I realize this may be more appropriate in the FE forum, but figured I ask here first. Always got great info from this group, so interested in thoughts.

Recently started chasing down a couple of issues with my truck (390 holley 4 bbl, points distr, automatic). The first, which seemed to be a random miss, sometimes stall, and hard start, was difficult to track down because it was so random and hard to duplicate. I believe I have solved that issue, with the culprit being the wire to the coil.
The second issue is now driving me crazy and seems to be worse, and that is the engine stalls when shifted into gear. In chasing down these issues, I have already done the following- changed coil, cap, rotor, points, condenser, spark plugs, wires, rebuilt carb. All replaced parts are known good, and/or Ford nos. Engine has been timed, dwell set, etc. Since installing rebuilt carb, engine starts, runs and idles perfectly. Have tuned carb to best of my ability. Immediately when shifting into gear, engine rpms drop by about 300, then further by another 100 before stalling. I've checked for vacuum leaks, and found none. Today I raised rear of truck and tried shifting into gear. With brake applied, stalls. Without brake applied, slight change in rpm when shifting into gear (would consider normal), wheels spin, engine runs fine, even accelerates fine. As soon as brakes are applied, rpms drop and stalls.

At this point, I'm leaning towards the torque converter, but have near zero knowledge in that area. Would be interested in what others have to say. Not wanting to overlook the obvious here, I will be doing a compression check and even though fuel pressure seems good, I have yet to put a gauge on it. Trans fluid level checked and is good.

Tony

***edit During the time it took me to rebuild the holley carb, I installed an old ford carb temporarily. Had similar issues with it, but gave up trying to get everything set right. With a bit of fancy foot work, I was able to give it a quick road test though, but hadn't solved coil issue at that time so basically just gave up.

 

Just out of curiosity, does your truck have a brake booster? If so, it could be leaking where the brake push rod enters the booster. Had that happen on my 75 F100. Stuck my head under the dash by the pedals and could hear an audible hiss when brakes were depressed. Changed booster and it made a world of difference. Just my 2 cents.

 

Second that. Could be leaking front side to. Check the check valve to booster while your at it.

 

Yes, but same thing happens when it's disconnected. Matter of fact, even happens when all vacuum ports are capped.

 

Did you change anything with the kickdown linkage when you rebuilt the carb.

 

No. Reinstalled and checked adjustment.

 

(I'm assuming you step on the brake when you engage a gear.) The brake lights - or a fault in the brake light circuit - could stall it if you don't have good voltage to the coil. A broken wire maybe. You could hot-wire a second battery to the coil + terminal and chassis ground to see if applying the brakes is causing a problem.
Eric

 

Ironically, after figuring out that the coil wasn't getting power, I used a jumper wire to power it, then continued to trouble shoot the stalling issue. No doubt, good, continuous power to the coil now. Also, rpms drop and engine stalls only after shifting into gear, foot on brake or not.

 

You need good voltage coming out of the coil to ground, too. Are you seeing a nice blue spark at the plugs and an audible sparking at the points when you crank it with the cap off? I had a similar problem on a Rover (Yes, I know...). The negative coil wire showed continuity but was in fact broken inside the insulation except for a single strand. I remember it ran okay when the alternator was on full boil but it would stumble and die at low speeds.
I think it's too soon to take out the torque converter.

 

Hmm. I always tell myself, when all else fails, go back to the basics. You're absolutely right. A weak spark would show exactly the same symptoms.
After now checking, looks like weak spark at the points. Spark at the plugs is orange.

 

A bright blue spark indicates good voltage. Orange or red spark indicates a weak spark. How is your resistance wire for the points?

 

Not to offend, but is beyond my thinking why points are even still an option. I've had a Pertronics for more than 6 years without a hiccup , same cap, rotor wires and a spare module in the glove box. Every now and then I check things out and don't see a need to change anything so far and I drive 5-10k mi a year. Just sayin.

 

Will have to sort that out in the morning. Do believe that was at least initially part of cause of no power to coil. Thinking to replace with new wire and use external resister.

I'm not easily offended. Did switch to duraspark distributor a while back. Had issues of intermittent no spark. All components tested good at the time. Resolved the issue by reinstalling points dist. Looks like things may have come full circle.

 

Duraspark was the hot stuff awhile back but to much going on for me. Modules on the fender and wires going back and forth and so on. Pertronics made it simple. 12v to the coil and hook it up, done. One less thing to worry about.

 

The second issue is now driving me crazy and seems to be worse, and that is the engine stalls when shifted into gear.

Try this. Unplug the vacuum line, start it up, warm it up,make sure it's idling below 1000 rpm so you aren't getting any centrifugal advance and set your initial timing at 12 degrees. Plug the vacuum line into FULL MAMIFOLD vacuum and make sure your vacuum can pulls in another 15 to 20 degrees for around 30 degrees advanced at idle. If you don't have that much advance at idle you will never get a crisp idle with the gas we have now.
If all that's good. Chock all the wheels or chain it to a pole, hook up your vacuum gauge put it in drive then adjust the carb.
The torque converter should only pull the engine down around 200- 300 rpm max depending on how much torque your engine makes at idle the more torque you make the more it will pull the engine down. If it chirps the tires when you put it in gear you need a looser converter. Most of the stock 390 converters are around 1600-1800 stall according to Ford but any converter shop will tell you that Ford lied and they are nowhere near that much in most cases. If your converter is the type that's smooth on the outside with no dimples in it you will be lucky if it's 1200 stall.