At 07:49 PM 7/14/2000 -0500, Ronald Olds wrote:
>.... assembling my TD engine. .... checked timed the camshaft .... exhaust
vale is closing at TDC and the intake valve is opening at 3 degrees BTDC.
>From what I understand I would need an key with a 1 1/2 degree offset.
Or a crankshaft key with 3 degrees offset, but the cam key is easier.
>Am I correct so far? The book say if you are within 2 degrees of TDC don't
worry about it. Am I close enough?
Unless you're a real fanatic, or you put it on a dynomometer, I'd bet you
would never notice any difference. While reading the specs for my new
Crane cam I found it to say that you can retard the cam timing up to 6
degrees to move the power band farther up the rev range, or advance the cam
timing up to 6 degrees to move the power band lower in engine speed. With
your cam retarded 1.5 degrees you might find it pulls a little better at
high end, or is just a tad sluggish around town, or you more likely would
not notice anything different at all.
As the timing chain wears and stretches it will retard the cam timing a
little. Are you using a new timing chain?
>I remember a little while ago someone was looking for a source of off set
keys. Was anybody successful in finding a source and is it possible to find
one with a 1 or 2 degree offset?
Well, that was me, and no, I didn't find a source. I did find offset keys
a little larger for some American iron, but not small enough for the MG. I
finally took a crankshaft key, 5/8 dia x 3/16 thick, and milled a 1/32
notch in opposite sides to make a camshaft key 5/8 dia x 5/32 thick with
the 1/32 offset. This translates to 3 degrees of rotation of the cam
shaft. I also made an extra one for a spare. If your TD key is the same
size as my MGA key, you could borrow it for a trial, and if it works out
return it (or another one) later. This 3 degree change would move your cam
from 1.5 retardeed to 1.5 advance though. For just 1.5 degrees total
change you would need a 1/64" offset key. If it was mine I wouldn't bother
with it. Like the book says, anything up to 2 degrees is a gimme.
1958 MGA with an attitude