mismatched tooth pattern on new cam

simon

simon

Famous Member
question: how can a slightly mismatched tooth pattern on a camshaft be corrected?

When fitted dry, there is some binding between the camshaft and the distributor gear. I've double checked with both used and NOS dizzy gears, and with both the old FoMoCo camshaft and the new ClaySmith grind. It only binds with the new cam.

Other than a hand crafted oil spray bar and replacing worn distributor gears until its all settled, what can be done?

Nitriding the f*** out of both gears and praying that increased surface hardness will take care for everything seems a bit, err, ignorant.

Also, there is absolutely NO company or service here that will even think of touching a set of gears. Already had a pretty hasrd time locating a business that will do some salt bath nitriding on small scale orders.
 
The outlook is not good.

This is exactly what I've been "thumping the tub" about for over a year now. It seems everyone is grinding off the same billets, and the drive helix is simply wrong. :x

I've been told that nitriding the drive helix is inadvisable; this comment came from a bunch of guys doing radical stuff with Renault camshafts for Gordini racers. Apparently it becomes a battle of hardnesses between the distributor gear and the helix, with both ultimately becoming fatally damaged.

The solutions as I see it, are use of a reground cam, or getting a billeted gear made up. The only people I can see making one (off the top of my head) would be Sainty Speed Works. Wouldn't be at all cheap...
 
I finally found the time to dig up my old 250 Ford cam and compare it to the clay smith grind. The drive helix on the ford camshaft is much wider and supports the driven gear of the distributor way better. On the new aftermarket cam, the drive helix has been narrowed by about one third.

I believe there isn't anything wrong with the geometry of the clay-smith grind's drive gear; it just ain't wide enough to fully catch the teeth of the dizzy gear.

Consequently, the load is applied unevenly, which leads to uneven wear.

the pictures of wsa111's failed dizzy gear fit this theory nicely.
 
I also had 2 dizzy gears eaten up by a Competition Cam 260 that apparently was the wrong helix. Also broke pieces off the cam gear, ruined it in 1500 miles, I could not figure out what was eating them up. Sad to say, but the clifford cam 264, I bought seems to be a better fit than any other I have. I just purchased a Clay smith from Classic and hope that they line up better when I install them. I bought a couple of original Dizzys off Ebay to utilize the original gears.
 
Yes, for me, the question is what are implications of this for the cams from Mike, and the stock Duraspark dizzy gear? How does one check this before installing a new cam with an old distibutor?
 
Simon
Do you still have the cam out of the engine?
On one of the ends is there a six digit number like 509306 or something like that?
 
simon":w2d08o4r said:
the only numbers on the old cam are 9 and OB, nothing else.

Is it a Ford cam after all?
Click to expand...

Don't know if about it being a ford cam. IF it had the number I was asking about it would have traced it back to a unfinished cam blank from a larger cam company.
 
I sense crossed wires. Simon, were you quoting the numbers from the OEM camshaft?
 
yup.

that is, IF its an OEM camshaft. It has no Ford or FoMoCo logos, and no date codes either... but then again, I don't know if it even should.
 
No other numbers on the unit? That's odd. I'm familiar with the theory of generic codes like Jim mentions - seen them here on stuff.
 
Wow, you guys are very intelligent. Good work Simon and Addo!

Crow cams in Australia had a similar issue, and in a world were there a likely to be more than 10 million potential Ford I6 customers, the supplier of the camshaft core needs to be factory spec of better to do the job. American cam grinders are the best in the world, and they just need a good core to work with.

Any Ford US cam will have a basic part number '6250' stamped on it.

Basically, the supplier of the core unit is hurting sucess of Clay Smith and other cam grinders, and I'd trust the supplier to take your recomendations, and help you out.

Everyone wants to solve the problem. Use due process and complain politely to the supplier, listing every morsel of info.

Cam regrinds are NOT the answer to the key problem you have identified, Simon. Cam regrinds have issues with base circle reduction. In order to get the right lobe centre displacement, lift and duration, the ramps, base circle and advance and retard have to be established, and then the whole shooting match ground down to suit. That influences pushrod and lifter geometery and introduces a raft of other problems to a cam which is already potentially 25 to 47 years old .
 
I've seen plenty of OEM Ford parts without the part numbers on them.

Also I don't agree on regrinds being unsuitable for hard usage. Even adding 100 thou extra valve lift, barely takes 75 thou off the base circle. You get inaccuracies approaching this, with valve seat sinking or stem tip grinding.
 
addo":38j3giju said:
I've seen plenty of OEM Ford parts without the part numbers on them.

Also I don't agree on regrinds being unsuitable for hard usage. Even adding 100 thou extra valve lift, barely takes 75 thou off the base circle. You get inaccuracies approaching this, with valve seat sinking or stem tip grinding.
Click to expand...

8) i dont think dean was saying that reground cams were unsuitable for hard use, rather he was pointing out the issues that need to be addressed when using a reground cam. hte biggest of which is getting the rocker arm geometry right. while one regrinder might take .075 off the base circle, another might take only .050 or even .100 off the base circle, and if the proper length pushrods are not supplied, it reall throws off the rocker arm geometry.

i also like the idea of contacting clay smith and letting them know of any and all problems so that they can cure them as needed,
 
The problem is not with the base circle of the lobe.....
It is the incompentance of the after market using mickymouse engineers who market the billets to the grinders.

The problems not are only with the cores available but the total lack of engineering follow up by the camshaft grinders.

The driven gears were designed for a stock type camshaft from the factory & are designed for that purpose.

The grinders need to step up & offer the correct hardness of the driven gear such as crow cams did in AU, & or correct the incorrect marriage of the 2 gears.

I can correct the problem real fast & put a 347" legged 302 in place of the botched up 200" six.

Simon & i are sick of this aftermarket junk being offered.

I'm tired of doing the engineering work at my expense, Bill :evil:
 
There is an article on slantsix.org where a similar problem is being addressed: gear failure on the cam-driven oil pump.

I think that might have been posted here before, it brought up the idea of nitriding the gear and to fabricate an oil spray nozzle on my own engine.

link

There is a company nearby that also does industrial teflon coating for engine parts, nothing like slick50, the parts are actually treated to a heat induced sintering process on the surface. Although coatings like that are merely intended for increased startup protection I just might give them a call. Its been reported that, while the majority of the coating will wear off eventually, enough particles will stay embedded in the parent material.

Still, it remains questionable if hardening and coating the gears, modification of the oil pump pressure relief valve, and an oil spray nozzle aimed at the contact area will address the problem sufficiently.
 
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