Mildly Surprised
Moderator: MalcolmV8
Mildly Surprised
So new motor after getting exhaust on it and stuff, I set timing and out of curiousity decided to check vacuum and idle (did it by ear first time) It holds 17lbs of vacuum at idle and in gear it idles smooth as silk at 770 rpm. Surprising since it has .544 lift
87 Ranger: Coast High Performance 331 kit 28oz balance, Comp XE264HR14 cam, 64cc 185 AFR heads, 1.7 roller rockers, Full manual reverse VB c4
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cgrey8
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Re: Mildly Surprised
Interesting.
BTW, lift doesn't mean much at idle. Duration, Intake Lobe Center, and LSA are the things in play at idle and lower RPM conditions. There are small duration cams with .544" lift that idle just fine at 600RPMs and can tolerate having the clutch let out with no throttle well into the 500s and 400s before they stall...the Comp XE258HR-12 comes to mind. Then there are lower lift cams, like the B303, that has much higher duration, a low LSA (more overlap), and only .480" lift that can barely idle at 700RPMs.
The benefit of lift is realized at high RPM/Loads, and then usually only on higher displacement engines or heads that don't flow that great to start with.
BTW, lift doesn't mean much at idle. Duration, Intake Lobe Center, and LSA are the things in play at idle and lower RPM conditions. There are small duration cams with .544" lift that idle just fine at 600RPMs and can tolerate having the clutch let out with no throttle well into the 500s and 400s before they stall...the Comp XE258HR-12 comes to mind. Then there are lower lift cams, like the B303, that has much higher duration, a low LSA (more overlap), and only .480" lift that can barely idle at 700RPMs.
The benefit of lift is realized at high RPM/Loads, and then usually only on higher displacement engines or heads that don't flow that great to start with.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org