[V8] Hot cams, more

[Mike Arman]

Had a lengthy discussion with the guy at Crane . . .

Seems if we are only increasing the lift by fractions of a millimeter, 
we are NOT going to need follower buckets. Keep that $500 in your pockets.

Depending on the pre-load of the stock parts, we may or may not need 
valve stem caps, and a set of these, depending on size, might cost from 
a guesstimated low of $40 (for 32) up to perhaps $80 (same) which sure 
beats the heck out of $500.

So it seems if we can do some calculations, we can get hot-rod cams for 
the Audi V8 in the $500 range for a set of four cams and the stem tips 
(if we need them).

Here is what he needs:

We need to know the preload of the cam follower on an assembled engine. 
They way we get this is with a dis-assembled engine.

1) Remove cam, remove one or two cam followers.

2) Measure distance between base circle of cam and tip of valve stem.

3) Measure distance on cam follower between top surface (what the cam 
bears on) and the inside surface that contacts the valve stem.

4) Subtract 3 from 2. This will determine the preload on the cam follower.

Example: Distance from cam base circle to stem = .300", thickness of 
removed follower (surface to stem contact area) = .325", follower 
preload thus equals .025".


Speaking in generalities, if the cam follower has .040" of possible 
travel, and the result of the above math exercise is .020", we'll know 
the follower is loaded to the middle of its travel.

If we wish to increase the lift on the intake valve by .4 mm and keep 
this same preload, since 1 mm = .04", we'll want a .016" stem cap.

On the exhaust valves, the lift is increased by .2 mm, or .008", so the 
shim cap for the exhaust is .008".

As you see, we need to measure this - anyone got an engine apart enough 
to try it?

Once I have these figures, I'm going to take a ride over and see these 
guys - they are 15 minutes away from me.

He also mentions that turnaround time is about a week right now, things 
are slow. Come February, it will be another story . . . all the racers 
are in town.

OK, group, someone break out some feeler gauges, calipers and a 
micrometer! He cautions us to measure CAREFULLY!

Best Regards,

Mike Arman
V8Q, awaiting another ?? hp for about $500 - or less!