Gun Jam

I seem to remember having this discussion a bit ago.

Anyhow I managed to wipe off the cam gear for the distributor.

Initially I was running a cast iron gear but switched to steel, ran one steel gear for about 2 years. It had to be replaced when it spun off the distributor shaft. The 2nd steel gear only ran for about 2 months before the cam gear gave up.

Any idea why?

This time Im going to run a composite gear.

I was running a comp 35-421-8 roller cam. Ive got the same cam on order but its out of stock it may take 10 days for them to build it. Im open to suggestions about another cam choice from comp if anyone has a suggestion. This cam ran well with my trick flow fast as cast heads (170cc intake runner and 65cc combustion chambers) and 3:80 rear end. I daily drive so fuel mileage is somewhat important.

Thanks

-Gun

69mach1377

All I know is that the gear on the distributor should be considered sacrificial as it is cheaper and easier to replace. The cam supplier should recommend the appropriate distro gear.
That being said, I've had the same one forever and don't even recall what it is made of. I might drive 2000 miles per year...

racer_dave

Another cam gear issue? Are you sure the distributor gear depth is correct? Odd to have so much trouble in one particular area.

Gun Jam

That was my thought dave...although the cam has 50,000 miles on it so its just barely not right.

They said A steal gear with melonite coating is recommended, so is bronze as well as a composite gear. The steel and composite gear should last many miles if evertyhing is okay.

Initially I ran the cam with a cast iron gear for half its life. The switched to a steel gear for the 2nd half of its life...Recently that steel gear spun off the dizzy shaft but was suspicious looking in wear marks as if it had been installed improper. (Drilled then slid on by hand so only the roll pin was supporting it) 2nd steel gear was installed and that ran for another 2 or 3 months. I had been noticing that the cam teeth looked narrower but figured it was too late to worry about.

So lets say the gear depth is wrong...how would I check for this? Gear contact patterns right? what should they look like for a ford 289 block?

drewsky

yes, we are the ones who were dealing with this last month, comp cams recommended melonized gear or a steel gear that has a softer coating on it "composite" this is the one I used part # 35200 from comp cams , weird everyone dealing with this lately, do you think it did damage to the motor at all ( debris clogging oil pump or anything?)

Gun Jam

I dont think it caused any other issues...Ill try to clear out as much debris as I can.

It says not for use on high volume high pressure oil pumps...I wonder what they consider high pressure. My system makes 65psi warm, 80 cold (until engine temps get to 170+) Thats the same oil pump ive run for the last 17 years in that engine.

drewsky

Depending on how accurate my gauge is. Mine is 70ish cold start, 60-65 when driving hot and 40-50 idle hot. So quite a bit less than yours. Believe mine is around standard heathy motor pressure

racer_dave

65psi warm would be high volume pump. They take a lot more force to turn so maybe that's increasing the wear.

Also, something I just thought of. You switched from a cast gear after running the motor 50,000 mi- The molecule transfer between the metal surfaces on the cam and distributor in that time would be pretty great. So if you then switched to a different material gear the metals/transfer may not be as compatible, creating even more wear. just a thought...

Gun Jam

So what is standard Psi? If I run that engine to 6,000 rpm for a shift are standard oil pumps going to be adequate? The flat tappet cam with cast iron gear on the dizzy ran with that oil pump for 120,000+ and looked fine when it was swapped out for the roller cam.

In addition to molecular transfer I was most concerned about non matching wear patterns. That probably didn't help either

Is 65psi going to cause rapid failure of a composite gear? Drewsky, how many miles are on your composite setup now? thats pretty similar oil pressures.

Thanks

-Gun

drewsky

only a few hundred so far, too early to tell anything yet