Throttle check valve

[David Thomas]

I believe the shop manual refers to the vacuum dash pot on the throttle relay lever as a check valve. I have finally corrected the other vacuum leaks in the A/C heater system only to find the vacuum unit on the throttle linkage will not hold a vacuum. My question is,  does this diaphragm have a calculated bleed or is it supposed to be vacuum tight? Mine is working with engine vacuum but I can't draw a holding vacuum with my mighty vac hand pump. Thanks.

[3ft7bqmb7dryo]

It should hold vacuum, and when the engine rpm's drop, the vacuum drops, allowing the plunger to come back out.

I have a good part, just send me an email;  [e-mail]

[Jason Edge]

Just to add to the discussion, Cadillac replaced the vacuum fed check valve early during the 1964 model production run, with a spring and orifice type dash pot.  According to the serviceman bulletin they went to the dash pot "to prevent stalling after sudden release of the accelerator pedal." according to the Serviceman Bulletin.  I've got both the vacuum check valve and spring and orifice dash pots.  If you wanted to switch over to the spring and orifice dash pot you would also need the throttle relay bracket it attaches to.  

[David Thomas]

Thanks guys!

Jason, is upgrading to the 64 design a remove and replace bolt it in, connect the linkage and go task? I like the prospect of eliminating a future vacuum leak if it is R&R then go. Thanks.