RE: Cam timing & wrist pin offset

[TOMAS.GUNNARSSON@eu.pnu.com (TOMAS GUNNARSSON)]

Borde inte kolvbultarna vara förskjutna i riktning med vevens rotation för
"lodrätare" kraft under arbetstakten? Då stämmer ditt antagande bra. Din kam är
nollad när veven pekar rätt upp i loppet men då är det en aning rörelse kvar
innan kolvarna når TDC.

Tomas
PS Hamnade mailet på rätt lista?
-----Original Message-----
From: Thomas Tornblom <Thomas.Tornblom@Sun.COM> at Internet-europe
Sent: den 11 april 2002 14:21
To: detomaso@detomaso.nu at Internet-Europe
Subject: Cam timing & wrist pin offset


I degreed the cam last night, and I found that the cam was advanced by about 1 -
2 degrees.

I have a new Crane hydraulic cam and a Manley true roller cam transmission.

I suspected that either the cam or the crank sprocket had a slight offset.

This morning, while driving to work, I remembered that the wrist pins on the TRW
pistons have an offset from piston center. The effect of this is that the crank
isn't at 0 degrees @ TDC of the piston.

1 degree offset @ 234mm (9.2") deck height equals 4.08mm in offset. I don't know
what the wrist pin offset is, but it was easily visible, even though I didn't
look specifically for it, so I guess it would be in that ballpark.

Is this the phenomenon I see? I can't remember which direction the pin offset
is.

Has others seen this?

The cam transmission can be advanced or retarded by 4 degrees, and the only
offset keys I've found has been for other engines.

Should I bother?

Thomas

Thomas Tornblom          Tel: +46 8 631 2100   E-mail: Thomas.Tornblom@Sun.COM
Sun Microsystems AB      Fax: +46 8 631 1102