didn't last any longer than it took me to type this.

I started using a bronze gear first after prepping the drive gears and found that they will run just about forever and show little if any wear at all. Below is a pic of my distributor from the last 455 after 10 years of hard use. Other than slight "witness" marks on the teeth it was in near perfect shape........

[25stevem]

Yup, prep of a new Cam gear is key even if it's being oiled by a galley bleed hole!

[HWYSTR455]

My last start up I used the gear that was shipped with the dizzy, ran it for 5 min, and that did the trick. Swapped to a bronze and checked at 1k miles, still was perfect. I do have the squirt hole in the galley plug.

Once I move into my new house, will build a shop, and I will get air tools and a blast cabinet.


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[Formula8]

BOP gear here. Ran in my cam on the stock gear for 10-15 mins, then swapped in the BOP gear. I just had it out this weekend and there were no signs of wear. I put the BOP gear on my Hyperspark distributor (a whole nother story) and noticed the gap on the Hyperspark with the supplied gear went from .010 to about .018 with the BOP gear. The .010 seemed entirely too tight anyway so I left it at .018. We will see how it turns out.

[HWYSTR455]

Originally Posted by Formula8

BOP gear here. Ran in my cam on the stock gear for 10-15 mins, then swapped in the BOP gear. I just had it out this weekend and there were no signs of wear. I put the BOP gear on my Hyperspark distributor (a whole nother story) and noticed the gap on the Hyperspark with the supplied gear went from .010 to about .018 with the BOP gear. The .010 seemed entirely too tight anyway so I left it at .018. We will see how it turns out.

Agreed. My Dual-Sync was .022 or so with the MSD bronze, though it was too tight still, so lightly sanded the side of gear that faces dizzy body, got it to @ .028, and left it.

Didn't want it to impact the trigger so didn't want to go too far with it. I will check it at like 25k miles, see what it looks like and go from there.


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[Bill Meyer]

Lots of good advice here. Be sure to get the right gear though as there are two sizes of distributor shafts
.491 and .500. My preference is the BOP.

[Formula8]

Originally Posted by Bill Meyer

Lots of good advice here. Be sure to get the right gear though as there are two sizes of distributor shafts
.491 and .500. My preference is the BOP.

Just FYI, if anyone is installing a Holley distributor, it uses the .500 MSD shaft size so another cost to roll in if you are converting to FI. I ended up drilling my BOP gear to .500 but if I ever want to put the stock distributor in, I will end up having to buy a new BOP .491 gear

[Schurkey]

1. Rear-end gears are tapered, and offset (Hypoid). Cam-and-distributor gears are not. Set-up on rear-end gears is critical. There is no set-up on cam-and-distributor gears aside from polishing roughness--there are no adjustment shims that affect the quality of the mesh, no bearing preload, no backlash adjustments. The entire "set-up" is dependent upon having the gears made properly and the block being machined correctly. Distributor shaft end-play does not change the gear mesh aside from where on the distributor gear the wear is positioned--and the helical angle would affect timing, slightly, requiring a small change in the distributor body position.. Anyone who thinks that rear-end gear and distributor gear meshes are similar is NUTS. Distributor shaft end-play is strictly dependent on the thermal expansion of the distributor housing. If you have enough end-play so that it's not bound-up when hot is OK, provided you don't have so many thrust shims in place that it binds-up the oil pump. In service, the helical angle of the gears, and the drag of the oil pump should cause the cam to thrust rearward, and the distributor shaft to thrust against it's thrust surface--down for Oldsmobile, up for most others.

2. I can completely agree that distributor and cam gears should be dressed/polished to achieve longest service life. In an era when new engines don't have distributors, and therefore distributors and parts are sourced primarily from offshore third-world hell-holes, assuring proper surface finish is only going to become more critical.

3. "Bronze" is an alloy of copper and tin, with other elements in the alloy depending on the mixture. (By contrast, brass is an alloy of copper and zinc.) QUALITY "Ampco 45" bronze, properly machined, is hard and long-wearing in distributor-gear applications. Cheap-shiit Chinese bronze...well...

4. Having an oil-spray directly onto the gear mesh can't hurt. Also tends to keep the oil gallery clear, instead of being a dead-end where sludge accumulates.

5. An American company, making distributor gears from quality material, is https://distributorgears.com/ .

6. The best way to avoid problems with "special" distributor gears is to have the camshaft made with a cast-iron gear. Even steel-core camshafts can have a cast-iron gear pressed onto them; which often means the rear cam journal is also cast iron. Yeah, this costs more.

[Verdoro 68]

Tangential question for you all - I just got this cam today from Butler and the gear is noticeably thinner than the Comp roller I got from Kauffmann last year. Wondering if this might be done to prevent distributor gear wear or maybe they just used a different core?

Butler:


Kauffmann:

[HWYSTR455]

It should say on the cam card if it accepts a standard dizzy gear. (or if it requires a 'soft' gear). If there's no indication of type gear required, I would suggested calling Butler to ask what kind of gear it uses.

Dizzy gears are meant to be sacrificial. (in general). So technically, you could run a softer gear on any cam. The point is, not having to replace a cam if the gear on the cam wears. (Which is much more work and cost).



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[Steve C.]

Anything made from a billet core will typically carry a part number ending in “-9” or higher.


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