Hot Start Problem
 

This is probbaly old hat to some of you but my engine just won't crank over when it's hot. I have a 351W rebuilt to 427, roller cam, 11:1 compression, etc. MSD ignition & Pro Billet distributor. It starts just fine when cold. But when it's hot, it only gives me an "r" then nothing. I push started it last night and it ran fine. And after sitting in my garage for about an hour it started without a problem.

I have a brand new starter from Sumitt and I wired it like the instructions said. That is, bypass the Ford solenoid that I put on the firewall.

Any ideas?

Dave

Wherehave you got your initial timing set? Mine (10.7:1) has cranked fine everywhere from the current 13-14 BTDC all the way to 19-20 BTDC. I have the firewall solenoid hooked up, with a jumper wire from the battery terminal on the starter to the starter solenoid terminal.

I had the same hot start trouble with my 418 stroker until I installed a Ford Racing hi-torq starter last year. Noooo problems since. Timing is set at 18 degrees initial, 10.25:1 CR 220 lbs cranking pressure.

Before all these fancy electronic devises to retard timing while starting we just flooded the engine a bit. Pump throttle pedal 2 or 3 times (with key on for injected engines) then start her up.
A flooded engine will not try to start until it purges excess fuel and this allows cranking RPM to increase without load of firing agianst starter.
If starter is just bad and dragging then replace starter and your off and running. Amp check of cranking amps should be below 100 amps on most, if up to 200 or more she is JUNK !

Hi torque starter is good, 20 deg start retard is good and sometimes it could be the battery cable is too small. Should be 0 or 1 gauge.

Roscoe

I have the high torque starter and also I don't use the solenoid. I also have my starter shielded from any header heat and have never once had it even grunt when starting hot. You could possibly have a heat problem if the headers are close to it.

Ron

I would agree with the heat problem being the main culprit; otherwise, why does it perform well when cold and not well when hot? The starter is acting like a heat sink for all the header heat.

Older Corvettes we used to work on had the same trouble if the performance headers were too close.

Run a cable from the negative side of your battery to one of your starter mounting bolts, I'll bet that will cure your problem.

Poor starter ground will cause the hot start problem you have described

If your car starts fine when cold but not when hot, then it most likely is boiling the fuel in the Carburetor or vapor locking. My 514 did the same thing. Good fix is put a heat insulator under the carburetor which keeps the fuel cooler. You can buy them through Jegs or Summit. They also make aluminum heat disapaters (Mr. Gasket) that are real thin with gaskets so you can put 2, 3, 4 .......together for the hood clearance you need to consider. I have done this on all the Cobras I have had and never had a "Hot Start" concern since and I live in Dallas where it get's Hot!

P.S. If you click on my gallery you can actually see the Mr. Gasket spaces on the 514 Engine Pic (close up shot) in the Royal Blue SPF. I had them on the 427 small block stroker (638 HP) in the Black/Gold SPF also.............

Now that I said all this and read some replies I guess I did not read your post very well and missed not cranking. Sorry I missed that as this "Hot Start Solution" is when it cranks fine but does not start. I'd also try the negative battery cable solution and starter!

It sounds to me, based upon your statement that when hot the engine is reluctant to turn over and makes a single or slow "rrr" sound that one of two things is going on...

1) you can discount fuel as this has nothing to do with the hot engine turning over. The fuel system is separate and would not balk the engine up at all.

2) A cast iron block is thermo-filic or absorbes heat. That said, a new or tight engine that has close tollerances will expand when hot and tighten the clearances. Thus the moving mechanism (Crank, valve train and cylinders) will offer greater resistance to the starter when hot and expanded.

3) The starter will then have a harder time turning over the tighter engine when hot. A borderline maximum advanced timing will just make this worse. This is quite common with higher compression engines that are new and not broken in. Is this your case?

So the fix is....

1) Make sure your power to the starter is up to snuff. The windings can prematurely age with heat. Perhaps put a heat shield on the starter.

2) Perhaps slightly back off on your ignition advance towards retarding the ignition. Reason I say this is that the ignition is probably the culprit being just slighly over advanced. This would cause hard starting when HOT. The FE is a counter rotating engine (anti-clockwise). You should scribe a mark on the distributor body and then carry this line onto your intake manifold. This will be a reference line for your current ingnition setting. You can then loosen the bolt for your distributor and turn the distributor CLOCKWISE (right) (to retard) so that the amount of turn is just one line width or about 1 or 2 degrees. This may solve the problem. Make sure to then tighten the distributor lock bolt. You can always go back to the old setting by aligning the marks. This should do it. This is a trial and error type of adjustment. Note: moving the distributor counterclockwise would ADVANCE the timing.

FWIW, I sometime have this same problem in really hot days in the summer. However, this does not happen to me in the cold of winter.

Hope this helps?

Vapor locking? If it was vapor locking it would still crank fine, It's sounds like the motor is not cranking when hot.

Sell it and buy a Toyota.

Hot start
 

Dave,
I had the exact same problem as you with a slow crank or no crank when hot.
The problem fix for me was the same as Peter Wolf's.
My battery negative went from battery to frame to engine block.
I ran an extra negative from the battery directly to a starter mounting bolt and have had no more hot start problems.
And there was nothing else done to the car eg. timing changes etc.
Regards,
Bryan Wilson

Like Roscoe said get a Powermaster starter with the highest torque rating, inst all a 20 degree retarder from MSD and make sure all of your cable connections are tight and your problems will be solved. -Bob

Thanks for all your input. At the moment, however, I have a broken rocker stud. After I fix that, I'll work on the hot start solutions you've suggested.

Dave

Dave,

I stated in one of my posts that a 20 degree retard may help. I think that these were really meant for distributors with a locked mechanical advance and should not be necessary with a centrifigal style of distributor. If too much ignition lead is the problem you can just adjust more mechanical advance into you distributor and run less static lead. -Bob

I had the same problem with my 351W--drove me crazy. I had to wait at least 10 minutes to restart every time the motor was hot. Replaced the starter with a rebuilt OEM starter--no improvement. I finally got rid of the problem, but I'm not sure which of the four things I did was the fix. All four probably contributed.

1) high torque starter (smaller than OEM and thus farther from the headers as well as more powerful)
2) heat wrap for the starter
3) heat wrap for the headers
4) optima battery with 975 amps (or something like that)

I no longer have any problem whatsoever. Total cost was around $600, but it sure is worth it not to have to listen to all that static from the other guys. Just swallow hard and write the checks.:cool:

Allen,

Heat problems have been one of the biggest hot start problems we have had around here. I had to get a high torque starter anyway when I built mine as the stock starter wouldn't turn it over after it ran for about 5 minutes. Then I put heat shield around the starter area and have never had a problem since.

Ron :)

I understand this is a common problem with big blocks, Ford and Chevy. On my top oiler, I had 1 guage cables and a high torque starter. What solved it was an MSD box that retards at start time. I even went with a stock starter which I found to be better than a mini-torque one.

To me , it sounds like your car is just a bad starter , but I don't know for sure

Just so you know , the timming re-tard box is for race engines with no centrifical advance , this is where the timming pick up is on the flywheel . There cars initial timming is full advance .

I just fixed my hard start when hot problem with 1/0 ga. and a optima battery , I always had a tildon hi tork starter . 10.7 to 1 , 17 -36

John