p/v clearance

General engine tech -- Drag Racing to Circle Track

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Frankshaft
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Re: p/v clearance

Post by Frankshaft »

donclark wrote: Tue Sep 25, 2018 4:07 pm
donclark wrote: Sun Apr 01, 2018 12:47 pm Mocking up for piston to valve clearance on a new combination. For various reasons, the 3.275" stroke crankshaft I will be using will not available for some time. I have a 3.1" stroke crank I can use. The question is will the longer stroke crank change the p/v clearance appreciably? Both will end up with the piston 0.015" in the hole.
Thanks,
Don
Finally got all the new parts and assembled this dog. P/V clearance ended up at 0.090" on the intakes and 0.130" on the exhausts, pretty much what I determined from the mock-up. Got on the track this weekend, ran back to back 5.38 @127 with 1.15 60' times, 352" SBF with C3 heads in a 3050 lb brick. Gotta love it when stuff actually works out.
N/A? That's fast, good job if so. Even with nitrous.
donclark
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Re: p/v clearance

Post by donclark »

N/A, Liberty Equalizer five-speed. I will try to post a link to video.
donclark
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Re: p/v clearance

Post by donclark »

anyone know how to post a video from facebook messenger?
donclark
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Re: p/v clearance

Post by donclark »

swampbuggy
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Re: p/v clearance

Post by swampbuggy »

Loved the video Don, love a stick car, do you drive the car ?? Mark H. :D
donclark
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Re: p/v clearance

Post by donclark »

Grandson is 23, he can see at night and doesn't get tired after 8:00 pm. Not the smoothest pass, we raised the wheelie bars and tightened the rear shocks for the next run and it picked up 0.01. Still too much clutch in it but we are getting there.
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Re: p/v clearance

Post by piston guy »

A shorter stroke and longer rod will have less piston to valve than a longer stroke shorter rod combination if all else is equal. Piston speed is slower near TDC and dwell time is increased .
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