I have a 63 Galaxie with a recently rebuilt 390 and brand new Holley 600. Every time I turn the car off while it's in drive the engine diesels for about 2-5 seconds. It even did this before I had the engine rebuilt and got the new carb. It doesn't seem to have gotten any better or any worse with the rebuild and carb. There are no vacuum leaks, and I have been through several tanks of gas from several different stations and always the same thing. I'm a newb to older cars, but I read that timing can be the culprit. Can anyone tell me what the timing for this engine should be? Any other suggestions?
Timing advanced too far for octane of gas, -390 high compression engines under 10.5 to 1 ratio should be ok on regular fuel With standard, none electronic ignition (points style distributor) Set timing at 6 degrees initial at 650 rpm idle warm. Remember to remove the vacuum line from the distributor and temp plug it with a small bolt/screw/dowel so as to not effect the setting of the timing at idle. Replug vacuum line into distrib when done. The above specs are for late 60's 390 but should be about right for 63 .
Oops, I should have mentioned it has an electronic Davis Unified Ignition distributor on it. It was put on when the engine was rebuilt.
Unless you had the 390 built up you should be fine with low to mid grade gas. I have a 390 in my 61 Galaxie and don't have any problems with it.
Still set initial timing at 6 degrees Run engine rpm up to 2500 rpm and make sure that timing does not exceed 35 or 36 degrees total at rpm. Any more than about 36 degrees at rpm and you will have problems. It is possible that your aftermarket distrib is allowing too much advance at rpm .
Yeah it was a pretty stock rebuild. New pistons, rings, lifters, br*** freeze plugs, seals, new oil pump, cam, bearings, valve job (stock heads), etc. The only thing that was really "upgraded" was the dizzy. It's just killing me that it still does it after all that.
When I turn it off in gear it seems to be ok. Maybe an occasional "spit", but no more than once. Not nearly as bad as when in park.
These guys are good, a lot of good suggestions. What probably happened is when you rebuilt the enigne, you restored the proper compression, which is border-line high for today's gas. Go with the highest octane you can get. check timing, idle speed, and mixture (lean mix is BAD) Proper spark plugs, etc. If all else fails, you might try using a thicker head gasket to lower the compression a bit...it's probably all you need to run on today's fuel. Also check your running temp, and perhaps lower it with a colder T-stat, might help.
Ford couldn't fix this problem with timing, etc. so they installed a idle solonoid on the carb that lowered the idle down to hardly anything when the key was turned off.( but not too far that the ****erflies would stick). See if you can get the setup off of a 68 up ford & it will solve your problems, ya just have to tap the gas pedal with the key on so that it sets itself up. JimV
Usually too much closed throttle airflow. Means the idle speed screw is set to high on the carb. Closed up the idle screw until the plates are barely off the closed stop. If you need more idle speed advance the timing - that's right - advance it. Plugging the vacuum advance to manifold might do that for you. Once you kill the ignition the vacuum will drop out, the timing will retard, and the engine will stop running. The idle solenoid the other guy mentioned will do the same thing and is a very viable alternative solution.
Probably would work if your pulling vacuum right off the manifold, but it will change when accelerating.Also closing the ****erflies alot runs into problems cause the linkage is past its "center". Way i figure it detroit engineers know alot more then us jamooks on here!!LOL So whatever they do to resolve a problem has to be right.If they could have done it thru timing they would have, they cut cost anyway they could so if they went through the expense of a solonoid its the right way to do it!lol jimV
Since the engine did it before and after rebuild, I would look into running too lean or the wrong spark plugs. If the problem is in the timing or any of the advance systems, you should be hearing some valve rattle. All the suggestions are good possibilities, but you should see other indicators of what is wrong. Does the engine temp run high, valves rattle on take off or acceleration, spark plugs show detonation? The old vacuum advances could be adjusted with springs, stops and shims. If the vacuum advance is too much, make sure everything is still right inside the can. You could disconnect and plug it while trying to narrow down the problem. Should be easy to trace and fix. good luck,
The Jalopy Journal
