not enough spark? what does it feel like?
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Burning Brakes
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From: JUPITER FLORIDA
not enough spark? what does it feel like?
what would be an indication that your car is not recieving enough spark?
i was wondering this because i have a new engine built and i have all stock ignition components, can you feel it at wot if you are not getting enough spark? if so what does it feel like?
i was wondering this because i have a new engine built and i have all stock ignition components, can you feel it at wot if you are not getting enough spark? if so what does it feel like?
Team Owner
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From: SE NY
Cruise-In II Veteran
I'm not sure what you mean by "not enough spark"??
Our stock (L98) HEI tends to nose over around 5k RPM or slightly below, so you would just run out of power up there. Of course the stock TPI limits high RPM performance so that would not be detremental.
If you have raised the practical RPM limit of your new engine I suggest you go with a HyperTech coil/cap/rotor combo. This system not only provides a hotter spark (>53kV) but will fire relaibly to well over 5k RPM.
BTW, long ago when I had bad secondary ignition wires on a car it would simply not take much throttle, sort of like fuel starvation.
Our stock (L98) HEI tends to nose over around 5k RPM or slightly below, so you would just run out of power up there. Of course the stock TPI limits high RPM performance so that would not be detremental.
If you have raised the practical RPM limit of your new engine I suggest you go with a HyperTech coil/cap/rotor combo. This system not only provides a hotter spark (>53kV) but will fire relaibly to well over 5k RPM.
BTW, long ago when I had bad secondary ignition wires on a car it would simply not take much throttle, sort of like fuel starvation.
Race Director
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From: The Top of Utah
Originally Posted by cplonner
what would be an indication that your car is not recieving enough spark?
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Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by 65Z01
BTW, long ago when I had bad secondary ignition wires on a car it would simply not take much throttle, sort of like fuel starvation.
I've seen ignition or weak spark conditions even manifest themselves as black smoke that would lead you to believe that an engine had a rich fuel condition. Also you could get spark scatter or break-up at higher RPMs due to a distributor or other components exceeding their design limits or worn, weak parts, etc.
Burning Brakes
Joined: Feb 2003
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From: Rolla Mo
Originally Posted by CFI-EFI
How radical is your engine? I twist my Crossfire past 6000 rpms, and it isn't the ignition system that limits the rpms. The stock HEI has a lot of "head room" for modifications. Very high rpms and very high compression pressures can strain the stock system.
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Doug
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From: The Top of Utah
Originally Posted by Dougs 90
What modifications are we talking about here? Just interested as I have done a few, want to make sure I am in the right direction to spin 6200rpm....
Doug
Doug
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Burning Brakes
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From: JUPITER FLORIDA
right now i have vortec heads,largemouth intake and runners,.474 int/exh cam, hooker headers and full custom exhaust, custom chip, 24 lb injectors and everthing is pretty much stock. i feel a solid buzz/vibration at high rpms and that is when the power drops of until next gear. im thinking its the tranny but i dont know if it could be not enough fuel, or strong enough spark. some one educate me please. 
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Race Director
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From: The Top of Utah
Originally Posted by cplonner
i feel a solid buzz/vibration at high rpms and that is when the power drops of until next gear. im thinking its the tranny but i dont know if it could be not enough fuel, or strong enough spark. some one educate me please.
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Burning Brakes
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From: Rolla Mo
Originally Posted by CFI-EFI
6200 rpms, no problem. You need some pretty high pressures to "blow out the spark" of an HEI. I had a buddy (R.I.P. Wayne) racing an alchol powered 350, twisting near 8000 rpms with an HEI with just a coil and a module . Most, don't even need that. Even I don't have ignition problems at 6200 rpms.
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Doug
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Burning Brakes
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From: JUPITER FLORIDA
the problem is at about 5000 rpms give or take a little (dont wanna fly off the road watching rpms!)
what do i do to stop valve float and valve train problems if thats the case?
The scan tool is a good start too
what do i do to stop valve float and valve train problems if thats the case?
The scan tool is a good start too
Team Owner
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From: SE NY
Cruise-In II Veteran
I'm still running stock cam but with 1.6:1 RRs so I upgraded to 7/16" rocker studs and Ti retainers with 10deg locks along with stronger valve springs shimmed for a little more seat force.
I assume you matched valve springs to the cam but don't think you would be getting float by 5k RPM.
Also I think your stock HEI should still be doing ok near 5k RPM.
Yea, buzz & vibration might be farther down the drive train than the engine.
If you are getting either valve float or missfires due to ignition a O2 sensor readings at WOT should be useful. If readings are solid through the RPM range of interest check out other potentials.
I assume you matched valve springs to the cam but don't think you would be getting float by 5k RPM.
Also I think your stock HEI should still be doing ok near 5k RPM.
Yea, buzz & vibration might be farther down the drive train than the engine.
If you are getting either valve float or missfires due to ignition a O2 sensor readings at WOT should be useful. If readings are solid through the RPM range of interest check out other potentials.
Team Owner
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From: OBAMA IS HITLER
In David Vizards book "How To Build Max Performance Chevy Small Blocks" the Man says that higher preformance coil and/or module would be needed if going over 5,500 rpms.
I would say CFI-EFI is right.
I'm keeping my stock HEI system, as a whole, in tact. I see no reason to change the coil or module unless there's a failure condition. I'm not living over 5,500 rpms, only getting there to make a 1rst/2nd/3rd gear shift in street driving.
I would say CFI-EFI is right.
I'm keeping my stock HEI system, as a whole, in tact. I see no reason to change the coil or module unless there's a failure condition. I'm not living over 5,500 rpms, only getting there to make a 1rst/2nd/3rd gear shift in street driving.
Last edited by Red Tornado; May 9, 2005 at 12:01 AM.
Drifting
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If you have a weak (or no) spark, you have unburnt fuel, and - more importantly - unburnt oxygen.
The O2 sensor "sees" this oxygen , and so the ECM reads this as a weak mixture, and so adds more fuel. This fouls the plugs, even more, more o2, >more fuel.
So the engine runs pig rich, runs rough and misfires, maybe even your oil level increases as unburnt gas gets into the oil. The oil stinks of fuel. Gas mileage suffers .......not a lot going for it really.
John
The O2 sensor "sees" this oxygen , and so the ECM reads this as a weak mixture, and so adds more fuel. This fouls the plugs, even more, more o2, >more fuel.
So the engine runs pig rich, runs rough and misfires, maybe even your oil level increases as unburnt gas gets into the oil. The oil stinks of fuel. Gas mileage suffers .......not a lot going for it really.
John