Idle speed vs dynaflow

[1956322]

My 56 seems to run best at about 725 in gear which is about 975 in park is this a concern for the dynaflow particularly engaging reverse??

[Fr. Buick]

That does seem a little fast, and I would give it a good tuning and slow it down.

 

Gear shift,  or more precisely engaging reverse, will be much smoother with new engine and trans mounting pads and thrust pad.

[1956322]

Actually this is after a good tune i can get it lower but it’s not as smooth... the mounts are all pretty fresh

[Ben Bruce aka First Born]

You MAY have a small vacuum leak that is affecting the slow idle.

 

  Ben

[JohnD1956]

2 hours ago, 1956322 said:

My 56 seems to run best at about 725 in gear which is about 975 in park is this a concern for the dynaflow particularly engaging reverse??

I'd say yes. That must really jar the vehicle even when goin into low too.  I set mine back to 550 and had to set the timing back to 2 1/2 degrees and am very happy with it. 

 

Are you still running a stock distributor? Have you oiled the bearing and the oil fill on the points base?  

[old-tank]

2 hours ago, 1956322 said:

Actually this is after a good tune i can get it lower but it’s not as smooth... the mounts are all pretty fresh

At 975 rpm the idle mixture screws will have no effect.  Idle it down to at least 600 rpm then adjust the idle mixture screws to smooth the idle.  If no joy then check for vacuum leaks as Ben noted.  Do this of course after warmed up, with it off the fast idle cam.  What carburetor?

[1956322]

Ok i got it much better turns out my vacuum gauge has seen better days..575 in gear 725 in park timing is 14...edelbrock 1906 carb and msd distributor new intake gaskets..vacuum in park is 16 in gear 12 keep in mind in at 5500 ft altitude 

Edited September 16, 2020 by 1956322 (see edit history)

[Fr. Buick]

Isn't it an inch of mercury for every thousand feet of elevation?  Then that sounds like good vacuum.

[1956322]

That’s what I’ve read:)

[old-tank]

4 minutes ago, 1956322 said:

timing is 14

Service manual states to set initial timing at 5*...I set mine at 7*.  Set with it barely ticking over (300 RPM)with the vacuum advance disconnected.  Bringing up the rpm should get another 10* (approx from the centrifugal advance) and connecting the vacuum advance another 10* with total advance not to exceed 30* unless you have some obscure cam grind and timing.  That MSD distributor may have additional instructions.

[1956322]

I set mine at 14 based on experience with other engines at this altitude and the Centerville boys recommendation of 10-12...