Tweaking a G80...

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Re: Tweaking a G80...

Postby cfaber » Thu Nov 30, 2017 4:31 am

so here's a question, if I recall correctly the manual states zero cold clearance when adjusting the push rods, am I mis-remembering or is this actually the case? And if so, has anyone found a better spacing? 0.005 maybe on the intake and 0.010 on the exhaust? Wouldn't that reduce the clack a lot?

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Re: Tweaking a G80...

Postby zwarts » Thu Nov 30, 2017 5:05 pm

cfaber wrote:so here's a question, if I recall correctly the manual states zero cold clearance when adjusting the push rods, am I mis-remembering or is this actually the case? And if so, has anyone found a better spacing? 0.005 maybe on the intake and 0.010 on the exhaust? Wouldn't that reduce the clack a lot?


In a word - NO! A wider tappet clearance will increase the 'clack'. When they were new, our beloved AMC singles were renowned for their mechanical quietness, this with the zero cold tappet clearance. Excessive clack can be due to many causes including accumulated wear in the valve train. Careful assessment of wear during the engine rebuild will minimise the problem.

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Re: Tweaking a G80...

Postby StephenG80 » Sat Dec 02, 2017 10:10 pm

one final question :roll: :shock:

Is it recommended to fit both H intake cam AND the smaller rocker arm from the G2 or G5 and re-time to the 350 markings, OR just to do either the cam or the arm and re-time to 350 markings? Would the former give too much lift?

If I change the intake cam to H, is it essential that I also change the exhaust cam to H or can I leave that as a standard SS cam without losing much performance?

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