Posted By: 68LAR
Hard starting and slow shut off - 01/03/24 06:11 PM
I think I'm confused. Lately, I've noticed that my engine on start up, will spin freely, but not fire quickly. On shut down, I turn the key off and the engine will free wheel for a second before coming to a complete stop. It's not the "turn the key on and it makes a half a rotation and fires then turn the key off and engine stops instantly" kind of thing. This has been going on this past year. I want to address it over the winter. I've tried adjusting the advance curve, adjusting the idle mixture screws, adjusting the fuel pressure up and down. Ignition is a Digital MSD 6AL. Distributor is a Mallory with Pertronix conversion kit that I've used for years with no issues. The kit is new. Replaced it last spring and ran it all last year. Timing is all out by 1500 rpm at 35*. Initial is at 13*. Plugs 3924's gapped at .045". Carb is a 1050AN Quickfuel. with 84P-92S jets. air bleeds 73/31. I can't put my finger on when this all started, sorry. Any suggestions????
Posted By: Brad_Haak
Re: Hard starting and slow shut off - 01/03/24 07:28 PM
Sounds like you've checked the basic things that I would have
Any chance the quality of the local pump fuel is getting worse?
Posted By: Cab_Burge
Re: Hard starting and slow shut off - 01/03/24 08:53 PM
Posted By: topside
Re: Hard starting and slow shut off - 01/03/24 10:05 PM
Slow to light: how good/clean/tight are the Grounds ?
I've had very few engines that would light off immediately unless they were already warmed up.
Continuing to spin: ya got me on that one, as there's nothing in the description that indicates dieseling.
Y'all have probably forgotten more than I know...
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/04/24 06:07 PM
Slow to light: how good/clean/tight are the Grounds ?
I have grounds from frame to block. Grounds from firewall to block. Battery to frame. You might say that I have grounds to groundsšš
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/04/24 06:10 PM
Slow to light: how good/clean/tight are the Grounds ?
I've had very few engines that would light off immediately unless they were already warmed up.
Continuing to spin: ya got me on that one, as there's nothing in the description that indicates dieseling.
Y'all have probably forgotten more than I know...
Not dieseling. Just not an instant shut down. Not a run on either. Just not an instant shut down.
Posted By: INTMD8
Re: Hard starting and slow shut off - 01/04/24 07:31 PM
Maybe ignition switch failing? I would monitor ignition power vs key position.
Posted By: NITROUSN
Re: Hard starting and slow shut off - 01/04/24 07:39 PM
Are you running electric fans?
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/04/24 07:48 PM
Maybe ignition switch failing? I would monitor ignition power vs key position.
Brand new ignition switch. No electric fans. Just a Jag clutch fan.
Posted By: INTMD8
Re: Hard starting and slow shut off - 01/04/24 08:15 PM
So same before and after the new switch? Just saying I would check and confirm because new isn't always good.
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/04/24 08:46 PM
So same before and after the new switch? Just saying I would check and confirm because new isn't always good.
Was having the same issues and others before changing the ignition switch. The new switch didnāt change anything but my piece of mind that the switch wasnāt an issue. The engine eventually starts and runs strong.
Posted By: Jeremiah
Re: Hard starting and slow shut off - 01/05/24 02:51 AM
A few things I would check that have not been mentioned:
1) I would check the i tegrity of the floars in your carburetor. It would not hurt to change the needle&seat assemblies as a maintenance item.
2) I would 2x check for a vacuum leak. Verify the base plate to main body screws are tight, etc. Not all vacuum leaks come from the manifold.
My guess is this is not ignition related. One way to peoce that is to ensure there is not output from the MSD is switched off. You could test that with the white points trigger wire and a spark plug plugged into the coil wire.
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/05/24 01:31 PM
A few things I would check that have not been mentioned:
1) I would check the i tegrity of the floars in your carburetor. It would not hurt to change the needle&seat assemblies as a maintenance item.
2) I would 2x check for a vacuum leak. Verify the base plate to main body screws are tight, etc. Not all vacuum leaks come from the manifold.
My guess is this is not ignition related. One way to peoce that is to ensure there is not output from the MSD is switched off. You could test that with the white points trigger wire and a spark plug plugged into the coil wire.
The floats are good. The float level is steady as a rock. The MSD is something that I haven't thought of. If I recall, with my old 6AL I didn't have this problem. Maybe explain in detail your recommendation for checking it.
No vacuum leaks. I checked that.
Posted By: moparx
Re: Hard starting and slow shut off - 01/05/24 07:44 PM
stick or automatic ?
if automatic, how does it shut off in gear [third or drive] ?
i know you said the MSD distributor works good, but could the weights be sticking a little in just one spot ?
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/05/24 10:40 PM
stick or automatic ?
if automatic, how does it shut off in gear [third or drive] ?
i know you said the MSD distributor works good, but could the weights be sticking a little in just one spot ?
Stick car. Iāve bin thru the distributor, everything is free no sticking weights or anything else.
Iām thinking maybe to lower my idle speed. Itās at 950 now. Not sure if that will work cause if I remember, the engine had a hard time idling anything lower than that.
Posted By: topside
Re: Hard starting and slow shut off - 01/06/24 12:32 AM
Hmmm...you might find that closing the butterflies works for the shut-off.
Heck, might even help the startup.
Posted By: 68LAR
Re: Hard starting and slow shut off - 01/24/24 09:17 PM
Okay, an update!! As far as my issues, it was something stupid. Low battery voltage!!!! I also closed the idle mixture screws a bit. From 1 turn to 3/4 turn out. Everything good again. Thanks for all the input. š