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-   -   need advise on testing msd btm with pump (http://www.hotrodders.com/forum/need-advise-testing-msd-btm-pump-226843.html)

menoaz 12-05-2012 01:52 AM

need advise on testing msd btm with pump
 
need advise on testing msd btm with pump

Im going to the track this weekend for the first time and running only 5# of boost on the 427bbc with 8-71. Here at home i cant get enough boost into the btm to show me that it works like it should when i got #5 pounds at wot. I can only get #2 of boost on the gauge. @4000. I have the knob all the way to 3 degrees removed and starting at 0 pounds of boost. I have my timing at 38. I see no retard when i rev it up past 3500 with the timing light.. so im planning on buying a handheld vacuum pump from autozone and testing the btm. So any advise on using the pump? Rpms? how much vacuum on pump equals 5# of boost.

F-BIRD'88 12-05-2012 04:00 AM

Vacuum is the oposite of boost pressure. The pump needs to create pressure.
If it cannot be reconfigured to be a +pressure pump, it will not work for you.
@ just 5 psi boost you should not need much retard. (assuming good fuel)

menoaz 12-05-2012 04:35 AM

Okay thxz, so it has to say pressure pump. Do you agree that timng should not be coming out until 2# of boost starts? Im planning on mixing 50/50 91 octane and 110 race.

menoaz 12-06-2012 08:59 PM

Tested the btm today with the air compressor set atat 5psi. Moved the btm knob from 0 to 3 and watched with the timing light the timing go down just like its simulating boost. So from what iv read in threads im going to set btm to start taking out timing at 1-2 lbs of boost and going to take out 2 degrees of timing per lb of boost. car ran 12.1 with no 8-71 so im hoping for a low 11 to high 10's with 5lbs of boost. Going to make some passes at 5000rpm shifts and make sure everthing is staying together

menoaz 12-13-2012 11:24 PM

Ran the car at the track and and video taped the boost and tach. Didn't get 5lbs of boost until around 6000rpms. Then ran into more problems with rams raising way to quick and not going down when I shift. If my converter is flashing to high would it still let the tires come off the ground. So I'm going to change my gears from 4.88 to 4.10s see if that helps before I spend a bunch on a Hughes converter.


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