Hard/Slow Crank When Hot

A lot of times when the engine is replaced, paint is different and there is more of it where the battery cable connections are made, making for higher resistance. I had this problem on my '70 Chevy truck, even with a high torque mini-starter, new battery and new cables. I cleaned all the paint away from the connection points, and ran the ground cable all the way to one of the the starter bolts, instead of the block by the fuel pump. I used #4 copper battery cables, as well. Problem solved.

 

You should also check to make sure your alternator is charging. Battery may have enough power to start the car
and idle, but while the car is idling it could be running the battery down. Alternator should put out 14-14.5 volts.

 

Any changes to timing?

From day 1?
I guess I read that as a change from the last engine. See how that conflicts?
May also need to check that the distributor isn't stuck advanced. That happens often.

Every response has been valid so far.
I see a lot of new engines installed where the owners bolt the Bat cable to a painted surface, as mentioned already.

 

To add- a fully charged battery is 12.6 Volts. At 12.35, that battery is pretty seriously low on charge already. Also, absolute minimum charging voltage is 13.5 Volts. 14-14.5 is fine, but not the minimum.

 

Thanks for the continued support.

No changes were made to the timing by me after the new engine was installed. That's what I was trying to convey.

 

^^ Thanks Larry, that's what I was trying to convey

I suppose random responses from the internet are frustrating.
Just gotta start from one end of the problem and work your way through.

 

Battery good? - Check

Timing not advanced? - Check

Then, perform a voltage drop test.

This will show if you have excessive current draw and bad grounds.

The slow crank problem is always worse when the engine is hot.

If the grounds are not clean and tight, the starter will not be able to get full current.

 

It's written on the build sheet, which I don't have with me right now.

And no, I don't know what the actual timing is...as I don't even own a timing light (yet). But I will...soon.

 

Thanks again. I'm not frustrated at all, I guess I just didn't fully understand at first. I sincerely appreciate all of the responses!

 

Got this light...

http://shop.advanceautoparts.com/p/...ght-cp7529/9090011-P?searchTerm=timing+light#

Got $40 off.

 

Ok, initial timing is slightly lower (more retarded) than it should be. It reads at 10.0 degrees...

Upon very first start, it was closer to 12 degrees, but once the engine warmed up closer to normal operating temp, it settled in at 10. I first checked it by simply reading the mark on the timing tab...which was approximately 10. I confirmed/verified this by dialing the light up until the mark was steady at 0 on the timing tab, point at which my light read 10.0.

Just for the sake of checking, my timing curve is as follows:

DEG/RPM
15/1600
20/2200
25/2700
30/2950
32/3100

The dial-back timing was very easy to use. The built in tachometer really was useful, seeing as though my car doesn't have a tach. I was able to get these readings by myself.

In park, it idles at approx 810-850. In drive, approximately 650.


So if I am understanding correctly, overly ADVANCED timing can/will cause hot start issues? correct? My timing is NOT advanced, as the initial advance is only set at 10 degrees. Should I adjust my distributor to have my initial advance set at 12?


And just for the record, vacuum advance was plugged.

 

It does. At 34 degrees it read around 3450. Couldn't recall for sure because I didn't write it down.

The battery is charging now. I'll hopefully revisit tomorrow. (I don't keep the car at home.)

 

Sounds like you have eliminated overly advanced or stuck advanced condition. Good work!

 

Similar symptoms to a couple motors I repaired for some customers. Went thru all you have, then disassembled the top end and removed cam, the front cam journal was toast. When cold it had no problems, but when hot barely turned over. Hopefully this isn't the issue, just thought I'd throw it out there.
gary

 

I hope you are running 93 octane....does it spark knock when trying to start hot?

 

A battery has to be fully charged to test. Charge it until it reads 12.6v. If it doesn't read 12.6 after charging, battery is no good. How did they come up with 500 cca? When testing a battery, your'e testing for voltage, not amperage. It needs to be load tested at 1/2 the cca for 15 seconds. The voltage shouldn't drop below 9.6v. Also, batteries can take up to 24 hours to fully charge at a slow rate, which is the preferred way to charge a battery.