What's Your Head Volume?

[ChrisBennet]

Tom,
With the heads shaved you should check the chainboxes and chain slack.
The chain boxes may need material removed from the sealing surface to recenter the cams in the chainbox hole for example.
-Chris

[tom1394racing]

Chris

Thanks for the advice. The chains seemed pretty tight when I did the first assembly. I'll watch it carefully when I reinstall the heads and time the cams.

[viejopatron]

Hmmm. So how much material has to come off the head to go from approx 90 cc to 84 cc? If I assume an annular cut, 120 mm OD and 96 mm ID, I get a thickness of 1.72 mm or 0.068-inch. That's a healthy bite.

Anyway, alls wells that ends well.

[ittia]

So this is the thread that made it all the way into Excellence magazine! One question: Is 84cc FACTORY spec? Seriously, I'm curious. No disrespect, just curious.

Have a great day.

[tom1394racing]

84 cc is not the factory spec for a stock SC head. A stock SC head should measure 90 cc for combustion chamber volume.

To get 10.5:1 CR the SC heads must be flycut to reduce the chamber volume to 84 cc.

[ittia]

Originally posted by tom1394racing
84 cc is not the factory spec for a stock SC head. A stock SC head should measure 90 cc for combustion chamber volume.

To get 10.5:1 CR the SC heads must be flycut to reduce the chamber volume to 84 cc.

Thanks!

[mb911]

so what is ideal deck height for larger then 95mm bore?? Just curious

[mb911]

so what is ideal deck height for larger then 95mm bore?? Just curious

[mb911]

so what is ideal deck height for larger then 95mm bore?? Just curious

[304065]

Here's a question:

When the heads are flycut, how much material is removed from the mating surface to reduce the chamber volume to 84cc?

What is the impact on the distance between the crank centerline and the centerline of the camshafts? This will affect the chain tensioner idler wheel size, no? Tom, did you end up using larger than stock idler wheels?

[quint22cp]

Good thread.

A question related to getting the right comp' ratio ?

How do you machine the heads to increase the CR ?

The heads on my 3.2 have the mating face with the cylinder recessed below the fins. Do I just fly-cut across the whole lot and forget the recess ?

Also how do I hold the head down in the mill ?