Hard starting when warm

Zspoiler

Veteran Member
May 6, 2012
4,365
Federal Way, Washington
I have learned over the years .And especially since my 1979 Z-28 is supercharged .As well as my other Chevrolet cars over the years .Is that heat can be an issue .I use a Moroso Heat shield on # 74299 mini starter and # 74300 for a stock Chevy starter . And carb heat shield and or thick carb gaskets .I even use the stock starter cable heat tube with a heat sleeve ..And never had any issues since
 

muscl car

Veteran Member
Lifetime Gold Member
Jul 8, 2001
23,965
Gallatin Tennessee
Is it cranking over slowly when warm then that's indicative of a overheated or warm starter solenoid . This is a very common problem with GM design starters and using headers as it'll heat soak

Your two options are ...

1) Install a heat shield or blanket around the starter to reduce heat soak

2) check your ignition timing and if timing is advanced to much then retard timing by 1-2 degrees



Now you didn't mention if it was turning over slowly or cranking over as If flooded . If you have a stock style Quadrajet carb they're known to leak fuel back into the intake from defective plugs in the float bowl . This will give a hard to start problem when warm . Also heat from the engine can boil the fuel from the carb causing a hard to start when warm problem
 

70RSZ28CAMARO

Member
Dec 19, 2003
75
Long Island, NY
When you say "3 to 4 cranks" before it will "turn over", what do you mean by that? Do you mean 3 or 4 attempts to start (twisting of the ignition key) before the starter will kick in? (bad battery cable, dirty/loose connections at the battery, loose at the starter, or defective starter itself)
Hi Mallard thanks for your response when I say 3 to 4 Cranks I mean that I’m holding the ignition key in the start position and the engine cranks 3 to 4 times and then finally starts I also have to work the gas pedal a little bit while I’m doing that
 

carhead22000

oldblue
Sep 5, 2011
1,050
canada
if it is a heat issue with starter i like wiring up a ford solenoid ,cures the heat thing and you no longer have a live wire down by your header .its covered before here somewhere.
 

G72Zed

Veteran Member
Sep 8, 2015
4,228
Canada
Hey guys my car starts up cold great and warms up fine then I’ll drive it for 30 minutes And park it at the car show leave it for about a half hour and when I go to start it warm it doesn’t turn over right away takes 3 to 4 cranks before it turns over what can be causing it appreciate your help

I have a 1970 Z 28 Camaro stock LT1 recently rebuilt and bored 30 over

Sounds like the idle circuit could be on the lean side when everything is at full temp & max heat soak set's in. Lower idle timing and long idle times can heat things up as well, and does not take long to migrate....and with today Ethanol fuel does not like the heat, assuming you may be using high octane pump with Ethanol....could be a combination of things.

Does it have the original holley 780 VS ? original cam specs and compression ratio?.
 

cadillac_al

Veteran Member
Apr 22, 2015
1,107
Maine
FWIW I have never used a starter heat shield with my headers. The temps never get over 90 degrees up here though. If I have my timing a little too far advanced I will give it a pump of gas to help it start.
 

mallard

Veteran Member
Oct 3, 2013
2,032
SK, Canada
So I’m gathering his issue isn’t a starter dragging issue but a “turn over and over” issue when warm (no choke). Do you have two healthy squirts of gas if you look down the carb and open the throttle a couple of times? To get it to start do you have to give the throttle several pumps?
 

70RSZ28CAMARO

Member
Dec 19, 2003
75
Long Island, NY
Sounds like the idle circuit could be on the lean side when everything is at full temp & max heat soak set's in. Lower idle timing and long idle times can heat things up as well, and does not take long to migrate....and with today Ethanol fuel does not like the heat, assuming you may be using high octane pump with Ethanol....could be a combination of things.

Does it have the original holley 780 VS ? original cam specs and compression
 




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