The car has the original 394 and transmission. Shifts out great but you have to manually shift down to second when you slow down or it dies. If you time it right you can shift down to second then right back to 3rd and all is well. What makes the tranny shift down during normal driving. It tries to stay in 3rd when slowing down. Thanks.

 

Slim-Jims are designed to stay in high gear until approximately 7 mph, then they downshift. Just one of their many great features. Lots of fun in stop and go traffic. These are in direct drive - no fluid coupling - in 2nd, so that is probably the reason behind it.

 

If your trans is upshifting correctly you may just have an issue with idle speed / carb mixture adjustment, try slightly increasing the idle speed. The stalling can also be an issue in cold weather if the choke kicks the fast idle down too soon, this also is an adjustment issue.

 

Just pulled the carb for a rebuild. I am very familiar with the shifting of these cars...I have 4 of them (Starfire 62') that run and drive. This one just came in from Florida and has a few more things to fix to make it a nice driver. It shifts up perfectly. I tried to increase the idle several times with no change to the down shift. I don't think the rebuild will fix it...but I have been wrong before.
Any suggestions would be great.

 

So you're saying that this one downshifts differently than the others?

 

OK...just imagine that you take your 4 speed manual car out and get up to about 35 mph in 3rd gear.....then you let off the gas and do not push the clutch in. At about 8 mile and hour it begins to shake the whole car until it finally kills the engine. That is what this 62 starfire with factory slim jim is doing. If you reach over and downshift to second and then back up to 3rd as it slows, it works fine.
Whatever makes a slim jim auto shift down is not happening. Hope this helps.
Shifts up with no problems...smooth as any slim jim.

 

Sounds like it's not automatically refilling the fluid coupling. Shifting manually forces the fluid coupling to refill. Must be something wrong in the valve body.

 

Slim Jims are extremely sensitive to linkage adjustment and fluid level. Have you checked the fluid lever? Mine doesn't have to be very low to start acting goofy. There is a linkage adjustment procedure in the service manual, with a late addendum in one of the Service Guild issues. I'm assuming you're running a stock carburetor. I'll have to check my "Principles of Operation" book and see if I can figure out what refills the coupling.

 

Black magic and voodoo make Slim Jims work!

Does 62 have that dashpot thing that keeps the carb from dropping to idle speed too quickly on deceleration? That may be somewhere to look. Otherwise it sounds like a governor or valve body issue.