brain teaser

r550s · Post by **r550s** » Tue Mar 20, 2007 10:06 pm

anyway.... if I've skimmed 0.5mm off the heads, how much has it altered the cam timing? (in crankshaft degrees). As a clue, the cam sproket is 17t @ 8mm pitch. I think I know, but a second opinion would be welcome ( and a third, and a fourth...)

Archie · Post by **Archie** » Wed Mar 21, 2007 10:15 am

According to my rough calculations it will retard the timing by about 1.3 degrees.

It's not going to help performance. You'll need to look at slotted cam sprockets, or waisted bolts, to get that back (plus a bit more?)

gus · Post by **gus** » Wed Mar 21, 2007 7:48 pm

Archie is way out with his calculations and is somewhat misleading you.

I make it 1.399 degrees retarded(bit like me then

).There will be a slight power loss of 0.754 at revolutions 2500 - 4500.This would be acceptable as the extra compression will add 0.996 from 4500 to the rev limiter.
OR
You could try drinking BANK,S!

GUS

r550s · Post by **r550s** » Wed Mar 21, 2007 9:43 pm

oh well, I got it to about 2.5 crankshaft degrees (crank = twice cam degrees) thanks archie. Now where's the Banks?

Archie · Post by **Archie** » Wed Mar 21, 2007 11:59 pm

Now if you took 5mm off the heads then you could simply shift the chain by 1 link. and hence get the cam timing advanced by 3 degrees.

With a compression of 22.3:1 it would then go like stink - for about 68.5 degrees, at which point the piston hits the head.

r550s · Post by **r550s** » Thu Mar 22, 2007 6:40 am

wow! d'you think I'd need octane booster?