I have a 68- with a rebuilt 454. when i purchased the car the stater seemed weak after the motor heated up. I bought a new starter from Powermaster that has more torque. The re-install went fine. The first start worked great. I let the motor heat up some turned it off. When I went to restart the engine the starter turned the engine over a couple of turns and the made a banging grinding noise. I then tried 1 shim just grinding noise. 2 shims same result. I called Powermaster finally got a tech after a few days of trying. He left a message to try the shims. I dropped the new starter and took side by side pictures sent them and he verified i had the correct starter as I thought.
I read somewhere that if the timing was to far advanced that it could have the same result. I did convert the distributer from points to electronic. When the engine was running I advanced the timing to its highest idle, I had not put the timing light on it yet because i cannot start the engine. Before I put the old starter back in to start it could the advanced timing be causing the grinding problem I am having
One thing that came to me i had to loosen the header to get the starter out. when i put the new one in i pull off the coil wire so it wouldn't start with the header loose. The motor seemed to work fine then now that i have exhausted all my options i remember when the coil wire was put back on then is when it started first time then grinding sound on the second try.

 

Interesting, I was under the impression that if it bolts up and started the first time, you had it in the right spot. Can you see the flywheel where it engages? On my 68 when I put a new engine wire harness in it, I put the two control wires on backwards and it would do nothing, but your issue sound different from that. Maybe it just landed on the worn tooth on the flywheel. I would think timing would not really matter on starter engagement. You might misfire, but it should roll over.
But I am far from an expert on these cars.

 

grinding and hard starts from to much timing are 2 different things
with the original starter it could be bad ground,bad battery,to much timming,
bad starter solenoid,no starter sheild when it gets hot. I have always used the
original type starters.

 

Hi and Nice Corvette!!!

Your zip looks like Abita Springs and I have a 454 68 LeMans blue roadster which is similar to yours.

My 2 cents:
I would try to get it back to close to original conditions and change one thing at a time to pinpoint the problem. So to see if mechanical, you might pull all of the plugs out, ground the coil, or ground the plugs and see if the starter will turn the engine smoothly with no compression. If not, then you figure out why. I think you can also check timing at starter speed anyway by still leaving all of the plugs out, grounding #1 plug and see what your timing light tells you. I would get the idle timing back to zero or a little more, hook it all back up and see if your problem comes back. Then you can advance the timing a little at a time and see if the problem comes back and where. This is what I would do, so maybe this will help. If all this checks out ok, then maybe as above your starter is suffering a heat problem maybe particularly with headers?

Good luck and hope to see your Corvette at the GNOCC or Northshore shows this fall or the Crescent City Boomtown show this May! All great groups!!!

 

When a starter has difficulty spinning , the first thing to check is the large ground cable from engine to frame.. the OEM aluminum strap was garbage, replace it with a heavy copper cable..

 

Thank you for all of your suggestions. I will post the outcome.
Thanks

 

Summit sells a heat wrap kit with stainless clamps that works very well
Cheap, easy to put on and works

 

In the 60's and 70's I worked in a Chevrolet Shop. Several things come to mind. Initial timing is too high, wrong bolts used to mount the starter (not knurled), wrong torque (not tight), ring gear to flywheel clearance off and the front starter brace is missing. All of these can cause your trouble. Some HP BBs would kick back and actually crack the casting on the block the starter was mounted to. I believe there was a Service Bulletin addressing this. We replaced several fitted blocks.

 

Thank you for the incite. I am going to be checking all of these things today

 

Had the same problem with them, I purchased one for my 427, 125 over with 13.5:1 comp. I worked fine a few times, then a lot of noise and sounded like it was grinding. I complained about it to them and they said to go pound sand! Purchased a hitachi and spins faster and no problems for 2 years now

 

The problem is likely due to a couple things... I went through this same problems with a Summit mini starter and a Proform starter. It would work fine sometimes then "grind" other times. The problem with the aftermarket mini starters with no "cone" over the starter gear is that the starter gear itself is flat faced, and there is no support of the starter gear once its deployed into the flywheel. The issue then is that the starter gear has to perfectly aline itself to the flywheel with this straight cut teeth, and a shaft that flexes from no support on the flywheel side of the gear. Adding to this is if your flywheel is not 100% true all the way around, you will lose/gain clearance in the starter gear/flywheel depending on where the flywheel stops when you shut it off...There is no real fix for any of this, doesnt matter what shims you put in it, or even using the GM metric shank starter bolts.
This is the type I am talking about:


Now if you are still with me after reading that ^^^... The fix is to go back to a GM/Hitachi style mini starter with the nose cone, starter gear pinion support etc.. Also the starter gear teeth will be beveled and twisted, making engagement into the flywheel very smooth and quiet, no shims needed.

I went to O Reilys and bought the house brand (Ultima) starter for a 1997 GM 350 Truck($150). The sucker is tiny, it went right in and is quiet with no shims. You do need to use the GM metric shank bolts, get them at your local dealer for $10.

That little starter easily starts my 10-1 compression, 496 with the timing locked out at 31*.

This is what you are looking for:


Notice how the teeth are more beveled on the cone style starter. That really helps with flywheel iregularities.


Here is a good deal on one:
http://www.ebay.com/itm/Chevy-305-35...-/130587673522

 

Ditto to what ajrothm said.

Ran into the same issue.

 

If you advanced the timing that way you are way I think you will find you are too far advanced and definitely will cause hot start issues