Sorry to be short before, I was rushed for time. But the main thing is that
I need to apologise 'cause I missed that you have a 1500 engine. But if the
manual calls for timing marks to be used on the chain sprockets, then using
the keyways is probably not accurate enough because you could easily be a
tooth or two out on the cam sprocket. so, how to do it right. Is the new
sprocket set that you have adjustable? If it is, then it probably isn't set
to the same stock relationship of teeth to keyway as the stock pulley is.
so you could be a half tooth off, so to speak, even if you were pretty
accurate in translating the keyway setup as you described.
To time the cam, you need the big round protractor that came with your kit,
and a dial indicator on a magnetic stand. you find top dead center on #1
piston, set the protractor to zero with an indicator that you make out of a
piece of wire, and then you put the dial indicator on the pushrod for #1
intake valve. Rotate the engine forward about 90 deg, and the pushrod will
start to rise. Note the point at which the pushrod is highest, and that's
maximum lift. Max lift should be about 100 to 110 deg after top dead
center, depending on your cam specs. If it's out by about 5 - 6 Deg, you
can try hopping one tooth on the cam sprocket. If it's out just a bit, then
you can adjust if it's an adjustable sprocket, or you can get off-set keys
to move the sprocket just a bit as it locks onto the cam.
The reason you need to check with an after market cam is that they grind the
hot cam from a stock cam, and to get the increased duration they may move
the lobe centers around a bit. So the original timing on the stock cam
might have been 110 deg, but the lobe center on the modified cam ends up at
105 deg in relation to the keyway. But the cam may need to be timed at 110
deg again, so you need to adjust for the 5 deg discrepancy. That's just a
fact of life when working with re-ground cams, and since hot cams ground
from new blanks are way expensive, that's what we all tend to get. That's
also why the valve clearance was out - to get the increased lift for the new
cam, they ground down the base circle, which is where the valve clearance is
measured.
But you can check for exhaust valve clearance if the engine is together.
Set the engine to about 5 deg ATDC, as the exhast valve is closing. The
piston chases the valve up the bore, and is closest at about 5 deg after top
dead center, as memory serves.
Get back to me if I can help in any way.
Brian
At 01:44 PM 2/3/98 -0500, you wrote:
>Well of course I want to do the timing right. Between the shop manual
>and the Haynes I did the best I could.
>
>If you have a suggestion of how to do the job right, by all means let it
>fly. I want my cam timed correctly.
>
>I adjusted the valve clearances on all 8 valves to .25mm as Haynes
>specified. They were all too large because of the new cam.
>
>eric
>
>-- ___
> __.o,\____ * Eric Mumford * ('v') -> BA-KUK!
>/__ \ / _ ) * mumford@rpi.edu * (( ))
> (+)`---(+) * http://travolta.stu.rpi.edu * --"---"--o
>
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