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[GMCnet] What happens inside a motor run too lean! [message #337285]

Wed, 26 September 2018 21:25

powwerjon

Messages: 849
Registered: March 2013

Karma:

Senior Member

Several weeks ago there was a discussion on leaning the motor down or run lean burn. Earlier tonight I was going thru several fiber pacs sorting parts and found a piston out of our 1985 alcohol funny car. The motor was a 540 cu.in. with a 12/71 blower and was mostly Keith Black parts. Back in the day and mostly today there are no electronics allowed on the alcohol funny cars. Most of the cars of the day had what was called a “go fast" button that would lean the motor in the top end just before the lights and give it a boost in power. Most of the time you didn’t damage the motor, but sometime when you already had the motor on Kill and it was the final round you would push the button and you let the smoke out of the motor. The satisfaction was that we did win the round and the race.

There are 6 pictures of one of the pistons that came out of the motor on that run. Notice that the intake pocket is melted and pushed in with a hole in the top of the piston. The ring land is gone on that side and on the exhaust side too is scuffed badly and the skirts are scuffed too. Needless to say the sleeve was in poor shape too! This is also was can happen in our motors too.

http://www.gmcmhphotos.com/photos/general-pictures/p65263-img-14881.html
http://www.gmcmhphotos.com/photos/general-pictures/p65262-img-14871.html
http://www.gmcmhphotos.com/photos/general-pictures/p65261-img-14861.html
http://www.gmcmhphotos.com/photos/general-pictures/p65260-img-14851.html
http://www.gmcmhphotos.com/photos/general-pictures/p65259-img-14841.html
http://www.gmcmhphotos.com/photos/general-pictures/p65258-img-1483.html

J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 30’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
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[Message index]

		[GMCnet] What happens inside a motor run too lean! By: powwerjon on Wed, 26 September 2018 21:25
		Re: [GMCnet] What happens inside a motor run too lean! By: Carl S. on Thu, 27 September 2018 09:39
		Re: [GMCnet] What happens inside a motor run too lean! By: James Hupy on Thu, 27 September 2018 11:04
		Re: [GMCnet] What happens inside a motor run too lean! By: Keith V on Fri, 28 September 2018 08:56

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