When I built my truck I put a rebuilt 350 in it with a rebuilt 350 turbo tranny with a shift kit. Everything in the engine was replaced, only kept the block, put a Comp Cam in it and that is still drivable on the street without any problems. One problem I had is with the tranny, when you stop at a traffic light it pulled so hard at idle that I put it in neutral and then when the light changed I put it back in drive but sometimes I had to race the engine to get the tranny to go back in gear. What happened is the cam has big enough lobes on it that it was losing most of the vacuum at idle and the 350 turbo uses a vacuum modulator, today I put a vacuum canister on it and my tranny problems have been solved. Tranny acts normal for the first time in 6 years. I am putting this info here for anyone else that has the problems that I had. I do not remember who told me years ago that a vacuum canister would fix it but to you, thanks. Gerald in Florida
Learned this lesson many years ago when I had a LUV with a 400 sbc and wild cam. At 70mph when the vacuum was up it had mucho brakes but at idle took King Kong on the brake pedal to keep it from creeping. Can't say about trannys but with power brakes it takes at least 14" of vacuum for much assist. Now hot rodders use the hydraboost unit that works off the power steering pump so vacuum isn't a factor.
Totally agree, trans will not shift without the modulator control valve. Remember when these trans were common everyday? Replaced a number of these when folks would bring in a vehicle for ATF loss but no sign of leaks.... yank the vacuum line and find it was leaking and just sucking the fluid slowly into the engine and burning it, with little to no smoke. The simpler days, at least for me.
