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Drain out all of the old gas, as the owner of a '71 LS5 for the past 45 years that I have barely driven for the past 30 years, I've experienced the problems with old gas. It would barely run, miss, pop, etc. New fresh gas and it smoothed out. Now I keep it filled with ethanol free gas and use it in my lawn equipment, then replenish with new gas as needed. I start it up at least once a week and drive it around the block.
Like my timing tape, I’m waiting on a five gallon jug to be delivered. I hope it’s really that simple. It sure sounds like my carburetor is set up properly so I’m down to either bad gas or a very weak, but functioning spark. Every time I’ve had issues like this the solution has always made me slap my head. Come on, FedEx....
2020 Corvette of the Year Finalist (performance mods)
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When you say you guess the timing is at 30* is that at Idle? Is the vacuum advance connected? If its not connected I would back the timing off to about 15* for your initial timing. Its usually a good place to start
When you say you guess the timing is at 30* is that at Idle? Is the vacuum advance connected? If its not connected I would back the timing off to about 15* for your initial timing. Its usually a good place to start
I'd recommend we all wait patiently, including the OP, to get his timing tape and gasoline in order.
But yes, 10-15 is a good start for initial timing with no vacuum advance engaged.
When you say you guess the timing is at 30* is that at Idle? Is the vacuum advance connected? If its not connected I would back the timing off to about 15* for your initial timing. Its usually a good place to start
My problem (among others) is that the engine won’t run AT ALL without that much initial timing. That has me stumped as well. I’ve tried with and without vacuum, obviously setting without, light springs, heavy springs, completely locked. I wish I could remember how I had it set the first time I owned this car. But I’m sure it wasn’t like this. And to reiterate, I did check the TDC mark using a stop. It’s just weird.
Well... Someone start the drumroll. And yes, I am now slapping myself in the head. I got out to the garage this morning to start some more seemingly futile diagnostics. When I started it I had a steady miss. That was new. Then a lightbulb came on for me. I pulled all of my plug wires and checked them all with an ohm meter. It turns out that my 454 was playing 283 on me. I had THREE bad plug wires. #’s 2, 8, and 3 were DEAD. DEAD!!! #2 would make intermittent contact if I bent it just right. How I was able to drive it at all was a miracle.
I made up three new wires and took it for a drive and amazingly it ran pretty good. Still a little down on power, but likely due to my 6 year old gas and having tuned the carburetor while only firing on five cylinders.
I had a feeling I’d be slapping myself when I finally found the issue, and I am. I had put these nice MSD wires on it probably ten years ago when I owned it the first time. Apparently during the time it was under another’s care he had been a bit forceful in removing and reinstalling the wires.
So, I’m embarrassed to say I did miss something simple. Thank you all for taking the time to walk me through my stupidity.
I started out being absolutely positive that my problem was ignition related. But after checking (or so I thought) EVERYTHING in the ignition system all I had left was the fuel system. Stupid thing is that I’ve literally had 75 or more cars in my life. I may have had two bad plug wires create a problem along the way. One for sure, but maybe two. I’ve literally NEVER encountered three bad wires on a running car. Ever! I can’t believe it ran at all. It just goes to show you that buying a car that had been disassembled by someone else requires checking everything as it goes back together.
By the way, if you don't want to wait out your timing tape and don't own a dial back timing light, you can make marks on your balancer by wrapping a piece of string around it, finding the circumference, and then marking the string at the appropriate degrees. IE if you have a 6" balancer, the circumference is (pi * 6), 18.84". (10/360) * 18.84 = 0.52". So make a mark about 1/2" from the TDC relief on the balancer and you'll have a 10* marker.
By the way, if you don't want to wait out your timing tape and don't own a dial back timing light, you can make marks on your balancer by wrapping a piece of string around it, finding the circumference, and then marking the string at the appropriate degrees. IE if you have a 6" balancer, the circumference is (pi * 6), 18.84". (10/360) * 18.84 = 0.52". So make a mark about 1/2" from the TDC relief on the balancer and you'll have a 10* marker.
I do have a dial back light. My biggest problem right now is that the timing tab is basically buried behind the idler pulley. At 60 years young it’s all I can do to lean my fat butt over enough to see my zero mark.
Since you seem to know your stuff.... whenever I set up a curve I generally time by the maximum advance at around 34° to 35° (without vacuum) then let the initial fall where it may. If too low I’ll shorten up the advance travel. I generally limit vacuum to about 10°. I’m certainly not racing but I’m not wanting to leave potential power on the table when it comes to the tune. Am I in the ballpark or should I rethink my norm?
I do have a dial back light. My biggest problem right now is that the timing tab is basically buried behind the idler pulley. At 60 years young it’s all I can do to lean my fat butt over enough to see my zero mark.
Since you seem to know your stuff.... whenever I set up a curve I generally time by the maximum advance at around 34° to 35° (without vacuum) then let the initial fall where it may. If too low I’ll shorten up the advance travel. I generally limit vacuum to about 10°. I’m certainly not racing but I’m not wanting to leave potential power on the table when it comes to the tune. Am I in the ballpark or should I rethink my norm?
That is very close to the @lars instructions that I followed. 36 total, initial falls where it may. My HEI distributor does about 21 mechanical, and I set the vacuum advance to 12.
I'm glad it worked out, and was something simple to fix, if not diagnose!
My biggest problem right now is that the timing tab is basically buried behind the idler pulley. At 60 years young it’s all I can do to lean my fat butt over enough to see my zero mark.
Worse then that, we can't see either!!! I Painted an orange line on my damper and on the indicator. (actually my steady handed daughter painted the line on the indicator with an artist's brush on a stick). It is a lot easier to line up the contrasting lines.
One other thing I would check "while you are at it" is the integrity of the balancer, and if it has slipped. Since you have another known good 454 it should be easy.
Find the bolts holding the pulleys on the balancer, or maybe you can see the keyway. Check the relationship of those to your "zero" mark on your balancer.. If it's close you should be good. If it's off, it's probably way off. Your 30 degree mark got me thinking about this.
Glad it has been mostly easy fixes so far!
Sounds like bubba took care of the car after it left your care
OK here is a fresh pic. Looks like one of the 3 pulley bolts lines up almost exactly in a straight line with TDC and the balancer retaining bolt. Lucky for you my engine stopped at almost exactly TDC, (It is at 4 after.) This is a new degreed balancer where I painted over most of it. It is not a tape.
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Last edited by leigh1322; Sep 19, 2020 at 10:15 AM.
One other thing I would check "while you are at it" is the integrity of the balancer, and if it has slipped. Since you have another known good 454 it should be easy.
Find the bolts holding the pulleys on the balancer, or maybe you can see the keyway. Check the relationship of those to your "zero" mark on your balancer.. If it's close you should be good. If it's off, it's probably way off. Your 30 degree mark got me thinking about this.
Glad it has been mostly easy fixes so far!
Sounds like bubba took care of the car after it left your care
OK here is a fresh pic. Looks like one of the 3 pulley bolts lines up almost exactly in a straight line with TDC and the balancer retaining bolt. Lucky for you my engine stopped at almost exactly TDC, (It is at 4 after.) This is a new degreed balancer where I painted over most of it. It is not a tape.
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I actually did one better and checked the TDC with a threaded piston stop tool. The TDC mark is right on the money with the indicating tab. Had I been thinking (or remembering) I’d have installed an adjustable pointer and moved the TDC mark up higher so that it’s more visible with the timing light. But... coulda’, shoulda’, woulda’... One day when I need to get the radiator out or do some other front work I hope to remember to do that.
Since it seems to be running okay now I figured a trip to the gas station was in order. It took 14 gallons of premium so I’m not worried about the 4 gallons of older gas. Two different guys at the station asked me if I was interested in selling it so I’ll take that as a good sign. Now for some more driving and fine tuning....
I bet that PVC got changed some time in it's life.
So pinch it off with some vice grips for a min and watch the rest of your
problems go away.
It's a wide open vacuum leak. OBD motors use idle air control.
Ours don't.
So I purchased a paint gun pressure reg at harbor freight.
Installed it inline before the PVC.
Dialed it down to a nice idle , and still pulled neg pressure.
Then start turning screws.
Hope that helps.
ramair in calif. (as we burn to the ground)...............
I bet that PVC got changed some time in it's life.
So pinch it off with some vice grips for a min and watch the rest of your
problems go away.
It's a wide open vacuum leak. OBD motors use idle air control.
Ours don't.
So I purchased a paint gun pressure reg at harbor freight.
Installed it inline before the PVC.
Dialed it down to a nice idle , and still pulled neg pressure.
Then start turning screws.
Hope that helps.
ramair in calif. (as we burn to the ground)...............
I think you mean PCV (positive crankcase ventilation) and not PVC (polyvinyl chloride [plastic])
I bet that PVC got changed some time in it's life.
So pinch it off with some vice grips for a min and watch the rest of your
problems go away.
It's a wide open vacuum leak. OBD motors use idle air control.
Ours don't.
So I purchased a paint gun pressure reg at harbor freight.
Installed it inline before the PVC.
Dialed it down to a nice idle , and still pulled neg pressure.
Then start turning screws.
Hope that helps.
ramair in calif. (as we burn to the ground)...............
keep looking up and smiling.
Hmmm... it just dawned on me that when I first owned this car it only had a breather filter and no PCV valve. I’ll cap it off at the carburetor base and see if it runs better or worse without it. Good suggestion. Thank you. I sure wish I could have gotten this car back with the same parts I sold it with. Oh well....
Well... I’m running okay now, but I need to address my ignition timing. Timing tape is on and, as suspected, it will only idle with about 30° initial. I’ll be starting another thread to question timing recommendations.
Thank you all for your suggestion that got me this far.
Well... I’m running okay now, but I need to address my ignition timing. Timing tape is on and, as suspected, it will only idle with about 30° initial. I’ll be starting another thread to question timing recommendations.
Thank you all for your suggestion that got me this far.
What's your idle RPM? Did you check for nozzle drip?
get out more..............