1970 Charger Heat Soak Issue

[bad88t-top]

Hi guys, I'm experiencing a heat soak issue with my freshly restored 1970 Charger R/T. She fires right up when cold. If you drive it in stop/go traffic for 15 minutes and shut it off, she barely cranks. If you let it sit for 10 minutes she'll fire right up. I noticed the negative battery cable that's grounded to the intake bolt and radiator support gets pretty limp when trying to start it when hot. Battery is a brand new reproduction that measures 12.7V when it's unhooked. 1970 B bodies only had these 2 ground points and none of my other 70's have this problem. I'm open to ideas and thanks in advance. Bill

[John_Kunkel]

Have you checked the battery voltage while it's cranking?

[bad88t-top]

I have not.   Are you saying check the battery voltage when you try to crank the engine to start?

[b5blue]

I bought a repop positive cable that had a bad crimp on the battery end. Made me crazy chasing the issue till I found it. Do not assume new parts are good, test! Removed cable and set on 2X4, 2 wacks with a hammer on the crimp and fixed.

[JR]

I would put a volt meter directly on the starter lugs when cranking to make sure it's getting the full 12.7 volts next.

[Bronzedodge]

Many times on a fresh build the paint is preventing a good connection, results in resistance, which results in higher amp draw.  Check under ALL the grounds.

[RSI700VIPER]

If it starts fine when cold or after a 10 minute rest, then I don't think it's a grounding issue.  Sound's more like a start issue to me, especially if you are getting 12 volts to the starter like others have mentioned.  The exhaust is very close to starter windings as you know, so a marginal starter will crap out when it gets hot. 

[70sixpkrt]

Nice car.

[John_Kunkel]

I have not.   Are you saying check the battery voltage when you try to crank the engine to start?

Yes, check the voltage while cranking the hot engine. It shouldn't drop below 9-10 volts. Then try it again with the ignition disabled.

[MGBRingo]

I would make sure ground is good and then replace the starter. 

[Kern Dog]

That is a sharp looking car though. It sucks to have troubles with any car but it is worse with great looking cars.

[BrianShaughnessy]

What you're describing is reminiscent of what used to happen on old Pontiacs with a rusty ground cable to the head.   Star washers work wonders.

Try hooking up a jumper cable from the battery to the engine block to test your cable theory.   Otherwise I suspect you're using the stock boat anchor starter and not the Dakota / mini starter ? 

Member Rick Keesler was making nice heavy duty battery cables awhile ago.   I got 2 sets but the last was like 10 years ago.      

[Stringbender]

I had exactly the same issue last year when I got my car running. Starter side of the engine wiring harness had barely come unclipped from the bulkhead. Was making enough contact to start cold no problem, once "Hot" not so much. I'd check that first, Wish I had! P. S. Gorgeous Car!!

[Moparpoolman]

solve problem yet? curious what it was

[AKcharger]

If that was rebuilt STOCK I'm betting your issue is Vapor lock in the carb, it's what happened to my '70 as well.  I replaced my intake gaskets and used a carb cooler fixed it! the problem is fuel today is hotter than the '70's

1st try this:
1) http://www.coolcarb.com/   That Should fix it. If it improves but still isn't quite right  swap out your intake manifold gaskets and block off the heat riser which I'm betting you aren't using

guys what's that part # for the intake gaskets?