Ok this is a strange one. And maybe I'm overthinking it. But my 84 is having a hard time starting when hot. So if the engine is cold it fires right up no problem. But when hot the starter sounds really labored. It sounds like the battery is about dead. The battery is fairly new and the starter only has about 50k miles on it.

So my first thought was either a failing battery or a failing starter. BUT I was board at work so I googled the issue just to see what other people had done with the same issue. The one thing I keep reading is that people claim this issue can be caused by excessive timing? Now this caught my interest because I do have a ton of timing added at low rpm to help with idle. But how in the world could ignition timing cause the starter to run slower? I could see cam timing but not ignition. Anyone ever heard of this? What am I missing?

I'm going to swap the starter this weekend with a spare I have on the shelf just to see what happens. And if that doesn't help I'm going to try it with my truck battery before I go parts cannon on it.

 

What model starter motor are you using? A PG260H or .................................

 

ACDelco 3361922A

 

That looks to be an ACD 'part number' and NOT a model number

 

Well that's what I got. I don't have a model number.

 

If you have too much initial timing it will ignite the mixture and build cylinder pressure before the crank has passed TDC and push the crank in the opposite direction, this could cause labored cranking when hot. To check this disconnect the distributer hot wire while cranking the car and see if the cranking speed returns to normal.

It may be a timing issue, starter issue, battery issue, or in rare situations a mechanical issue.

 

This is a used from your JY engine buys or an actual ACD purchase? I'd think you might consider a parts build of JY starter from your buys. Do a 'carbon pile' load test of electrical maybe. I would think yours is likely PG260 of sorts which vary from maybe 1.4 KW to much greater gear reduction. I've never investigated these. A 6.0 Vortec I'd think likely 1.7KW. Are solenoids a likely issue with these? Maybe.

*** Does you solenoid have a threaded stud for ignition wire OR maybe a pin?

 

An easy way to test if ignition timing is the culprit is to unplug the BAT wire from the distributor. This will shut off your ignition system. Then crank it and see if it is still slow. (when it is hot of course).

If your starter is the issue, I would recommend getting some kind of heat shield which may allow you to use your current one a while longer, or will at least extend the life of a new one. These cars are known for heat soak because of the starter's proximity to the catalytic converter.

I believe the problem with advanced timing is that cylinders will fire before they have reached TDC which pushes back on the starter. Some hot rodders or racers will have a timing retard switch or ignition cutoff switch that allows them to start engines with lots of advance.

 

Ok that makes sense. I didn't realize advanced timing could give that kind of pushback during starting. It probably doesn't help that the engine is 11:1 compression either. I can't disconnect the distributor because this car is LS swapped. But I can simply back off the low rpm timing advance or have the Holley ECU pull a little timing during starting.

 

I wonder how much of this is just heat on the starter itself. I have long tube headers and no heat shield on the starter. I might put a little header wrap on that part of the header and see if that helps.

I can add in the advanced IFS tables of the ECU a table that will pull starting timing based on engine temp. I'll definitely try that before buying anything. I hate throwing parts at a problem.

 

The starter on the car now is an ACDelco that I bought back when I first LS swapped the car. I have a starter on the shelf from an LQ9 that I pulled from a 04 Cadillac Escalade that has over 200k miles on it but if nothing else seems to remedy the problem I'll swap that on and see what happens.

I think first though before I swap parts I'm going to try backing off the low rpm timing. I made the timing at under idle speed so high because I was having IAC problems and it kept stalling out. It was just a band aid to keep it running. Well the IAC issue is fixed now. I never backed the timing off because it's under the idle speed. I didn't think it would make a difference. Huh... learn something new everyday.

 

The Holley ECU has a setting for cranking timing that is separate from the base timing table, make sure you check that also.

 

Thank you. I never messed with the cranking table. I just left it as default.

I won't get a chance to mess with it until the weekend. But I'm going to pull all the timing I added as a band aid, and if it still gives me problems I'll change that table a little.

 

never had an old school carb/distributor i see.

your car has been swapped for awhile, did you ever have this problem before? it sounds like a heat and/or grounding issue. gen v starters were doing this on basically new camaros, the fix was adding a stand alone ground wire.

 

This started sometime last summer. But that's around the same time I was messing with timing. So I'm going to say it's either a timing issue, or the fact that I've been cooking this LS1 starter with long tube headers and no heat shield for years now. I reused this starter off of my old LS6 I had before the LQ9.

But you are correct. I'm not much of a distributor/carb guy.

 

I'd say do the additional added ground while doing whatever you decide. A starter blanket for protection I believe would be a last choice to add. You've probably got appropriate gaged wire and eyelets already or they would be a very inexpensive 'local' buy. A solenoid maybe for your old starter?

 

I 100% agree on the ground wire. Also I have a whole roll of header wrap sitting on a shelf. Being the headers are stainless I don't have to worry (as bad) about then rusting out. So I might wrap the collector on the starter side to keep heat away.

 

Another thing you can do instead of wrap the starter is to add an external starter solenoid (like the old fords). Easy to do and it eliminates the heat soak/hard start when hot issue. Dont know if LS engines had that issue, but its easy and cheap to do (plus it gives you a convenient spot to use a jump button if you need to)

 

Well I won't have a lot of time to tinker with the car this weekend. I need to get power out to a carport on my property before winter. But I did have time to plug the laptop in and make some quick changes to timing and then see what happened. I noticed that the default Holley cranking spark timing was <400 rpm = 15 degrees. So no matter what I had in my timing table the crank timing will only be 15 degrees if the rpm is 400 or less. Well according to my data logs anyway during cranking it's showing an rpm of 400 to 500. 500 rpm is where the timing table starts. I had 26 degrees at this point to help keep a stalling engine running. So I made two changes. I removed my added "wall" of low rpm timing (pulled 6 degrees), and I raised the cranking timing rpm to 500 instead of 400.

So I started the engine and let her run until the fan kicked on. Then I shut it down and sat for just a minuet. Then started it back up. It fired up with MUCH less hesitation than before. The starter still sounds just ever so slightly slower than when cold. But unless you were that familiar with the car you wouldn't notice. I'm going to pull a couple more degrees of timing in the 500 to 600 rpm range and see how it goes. But so far I'm thinking this was the issue. I'm still going to install some kind of heat shield for the starter. It just seems like a good idea.

Thanks guys for explaining the timing issue to me and for all the other ideas. I just couldn't wrap my head around how ignition timing could do this when hot vs cold.

 

I do 10 degrees while cranking.
also, just to put out there, your hot starting will never be as fast as cold starting because the rings will be hot, fully seated and this makes a better seal of the combustion chamber as compared to a stone cold motor.