Chain Slop

Thought perhaps someone here knows; I'm indexing cams on a 20vt setup, I've got 7a ex cam, w/adjustable gear and 3b in cam w/adjustable gear. Adjustable cam gear on the intake does not have timing marks for TDC (which should open at 3deg BTDC). So I'm indexing with a degree wheel, got the dial indicator extension such that it is accurate - however, what I'm running into is chain slop - do I set timing based on no slop, a taught chain? or ignore and set based on whatever sag is in the chain as I manually turn the motor?

Neither - you take out the cams, measure the run out of the gears, throw away the bad one and get a replacement, then get a new timing chain, and mount it all up nice and proper.

Why do I know? 'Cause my 16V had the same problem with two adjustable gears, and I had valves (french) kissing the pistons due to lack of precision in the timing.

Do it right, do it light - do it wrong, do it long...

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Brgrds
Brian

Holy Cow!!

I had a new chain on the shelf - you could see the stretch in a side-by-side comparison - then installed a whole new scenario - nice an tight.

Have not started indexing again, but wow - I'll never build a head without checking that part again - let alone the whole motor.

I could literally measure 9degrees of slop on the timing wheel before the new chain...first time doing this cam indexing thing - so pardon the educational euphoria

Mine was really tough... what with one camshaft and all.

Quote
aj_johnson
Mine was really tough... what with one camshaft and all.

Didya finally get it ibn the end?

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
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Just started it an hour or two ago. Feels snappier- loads too much fuel as I reverted back to initial mapping.