1970 Ambo Rocker Adjustment Clearance Technical Questions.

[Tom H]

My 1970 Ambo rockers seemed a bit noisy. So I pulled the rocker covers and started on the LH side.

When I pulled the cover, the intake rocker was pushed down, but the exhaust was completely loose. So for S&G I check the clearance on the exhaust, for the moment didn't care where the piston or cam was. .008" is what my flat feeler slid in at.

I rotated the crank to put the LH at TDC. Now the same valve was only .006. I remember setting the valves to In .004" and Ex .006". With the feeler gauge, they were .004: and .006" at TDC.

I checked the RH exhaust while the LH was at TDC and got .009". Have not rotated the RH to TDC yet, I'm assuming the same approximate numbers.

So......Is this a normal thing while not at TDC  or is there a cam issue going on??

Thank you!
Tom

[chuck peterson]

Ummmm it's only useful to measure the rocker arm clearance when at TDC of the compression stroke when both valves are fully closed, and not during the rest of the four stroke cycle

Intake
Compression
Expansion
Exhaust

Suck
Squeeze
Bang
Blow

The only measurement that counts is the single moment between compression and expansion when both valves are fully closed. No other measurement is useful.

Per Guzziology on old hi mileage rockers you might have a worn spot leaving it too large a gap and noisy, easily solved by closing the gap to account for the worn rocker, or replacement.

This led to the hammer and anvil sound reputation for older guzzi......

[Antietam Classic Cycle]

Per Guzziology on old hi mileage rockers you might have a worn spot leaving it too large a gap and noisy, easily solved by closing the gap to account for the worn rocker, or replacement.

Or just reface the worn rocker tip...

.004" and .006" clearances? I sure wouldn't.

[guzzisteve]

What happened to .006" & .010" ?  It's in every book I seen. If you have notched rocker faces I use a wire gauge, problem solved.

[Tom H]

Thanks guys. Again the first check was for S&G only. Though I did think that the non opening section of the cam lobe would give the same clearance until you started up the ramp for the lift.

I have tried the .006 and .009 or .010 per the book on both Loops. Never ran right and sounded like a jackhammer working under the covers and felt down on power. I use to run .003 and .005 for many years, tried .005 and .007, .004 and .006 seems to make the bikes run good.

Maybe due to wear and using a flat feeler gauge, I may have more clearance than I think? When I need to pull the rocker assy, I'll check the rockers and valve tips for wear. I have had valves that had the wear line on them.

Thanks again!
Tom