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WHY ??

B67FSTB

B67FSTB

The NorCal dude from Belgium
Why doesn't my engine turn over when its hot ?
Is that due a bad starter solenoid ?
Or hasn't my starter not enough power because its hot ( although its not that old )
Its an old style starter but I am considering to change it to a mini stater. :confu
 
Could be too much advance timing, old or corroded ground or positive cables. Mini starters are the best!
 
Yep....a bit to advanced, a hot starter, and a so-so ground and you have a no start issue.
 
It is more than likely your starter, although it could be a weak battery, or over advanced timing. The old school sliding pole shoe starters are notorious for this problem, especially on big blocks. When they get hot they don't work well. Try retarding your ignition timing to around zero until you get a mini starter for it. That should help and be a temporary fix.
 
Do you have headers? I've found the stock large starters don't last long with hot headers. Even with stock exh. manifolds the starter internals will start to swell when hot, as it cools it can spin again.
Jon
 
Too much advance ? yeh , thats possible .
Headers ? Yeh , that too
Ground issues ? no way !! As an electrician , I know whats important .
Thanks for the directions.
 
Too much initial timing advance on a stock starter it sounds like. How much initial are you running and what compression ratio is your engine?
 
"6t9mach1" said:
Too much initial timing advance on a stock starter it sounds like. How much initial are you running and what compression ratio is your engine?
Click to expand...

Frankly , I have no clou of timing nor compression ratio.
I know, I know I should.
 
I'm confused. Why would advanced timing only be a factor with a HOT engine? I too have an old school starter with headers and the car starts great when cold, runs great hot or cold, but is slow cranking when the car is at normal operating temperature. I assumed that this was a starter issue, and that switching to a mini would cure the problem.......... :confu
 
"jmbour66" said:
I'm confused. Why would advanced timing only be a factor with a HOT engine? I too have an old school starter with headers and the car starts great when cold, runs great hot or cold, but is slow cranking when the car is at normal operating temperature. I assumed that this was a starter issue, and that switching to a mini would cure the problem.......... :confu
Click to expand...
Without any heat transfer, compression of a gas follows a set of laws that have to do with the relationship between the heat capacity at constant volume (pressure varies in a fixed volume as you change the temperature), and the heat capacity at constant temperature (pressure stays the same, but the volume is allowed to expand). The physics behind this is very involved.

There are formulas to figure out the pressure but it gets complicated.

Anyway, in reality, there are some troubles with this:

There is heat transfer between the air and the cylinder walls and it is significant. If you are dealing with a stone-cold engine, that heat transfer is going only one way ... out of the air and into the cylinder walls (that is if the temp is not the same). If you are dealing with a fully warmed up engine, then heat will be going into the intake air during the intake stroke and for the initial part of the compression stroke because the cylinder walls are at a higher temperature than the intake air (i.e. the intake air gets heated to higher than ambient). At low RPM (starting/cranking), the heat transfer is more significant than it is at high RPM because there is more time for it to happen.

So if the timing is significantly advanced and the temp (heat transfer) has increased the expansion or pressure, the engine essentially is trying to run backwards against the starter as it approaches TDC when it's hot (like a diesel more or less).

Also, from an electrical load standpoint (I'm not an electrician), I believe the resistance is higher in a high heat situation but I could be wrong about that. If that's true, the juice from the battery is not fully getting to the starter (amps). Someone correct me if I'm wrong on that!?!

I have a 429 with a stock starter, 10.5:1 CR 14* initial advance and headers. I also have a ground cables from the battery to chassis, engine to chassis and starter to chassis. Big ground cables. It helps.
 
FWIW
I finally got my mini torque starter and mounted it.
Will let you know if that solved the problem.
I must say that it sounds much better when cranking the engine. :thu :thu :thu
 

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