Lg4 running 6 degrees timing, pinging on 91?
02-19-2019, 12:51 AM
#1
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Lg4 running 6 degrees timing, pinging on 91?
For the folks running an LG4 with the Quadrajet, if you are running 6 degrees of advance do you get any pinging?
Heres the background...
So my 86 LG4 is running pretty good after a carb rebuild. Many thanks to naf and others for walking me through the process.
Now that it’s running well, running reliably and I have new tires on it I’m using it a bit more. I have the base timing advanced to 6 degrees and and part throttle it runs great, plenty of pep, no flat spots.
So last tight night I took it for a spin to the store and took the long way via my favorite on-ramp, and once I put my foot in it I can hear it pinging. I’m just running 87 right now, so I grabbed a bottle of octane booster for now until I can refill it with 91.
Obviously the true way to solve this is to refill it with 91 and repeat. If it still pings back off the timing and repeat. But I’m also wondering if I have some carbon build up in this engine since it hasn’t been run hard much lately.
just curious to hear others experiences. and I’m just an impatient bastard.
Thanks,
Ian
Heres the background...
So my 86 LG4 is running pretty good after a carb rebuild. Many thanks to naf and others for walking me through the process.
Now that it’s running well, running reliably and I have new tires on it I’m using it a bit more. I have the base timing advanced to 6 degrees and and part throttle it runs great, plenty of pep, no flat spots.
So last tight night I took it for a spin to the store and took the long way via my favorite on-ramp, and once I put my foot in it I can hear it pinging. I’m just running 87 right now, so I grabbed a bottle of octane booster for now until I can refill it with 91.
Obviously the true way to solve this is to refill it with 91 and repeat. If it still pings back off the timing and repeat. But I’m also wondering if I have some carbon build up in this engine since it hasn’t been run hard much lately.
just curious to hear others experiences. and I’m just an impatient bastard.
Thanks,
Ian
02-19-2019, 11:15 AM
#2
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Re: Lg4 running 6 degrees timing, pinging on 91?
six may be a hair high. if it's pinging under light throttle opening at cruise you can also check the function of the EGR.
I'd back it off a few degrees and see.
If it's pinging (knocking) under a lot of throttle it could be running lean on the secondaries. make sure the little cam is raising the secondary metering rods when the air valve opens (you shouldn't need to richen your secondary metering with an otherwise stock motor). Sometimes that cam can fail-crumble to dust-and the secondary rods fail to move up correctly.
I'd back it off a few degrees and see.
If it's pinging (knocking) under a lot of throttle it could be running lean on the secondaries. make sure the little cam is raising the secondary metering rods when the air valve opens (you shouldn't need to richen your secondary metering with an otherwise stock motor). Sometimes that cam can fail-crumble to dust-and the secondary rods fail to move up correctly.
02-19-2019, 08:55 PM
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Re: Lg4 running 6 degrees timing, pinging on 91?
Could be just bad gas if first time and you added octane and it helped. I would run through the tank and refill from a different station.
If it is pinging too much all the time than maybe back off the timing to avoid any damage. Maybe check your vaccum reading and make sure no codes.
If it is pinging too much all the time than maybe back off the timing to avoid any damage. Maybe check your vaccum reading and make sure no codes.
02-19-2019, 11:09 PM
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Re: Lg4 running 6 degrees timing, pinging on 91?
What are the grades of fuel in America? We've got some of the ethanol E10 91 here, actual 91 unleaded, 95 and 98 octane. My LG4 always needs to be dropped back a degree or 2 on 91, and moreso on the E10 but 95 seems to be its favourite.
Theres no real hard and fast rule of what degrees for what fuel, depends on the setup (EGR No EGR, CCC or no CCC etc.) Its more of a matter of giving it more degrees until it starts to ping then back it off. I do agree with 84Bronze though, sounds like a tank of **** fuel - happens from time to time.
Theres no real hard and fast rule of what degrees for what fuel, depends on the setup (EGR No EGR, CCC or no CCC etc.) Its more of a matter of giving it more degrees until it starts to ping then back it off. I do agree with 84Bronze though, sounds like a tank of **** fuel - happens from time to time.
02-21-2019, 06:15 AM
#5
Re: Lg4 running 6 degrees timing, pinging on 91?
Originally Posted by Alfisti
Now that it’s running well, running reliably and I have new tires on it I’m using it a bit more. I have the base timing advanced to 6 degrees and and part throttle it runs great, plenty of pep, no flat spots.
- Rob
02-26-2019, 03:50 PM
#6
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Re: Lg4 running 6 degrees timing, pinging on 91?
I recently filled it up with Chevron 91, and I'm running octane booster, and it's still pinging under hard acceleration. So I plan to dial back the advance a few degrees until it stops.
Thanks all.
Ian
Thanks all.
Ian
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