Tough Question - cams/chip/rough idle?
02-10-2005, 04:59 PM
#16
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John that is what Porsche decided when they opted NOT to use GT cams in the the GTS not the 5 speed or the automatics. The Elgin cam "Gibson profile" did not idle very well in an automatic.
02-10-2005, 06:53 PM
#18
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Yes, it is sounding like 1) replace cams; or 2) live with it. The rough idle is a little bothersome during, low speed driving, parking, etc., but it isn't that big a deal. The car accelerates and cruises smoothly. Thanks everyone for the advice!
02-21-2005, 10:31 PM
#20
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How old is the receipt from Elgins? If I remember right there was only 2 grinds Autothority burned chips for, the "Thompson" grind and the "Gibson" grind. Both named after the customers who first bought them. The Thompson grind was a mild upgrade and the Gibson was the wild cam.
All were welded and then reground. If it was a simple regrind the specs would depend on the donor camshafts the customer supplied, meaning what would fit the cam and still preload the tappet.
It may be a case of checking the camshaft timing. If one camshaft was off the engine might have a poor idle.
All were welded and then reground. If it was a simple regrind the specs would depend on the donor camshafts the customer supplied, meaning what would fit the cam and still preload the tappet.
It may be a case of checking the camshaft timing. If one camshaft was off the engine might have a poor idle.
02-21-2005, 10:52 PM
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There is no indication on the Elgin receipt, but "Thompson" is scribbled several times on various supporting documents. I will try to find out from either Elgin, Autothority, or the P.O. In the meantime, I'm learning to live with the idle.
02-21-2005, 10:58 PM
#22
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The DEVEK B1 cam is "slightly" more aggressive than the GT cam, by about the same amount as the GT cam is to the S4 Cam. And will idle at about 970 rpm well in a 5.0 l engine and at about 800 rpm in a stroker.
In both cases, using a single disc clutch is necessary. Usage of a twin disc will cause occaisional stalls.
Automatics are much worse, and needs an additional 100 rpm or so to remain running post high rpm idle down.
In both cases, using a single disc clutch is necessary. Usage of a twin disc will cause occaisional stalls.
Automatics are much worse, and needs an additional 100 rpm or so to remain running post high rpm idle down.
