Hot Starting Problem…solved

[Pat Landymore]

Ever since I completed my 35 kit I’ve occasionally had a hot starting problem, or more correctly stated a “when hot the truck won’t crank at all” problem.

For a while I thought it was my garden tractor battery so changed that to an Odyessy 925 type. Then thought it was heat soak in the starter. Recently had the truck out with my side dump exhaust installed (which is a foot away) and it wouldn’t crank…yet I could hold my bare hand on the starter so know that wasn’t the issue.

Have researched the amperage draw of the solenoid for the typical mini starter I’m using..only to find estimates anywhere from the usual 10 Amps, to folks that have done their homework and are claiming 30+ Amps initially.

Anyone that is using the supplied harness, especially if they are using an aftermarket automatic shifter with those tiny micro switches for neutral safety, know that those switches are sketchy at 5 amps…let alone anything more. Personally I’ll suggest the small diameter of the light blue wire for that circuit in the kit harness isn’t good for much more without significant voltage drop.

My solution was to mount a secondary relay right down at the starter…the typical auto parts store cube type supplied with a connector and pig tail wires. Now the truck harness wiring is only carrying less than an amp and the truck hasn’t missed a start yet…even when over 200 degrees.

Please note: this solution is only applicable to those running a legacy SBC, SBF or similar engine. The GM E-Rod or Ford Coyote Hot Rod packages will no doubt already have an intermediate relay built into the supplied wiring harness.

A photo of installation including 35 Amp fuse between battery post on solenoid and the relay.

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[first time builder]

Im glad that worked for you, we have a small block 427 with a Mini starter, Have a hot start condition that will crank but slowly then go to normal and the engine will start. Timming is correct. Have a heat shield blanket on starter, Have checked all grounds. Have installed the "ford " seperate solenoid kit. Still same problem . Have a brand new Red top. Only thing havent tried is replacing the starter. Anybody see what Im missing. ?

[Pat Landymore]

My suggestion is to get it good and hot so you’re certain when you turn it off and attempt a restart the condition will be there.

Shut it off, pull the coil wire (or otherwise disable ignition) and try cranking. If it cranks normally, somehow timing is fighting the starter.

If the cranking issue exists, then I’m thinking either battery wiring or the solenoid on the starter itself. Or are you running a battery cut off switch? Could be it has additional resistance(voltage drop) helping to cause your starting situation.

That’s the best I can offer.
Cheers

[first time builder]

I will try the coil idea, but I dont think thats it we have tried playing with timming with no results. We have already used the on starter solenoid jumper with a remote solenoid. Can try bypass remote switch but cant see that as a hot start thing.
Thanks for the ideas.