Install and Time Cam Gears Harley 45 Flathead
Text and Pictures by Mark Trotta
Intake and exhaust valves, crankcase breather, timer, oil pump and generator all depend on proper cam timing to work correctly.
Four Cams!
There are four different Harley 45 cams. They will be stamped 'W' 'G' or 'GE' with numbers after them (1 2 3 4).
The "G" cams for Servi-cars (models G and GE) are marked 1G, 2G, 3G and 4G. The early 2G cam, part# 25502-37, was used through 1958. The late 2G cam, part# 25502-59, was used 1959 through 1973.
Early and Late Cam Covers
There is an early style cam cover (up to 1958) and a late style cover (1959 and up) for Harley 45 engines. When the cam cover changed, so did the #2 (rear intake) cam.
You can use the early #2 cam with any early cam cover, or you can use the late #2 cam with any late cam cover.
Check For Binding (Test #1)
Before installing cams in chest:
Lay cam cover flat so the inside faces up. With a little motor oil on the cam teeth, stand the cams upright in the bushings.
Turn slowly. Listen and feel for any binding. If there is any, stop and find out why.
Install Cam Gears
Turn flywheel assembly slowly until you see the flywheel mark in the timing window.
Next, slide on the pinion gear. It can only go on one way.
Align all cam timing marks off the pinion gear mark. The cams are aligned to each other by lining up the notches on the outer face.
Starting at the flywheel mark, install the cams in this order: rear exhaust, front intake, rear intake, and front exhaust.
The notches on the cams won't always line up exactly--that's how they are.
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During engine assembly, you will be installing and removing the cam cover several times. The cover should go on with little or no effort. Only if necessary, tap the cover on carefully with a soft mallet.
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Check Binding (Test #2)
Temporarily install the cam cover with a gasket. The gasket is part of the end play you'll be checking later on.
Once the cam cover is on, install three or four bolts only. With the motor standing upright, slowly rotate the flywheel assembly.
If all is well, remove the cam cover, install the idler gear and generator, and check again for any binding.
By doing this in two steps, you can isolate what is causing any potential binding.
After they've all rotated together a few times, it's a good idea to re-check the cam alignment marks.
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Check Cam End Play
If no binding is felt, cam end clearance can now be checked. With the cam cover on and tightened down, but with tappets not yet installed, slide a feeler gauge down into the open tappet-block hole.
I prefer to check cam end play without shims first, write down the measurements, then add shims as needed. Acceptable cam end play is .001" to .005".
Most Harley 45 engines left the factory with one steel shim washer behind each cam, but some cams may require none, while others may require two. Hopefully you took notice of this during the disassembly process. The shims are installed behind the cams.
When you're ready to button up the gear case, lay the engine on it's left side, take off the cover once more, and pour about a 1/4 pint of engine oil all over the cams for lubrication. Install the cam cover with gasket using a non-hardening sealant. Install and tighten all cam cover bolts.
Tip: If the motor won't be started for awhile, liberally coat the cams with an assembly lube.
Cam timing is critical to a good running engine. Double-check your work before continuing.
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