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Ignition (?) problem, very strange


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This is very odd. About two weeks ago I put a new adjustable vacuum advance kit from Crane Cams in my 72 LeSabre 350 (HEI upgraded). I had no vacuum advance before that due to a hole in the diaphragm. When I had the distributor out I noticed my mech. advance was practically locked up and my weight pins were wore out. After I put my dist. back in I had to idle the car down due to increased advance I did this by adjusting in my fuel screws (lack of tools) it was dumb but my car was at about 1200 rpm at Idle. Wednesday, I took my dist. back out, re-bushed the weights and put the new weight springs in the from the kit on the dist. When I got home I reset my timing and test drove it. All my power is gone. Before I had respectable acceleration, now I can't burn the tires soakin wet. It back fires through the Carb at about half throttle (fuel screws have been set to original setting). I have a full race TH350 in this car and the weird thing is that about 2 seconds before it shifts into third gear I get a lurch of acceleration. It also shifts alot later than it used to. I don't have a tach but I would assume that at WOT it waits until about 6000 rpm to shift. (As opposed to about 5000 before) I am throughly boggled by this and any help would be fantastic. Thanks.<P><BR>---Jay

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Sound to me like there is a vacuum leak somehwere. Maybe the line to the trans or the pcv valve has fallen off. Also, where did you hook up the vacuum advance line to? I would put a vacuum gage on and see what is really going on.

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Vacuum has nothing to do with WOT shift points. That is controlled by the weights and springs on the govenor in the tranny. I noticed the term "adjustable vacuum advance kit" in your description. Not knowing anything about the kit, I would suspect that the problem may be in the adjustment of this unit.<P>Just an observation. <P>------------------<BR>George C. Thomas<BR>70 GS 455 12.teens<BR>86 GN Low 13's/ high 12's

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You didn't say what all you did to the HEI. back fireing through the carb means you could have miss set static timing, miss aligned rotor,cap not on right,voltage spill from non isolated coil (you must use dielectric grease), non grounded module, plug wires out of order, new weights holding rotor to high, thrust not set right allowing shaft to climb,some part of the new advance unit makeing or breaking ground incorectly,module to coil wireing loose,or a bad rotor. the trans thing sounds like you unpluged the vacuum line to the vacuum modulator on the trans. Good luck JIM

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Well, to answer all you questions: The vacuum advance is hooked up to a port on the carb, it is still getting manifold vac. instead of ported but I can't find a ported source. Yes, I removed the vacuum advance hose and plugged and and I am getting 17.3" of manifold vacuum at idle. (According to my Allen scope) Thank you all but I fixed it today. I removed the new springs and put the factory springs back in it and now it's back to it's old self. I checked my full throttle advance and I believe I had full mech. adv. at idle. Now when I rev it to about 3500 RPM the timing goes straight back to initial advance but it runs great so I am not going to mess with it for now anyways. Thanks alot.<P><BR>---Jay

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