AJ.
Active Member
Putting the marks on the balancer with a Sharpie, Is how I have done it too.
Your problem has nothing to do with the fuel delivery system. The fuel is already in the bowl. Most stock-cammed engines will idle for two or more minutes on the fuel that is in the bowl . So forget chasing filters and hoses for now.
But that fuel has to be fresh clear gas with no contaminants in it.
If your fuel is anything but clear, it is not fresh. At 115 measly psi, your engine is gonna demand fresh fuel. At 150psi, the engine will be a lil more tolerant. At 180psi, mine hardly cares.
If the fuel is yellow it will still work in an EFI car because the computer is gonna adjust the AFR and timing to work with it.
After yellow is orange. The EFI car will burn that too, but the power will be down because of pulled timing., and erroneous AFR readings. After orange she goes into pink and red.
RED IS SO BAD, it won't hardly light on your garage floor,and will sputter to death, while sending off puffs of black smoke.
Orange is only a lil better.
Your carbyed engine is more sensitive. It needs clear to slightly yellow.
Gasoline is made up of many many different kinds of molecules, some of which burn better than others. Those good ones are the fire starters, while the slow-burners come along for the ride. After a week in open air, the volatile fire-starters have evaporated, leaving you with some in-betweeners. By the third week those have evaporated as well, leaving you with the Orange and Pink laZy fatboys, that can't hardly get off the couch. When you slap the throttle, it takes time for them to get moving, and a bunch of 'em have heart-attacks before they ever get to the chamber, and of those that make it, most of 'em end up hiding. For every 10 you invited, maybe only 8 or 7 show up, and 3 end up hiding, leaving you with 4 lazyazz molecules to burn, and summa those are so fat they can't hardly walk, never mind scoot.
So, while. if you can get the engine started, it will idle. But the gas is just too lazy to respond to a slapped gas-pedal.
Do not say, your gas is fresh, until you have color-checked it. It has to be CLEAR.
Wiki says; Elevation Everett Wa is 82 ft.
why is this important? Cuz that is dense air. It does not make sense to me for your engine to have only 115psi, with a fresh valve job. Ima thinking the rings are done. Rings have a few jobs; one of them you know as making compression.
Another is to evacuate the chamber on the intake stroke.
Engines do not suck air in.
On the intake stroke,the falling pistons create a low-pressure area in the chamber, and air ALWAYS moves from a high-pressure area to a low pressure area.
The better your rings work, the easier and faster the atmosphere will fill the chambers with air, and the greater will be the air-density in the chamber when the intake closes.
On a running engine, that just "inhaled" mixture will have,HOPEFULLY, the right amount of fresh clear gas in it, so that when the spark lioghts it up, it will ALL OF IT burn asap, because the optimum point of energy transfer is fast coming up; and if the flame is lazy, it will end up still burning when the exhaust valve opens. When that happens, and if the manifold happens to have oxygen in it, or if the just burned slug brings oxygen with it, then the fire will continue in the exhaust manifold. But hang on... when that happens, the manifold comes under pressure. And if the pressure spike cannot get away, remember air always moves from a high pressure area to a low pressure area. So if the manifold ends up at a higher pressure, than another cylinder connected to the exhaust manifold,......... with it's exhaust valve open....then pow! this hot burning slug is taking the path of least resistance, and in she goes. If this chamber simultaneously also has the intake valve open,as it would oif it was on the overlap cycle, then POW! the fire gets into the intake manifold, and you get a backfire thru the carb. Flames often attending.
Ok I'll admit, on a stock cammed Chevy this would be a rare deal. But even a stock 318 cam has 20* of overlap at a specified 008 tappet rise, which is just the part that we know about........ but seat to seat, there is a lot more.
How did this scenario arise?
Well, it started with lazy gas, and ended with late ignition timing. And may have been exacerbated by a restrictive exhaust system.
I'm not saying this is your problem.
I am saying, that it can happen with old stale gas.
A far more likely scenario would be the accelerator pump-shot being lazy, late, too short, not atomized properly; or once again, stale gas.
Stale gas will not infuse the incoming rush of air with the right amount of combustible fuel.
And your 115 psi is not helping it.
If a cylinder goes lean, the fair and fuel molecules could be so far apart that transitioning from idle to open throttle, they just never find each other. The upcomong piston is supposed to squeeze them together, which is supposed to increase their temperature, to where the most freshest molecules are eager to begin burning. When the spark hits POW! they give it up. Which is supposed to start a controlled chain reaction amongst the fayboyz. That is the kind of gas the refineries are giving us these days. So if the early boyz don't light, or if they are jusy too far from the fayboyz, or just not excited enough about the whole affair; then the fire fizzless out and you get a misfire. Now.... all those unburned molecules are going where again? Hyup straight into the hot exhaust manifold .............. with predictable results.
How did this scenario arise?
That's hard to say exactly, it may have started with a lazy pumpshot, or a lazy transfer slot; but the lack of cylinder pressure just never brought the air and fuel close enough together in the end.
If I had this problem with known to be fresh and clear fuel
I would be doing a Leakdown test to see just how good the rings really are. I hate chasing my tail.
But if the LD shows good rings ( less than 4% leakage in my opinion, up to 10% by others on FABO, and for Performance, Smokey Yunich preaches 3 to 5% is good; 5 to 8% is toast), then I'd be checking the cam-timing. Since you have already done that,and are satisfied, then I'm going with the transfers and pumpshot. If you close the throttles too far, the transfers will get lazy. They could even dry right up. If the fuel level is too low, pullover will become difficult, and your idle wells will pull too much air in to the emulsion tubes. Pull-over is a term used to describe the fuel in the wells (idle and main) being pulled higher than the fuel-level in the bowl, up to the top of the idle-well and then over the top and cascading down to the discharge ports. Remember; the engine isn't sucking in the fuel, atmosphere is supposed to be pushing down on the fuel in the float bowl. The air coming in thru the bleeds at atmospheric pressure is moving to the low pressure in the chambers, and the fuel is coming along for the ride. If atmosphere cannot get into the bowls or airbleeds, all bets are off. If at idle, the throttles are closed too far, the inrushing air will go thru the transfer slots, above the throttles, and exit underneath, drying up the transfers. Then, at tip-in, there is no fuel there and a hesitation follows. The pump-shot is not designed to cover that, it is much too slow. So when you slap the throttle; first you get the hesitation, which is the engine trying to stall. Then the pumpshot comes along and trys to make it all better, but it's like putting a bandaid on a hemorrhaging artery, too little too late; and you get a full-fledged bog, or lean misfire, or even a backfire.. Worse if the gas is stale.
Gotta go, it's supper time, yay
Your problem has nothing to do with the fuel delivery system. The fuel is already in the bowl. Most stock-cammed engines will idle for two or more minutes on the fuel that is in the bowl . So forget chasing filters and hoses for now.
But that fuel has to be fresh clear gas with no contaminants in it.
If your fuel is anything but clear, it is not fresh. At 115 measly psi, your engine is gonna demand fresh fuel. At 150psi, the engine will be a lil more tolerant. At 180psi, mine hardly cares.
If the fuel is yellow it will still work in an EFI car because the computer is gonna adjust the AFR and timing to work with it.
After yellow is orange. The EFI car will burn that too, but the power will be down because of pulled timing., and erroneous AFR readings. After orange she goes into pink and red.
RED IS SO BAD, it won't hardly light on your garage floor,and will sputter to death, while sending off puffs of black smoke.
Orange is only a lil better.
Your carbyed engine is more sensitive. It needs clear to slightly yellow.
Gasoline is made up of many many different kinds of molecules, some of which burn better than others. Those good ones are the fire starters, while the slow-burners come along for the ride. After a week in open air, the volatile fire-starters have evaporated, leaving you with some in-betweeners. By the third week those have evaporated as well, leaving you with the Orange and Pink laZy fatboys, that can't hardly get off the couch. When you slap the throttle, it takes time for them to get moving, and a bunch of 'em have heart-attacks before they ever get to the chamber, and of those that make it, most of 'em end up hiding. For every 10 you invited, maybe only 8 or 7 show up, and 3 end up hiding, leaving you with 4 lazyazz molecules to burn, and summa those are so fat they can't hardly walk, never mind scoot.
So, while. if you can get the engine started, it will idle. But the gas is just too lazy to respond to a slapped gas-pedal.
Do not say, your gas is fresh, until you have color-checked it. It has to be CLEAR.
Wiki says; Elevation Everett Wa is 82 ft.
why is this important? Cuz that is dense air. It does not make sense to me for your engine to have only 115psi, with a fresh valve job. Ima thinking the rings are done. Rings have a few jobs; one of them you know as making compression.
Another is to evacuate the chamber on the intake stroke.
Engines do not suck air in.
On the intake stroke,the falling pistons create a low-pressure area in the chamber, and air ALWAYS moves from a high-pressure area to a low pressure area.
The better your rings work, the easier and faster the atmosphere will fill the chambers with air, and the greater will be the air-density in the chamber when the intake closes.
On a running engine, that just "inhaled" mixture will have,HOPEFULLY, the right amount of fresh clear gas in it, so that when the spark lioghts it up, it will ALL OF IT burn asap, because the optimum point of energy transfer is fast coming up; and if the flame is lazy, it will end up still burning when the exhaust valve opens. When that happens, and if the manifold happens to have oxygen in it, or if the just burned slug brings oxygen with it, then the fire will continue in the exhaust manifold. But hang on... when that happens, the manifold comes under pressure. And if the pressure spike cannot get away, remember air always moves from a high pressure area to a low pressure area. So if the manifold ends up at a higher pressure, than another cylinder connected to the exhaust manifold,......... with it's exhaust valve open....then pow! this hot burning slug is taking the path of least resistance, and in she goes. If this chamber simultaneously also has the intake valve open,as it would oif it was on the overlap cycle, then POW! the fire gets into the intake manifold, and you get a backfire thru the carb. Flames often attending.
Ok I'll admit, on a stock cammed Chevy this would be a rare deal. But even a stock 318 cam has 20* of overlap at a specified 008 tappet rise, which is just the part that we know about........ but seat to seat, there is a lot more.
How did this scenario arise?
Well, it started with lazy gas, and ended with late ignition timing. And may have been exacerbated by a restrictive exhaust system.
I'm not saying this is your problem.
I am saying, that it can happen with old stale gas.
A far more likely scenario would be the accelerator pump-shot being lazy, late, too short, not atomized properly; or once again, stale gas.
Stale gas will not infuse the incoming rush of air with the right amount of combustible fuel.
And your 115 psi is not helping it.
If a cylinder goes lean, the fair and fuel molecules could be so far apart that transitioning from idle to open throttle, they just never find each other. The upcomong piston is supposed to squeeze them together, which is supposed to increase their temperature, to where the most freshest molecules are eager to begin burning. When the spark hits POW! they give it up. Which is supposed to start a controlled chain reaction amongst the fayboyz. That is the kind of gas the refineries are giving us these days. So if the early boyz don't light, or if they are jusy too far from the fayboyz, or just not excited enough about the whole affair; then the fire fizzless out and you get a misfire. Now.... all those unburned molecules are going where again? Hyup straight into the hot exhaust manifold .............. with predictable results.
How did this scenario arise?
That's hard to say exactly, it may have started with a lazy pumpshot, or a lazy transfer slot; but the lack of cylinder pressure just never brought the air and fuel close enough together in the end.
If I had this problem with known to be fresh and clear fuel
I would be doing a Leakdown test to see just how good the rings really are. I hate chasing my tail.
But if the LD shows good rings ( less than 4% leakage in my opinion, up to 10% by others on FABO, and for Performance, Smokey Yunich preaches 3 to 5% is good; 5 to 8% is toast), then I'd be checking the cam-timing. Since you have already done that,and are satisfied, then I'm going with the transfers and pumpshot. If you close the throttles too far, the transfers will get lazy. They could even dry right up. If the fuel level is too low, pullover will become difficult, and your idle wells will pull too much air in to the emulsion tubes. Pull-over is a term used to describe the fuel in the wells (idle and main) being pulled higher than the fuel-level in the bowl, up to the top of the idle-well and then over the top and cascading down to the discharge ports. Remember; the engine isn't sucking in the fuel, atmosphere is supposed to be pushing down on the fuel in the float bowl. The air coming in thru the bleeds at atmospheric pressure is moving to the low pressure in the chambers, and the fuel is coming along for the ride. If atmosphere cannot get into the bowls or airbleeds, all bets are off. If at idle, the throttles are closed too far, the inrushing air will go thru the transfer slots, above the throttles, and exit underneath, drying up the transfers. Then, at tip-in, there is no fuel there and a hesitation follows. The pump-shot is not designed to cover that, it is much too slow. So when you slap the throttle; first you get the hesitation, which is the engine trying to stall. Then the pumpshot comes along and trys to make it all better, but it's like putting a bandaid on a hemorrhaging artery, too little too late; and you get a full-fledged bog, or lean misfire, or even a backfire.. Worse if the gas is stale.
Gotta go, it's supper time, yay
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