Topic: 1967 GT500 428 starts cold but not hot

[kkupec02]

My 1967 428 has always started well when cold, but lately has been giving me trouble starting when hot like in a gas station. I had a mechanic look at it and we changed out the old electronic distributor for a rebuilt original. The cam is not radical. I can get either a good running motor or a hot start but not both. When hot it gives the sound of a bad battery slow turn over. If it isn't the distributor/timing or the battery, maybe the starter is getting hot and old? Any thoughts? Thanks.

[Bob Gaines]

My 1967 428 has always started well when cold, but lately has been giving me trouble starting when hot like in a gas station. I had a mechanic look at it and we changed out the old electronic distributor for a rebuilt original. The cam is not radical. I can get either a good running motor or a hot start but not both. When hot it gives the sound of a bad battery slow turn over. If it isn't the distributor/timing or the battery, maybe the starter is getting hot and old? Any thoughts? Thanks.

That is referred to as big blockitis. It is something that is most typical on the big block engines in Mustangs.  It is caused by heat soak that effects the starter. This is caused by many things . Changing the timing can help the engine spin easier on start up but offsets performance. Headers cause excessive heat under the hood and transfer heat to the starter ,overbored engine causing additional heat. These are just some of the possible causes. The thinner stock battery cables do not help the struggling stock starter. Some have made up thicker some what stock looking cables that in some cases help but in others not. I think Mansfield sells a thicker set of cables that look some what stock.  If you want to eliminate the problem for sure switch the stock starter out for one of the gear reduced starters that are very affordable now compared to years past. https://www.summitracing.com/parts/pwm-9606/make/ford/model/mustang/year/1967    is one of many such alternatives . If that negatively effects your sensibilities you can also try but not as sure of a thing   one of the modified stock starters that the after market sells . https://www.summitracing.com/parts/pwm-3131/make/ford/model/mustang/year/1967  is the modified stock starter alternative. I sell as a hobby rebuilt starters detailed for concours and have had my rebuilder put heavy duty windings into some at extra cost to try and side step the starter drag issue. It turns out the results are a crap shoot. Helping on some and not making a difference on others.  I think that the different windings like I have had done is what the "high torque replacement" aftermarket starter has had done inside.

[Bob Gaines]

I should also mention that with the sure thing gear reduced starter you can use the factory concours correct battery cables with no ill effect. When I have helped others do the gear reduced starter change I have them paint the entire starter black so as to disguise it some. It is not a concours solution unless you are willing to take the deduction but is definitely gives piece of mind if you pleasure drive your car. Of course changing out a starter for a concours show is not that big of a chore.

[Keith Stem]

 A 428 take a lot of amps to start when hot. I had the same problem with my 68 CJ, it would turn over good and start when cold, but if it was hot, it would turn over very slow and was very difficult to start. The battery tested good for 12.5 volts, all the battery cables and starter cable tested good with no voltage drop under a load. I replaced the battery with an 850CCA battery and no more problems. It now starts hot just the same as cold. Check the voltage at the battery post under starting when cold and then compare that voltage to starting when hot. A large voltage difference would indicate a lack of the battery capacity. A new high CCA battery will solve that type of problem.

[rockhouse66]

If you suspect timing is causing the engine to turn over slowly when hot, simply pull the wire off the coil and see what happens.  It won't start, but will eliminate timing as the cause of the slow crank and help you pinpoint the issue.  My experience is that it is not timing related, but heat soak as others have said.

[Bob Gaines]

The gear reduced starter and its use of a smaller motor that takes less juice to turn because of its gear reduced drive is why it works perfectly well using the thinner factory battery cables.

[jwc66k]

It is normal for metallic parts to expand when heated.
Jim

[J_Speegle]

A fairly common problem especially with a fresh engine with a factory style starter

[kkupec02]

Thanks all. I'll have to do some checking and thinking this weekend. My car is a driver anyway.

[kkupec02]

Thanks Bob. I just ordered the 9606 starter and will put my original one aside so it stays with the car.

[kkupec02]

I got past the pesky upper starter bolt today with a 13" long 1/2"ratchet wrench from the top and installed a Summitt Racing gear reduced starter. The flywheel spins like crazy now and the car pops to life immediately. I haven't tried a hot start yet. I am a little worried though about the two #25 torx screws that allow you to move the starter housing around 360 degrees. The screws don't go into a designated hole so it looks like they just hold the housing in place by screw pressure on an interior plate? I never took the screws out totally. I probably should have for my own curiosity. I guess the 3 starter bolts are what actually holds the gear spindle in place in the starter so no real pressure is on the two torx screws.

[rustbucket]

it is possible that you have too much initial timing. Been there and done that with a few projects over the years.
If you bump down the initial timing a few degrees and it cures your problem, then you may want to re curve your distributor so you can get the total timing you want