Ironhead Harley Davidson Sportster Ironhead 1973 XLCH - XLH - P Cam Gear Wrongly Marked

[XLXLXL]

Harley Davidson Sportster Ironhead 1973 XLCH - XLH - P Cam Gear #3 Wrongly Marked.

Mine has this flaw from the factory, which made me really in the depressing moment. It is written in the Clymer, but wasn't clear which # of the gear.

So I posted here to make a comparison for those who have a similar items for cam gear #3 of P cams. Hope this helps.

Here is the video to help you understand this


the blue marker is aligned with top cam lobe
the white mark is the correct ones

https://youtube.com/shorts/42CyAinCWr0

[DDDDylan]

You said it is written in the Clymer... I have Clymer M419 and I see on page 124 they mention some early 1980 models have incorrectly marked cams, I believe this is also in TSB M-757. Is this to what you are referring? I don't see anything mentioned about older models like your 1973.

[bustert]

yes, it is true
my 1974ch had twin marks.

[XLXLXL]

Originally Posted by DDDDylan

You said it is written in the Clymer... I have Clymer M419 and I see on page 124 they mention some early 1980 models have incorrectly marked cams, I believe this is also in TSB M-757. Is this to what you are referring? I don't see anything mentioned about older models like your 1973.

Yes, mine is Clymer M419, when I read that one for the 1980, I then suspicious to what I have in my 1973. Apparently, it is wrongly marked as well. Good for Clymer to update theirs.

Originally Posted by bustert

yes, it is true
my 1974ch had twin marks.

Now I'm getting suspicious to all cam gears on this one.

[needspeed]

How did you determine that the marks were wrong?

If #4 cam is marked correctly its timing will be wrong because it is lined up with #3 that is marked wrong?


^^
No, I think I've got that wrong. If the 2 marks on #3 are spaced the right amount to each other, the gear tooth relationship of #4 to #2 will be correct and #4 will be timed right, but the #3 lobe will be out of position.

[bustert]

actually, the machine ran but was wayyyyy off, no power or throttle response.

[needspeed]

If I've got this figured right the #3 error retards the front cylinder intake valve timing roughly 90 crankshaft degrees. So if the P cam intake normally closes at 40° ABC, yours would stay open to about 130° ABC (or 50° before top dead center).

The front compression stroke would be almost over before the intake closed.

I'm curious. Did you ever do a compression test? It seems the late closing of the intake wouldn't give the piston on its way up a chance to compress much of the charge.

[XLXLXL]

Originally Posted by needspeed

How did you determine that the marks were wrong?

If #4 cam is marked correctly its timing will be wrong because it is lined up with #3 that is marked wrong?


^^
No, I think I've got that wrong. If the 2 marks on #3 are spaced the right amount to each other, the gear tooth relationship of #4 to #2 will be correct and #4 will be timed right, but the #3 lobe will be out of position.

I just think simple, when the push rod doesn't go up and down like in order, we realize something wasn't correct. But initially we are thinking about pushrod is bent, etc etc. Until a friend came for help, offering stock cam gears that came off from proper running bike

Originally Posted by bustert

actually, the machine ran but was wayyyyy off, no power or throttle response.

exactly, it ran, but not nicely. The machine coughing, and after running several minutes 2k-4k rpms, machine start falling stalling...

Originally Posted by needspeed

If I've got this figured right the #3 error retards the front cylinder intake valve timing roughly 90 crankshaft degrees. So if the P cam intake normally closes at 40° ABC, yours would stay open to about 130° ABC (or 50° before top dead center).

The front compression stroke would be almost over before the intake closed.

I'm curious. Did you ever do a compression test? It seems the late closing of the intake wouldn't give the piston on its way up a chance to compress much of the charge.

yeah, you are right. we should have done the compression test in the beginning.