Optispark vs HEI
11-15-2006, 12:40 PM
#1
Racer
Thread Starter
Optispark vs HEI
Is the optispark really a better system than the HEI. We used the Mallory HEI in our late model and never had an ignition problem. I realize progress is good but I'm not convinced the opti is improvement.
11-15-2006, 12:53 PM
#3
Le Mans Master
I'd take the HEI anyday over the opti...simply because it's not so sensitive (never had to replace a HEI because it got wet) and cost is less. Besides, I think either supplies enough juice to handle most sbc.
11-15-2006, 12:53 PM
#4
Le Mans Master
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St. Jude Donor '07
I don't have enough knowledge to compare the two, but i don't understand why they went with the Opti instead of a HEI/traditional distributor. Apparently, The Opti wasn't the greatest thing since sliced bread, because GM went to DIS for C5's, if memory serves correctly, the ZR1 was also a DIS.
Last edited by VetteUSA; 11-15-2006 at 12:58 PM.
11-15-2006, 01:42 PM
#6
Le Mans Master
It gets into a discussion concerning engineering...square wave output versus sine wave and the advantages of one over the other. 97 went back to a sine wave with hysteresis correction programmed in the computer. The Opti is based upon a sound principle and can do things DIS cannot but the engineers screwed up by not realizing C4 owners might hose their engines down so it went away after it generated some warranty costs. In other words we owners taught GM that they will have to build stuff more bullet proof than that.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
11-15-2006, 01:47 PM
#7
Team Owner
The opti is an improvement but has its own flaws, most notably the water damage issue. However, it doesnt need to be set for timing like HEI as the computer controls that and the LT1 operates a lot smoother because of this. I prefer HEI because its cheaper and a lot easier to replace.
The same could be said comparing carbed to fuel injected.
The same could be said comparing carbed to fuel injected.
11-15-2006, 03:17 PM
#8
Le Mans Master
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St. Jude Donor '07
Originally Posted by Greg Gore
It gets into a discussion concerning engineering...square wave output versus sine wave and the advantages of one over the other. 97 went back to a sine wave with hysteresis correction programmed in the computer. The Opti is based upon a sound principle and can do things DIS cannot but the engineers screwed up by not realizing C4 owners might hose their engines down so it went away after it generated some warranty costs. In other words we owners taught GM that they will have to build stuff more bullet proof than that.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
You completely lost me after you said "engineering."
11-16-2006, 04:39 PM
#10
Racer
Thread Starter
Originally Posted by Greg Gore
It gets into a discussion concerning engineering...square wave output versus sine wave and the advantages of one over the other. 97 went back to a sine wave with hysteresis correction programmed in the computer. The Opti is based upon a sound principle and can do things DIS cannot but the engineers screwed up by not realizing C4 owners might hose their engines down so it went away after it generated some warranty costs. In other words we owners taught GM that they will have to build stuff more bullet proof than that.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
11-16-2006, 10:05 PM
#11
Le Mans Master
I didn't mean to imply HEI was not reliable because it is. I was trying to point out some engineering objectives and advantages that going to a front drive distributor provides. Optispark would be unnecessary in a racing application due to no need to alter timing from base setting.
11-16-2006, 11:33 PM
#12
Burning Brakes
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Originally Posted by Greg Gore
It gets into a discussion concerning engineering...square wave output versus sine wave and the advantages of one over the other. 97 went back to a sine wave with hysteresis correction programmed in the computer. The Opti is based upon a sound principle and can do things DIS cannot but the engineers screwed up by not realizing C4 owners might hose their engines down so it went away after it generated some warranty costs. In other words we owners taught GM that they will have to build stuff more bullet proof than that.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
The Opti also solves these issues which affected timing accuracy:
1) Torsional twist in the cam core.
2) Backlash that would be present in the distributor/ cam gears.
3) Distributor shaft end play between the housing and the gear thrust surfaces which translates to advance-retard movement due to gear helix.
4) Camshaft distributor drive gear runout; gears are never hobbed to concentricity on the cam cores and the norm is .002 - .004 runout.
5) Aluminum distributor housing sensitivity to heat and length change. Helical gear advances timing as distributor housing is heated.
6) Wear in the distributor gears or shaft bushings
In addition if you throw or break a belt you do not overheat due to the water pump being direct drive. Direct drive also eliminates lateral belt loading on the water pump bearings.
11-17-2006, 02:39 AM
#13
Team Owner
I don't think there is any conversion from HEI to Opti. Would I do it? No, I would skip over it to DIS and be done with it.
Greg's post is very accurate. In short, the Opti is the best distributor ever made. I know... damning it with faint praise.
The Opti isn't all that bad... I have an older one attached to an LTCC system, and it's been there for nearly 5 years and 100k miles... knock on wood. The optics are seriously reliable... it's the bearings that suck... and the crappy nature of the ventilation - or lack thereof - in the early units. It's that lack of ventilation that leads to premature carbon tracing... and the wondering idle.
Greg's post is very accurate. In short, the Opti is the best distributor ever made. I know... damning it with faint praise.
The Opti isn't all that bad... I have an older one attached to an LTCC system, and it's been there for nearly 5 years and 100k miles... knock on wood. The optics are seriously reliable... it's the bearings that suck... and the crappy nature of the ventilation - or lack thereof - in the early units. It's that lack of ventilation that leads to premature carbon tracing... and the wondering idle.
11-17-2006, 12:45 PM
#14
Le Mans Master
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Originally Posted by rick lambert
I'd take the HEI anyday over the opti...simply because it's not so sensitive (never had to replace a HEI because it got wet) and cost is less. Besides, I think either supplies enough juice to handle most sbc.
The juice isn't the issue, emissions was....GM invented the SBC and with the opti the Dark Ages........Is it any wonder that GM is on the ropes?
GM should put an add in the paper for a engineer, one would do it.
The opti-spank is the one bad spot in an otherwise very good car.
Even at that its not all that bad.
11-17-2006, 12:47 PM
#15
Le Mans Master
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Originally Posted by bogus
I don't think there is any conversion from HEI to Opti. Would I do it? No, I would skip over it to DIS and be done with it.
Greg's post is very accurate. In short, the Opti is the best distributor ever made. I know... damning it with faint praise.
The Opti isn't all that bad... I have an older one attached to an LTCC system, and it's been there for nearly 5 years and 100k miles... knock on wood. The optics are seriously reliable... it's the bearings that suck... and the crappy nature of the ventilation - or lack thereof - in the early units. It's that lack of ventilation that leads to premature carbon tracing... and the wondering idle.
Greg's post is very accurate. In short, the Opti is the best distributor ever made. I know... damning it with faint praise.
The Opti isn't all that bad... I have an older one attached to an LTCC system, and it's been there for nearly 5 years and 100k miles... knock on wood. The optics are seriously reliable... it's the bearings that suck... and the crappy nature of the ventilation - or lack thereof - in the early units. It's that lack of ventilation that leads to premature carbon tracing... and the wondering idle.
11-18-2006, 02:32 AM
#17
Safety Car
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I still remember the day I aided a good friend in the replacement of the POS Opti in his 93 Camaro. What a ****ing pain in the ****!!! Took us 4 hours and about $400 worth of parts, of course all from the GM stealership. The 10000 mile new water pump leaking was responsible for the old Opti's death, which btw, also had 10000 miles...
GM replaced all that garbage a little over a year ago with a nice 12 month warranty. After a year, the warranty expires. So its either $1400 at a dealer to have it done, AGAIN, or $400, our labor.
****, it would take me less than 20 minutes to R/R the distributer on my Vette. If I had an LT1 Vette, It would have either been sold, scrapped, ran into the wall, or with enough patience, the motor replaced with a standard SBC.
If I were him, I'd do what the rednecks do to their trucks when swapping to an LT1. Drill the back of the intake for a HEI distributer and leave the Opti on as a nice underhood decoration marking GM's failure of the past. At least they'd reap the only benefit the LT1 motor, reverse flow cooling...
ps. My friend told me if you really wanna screw someone over who owns an LT1 equipped car, just pop the hood and pee on it.
HEI all the way! Now I see why Optis were ended early from GM. Mounting a distributer under the water pump is one of the stupidest ideas! Sure, the Opti would have been a good idea, if protected well. But because of the lack of protection the Opti initially had, it made a lot of LT1s run on 7 cylinders, or less! Hell, my buddy's 93 3.3L V6 Grand Am was more high tech than the LT1. Although a lot slower, it had a DIS. It has over 200k miles on it! Still running good today. GM didn't use that feature on their beloved V8s till 97 with the LS1. WTF!!! What a way to go...
No wonder why a lot of people consider the LT1 a bastard motor... No wonder why police departments quit using 9C1 Caprices. They'd be in a high speed chase and suddenly the motor would start missing or even quit. The suspect would get away...
I might not be the smartest tool in the shed as well as the CF bandaid bandit ghetto rigger, but I CERTAINLY know that LT1s ain't no super motor either!
Now flame me for being such a drunkazz...
GM replaced all that garbage a little over a year ago with a nice 12 month warranty. After a year, the warranty expires. So its either $1400 at a dealer to have it done, AGAIN, or $400, our labor.
****, it would take me less than 20 minutes to R/R the distributer on my Vette. If I had an LT1 Vette, It would have either been sold, scrapped, ran into the wall, or with enough patience, the motor replaced with a standard SBC.
If I were him, I'd do what the rednecks do to their trucks when swapping to an LT1. Drill the back of the intake for a HEI distributer and leave the Opti on as a nice underhood decoration marking GM's failure of the past. At least they'd reap the only benefit the LT1 motor, reverse flow cooling...
ps. My friend told me if you really wanna screw someone over who owns an LT1 equipped car, just pop the hood and pee on it.
HEI all the way! Now I see why Optis were ended early from GM. Mounting a distributer under the water pump is one of the stupidest ideas! Sure, the Opti would have been a good idea, if protected well. But because of the lack of protection the Opti initially had, it made a lot of LT1s run on 7 cylinders, or less! Hell, my buddy's 93 3.3L V6 Grand Am was more high tech than the LT1. Although a lot slower, it had a DIS. It has over 200k miles on it! Still running good today. GM didn't use that feature on their beloved V8s till 97 with the LS1. WTF!!! What a way to go...
No wonder why a lot of people consider the LT1 a bastard motor... No wonder why police departments quit using 9C1 Caprices. They'd be in a high speed chase and suddenly the motor would start missing or even quit. The suspect would get away...
I might not be the smartest tool in the shed as well as the CF bandaid bandit ghetto rigger, but I CERTAINLY know that LT1s ain't no super motor either!
Now flame me for being such a drunkazz...
