Progress report..and a cam timing question

[Ho Hum 74]

Well after all my parts issues I'm getting closer. This weekend I got on the cylinders, heads, timed the cams and started sealing things up.

The cam timing was...interesting. I needed 4.5mm valve movement at overlapping TDC. I got 4.572mm on the left and 4.5974 on the right. My thoughts are that with the backlash and the fact that you cannot get the dial gauge entirely parallel to the valve that these #s should be within acceptable range. I have a modified S cam that needed to be set at 4.5mm. What are your thoughts? Will I be OK?




2.7 MFI with 9.8:1 JE

[dtw]

Most cam specs I've read appear to give .1 - .2 mm of slack in either direction. In this case, being off around .1mm on each side should be fine. Of greater importance is getting both sides the same. Looks like you are fine on this count too.

I've had pretty good luck getting the dial gauge parallel to the seat - how far off were you? This should be pretty darn close to parallel if not right on it.

That motor looks very nice! Thanks for the pic.

[Ho Hum 74]

Dave,

Thanks for the kind words and encouragement. What I meant was that I wasn't sure that I could repeat the alignment of the dial gauge every time but I think I'm pretty close. Definitely a 2 man job though. I got a neighbour over to hold the cam steady while I torqued the nut. I have a few grazed knuckles to prove it

Cheers,

Tristan

[camgrinder]

Your numbers are within .001" of each other and within .003" of the spec for the Mod-S cams. You are less than a 1/2 degree off of spec.
The higher the lift at overlap the more advanced the cam is.
Sounds good to me.

[Wayne 962]

Seems fine to me!

-Wayne

[Ho Hum 74]

Thanks John. I have your Modified S-cam grind which, by the way, makes the motor just a whole lot more flexible. Can you explain what the mod does and how it differs from the stock S-cam?

Tristan

[camgrinder]

The Factory early S cam has closer lobe centers than the Mod-S cam. By speading the lobe centers widen the power band.
The lobes we use also have more valve lift. This increases cylinder filling without having to add a lot of duration. This cam always gains both in torque and HP.
I have also been grinding a lot Solex cams on 102 lobe centers and have been getting good feedback on those as well.