hey guys, i haven't been here in a while. but here goes.

the car will not start when it gets hot. the engine will barely turn over. it restarts perfectly when it cools down for about 15 mins.

the problem started when a installed my 406 10.5 to 1 comp, fast burn headed, mini ram motor. i never had this problem with my stock tpi engine, even with full length coated hooker headers that i re used when i put my 406.

heres what i have done so far to fix the problem.

-removed the full length headers and installed stock exhaust manifolds and y pipe.

-put in a ford style remote solenoid.

-switched out the stock starter and put in a high torque ministarter from summit racing.

-put in a one gauge thick wire going from the battery to the starter

-retarded the timing to 0 degrees.

-cleaned all grounds and added an extra ground from the chassis to the battery.

-the battery is new, and i had it checked at kragens and auto zone.

after all this, the car still not start when it's hot. however. before all these modifications the car would need about half an hour to start. now it takes about fifteen minutes to start. the car runs excellent and has a ton of power, no stalling issues, no issues what so ever.

the car starts perfectly in morning.

i also tried to disconnect the main power line going to the dizzy when it does not want to start and it did not do anything, remained the same.

im really out of ideas now and do not know what to do next other than put in the stock engine and see if this helps. what do you guys think it is?

 

!) piston skirt clearance ? (forged/hyper/cast, mfr ?)

2) motor oil brand/vis ? (hope it's not 50w glue)

 

oil is 10/30 penzoil, i did not check piston to skirt clearance.

pistons are hyperutectic, engine was bored 20 over, moly rings. stock crank and rods.

 

are you saying the car turns over slowly or what?

 

machinist that punched the block 'should have' checked both piston mfr recommended clear before starting work and actual clearance when done...check with him and watch his eye reaction when you tell him it won't crank good when hot.

to help i.d. the gremblin, i would check torque reqd to turn engine over cold and hot using a torque wrench on the harmonic balancer retainer bolt (pita to get in there re socket/wrench length)... spark plugs should all be out to avoid over-tightening harmonic bolt.

might try 'cutting the mica' on your oem starter armature to add guts to it (typ 25-50%)...check with any local elec motor service shop or ask an 'old timer' electrician for details, ez DIY.

 

Next time the motor is warm, remove the spark plugs and turn the motor over by putting a socket over the balancer bolt and turning it with a large torque wrench or breaker bar. If it is hard to turn, then your problems are mechanical, possibly piston-wall clearance minimal. If the motor turns easily, it's still probably electrical, or a bad starter .

 

i had this very same problem with a 301 Pontiac engine on a 1981 TTA
we've done everything to repair it...its been 12 years and always have that problem !!!

 

it was the battery.

i pretty much replaced everything related to the starting system.

even though the stock battery is in perfect working condition, it simply did not have enough cranking amps. the stock battery was rated at 530 cranking amps. i replace it with an optima with 1000 cranking amps.

i discovered this one day when i was looking at the battery in my 66 buick gs and i noticed that this battery had 630 cranking amps.

anyway, since then, i have have removed the ford style remote mount solenoid, reinstalled my full length headers and exhaust, and advanced the timing again. so far so good.

the optima is a 34/78 style and is a little larger than the stock corvette battery. it required moving the a few cables to make it fit. the guy at the battery store was trying to convince me that i should buy the smaller optima to ensure that it will fit in the stock location. the downside to buying this optima is that is does not have the 1000 cranking amp rating. so i said no, and that i will make the 34/78 fit. i had already tested and measured to see if the battery was capable of fitting.

this has been a two year ordeal and i'm glad it's finally over.

 

Removed

 

While a new bigger battery fixed your hot crank problem, I doubt a higher CCA battery was really the fix. You likely had a battery that was near the end of its life and had higher than normal internal resistance. One reason batteries have low CCA is from letting them sit for long periods. Batteries self discharge even disconnected and collect lead sulphate on their plates. If charged right away the lead sulphate converts to lead and sulfuric acid. If left sitting the lead sulphate becomes hard and is a good insulator and won't convert to lead etc when charged and you then have an electrically smaller battery. Never leave batteries sit doing nothing for long periods (4+ wks). Always use a battery tender. If you run a battery down, charge it back up as soon as possible. One way you can test a battery is to measure its voltage at the battery terminals during cranking. It should not fall below 9.0 volts or it is discharged, battery terminals need cleaning or the battery is at the end of its life.

 

you know, the car would sit for long months at time while i was trying to figure out what was wrong with it. i removed the old battery twice to have it checked at two different places and both places said it was good. my old battery was less than a year old as well. sometimes when i would not start the car for while, the battery needed to get recharged because it would not turn over at all. remember too that this problem started when i dropped my hot 406 engine. it was starting fine before the 406 and it was the same battery, however, it did sit for few months before i finished the engine installation.

my next mod will be a battery tender.

 

I didn't read about anything about you changing the ground cables. Just the pos cable going to the starter. If you did change the ground cable all well and good. If you didn't you might want to look there for a problem. Doesn't seem like you would need a 1000 amp battery to turn over a 10.5 engine unless you were covering up another problem.

Moon