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Rebuilt 440 engine in a 70 Road Runner, mostly stock. Engine fires up immediately when cold, but after warming up (10-15min) will crank slow making restart difficult. ETCG starter vid didn’t directly address this issue. Tried different batteries, swapped voltage regulator, alternator dynamic tested OK at 60amps. Stock Chrysler starter, rebuilt and tested before installed. Cables all new. Battery at 12.7v, dips to approx 8v when warm starting (hard to determine precisely without min/max on VOM). Once started, batt volts at 14.5v.
Suggestions?
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My first thought based on the temperature as a variable in this case, would be “temperature induced” resistance in the starting circuit.
There are things that can create (unwanted) resistance in a circuit:
- The material of the conductor used (number of free valence electrons)
- The gauge (size) of the wire
- Corrosion (electrolysis, galvanization, or oxidation)
- Quality of connection
- High temperature
Q: are your starter wires close to the engine block or exhaust manifold or something really hot..?
Also, go down to autozone and see if they can perform a ‘starter amperage draw test:’
Typical results:
Voltage should not go below 10 volts. Amperage or current draw varies depending on engine size and compression. A four cylinder gasoline engine does not require as much current draw as a six or eight cylinder engine does. A typical four cylinder engine requires 150-170 amps. A six cylinder requires 200-220 amps and an eight cylinder even more requiring around 240-270 amps.
Anything above the aforementioned stated criteria might result in excessive heat in the starter circuit.
One test that I would perform on the starting circuit would be ‘voltage drop:
starter circuit voltage drop test at 9:37 on the following video:
Thx for the suggestions. On 440s the starter sits below the left manifold, the wires run down the inner fender, not really too close to the manifold.
I’ll do the starter test and voltage drop tests. Another interesting aspect of this was the 440 was broken in on a test stand and didn’t have the warm cranking problem.
I just seen the results of your testing. The battery should not drop below 9.6 volts after cranking as per ASE standard.
Get that battery charged and tested and see how it goes.
Q: what CCA battery does your rebuilt engine/starter call for..? are you using the correct battery for your application?
Being that it is fresh rebuild means the starter is going to have to fight some pretty hefty compression. My instructor used to tell us stories of how these old cars with big block engines often experienced problems with getting them to turn over sometimes because the starter could not beat the compression of these monster V8’s. I think he said he had to bump the starter a couple of times before giving it full starting power.
One possible solution could be to wire an additional battery in parallel not series to get twice the amperage (but still the same voltage.) Or, the simple solution of course is to just replace your existing battery a higher amperage battery.
did you crank up the compression ? if so you may need a high output starter. are you running headers ? if so you may be ” heat soaking ” the starter solenoid. a starter wrap and or header wrap will cure that prob.
No problemo. The 8v “reading” is ambiguous at best. VOM was jumping around. I need to find one with a storage (min/max) feature. Autozone can probably test it also.
[quote=”619DioFan” post=50651]did you crank up the compression ? if so you may need a high output starter. are you running headers ? if so you may be ” heat soaking ” the starter solenoid. a starter wrap and or header wrap will cure that prob.[/quote]
no headers, compression is 10:1, base timing at 19deg; the base timing may have an effect here, but it won’t idle or run right without that much base (its a 6 pack)
as to heat soaking, it is definitely heat related, perhaps ignition or starter contacts
I cant see it being the battery as it starts fine cold. 2 things I know usually cause this is heat soak (like previously said) and fuel dribble. Easy way to see which one, warm it up normal and shut it off immediately restart, if it starts fine it is probably fuel, if it struggles then probably heat soak. Not sure what ignition system you have but distriburtor advance weights can get stuck out and do it too then overnight work back in place but that is rare.
19deg; the base timing Is WAY to much. Built many 440 six packs and ran them at 8 to 12deg base timing
First off when its hard starting try dropping the timing a bit back and see if it will turn over any better and if that does not work you have a bad starterI agree, it is too much base timing, but it won’t idle below 18-19deg. I’m idling on the transition circuit – have tried everything to get to “square”, except drilling the center butterflies. Leaving that as last resort. Been thinking about going to one of the new high torque mini-starters to see if that helps.
I agree with the timing is a bit too high,also go with the biggest gauge wires you can to the starter.
I had several big blocks that would crank poorly with a hot engine,mostly a timing issue,allthough I live at 6000′ not sea level.I agree on the base timing. That may be contributing to the hard starting. That car was never designed to run on modern gas. As a result I find that making an older car like that a little rich helps a lot. Less timing and a little more gas might help.
I have something else that might help you. I had a similar problem on my Ford with a 429. It would crank slow when hot. I finally came to the conclusion that the starter may be getting ‘cooked’ by the exhaust during hot soak. My thought was to place a metal shield over the starter to help keep some of the heat away. This is something you might want to consider because the heat will cause increased resistance in the starter windings. Especially on a ‘fresh’ engine the starter has to work a little harder and you want to give it every advantage.
Keep us posted.
I believe there are several things working against me…2 of them you mentioned. The necessary base timing and heat soak. Using the original starter, even tho rebuilt, probably makes it more susceptible to heat soak. I’ve picked up a new, higher torque, starter that a lot of guys are using on these cars. Gonna try the new starter and see what happens. If it starts when warm, probably means the orig starter, even tho rebuilt, is overmatched by the base timing, heat, and tight engine tolerances.
It can’t be base timing or it would be hard starting cold too. Heat soak is still my best guess, if you get a high torque starter or even reuse the old one get heat tape or a shield. It will help it anyways. I would get the heat tape and try that first, it will probably fix it and it is cheap.
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