FMX TRANSMISSION ISSUES

[ALLWELD488]

Well, im new to this so bear with me abit,My problem is when i shift from part to drive the fmx tranny shifts so hard it kills the engine,if i keep my foot on the gas it helps but then it shifts so hard it engages and then just sits there spinning the tires in one place until i let my foot off brake.is there any way to adjust this thing. here is what i have, 1972 convertible with fmx tranny, 351 cleveland (stock) except for 4 barrel intake and 600 edelbrock and hei distributor , i checked vacuum its at 18, timing is at about 12 with vac unplugged, idle is at about 800 in park, now hear is the issue, this car sat since 1996 and it took all of about an hour to get it running, but it runs and drives great except for the stalling issue, any thoughts?

 

[CZ-75]

Sounds like your torque converter may be shot. The torque converter should "slip," allowing your car to idle without turning your drive shaft until you get into higher RPMs.

 

[Jeff73Mach1]

Vacuum Modulator on the transmission may be bad. That creates a vacuum leak. You tuned and set the idle to compensate, but when vacuum drops as a result of opening the throttle plates, the fuel falls out of suspension and the car bogs or dies. I'd bet it is a vacuum leak-if not at the modulator, then at the intake manifold or under the carb or a cracked hose somewhere.

 

[ALLWELD488]

I already pulled tranny and put new convertor in and changed all fluids along with new modulator,they made no change, now as for the vacuum it holds 18 even after i open the carb, i left gage on to see what it would do and there is no change, now heres a question, when i pull off every vacuum line one at a time none of them make the car run funny, except the vac advance line,what does that say? this motor also has the 2v heads, ive sprayed all around the intake and all around carb with starter fluid and there was no change in idle.

 

[CZ-75]

Was you vacuum advance on a manifold port? Sounds like it... I think you may need more advance. Try another 5 degrees or so. My H code really likes 17 degrees before vacuum advance.

 

[ALLWELD488]

yes it is plugged into the manifold,if i degree it any more it starts to run choppy and i start to loose alittle vacuum. i forgot to add if i press the brake just enough to slow the car down when i shift into gear and let it roll alittle forward then apply the brake fully, then it will idle,but the rear of the car is picked up about an inch like the car is waiting to launch,it seems like if i could just get the tranny to shift into geat alittle easier i would be fine.