.25 inch of standard late head leaves a head of about 3.30 inches height.
That is around 11.5:1 or so. Hope you did not mill it that much or you need
race gas!
Do not know if the chart I attached below came through your email, but it
shows compression for various head thicknesses and piston diameters.
Standard is 3.55 thick and yields 7.6 ratio.
Head Thickness
[inches]
Combust chamber volume in cc
STD bore Comp ratio
Ratio .020" over
Ratio .030" over
Ratio .040" over
3.550
58.5
7.62
7.71
7.76
7.80
3.539
57.7
7.75
7.84
7.88
7.93
3.518
55.5
8.00
8.09
8.14
8.18
3.498
53.4
8.25
8.35
8.4
8.45
3.479
51.5
8.50
8.60
8.65
8.70
3.462
49.7
8.75
8.85
8.91
8.96
3.445
48.0
9.00
9.11
9.17
9.22
3.430
46.5
9.25
9.35
9.41
9.47
3.416
45.0
9.50
9.61
9.67
9.72
3.402
43.6
9.75
9.86
9.92
9.98
3.388
42.2
10.00
10.13
10.19
10.25
3.377
41.0
10.25
10.37
10.44
10.50
3.366
39.8
10.50
10.63
10.69
10.76
On Sat, Jun 14, 2008 at 5:43 AM, michael lunsford <mblunsfordsr@yahoo.com>
wrote:
> Al,
>
> I found the Goodparts G-2 cam to be a little more radical than I expected.
> It works fine but it is lumpier than expected at idle. Most people who hear
> it at idle and know about these things ask if I "have a cam" in the car so
> it is noticeable. I think I have between 9.5 and 10.0 to 1 compression
> ratio on my car and have to use premium. If I get a dose of bad gas I can
> tell it from the pinging under light load. I took a lot, I'm not sure but I
> think it may have been as much as .025 (1/4 inch) off of the late model head
> I purchased for the experiment. From the responses you got to your question
> I ported, and deburred the head, intake and exhaust and the car runs great,
> especially with Rick Patton's TBI setup.
>
> Mike Lunsford, 1970 TR6
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--
Chuck Arnold
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