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Putting New Rocker arms on?

506 Views 3 Replies 2 Participants Last post by  roadracer
I am having trouble with putting my rocker arms on. The manual says rotate the crankshaft until the tappet is on the base circle of the camshaft lobe(all the way down), whats that mean and how do i do that?

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For each cyl. on the ignition stroke at top dead center both valves should be completely
closed (the tappet is on the cam's base circle). Find TDC for cyl. number 1. At 90 deg.(damp. pulley) intervals using the motors firing order as a guide you should be able to adjust the rockers.
Read the book 10 times.

M.C.A.# 50000
There's a couple schools of thought on adjustment procedures...

Personally, I just rotate the engine (by bumping the starter) and watch the particular cylinder I'm going to adjust....I look for the exhaust valve closing and, as it does so, the intake is opening...I bump a bit more till the intake closes and then maybe a half rotation which gets it just past TDC compression....
I then adjust both valves since they are both on their base circles at this point...

Then on to the next cylinder....

When I run the valves on the race car, I just go down the line on the drivers side and passengers side without regard to firing order....this means bumping the engine a bit more but for me it's faster ( I have a bumping button mounted on the cowl at the back of the engine)...

Usually takes about 15 minutes or so to run the valves and adjust any loose ones (solid lifter cam and no stud girdle).

To answer your question, the base circle is where no lift activity is taking place and no lash nor clearance is being taken up (on solid lifter cams there is a clearance ramp in addition to the lift ramp)

The other folks here will outline the other methods for's really no biggie once you get the hang of it...

Good luck!

Edited to add: you can watch the pushrod the same way I watch the valves since you are installing your rocker arms...

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I do it the same way as Pat described. One helpful thing to do is remove the plugs so you won't be bumping the motor against compression.

I use .025" clearance when hot.
"If you're under control you're not going fast enough"
Parnelli Jones
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