Vortec 383 TPI. Engine is all new.

CSI was disabled and this is reflected in the new prom. Prom riding piggyback is a 1989 305 TPI prom. Dont remember the code on the prom but I know it's a 1989 chip. Car is a 1988 GTA.

Starter is a new LT4 unit. Checked out ok.

Cables checked out ok. All grounds are connected and in good shape.

I've tried everything, playing with the distributor, even to make sure it wasn't 180 out, and it still lugs so slow it wont start, not even close.

I got it to run for 5 seconds ONCE. It was so far out being newly installed that it stalled. I can't find my noid lights, but I know I have fuel and spark.

It lugs like the spark is way out of time but no matter where I put it the thing wont spin over normally. I'm tired and out of ideas and am probably overlooking something small and stupid. Ideas?

 

Try disabling fuel and spark to verify it's not just a weak starter, weak battery, or poor connection.

 

battery is fresh and was running piggyback with the battery charger on. I verified that the starter works on another engine on the stand. Well, better than the stocker, and it still worked fine. I'll be taking it in to get tested tomorrow to be sure but I doubt the starter is the problem.

Wont disabling fuel and spark make it harder for the engine to crank (no combustion aiding the cranking process)?

 

No. The starter will dry crank the engine fine, as in a compression test, unless there's a problem in the cranking system. If you think that ignition timing might be causing it to fire back on it's self, a dry crank test will verify that the starter is good and clarify whether it's in the cranking system(starter, battery, cables), or wether it's an ignition problem.

If the starter wont turn the motor sufficiently without fuel or spark, perform a volt drop test on the starter circuit. Using a DVOM, first watch voltage between the starter + and block while cranking. Does it drop below 10v? If so you either have a weak battery, a bad cable, or a poor connection. To verify which it is, perform a volt drop test across each cable from end to end. This will tell you if a cable is dropping power due to a break or poor connection. If the starter dry cranks the engine fine, then you know to look at the ignition system. How is your dist cap? Is it carbon tracked?

 

Something just crossed my mind as I was reviewing my subscriptions. This is a new motor. I would suggest trying the starter on a known good engine to verify it is good. The starter may have just taken a dump. Once you know the starter has good torque, reinstall it on the new engine. If the engine still doesn't crank at proper speed, try removing spark plugs and see if it improves.

If not, and voltage drop tests don't reveal a problem, try turning the crank by hand with a breaker bar. If it turns hard, barring some sort of bind in the trans, clutch, or TC, you likely have a tight bearing in the new engine. If so, it's good it happened now rather than at 6,000rpm.

 

Engine was good to go on the stand. I think I found the culprit. When I installed the new engine, I paid alot of attention to detail, like sandblasting the brackets and repainting them aluminum and clearing them so they looked good and new...and because of that, I have a weak ground where my battery cable bolts to the bottom of the driver's accessory bracket. Figures. My starter also tested out of spec so it's also going to be replaced. Cable speced fine on it's own, but when I tested the resistance between the block and the negative terminal, the resistance was WAY out of spec. The only ground I was getting was probably from the back of the cylinder head ground strap through the small secondary lead to the negative terminal.

Didn't even think about it because it all looked just like shiny new aluminum, lol...

Why not to work at night when you are tired We'll see tomorrow if that fixes the problem.

 

Yeah, that makes sense. Sounds alot less painful than a bad bearing too. Sorry to even bring that up, but it does happen.

Beware of testing wiring with an ohmmeter. The ohmmeter produces very low current in the circuit and may produce low readings, even when a wire is mostly severed or even broken and just laying loosely together. This is a huge issue on high current circuits like the starter. The circuit may test good with an ohmmeter but won't support the high current when the circuit is loaded. That's why I recommended the volt drop test. This test is much more reliable for finding poor connections and wiring.