Slow Starting 77 Gmc

[just_a_guy84]

Hi, I just recently purchased a 77 gmc with a 350 and turbo 400 trans. It is quite slow to start, The battery has tested good, and I just replaced the starter last weekend. Battery cables are in good condition, and the battery has 650 cranking amps...should be plenty. SO...what am I missing? It starts even slower when hot, I understand this is because of the location of the solenoid on the starter getting warmed by the headers and reducing conductivity. however, it is still slow to start even when cold.

 

any help is greatly appreciated.

 

Thanks,

aaron

[Zembonez]

Hi, I just recently purchased a 77 gmc with a 350 and turbo 400 trans. It is quite slow to start, The battery has tested good, and I just replaced the starter last weekend. Battery cables are in good condition, and the battery has 650 cranking amps...should be plenty. SO...what am I missing? It starts even slower when hot, I understand this is because of the location of the solenoid on the starter getting warmed by the headers and reducing conductivity. however, it is still slow to start even when cold.

 

any help is greatly appreciated.

 

Thanks,

aaron

 

It could be a compression issue. Do you know what has been done to the engine? High compression engines are notorious for hard cranking - especially when hot. I'd also make sure the timing is set correctly.

 

Battery cables can also look good when they are corroding internally and building up resistance. You can check resistance with a volt/ohm meter.

 

Welcome to the ZOO!

[Heavy Cruiser]

As said, compression was still fairly high, but other things to consider is replacing the battery cables with 1 AWG cabling with the molded clamps, if they present a question.

 

After cranking, you migfht feel the clamps and cables for 'hot areas' as these hot places are a sign of corrosion.

 

Ground cable should be tied to the block rather than the cylinder head or alt bracket.

You also might check there is less than a couple ohms conductivity between the alternator case and neg battery post.

Check charging voltage to the battery, no less than 13.8 volts with a warm/hot battery. temperature of the battery does make a difference in charging voltage needed, the hotter the battery, the less voltage needed.

[grampadirt]

A '77 owner,WooHoo!.I have/had one too...except mine has a 454.Like was mentioned earlier check to see if the timing isn't advanced too much,for a 350 it should be:

 

2-barrel carb 2*BTDC (manual)

'' 6* '' (auto)

 

4- '' 8* '' (same for both)

 

Ca. 6* '' (Commiefornia strikes again ) be sure you unplug the vacuum advance hose & plug it with a golf tee

 

thought I'd throw in a pic

[just_a_guy84]

Thanks for the advice guys, I will check the timing this weekend, it seems that would be an obvious culprit. I will also break out the trusty ohm meter and see what I can't figure out.

 

thanks again

Aaron

[grampadirt]

No prob,let us know how it turns out...