Hard starting 390

[boaterbob]

After my 66 390 warms up it seems to crank to long to restart. Cold start it fires right up. It's got a new carb and rebuilt engine. Could it be a coil problem?

 

[64RREDCONV]

My 64 does the same thing. I hope someone has some suggestions.

 

[Yoda]

I was having some issues with that myself. I'll let you know if my new Ignitor II ignition and FlameThrower II coil fix things after I've driven for a few days.

I will say that prior to the upgrade, I would get an odd noise from the carb and some white smoke in the back if I accelerated hard at crusing speed. I think it was unburnt fuel. The new ignition parts seem to have completely fixed this and I have really nice acceleration at crusing speed now.

 

[boaterbob]

I had the Petronix on already. I just added the Flame Thrower coil today. So we have the same test going. I'll look for your post.

 

[t-bird-art]

RE: Cold start OK Restart slow: Is the engine cranking slow or is it slow to fire up? Could be couple of things.A) Yes, a bad coil could have internal shorts and is overheating reducing output on re-start. Don't need fancy/pricey coils. Original correct Ford coils work correctly. Would not recommend High Intensity Coils (40K volts) they will burn hole in top of piston. B) Make sure the choke is fully open on re-start. C) On 1966 Bird make sure the Heat Riser ( mounted below passenger exhaust manifold) is rotating (opening and closing) easily. Test rotation when engine is COLD. D) Engine should crank at same speed and sound the same with hot or cold engine . If engine cranking speed is slow on hot engine , test Battery and starter and check Ignition timing . All three will result in slow engine cranking on hot engine.
E) On re-start, does engine TEMP read very hot. Ever had radiator boil over? On engine rebuild, did they pop the freeze plugs and flush the block?

 

[t-bird-art]

P.S. Have you driven 500 miles on the rebuilt engine?

 

[Yoda]

So far I'm getting pretty quick restarts on a hot engine. Drove 45 miles tonight. Stopped for two errands a few minutes apart and only had to crank for a couple of seconds to restart.

 

[t-bird-art]

A warmed up engine firing/starting after a few seconds cranking is tolerable. But, your 390 can do better. When everything is right, you should be able to reach in the (open) window, turn the key, and it should fire up immediately. Now that's the Holy Grail. If you have driven 500 miles and used a local engine & carb rebuilder, I would re-visit them . Throw the challenge to them to dig in their bag of training, and experience to get it to fire immediately. They would be glad to do it.If rebuilders are not local, find a local mechanic with GREY hair still running his own 1-2 man shop. He's a gold mine of experience , especially, if he is a Ford man and/or former race car driver. With immediate starts ( of warmed-up engine ) you know the engine is running at peak efficiency and peak gas mileage and so does everyone else . You're at the fun part now !

 

[boaterbob]

I live in NJ where it's been pretty cold. If you put your hand in the window after it's been off 3 or 4 minutes it fires right up. Only after it sits 15 minutes or so does it crank more the n it should. Changed the coil, Not the problem. I'm thinking i have to check and see if the electric choke is resetting. Glad to hear your running good Yoda.

 

[Yoda]

Drove some more today and I should clarify my earlier post to say a couple of seconds at most. Made two quick stops today where it cranked back up immediately.

 

[t-bird-art]

Sounds like your engine is starting OK now. Maybe , don't mess with it and just drive it like you have been doing. These beasts must be driven regularily for best performance. Worst thing is to leave them sit.

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[tbird5866]

If you have hard starting on a warm engine after sitting 15 minutes or more, you may have fuel leaking from the carburetor into the intake manifold.

 

[boaterbob]

Okay I'll Check that. How about vapor locking, Is that possible?

 

[t-bird-art]

Vapor Lock is unlikely in Cold Winter. The Ford Carb on the 66 has a "Hot Idle Compensator" inside the carb designed to prevent vapor lock during Summer when it just gets too hot under the hood. Need correct gasket between carb & intake manifold . I have seen gas boil in the carb bowls because the insulating gasket was not right. FelPro Gaskets are right. After 15 minutes shut off, with engine OFF, look down the throat of the carb to see if it is wet ( with Gas) . Sometimes it is hard to see. A small strip of cardboard will soak up the Gas and you'll see a gas stain on the cardboard. ANY gas here means carb is leaking into Intake manifold. It should be dry as a bone.

 

[boaterbob]

If you have hard starting on a warm engine after sitting 15 minutes or more, you may have fuel leaking from the carburetor into the intake manifold.

Kind of a late post, To my hard starting problem. I fixed this in the Summer. It was the secondaries leaking into the manifold. Took off the rear tank and found the float to be stuck. Thanks for the info Harley.