re: Cam timing and clearances

["Tony Sims" <simstony@domain.elided>]

Norm Riffle <normriff@domain.elided> wrote:

>      Russ laid this out when he talked about his race car....A little
>more overlap for better top end.  i think this means 104 deg centers.
>(or thereabouts)
>  Tighter clearances make a bigger difference but the tighter you go the
>quicker you wear out the cams and followers.
>
>    Tony, did you note the clearances before you took the engine apart?

No Norm, I didn't check them.  I thought about it, but decided I wouldn't
really need the info later as I knew they'd be different after the head is put
back together (and I'll need to adjust them then).  I plan to keep the
clearance readings in my file for the car going forward just to be on the
lookout for stretching valves.

Are recommended clearance specs different for the 10548 cam than the 10520 my
car would have had from the factory?

Another question that I'd like to try to answer before I bolt everything back
together -- is there a visual reference to tell the difference between 9.1,
10.0 and 10.4 pistons and liners?  I.e. a part number I can see on the liner
or piston, or a notable difference in the piston crown or skirt, etc.?  With
all the other mods I'm finding on this car I figure it's worth checking to see
if it still has stock compression.  I don't have the benefit of having ever
driven a stock 2 liter, so I have no idea how this car compares.  I do know
the only other car I've owned that would light up rear tires easier was a '70
El Camino with a 396 (estimated f/r weight allocation 90/10 -- not a useful
car in the rain...).

Tony
Portland OR
74 GTV

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