Cam specs and info
11-16-2007, 02:58 PM
#16
3rd Gear
Join Date: Nov 2003
Location: Southern New Jersey
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Bill,
Thanks for the clairification on the cams. Do you know if the net lift that Andial has posted for the 993 105 246 70 & 993 105 247 70 cams is correct at .490 inch (intake)? My heads are at the machine shop now and I want to be sure that they shim the valve springs correctly.
Thanks for the clairification on the cams. Do you know if the net lift that Andial has posted for the 993 105 246 70 & 993 105 247 70 cams is correct at .490 inch (intake)? My heads are at the machine shop now and I want to be sure that they shim the valve springs correctly.
11-16-2007, 03:18 PM
#17
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I think my 9M cams are around 310 deg duration.....which makes for a very lumpy idle....no stalling issue really, I think it has stalled once when very cold and once when very hot in the last few months. Idle seems to be arund just under 1000rpm on mine up from the usual 840 or so on a standard car. Mine also seem to perform well but if one floors the accelerator in any gear above 1st at under 2500rpm then there is occasionally some 'jerking' (technical term) so you quickly learn to feed the power for a split second to avoid that. No problem.
11-16-2007, 03:44 PM
#18
Bill,
Thanks for the clairification on the cams. Do you know if the net lift that Andial has posted for the 993 105 246 70 & 993 105 247 70 cams is correct at .490 inch (intake)? My heads are at the machine shop now and I want to be sure that they shim the valve springs correctly.
Thanks for the clairification on the cams. Do you know if the net lift that Andial has posted for the 993 105 246 70 & 993 105 247 70 cams is correct at .490 inch (intake)? My heads are at the machine shop now and I want to be sure that they shim the valve springs correctly.
11-16-2007, 03:59 PM
#19
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Is that seat pressure correct Bill?
To convert Newtons to Kgf you divide by 9.81, then to convert kgf to lbsf you multiply by 2.2 which gives a result of 233lbf. Seems high to me, most springs are in the order of 80lbf on the seat and 220lbf on the nose, which equates to around 360N and 1000N respectively.
To convert Newtons to Kgf you divide by 9.81, then to convert kgf to lbsf you multiply by 2.2 which gives a result of 233lbf. Seems high to me, most springs are in the order of 80lbf on the seat and 220lbf on the nose, which equates to around 360N and 1000N respectively.
11-16-2007, 04:34 PM
#21
Nordschleife Master
I've tested a number of 964 engines and they have roughly 45-50ft/lb of seat pressure which is the #1 reason I say that when Porsche says the rev limiter is 6800, they mean it.
11-20-2007, 10:12 AM
#22
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Bill, from the Porsche specification the 1040N quoted is the nose pressure at dimension a which is 29.5mm. The installed height is the 29.5mm plus the 12.5mm specified lift = 42.0mm, which of course would be at the reduced seat force which is not specified.
