Compression test
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Joined: May 2018
Posts: 4,576
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From: Viet Vet, crossroads
(Or unhook power to the coils )
So you do not cause tracks and forever have bad wires, coils failed ignition parts.
Electricity is lazy and will take the most EZ path.
If the gap is too large for the spark to jump, it will create a new path and probably follow it forevermore.
Or at least under full throttle, you can get ignition breakdown from it .
So you do not cause tracks and forever have bad wires, coils failed ignition parts.
Electricity is lazy and will take the most EZ path.
If the gap is too large for the spark to jump, it will create a new path and probably follow it forevermore.
Or at least under full throttle, you can get ignition breakdown from it .
Last edited by Kingglide549; Aug 30, 2018 at 06:56 PM.
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Joined: Mar 2010
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From: Poolville
Need a little more info on the cam.. all you said was Andrews cam. The IVC timing will also change your ccp... Any other engine mods? Pistons?
Last edited by 98hotrodfatboy; Aug 31, 2018 at 08:34 AM.
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From: Tampa
FYI, I did a compression test in my hi-CR engine and followed all the rules, then when I opened the throttle a big stream of fuel went down the throat of the carb from the accelerator pump. When I hit the starter the hot engine lit that stream of fuel from a hot spot and blew the gauge apart in my hand! No physical damage, but the bellows within the gauge was shot and the needle was stuck at 280 psi. Ever since then I pin the throttle open with a throttle lock, then with plugs removed I crank the starter over a few times first, THEN hook up the gauge.
Banned
Joined: May 2018
Posts: 4,576
Likes: 978
From: Viet Vet, crossroads
FYI, I did a compression test in my hi-CR engine and followed all the rules, then when I opened the throttle a big stream of fuel went down the throat of the carb from the accelerator pump. When I hit the starter the hot engine lit that stream of fuel from a hot spot and blew the gauge apart in my hand! No physical damage, but the bellows within the gauge was shot and the needle was stuck at 280 psi. Ever since then I pin the throttle open with a throttle lock, then with plugs removed I crank the starter over a few times first, THEN hook up the gauge.
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
True, and my situation was the exception to the rule. His motor probably didn't have the squish and CR mine did at the time so the moons were aligned for me, not him. I've done compression tests exactly the same way on stock Evo's, TC's, and Sportsters, all with the same accelerator pump and never had a compression ignition.
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