entropy
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posted August 19, 2010 09:23 PM
motor building guys - a tip
Tonight i'm working on putting my Busa motor back together for Mojave and checked for leaky valves by filling the ports with water, look for beading up on leaky valves.
no beads, great
then i hit ea valve with compressed air around the edge of the face/seat.
ooops, #6 exh valve got a buncha bubbles in the water filled port
pulled the valve, cleaned the face & seat with scotchbrite.
still got bubbles
replaced the valve, bubbles gone.
Hopefully dodged a bad leakdown.
if anyone has a other/better ways to do this, please chime in 
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whitehendrix
Zone Head
fails!
Posts: 757
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posted August 19, 2010 09:30 PM
great idea!
i have seen it done from the other direction as well, where the chambers are filled with alcohol or colored water and one of two things is done. the tester pulls vac on the port for 30 sec and afterwards, looks for shit in the ports, or, introduces a little air to the ports and looks for a leak from the port to the chamber.
io have seen people use gas too, since its thinner than water and tends to want to wick easier, making the most minute leak that much more noticeable.
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Duct tape is the handyman's secret
weapon. The black is for formal
occasions. - ZRXDean
ill never own a busa unless
someone gives me one.... and then
ill sell it -KZScott
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entropy
Moderator
Posts: 8671
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posted August 19, 2010 09:36 PM
quote:
io have seen people use gas too, since its thinner than water and tends to want to wick easier, making the most minute leak that much more noticeable.
Back in the day, i used gas but then i started smoking...
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whitehendrix
Zone Head
fails!
Posts: 757
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posted August 19, 2010 09:39 PM
lol.. well, that is a great reason to use water!!
(unless you're one of those poor bastards living by a gas well who's tap water is flammable..)
____________
Duct tape is the handyman's secret
weapon. The black is for formal
occasions. - ZRXDean
ill never own a busa unless
someone gives me one.... and then
ill sell it -KZScott
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted August 20, 2010 02:55 AM
Mineral spirits works well too. We also use vacuum testers. But using a set of V blocks and measuring the 45 faces for runout is the best. Then using a dye on the seats and rubbing them in gives good piece of mind. We also use runout indicators on the seats.
Theres many ways....
Do you think you tagged a valve? Or do you think it warped from heat? You can lap the valve and watch the seat contact area. See if its consistant on the 45 deg contact width all the way around.
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Y2KZX12R
CompetitionCNC.com
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entropy
Moderator
Posts: 8671
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posted August 20, 2010 04:18 AM
For sure i didn't tag a valve, i looked carefully at valves & pistons.
The head, valves & pistons on cyl 2-3-4 which had lifted/melted lands showed evidence of some shit bouncing around, i suspect pieces of piston.
#1 cyl with its perfect piston showed no such evidence.
My theory is that some lil chunk of aluminum got caught between that exh valve & seat.
or
Like Jim says. maybe it just warped from the heat
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