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sbc 350 cranks slow when hot

57K views 24 replies 10 participants last post by  the82elco 
#1 · (Edited)
:mad::mad:my car starts fine when its cold but after i drive it for about 10 mins it cranks over slow like the battery is dying & will not start. if i wait for a lil bit it will start back up. will a remote solenoid held this problem?
 
#4 ·
Heat soak is a common Chevy problem especially with headers. You can get a variety of after market heat shields and thermo wrap. These generally cost around $30 and are easy to install. Since the solenoid actually a magnet that engages the starter to the flywheel you can't remove it. Fords work differently and I've never seen a ford type starter with a separate relay that is made for Chevrolet.
 
#7 ·
That is just a mid seventies ford starter solenoid. You can get that at autozone.

I had that problem many times in the past. Starts well cold then turns slowly when hot. And every time it was the battery. I have done new cables, new starters, ford solenoid conversions trying to fix the problem, but never fixed it. I say get new battery.
 
#8 ·
You can try the solenoid first. What is happening is you have the big GM starter with headers installed. There is no room for cool air to circulate around the starter and you can look to see the headers are against the starter. There is 3 options. 1. wrap the headers causes headers to rust. 2. install a heat shield on the starter. 3. Replace with a mini-starter that provides room for air flow. Good luck.
 
#9 ·
In some cases using the larger 14 inch flexplate/flywheel vs the smaller 12-3/4 diameter version will add mechanical advantage to the starter performance, check and see which one you have, 14 inch has 168 teeth 12-3/4 has 153. If it is a 153 tooth version then a high torx starter may be the ticket or use a 168 tooth to help out.

Some starters have bolt patterns and nose cones for both sizes, some are designed specifically for one or the other but not both.
 
#12 ·
Since I've did many performance builds with headers and high compression and never had any starter issues says to me the chevy starter has no issues with doing the job, however it's important it be did right. Before you do anything first off, and this is vital, Improve the grounds. If you've got what I've seen on the majority which is ground cable going to alternator bracket that ain't gonna cut it. Run the ground directly to the block. Make sure where you connect it on the block is sanded down to it makes a excellant contact. Next run another ground from the block to the frame and again, make sure it's getting a good connection. If there are factory ground straps hanging around unused from the firewall reconnect them.
Next, get the vehicle on a set of ramps and torque the starter bolts to 35 ft lbs.
This is what I've did on each build I've did and none give me any problems. What made me start doing it this way? Before I did it my car ate a total of Eight starters and I'd decided enough is enough.
When you improve the grounds you'll notice everything in the electrical system will work better.
 
#13 ·
A starter kit will not improve the cranking when it's hot. It only good when the soleniod will not engauge because of a hot engine heating the soleniod.
You need a super high torque mini starter to make it crank faster. Also check the battery charge volt it should read 14 to 14.5 volts when running.
 
#14 ·
I definitely agree that the initial solution could be a heat issue and there are a few solutions already listed above, but I also have seen ground issues cause this too. Getting a good solid ground to the block is very important, as already mentioned, for good starter activity when hot, and I have even gone as far as running a 4 gauge or 6 gauge gound wire directly to the starter.
 
#15 ·
Also check if battery ground is bolted solid to the engine block and there is no corrosion around the lug of the ground cable and battery terminal and the cable itself. Like oldchevy1956 wrote, you need a "good solid ground" connection. Make sure the battery does not have a dead cell.
 
#23 ·
I had the same problem,what I did is I wrapped my headers,mainly to get rid of under hood heat and I chunked the overly large Chevy starter an replaced it with a 4.3 v6 starter.No more starting problems.I shaved off 9 1/2 lbs. with the starter change.My battery is in the trunk,run your ground wire to a tail shaft housing bolt if your using an auto trans.
And the more bigger the wire the more gooder.....
 
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