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Location:
Brisbane
Registered:
October 2002
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cam timing experts please
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Mon, 31 January 2005 09:18
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ok, just put my head back on, its as below.
with the cam sheet i got with my cams, it says u have to set up the buckets with X amount of lift at TDC
in: .81" at TDC
ex: .125" at TDC
now, these are just base circle grinds, so thay havent welded them up and moved the lobe, when i first put the head back on back 6 months ago, i set he cams up to standard spots {slits on top of the cams vertical}.
now when i set them up to the specs they tell me, they slats are sittin at 10 and 2 {if u are standing at the front of the shitbox}, approx 45 degs.
that didnt work, valves hit, now i have tried to reset them up, but the exh is at like 12:15 and the intake is at 11:15, it will barely idle and when i try to drive it it has an odd noise {like a hollow noise} coming from the carbs, it'll rev, but makes no extra power as u rev it,
does this make sense to u, what could it be.
exacly wha does advancing or retarding the intake or exhaust cam actually do,
eg, retarding exhause make the power band higher ect ect
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Location:
Tasmania
Registered:
May 2002
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Re: cam timing experts please
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Mon, 31 January 2005 10:40
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I think you should forget those setting and time it properly.
Borrow a degree wheel, dial gauge and stand.
Put the degree wheel on the crank pully, take the spark plugs out. Search the net for more instructions. Find TDC (not always exaclty where the mark on the crank is). Find TDC with the dial gauge down the spark plug hole, or there are other ways.
Then put the dial gauge on no.1 intake bucket if you can (not easy I know). Note the opening and closing times for that valve, at any given setting. Then find where the middle of those opening and closing times are. This is the lobe center. The do some maths and adjust things so the lobe center is about 105 degrees from TDC. Do the same for exhaust. 110 degrees is a more conservative setting, 100 degrees is more a wilder max power setting for high rpm.
Get the valve clearances right first before you do any of this. And be carefull not to have the 2 cams miss times too badly at any one time, or the valve will hit things!!!! Observe the factory manual for setting valve clearances!!!!
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: cam timing experts please
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Mon, 31 January 2005 14:46
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at TDC the exhaust will be almost closed and the intake will be just opening, both an identical amount if their lash/gap is the same.
split overlap. this timing will work & run pretty well, if not the best, and then you can fool around with a little + & - on each one to see the effect.
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