45 Cam Timing

[Rex]

Another timing issue has occured.
With Indiannut's help concerning the TDC determination, I ran through the valve action vs. piston position measurements. Both front valves and the rear intake valve opened and closed at exactly the right time.

The rear exhaust valve opens and closes when the piston is 5/8"
farther into the bore than is should be. I took the cam case off and found the rear exhaust cam mark almost but not quite lined up with the mark on the rear intake cam. All other marks look good, except the breather hole is behind it's notch.

I also found the front exhaust cam inner spacer to be a chewed out home made washer, and no spacers in the case cover for the front cams as specified in the manuals.

Any advice except shifting of the cam and breather?

Upon further investigation, the breather hole is exactly 180 degrees away from it's notch when the flywheel timing mark is centered in it's hole.

[Rub]

Do you know if you have early(one piece) or later(pressed on gear) type cams? I have run into issues where the gear has actually shifted on the cam making timing impossible. Also the breather gear should line up in the notch when the pinion gear is spaced out 5/16 of an inch from the face of the case. If it is pushed all the way in it won't allow the hole to line up in the notch. There should not be spacers on the cams, only shims which are used to set side play on the cams. They only come in .006 (6 thousandths) thickness. Something the thickness of a washer indicates a problem somewhere! Use a Harley-Davidson factory manual and not a military one for the correct sequence and specs. Good luck! Robbie

[Rex]

Rub-

Thanks for the heads up about the details. Every little bit helps.

Cams 1 and 3 are one piece, 2 and 4 are pressed. Since all the other valve positions except the rear exhaust were right, it doesn't seem like I've got a slipped gear.

The spacer I refered to is actually a shim of .030" thickness. Poor choice of word on my part. It looks like the builder filed out the i.d. to fit this application. The manuals indicate that there should be outboard shims on the front 2 cams, but I didn't find any, and this may be the reason for the thickness. I've got a full set of new shims on the way with gaskets for the cam cover and scavenger pump.

I made a timing chart showing the piston and valve positions, and saw that the rear exhaust was consistently late by @ 5/8" of piston travel. advancing it's cam by one tooth corrected that problem. I'll include this chart in a future post.

When I first mentioned the breather timing position, I was looking at it when all the cam timing marks were in alignment, which apears to be what the buider did. This put the breather timing hole @ half way out of it's notch.

When I realized the manuals showed that the breather is to be timed using the flywheel timing mark, I checked it again and found it to be exactly 180 degrees off. The pinion gear's outside face was 5/16" out from the timing chest gasket surface at the time of measurement. In fact it was just a little stuck a the that position, but is a free slip fit now.

Again, thanks for the info, and more is always welcome.

Rex

[AdminGuy]

I believe cams being marked wrong is a common problem. Good on you for checking. Repunch and a little white dot of paint maybe. Now for you to get into your advance on the distributor.

[Rex]

Thanks for the support, A.G.

I felt reasonably confident setting the circuit breaker using the front piston position and flywheel timing mark after indianut set me straight about the TDC vs. cylinder top issue.

I was ready to call it all good and put the heads back on when I remembered seeing a description of piston position & valve action in a manual. That combined with Cotten's voice in my head saying "Leave No Stone Unturned" lead me to check all those points. I think that rule is number 2, closely behind "Pressure Test The Intake System".

Anyway, that's when I found the cam error, leading to the much dreaded removal of the gearcase cover and contents.

Last winter before the first test run I checked the timing with the flywheel mark and found it to be correct. The mark on the circuit breaker band wasn't lined up with it's mark on the breaker head, but it will be now.

Again, if anyone has any thoughts on that aspect, let me know.

Rex