[V8] Hot cams, more

[sdewitt at stx.rr.com]

Mike,
Just and FYI..There is also a limit as to how high the lifter can go, if it is placed too high in the follower, then oil supply will be cut off and the lifter will fail. From what I recall even grinding the valves too much will raise the lifter to an inoperable level. I'll dig up my repair info and see if I can find the proper dimensions for what I'm going to talk about.
 

----- Original Message ----- 
From: Mike Arman <Armanmik at earthlink.net> 
Date: Wednesday, November 29, 2006 12:36 pm 
Subject: [V8] Hot cams, more 
To: v8 at audifans.com 

> 
> 
> 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! 
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