Timing drops from Park to Drive

M

mugsy

Famous Member
Well its been a long struggle to get my Mustang reliable and trouble-free since the re-build but I made great strides with summer. One thing that I noticed was that the engine idle somewhat high (sorry never put a tach on it) in Park, but the when placed into gear the engine would almost stall out and had a very rough idle. I finally timed the dizzy in both park and drive and found out that the inital timing was dropping like 8*-10* :shock: I bumped the timing up to about 8* in Drive and it idled pretty good; but then is idled really high in Park :unsure: . So my question is why is there such a drop? I was always under the assumption that the intial timing of the dizzy should stay the same (or vary just a little) between Park and Drive.

For some background here is the current state for the engine

-Rebuilt 200 with 0.030" over pistons. CR is about 9.1:1
- Carb is model 1940 w/o the SCV
- DS-II dizzy with the lighter spring upgrade. Dizzy was a JY find.
- Post vacuum (verfied no vacuum to the dizzy at idle)
- "Larger" camshaft (I forgot the specs)
 
I usually time by ear as the balances slip due to age. So turn the dizzy till highest idle. Then drive if ping back it off till no ping. Then adjust your idle. Others will chime in and will be much more help. This has worked for me in the past.
 
Oh, its a new balancer when the engine was rebuilt. Less than 1K miles since rebuild. Balancer was done by Damper Doctors and is spot on. Verified to couple times.

Also I plugged the PVC and no change to the dizzy dropping 8-10* when the engine went from Park to Drive.... Check for vac leaks and found none as well...
 
Mugsy, your centrifigul advance is advancing too early.
Lower your curb idle in park & then place into drive. If you see a change put more spring tension on the primary centrifigul spring.
That will correct your condition. Bill
 
8) first thing to remember is that all initial timing and idle speed adjustments are done with the transmission in drive(remember to set the parking brake), and the vacuum advance line disconnected and plugged. the reason for this is that the load on the engine goes up when you shift from park to drive and the idle speed, as well as initial ignition timing, drop.
 
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