new engine wont start (weak crank)

[Mike_B]

I've got a new longblock on a stand that will barely crank over. I'll get 1 or maybe 2 slow bumps but nothing close to a decent crank. I've been jumping it from my car. I've used 2 separate jumper cables, 2 different vehicles/batteries and 2 starters with the same results. I'll keep trying different batteries/cables but I'm concerned that there might be something wrong with the longblock I ordered. How hard should it be to crank over by hand?

Not sure it matters for this problem but I cant guarantee the distributor is working properly.

pre-86 gm 355ci
Holley 4010 carb
mechanical fuel pump
no accessories belted up, just the water pump

 

[Coors]

Re: new engine wont start (weak crank)

Pull out the spark plugs, and turn it by hand.
If turns over that way, it is timing, or bad battery, cables, connections.

 

[Mike_B]

Re: new engine wont start (weak crank)

With the plugs out it took 50-55ft/lbs to turn the engine over by hand. If that sounds acceptable it will put my mind at ease that it's just an electrical problem.

 

[Zackman]

Re: new engine wont start (weak crank)

Mike, 50 - 55 ft lbs sounds reasonable. When using the jumper cables make sure your negative lead is not attached to a painted surface and it is making very good contact with bare metal on your new engine block.

 

[Coors]

Re: new engine wont start (weak crank)

I dunno how many ft/lb's, but every engine I have built; if I can spin it with a 16 inch, 1/2 drive ratchet- it always ran good, and long.

 

[Mike_B]

Re: new engine wont start (weak crank)

I yanked the battery out of a truck and bypassed the jumper cables and got a good crank. I guess the both my old and new jumper cables I bought the other day couldn't handle the amps... too long perhaps. Anyway thanks for the replies gentlemen. I know it was a very noob topic but the peace of mind I get knowing the longblock turns with the right force was worth the post.

 

[Coors]

Re: new engine wont start (weak crank)

great.