Hey yall.
I bought a 1984 a few months back and I am having problems with it reliably starting. I have done just about everything I can think of and have researched on the electrical/sensor side of things and its getting fuel.

My problem has always been that the engine cranks really slow. I've got a little bur somewhere on the flywheel that I can hear click as it cranks and I would guess it cranks around 70rpms or so.
Its got a new battery and new starter. I've checked and cleaned grounds. I'm not sure what else to do. From videos and such online its cranking about half as slow as most other 1984s.

It does turn freely by hand with a ratchet on the crank.
It runs great once it starts. No ticks or odd noises. Has good power driving.

Any thoughts would be great yall.
Thanks

 

Have you measured the volt drop across the battery cables?

I expect if you have a fuel injection era car, you already have a multi meter.

If you haven't done the test:

Attach each lead to one end of the power cable (battery + and power lug on starter solenoid) set the meter to read the lowest DC volts, if it's not auto ranging.

Crank the engine and read the meter, it should be less than 1/2 Volt (0.5V) anything higher suggests a defect in the cable itself.

Repeat the test for the ground cable.

When I've done that, I connect between the - terminal at the battery and one of the starter mount bolts.

Same standard applies, less than 1/2 volt or there is a problem.

Difference from the power cable is, the ground has additional connections.

I don't know where the engine ground connection bolts on an '84, but I doubt it's directly to the starter. Every mechanical interface between the starter itself and the ground cable needs to be clean and tight.

Best of luck with it.

Edit: Upon further reflection, as I recall the parts books, your '84 came with a more traditional (non PMGR) starter, it's brace, if equipped is not only structural, it is an additional path to ground for the electric motor.

 

Okay. So multimeter should start at 0 volts correct?

 

Yes.

If it starts off showing anything, you not only have a short or draw, but excess resistance in the cables.

 

Hi to figure this out you need to do a few checks, as from what others have already mentioned.

I would confirm actual battery rated capacity is it correct for your year corvette, Get the battery capacity tested to confirm its close to the rated CCA capacity as per label on battery. Low fluid, age of battery even ones stored a long time at low volts, has the battery been completely discharged even once? it greatly affects their ability to deliver the rated amps. Most automotive battery shops will have a battery capacity tester. Its the place to start.

Then check the battery and ground leads, any prolonged movement vibration fatigues can fracture the bunch of wire strands, an ohm meter wont show load capacity only measuring load via amps drawn will. The flat braid type ground strap can get corroded, and start to come apart. Feel the battery lead and ground strap temp after cranking the engine, any restriction in cable thickness / capacity loose connections will generate a lot of heat.
Visually inspect and feel every inch, is it firm when bending the cable look for any obvious looseness.

Then check the starter for worn brushes or solenoid contacts, however a new starter should be ok and usually have to pass a test.

The starter contact to flywheel can cause issues if not shimmed correctly, you want a paper clip thickness between where the lows of ring gear and highs of starter teeth mesh. I have come across a starter that was a bit slow on my 85, didn't think much of it until the aluminium housing broke.
Someone mentioned to check the starter gear and ring gear mesh, to check with a paperclip when fitting a new starter. And yes i had to use shims to get this right, it can all add added strain to the starter and speed of cranking.

The only other issues can be high compression and likewise any head gasket or coolant leak into cylinder, check spark plug colours for any sign of coolant.

For a standard engine a normal starter & battery will be fine, for modified high compression engines you can get a gear reduction starter.

Good luck.

 

Thanks guys.
I ran the test and got .1 to .2 volts on the positive side and 1.2 volts on the negative side. Ive just ordered new engine block to frame and frame to battery ground straps.

I did have to shim the starter as well when I installed it a few weeks back.
The battery has been almost completely discharged once on accident when the door lights stayed on over the weekend. If the ground straps dont help too much ill see if I can get the battery warrantied.