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1992 4.3 mercruiser alpha one gen 2 thunderbolt 4 ignition timing/starter issue.

Nelsonproffitt

New member
So Labor Day weekend my boat thew a rod through the block. I bought another engine. Swapped it all over new intake and carb as well. Put it all back into the boat and got the timing set. This weekend I let it run outside of water for 30 minuets hooked up on hose like stated in the break in procedure. Everything is great. Well we take it out on the water and she cranks up just fine we get going down the lake I let it heat up and i shut it off just checking for leaks and everything of that sort. Went to crank it back up and nothing. I look at the distributor and it’s loose I forgot to tighten the bolt. So I twist it and finally get it running and I turn it to where she is running perfect by ear so I could get back to the ramp and go time it. Have the wife start it and it grinds real bad and breaks the starter bolt. So I get a tow in and took it home and put new starter bolts on and started checking timing. Well now the starter is grinding terribly. It will turn the motor over but makes an awful grinding noise. It works fine if the timing is set on top dead center but if you go to retard it 8 degrees where it’s supposed to be it makes the grinding noise and will barely turn it over. I’m at a loss, I’ve checked the flywheel and it seems fine alittle bit of ware but no missing teeth. I’ve checked and double checked that it is in fact on top dead center and I’m not run out a notch or anything. The starter is working when you hook it up to a battery and the teeth isn’t that bad on the starter either.


So any insight would be greatly appreciated thank you.
 
..."It works fine if the timing is set on top dead center but if you go to retard it 8 degrees where it’s supposed to be it makes the grinding noise "

What? The timing is supposed to be around 8 degrees of advance at idle. Something's really messed up here.

Jeff
 
..."It works fine if the timing is set on top dead center but if you go to retard it 8 degrees where it’s supposed to be it makes the grinding noise "

What? The timing is supposed to be around 8 degrees of advance at idle. Something's really messed up here.

Jeff


Yes i meant 8 degrees advanced sorry
 
Change the pick up in the distributor. On TB4 systems the pickup can change the timing when it goes bad and lock the engine up during cranking. Pull the coil wire off, if the engine cranks normal.... change the pick up.

If your pick up has screw terminals or has just two wires it is time to change it.
 
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