Hot Start Issue

[BDK]

OK Guys, need some help here. Have a newly rebuilt 351C with Edelbrock intake, Holley 600CFM with vacuum advance and electric choke, roller cam, roller rockers, 9.5:1 comp. Pertronix Ignitor I, and bored .030 over.

My Issue: Car will start wonderfully when cold, quick 2 presses and then she is off and running. Let her warm up and have normal operating temp and then shut off. Try and start when hot/warm she attempts to crank but really problematic, hardly turns over and jerky.

What I have done: I'm not a pro at carb tuning, or timing for that matter, and have used a vacuum gauge to set the timing. Pulling about 15" at 1250 RPM and adjusted the idle mixture screws to just start having the engine die then backing off about 1/8 to 1/4 turn. Idles well now and all is good until I shut her off, then the restart is an endeavor. I've replaced the Ford coil with a Pertronix Flamethrower coil, replaced plug wires, replaced plugs, covered the starter with a heat shield blanket all with no change to the issue. The other slight issue (not sure if related) is when I floor it she hesitates for a second and then takes off. I've replaced the accelerator pump nozzle by jumping up 3 sizes (Holley recommended) but no difference here as well.

Really in a bind and hate to keep throwing parts at an issue that is kicking my butt. Any clues? Could the Pertronix be bad, why would it start fine when cold if so?

ANY help is greatly appreciated.....

BDK

 

[timsweet]

To you have the Pertronix chip under the distributor cap or the points and condenser.

I did have trouble with Pertronix chip and a similar starting issue. The chip actually shorted out!!!

 

[BDK]

To you have the Pertronix chip under the distributor cap or the points and condenser.

I did have trouble with Pertronix chip and a similar starting issue. The chip actually shorted out!!!

Tim,

Ignitor I module is under the dist. cap....When yours shorted out did it still cold start OK??

BDK

 

[barnett468]

put the other pump nozzle on it.

set the gas level so it is just below the inspection hole at idle or 1/4 way up the clear window at idle.

disconnect and plug your vacuum advance hose.

if it still does it, retard the timing 3 degrees.

 

[BDK]

put the other pump nozzle on it.

set the gas level so it is just below the inspection hole at idle or 1/4 way up the clear window at idle.

disconnect and plug your vacuum advance hose.

if it still does it, retard the timing 3 degrees.

The carb is a brand new, so you think it may be a fuel starvation issue? How would that affect cranking over the engine? It's the cranking that is extremely difficult. As I crank I can see the atomization of the fuel around the carb (slight mist or cloud) so it seems there is fuel but without the car turning over maybe a spark issue.....not sure, just thinking out loud.

 

[digithead]

do mean cranking hard as in its not even turning over at proper speed? Could it be a starter motor issue when the starter is really hot?

 

[Don C]

do mean cranking hard as in its not even turning over at proper speed? Could it be a starter motor issue when the starter is really hot?

+1, we need a better explanation. Does the starter turn the engine at normal speed when cranking but it won't start? Or does it crank slowly, or not at all sometimes?

 

[73pony]

I had the issue of it cranking over very slowly when trying to start it hot. The problem started after I installed headers. I have since switched over to a T-5 trans and as part of that project installed a gear reduction starter that is much smaller and leaves a larger gap between the headers and starter. I have not had the issue since so in my case I am assuming it was the starter getting too hot from the exhaust.

 

[TommyK]

Try and start when hot/warm she attempts to crank but really problematic, hardly turns over and jerky.


BDK

This sounds like a starter heat soak issue, a grounding/connection issue or perhaps a little too much initial timing or a combination of any or all of the above.

 

[barnett468]

put the other pump nozzle on it.

set the gas level so it is just below the inspection hole at idle or 1/4 way up the clear window at idle.

disconnect and plug your vacuum advance hose.

if it still does it, retard the timing 3 degrees.

The carb is a brand new, so you think it may be a fuel starvation issue? How would that affect cranking over the engine? It's the cranking that is extremely difficult. As I crank I can see the atomization of the fuel around the carb (slight mist or cloud) so it seems there is fuel but without the car turning over maybe a spark issue.....not sure, just thinking out loud.

do everything i said then see what happens.

you can also remove the coil wire and turn it over the next time it does this and see if it starts easier.

 

[BDK]

put the other pump nozzle on it.

set the gas level so it is just below the inspection hole at idle or 1/4 way up the clear window at idle.

disconnect and plug your vacuum advance hose.

if it still does it, retard the timing 3 degrees.

The carb is a brand new, so you think it may be a fuel starvation issue? How would that affect cranking over the engine? It's the cranking that is extremely difficult. As I crank I can see the atomization of the fuel around the carb (slight mist or cloud) so it seems there is fuel but without the car turning over maybe a spark issue.....not sure, just thinking out loud.

do everything i said then see what happens.

you can also remove the coil wire and turn it over the next time it does this and see if it starts easier.

Barnett, Will try what you suggested and see what happens this weekend. As for the starting issue it does not crank properly. Hit or miss with the starting as in cranking very difficult and not spinning correctly. I thought about the heat soak issue that is why I wrapped the starter in the heat blanket...never made a difference....

BDK

 

[barnett468]

i know what you are talking about.

 

[Don C]

A hot starter draws more current than a cold one. It could be battery cables, cable between solenoid and starter, engine grounding, or solenoid. The cables can look OK but be corroded inside of the connector or insulation. The starter may be bad. Too much timing can keep a hot engine with a weak starter or low voltage from turning over correctly.

A few days ago another member had starter issues, turned out to be a bad ground cable.

 

[BDK]

So tried a few items, unplugging the coil allowed the engine to crank over just fine....EVEN when hot. My assumption is that this rules out the ground, starter and cable concerns or am I wrong?

The timing is a bit trickier, advancing or retarding did not seem to make any HUGE differences but a bit better when retarded. However, my timing is VERY finicky. A slight movement seems to throw it off quite a bit. Will do more testing tomorrow but wanted to report back to see if anyone had more ideas?

BDK

 

[barnett468]

So tried a few items, unplugging the coil allowed the engine to crank over just fine....EVEN when hot. My assumption is that this rules out the ground, starter and cable concerns or am I wrong?

The timing is a bit trickier, advancing or retarding did not seem to make any HUGE differences but a bit better when retarded. However, my timing is VERY finicky. A slight movement seems to throw it off quite a bit. Will do more testing tomorrow but wanted to report back to see if anyone had more ideas?

BDK

you are getting way ahead of things.

do what i suggested.

after you do what i suggested, we will know what you should do next.

it sounds like the timing is at least part of your problem . if it is, you may need to buy a timing retard box so it retards the timing when you start the car . i think msd sells them . i can tell you how to set it up.

how many degrees did you retard the timing to start it when hot?

you may need to retard it more and see if it is even better.

 

[BDK]

So tried a few items, unplugging the coil allowed the engine to crank over just fine....EVEN when hot. My assumption is that this rules out the ground, starter and cable concerns or am I wrong?

The timing is a bit trickier, advancing or retarding did not seem to make any HUGE differences but a bit better when retarded. However, my timing is VERY finicky. A slight movement seems to throw it off quite a bit. Will do more testing tomorrow but wanted to report back to see if anyone had more ideas?

BDK

you are getting way ahead of things.

do what i suggested.

after you do what i suggested, we will know what you should do next.

it sounds like the timing is at least part of your problem . if it is, you may need to buy a timing retard box so it retards the timing when you start the car . i think msd sells them . i can tell you how to set it up.

how many degrees did you retard the timing to start it when hot?

you may need to retard it more and see if it is even better.

Sorry, just trying a few quick items. I replaced the nozzle to the original (#31), and checked the fuel level as it is just below the inspection hole (but didn't do this while the car was running) was just a quick check so will do that today. Not sure how many degrees I retarded the timing as I am using a vacuum gauge and not sure how many degrees of retard equates to inches of vacuum?? very new at this......

Really hope I don't have to use any retard controllers as I don't want the MSD or other big ugly boxes in the engine bay. Since I am running the Pertronix ignitor do you think this may be a contributing factor in the issue?

BDK

 

[TommyK]

With all due respect, if you don't have a timing light you need to beg, borrow or steal one because the first step here is to know what your initial timing is.

 

[Don C]

With all due respect, if you don't have a timing light you need to beg, borrow or steal one because the first step here is to know what your initial timing is.

+1, there are too many variables to time by vacuum, alone, including carburetor setup, camshaft, and possible vacuum leaks. Trying to time by vacuum alone will try to compensate for other problems and wind up with the timing way off.

 

[barnett468]

what they said.

checking the gas level after the car has been sitting is not accurate.

AFTER you do some more retard tests you really need to set the idle timing so it just reaches the highest idle as you turn the distributor then tell us where it is, but this requires good ears and some practice . using a tach is helpful for this.

once you have this setting, you need to determine the best timing at around 2500 rpm.

after you have done the gas level and have your timing set to the optimum level for idle and have cleaned the cable connections, especially the ground where it mounts to the engine etc, if it still turns over slowly when hot, you can set the timing to 6 degrees btdc and see if that makes a bif change . if it does test this a few times and if it continually starts ok, that setting will be ok . you then buy the timing retard box and set the timing where it idles best then subtract the timing number where it starts best from the other number then install the chip that retards the timing that amount during starting.

the msd timing retard box is only around 2" x 2" and you can install it inside the car.

i can also tell you that if you dont have the mini starter wired properly, you can have starting problems.

.