Advanced Opti Thread.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
Advanced Opti Thread.
Okay, When installing a Opti spark, what measurements, after a new cam, timing chain, cover or whatever, should you take to ensure as little possible breakdown.
Its strange how a Opti survives in a stock motor for so many years for some, even when hiting redline occasinally, but when someone modifies there motor, there seems to be more breakdowns. Why? Several Builders here should have some insight.
I am looking at Dowel Pin lengths, possible camshaft problems(hole for opti not right size causing looseness?, camshaft bolts not fitting fluch inside Opti casuing problems, dowel pin banging the opti becauses of thrust loads. Who knows.
I have had several break within a year. Different cams, different timing chains, same cover, different valve springs, and raised my shift points to 6300rpm from 5800rpm.
There have been several thousand Opti discussions. But we need to ensure we cover everything mechanical we can. Thanks, lets see if something can be enlightened.
Its strange how a Opti survives in a stock motor for so many years for some, even when hiting redline occasinally, but when someone modifies there motor, there seems to be more breakdowns. Why? Several Builders here should have some insight.
I am looking at Dowel Pin lengths, possible camshaft problems(hole for opti not right size causing looseness?, camshaft bolts not fitting fluch inside Opti casuing problems, dowel pin banging the opti becauses of thrust loads. Who knows.
I have had several break within a year. Different cams, different timing chains, same cover, different valve springs, and raised my shift points to 6300rpm from 5800rpm.
There have been several thousand Opti discussions. But we need to ensure we cover everything mechanical we can. Thanks, lets see if something can be enlightened.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
Wiring is fine, all soldered for the connector going from 93 to 95 Opti. Continuity checks fine. I think there are mechanical features that break optis too, not just crappy design and build. I think the measurements for fitment are critical, and GM people havent figured it out. A factory OPTI taken out and have all measurements done for fitment within Timing cover, to camshaft etc would be valuable.
Last edited by steve40th; Oct 15, 2005 at 03:09 PM.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
It depends what kind of Opti-Spark "break-downs" you are talking about.
If you are talking about the arcing of the high-voltage section, I believe anytime you have more horsepower/torque you also have more cylinder pressure, and that means it takes a higher voltage to jump the spark plug gap.
The voltage on a spark plug wire and the Opti-Spark high-voltage section is limited by the amount required to jump the spark plug gap. When the gap is ionized, the current bleeds the voltage from going any higher.
So, higher cylinder pressure requires a higher voltage to jump the gap, which causes this higher voltage to be reflected back into the Opti-Spark. And, this can cause carbon tracking of the cap.
The voltage requirement due to cylinder pressure is the principle on which a "waste spark" ignition system is based.
There are two plugs firing in series, but the plug on the compression stroke is the one that requires the much higher voltage to cause a spark to occur. The plug on the exhaust stroke has very little voltage requirement.
Tom Piper
If you are talking about the arcing of the high-voltage section, I believe anytime you have more horsepower/torque you also have more cylinder pressure, and that means it takes a higher voltage to jump the spark plug gap.
The voltage on a spark plug wire and the Opti-Spark high-voltage section is limited by the amount required to jump the spark plug gap. When the gap is ionized, the current bleeds the voltage from going any higher.
So, higher cylinder pressure requires a higher voltage to jump the gap, which causes this higher voltage to be reflected back into the Opti-Spark. And, this can cause carbon tracking of the cap.
The voltage requirement due to cylinder pressure is the principle on which a "waste spark" ignition system is based.
There are two plugs firing in series, but the plug on the compression stroke is the one that requires the much higher voltage to cause a spark to occur. The plug on the exhaust stroke has very little voltage requirement.
Tom Piper
Drifting
Joined: Aug 2000
Posts: 1,614
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From: Colleyville Texas
Add washers to cover+loctite rotor screws+Delteq= no problems for my 396. 6800 RPM's at the track with no more failures. Use to go thru two new opti's per racing season.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
Originally Posted by Red Rocket
Add washers to cover+loctite rotor screws+Delteq= no problems for my 396. 6800 RPM's at the track with no more failures. Use to go thru two new opti's per racing season.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
Washers for cover?
Loctite screws, yes I can see that.
Mine just died and the DELTEQ cant fire properly because of it, it must have hit or jammed the Opti to where the sensor for the DELTEQ isnt useable,.
Steve
Drifting
Joined: Dec 1999
Posts: 1,330
Likes: 36
From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Originally Posted by Red Rocket
Add washers to cover+loctite rotor screws+Delteq= no problems for my 396. 6800 RPM's at the track with no more failures. Use to go thru two new opti's per racing season.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
The modified cars do seem to have alot of problems. My rotor kept breaking apart. Either the screws came loose or the rotor broke apart. Felt the vibration and possible banging against opti cover was the problem. The washers added more clearance.
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Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,922
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From: South Carolina
St. Jude Donor '03 & '05
Originally Posted by POLOVETTE 94
I have the Delteq setup, and my car is somewhat apart right now. Should I remove the rotor, or put loctite on the screws?
Last edited by steve40th; Oct 16, 2005 at 12:15 AM.
Thread Starter
Le Mans Master
Joined: Feb 1999
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From: South Carolina
St. Jude Donor '03 & '05
Originally Posted by Dan Parker '96
I'd imagine that cam pin length would be crucial to longevity. I'm not so sure that some pay that much attention to it after a cam change. Could be a contributor.
Safety Car
Joined: Feb 1999
Posts: 3,504
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From: Mexico Beach FL
Originally Posted by steve40th
I concur. Should it be tight in there, loose(as in to close or away from the slot it goes into, .620" for a newer one, or .590" , for example, is that okay etc.
But, you don't want the pin in there far enough to bottom out in the Opti-Spark.
I calculated the distance from the cam gear surface (not from the camshaft) for mine to be ideal at about .375". This gives it plenty to drive the Opti but a good tolerance so not to be too long.
I personnally think the rotor should be taken out completely for the Delteq -- I'll probably make something to take up the space.
Tom Piper
Le Mans Master
Joined: Aug 1999
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From: WilkesBarre PA
DEFINATLY Check the pin length. If it is too long the Opti will push back on the cam pin, pushing the upper gear into the cam retainer plate. This will grind down sending metal into the motor.
I had this problem with my Comp cam when I first built my 396. After that I only replced my opti once just for preventive maint reasons last winter.
I had this problem with my Comp cam when I first built my 396. After that I only replced my opti once just for preventive maint reasons last winter.
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 steve40th
I concur. Should it be tight in there, loose(as in to close or away from the slot it goes into, .620" for a newer one, or .590" , for example, is that okay etc.
.620" is precisely what the pin length measures at on my original factory '95 LT1 cam. The pin length spec for the early opti set-up, should anyone need to know is .322" or thereabouts. Not as critical of a measurement on these though.Afterthought: I've also often wondered if people who've had repeated opti problems of this nature have verified that their cam end play is within spec.
Last edited by Corvette Kid; Oct 16, 2005 at 11:13 AM.
Drifting
Joined: Dec 1999
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From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
How crucial is it to remove the rotor, or to loctite the rotor bolts, for 6000-6300 rpm? I have a 383, LT4 heads, vortech s-trim, and the Delteq opti direct system. Did the stock LT4's have a problem with opti rotors, as there redline was 6300? I am installing Greg Carroll's 8 rib setup, and right now I am ready to bolt the crank pulley to the ATI hub, then reinstall the rack (I got the bushings out, and the poly ones in---see my other post), then bolt up the new bracket, and so on. This would be a good time to address the rotor, as there are only 6 bolts and one hose attached to the water pump, and the crank pulley is off. I wanted to get this running again today, but if I need to do something with the rotor, I'll need to go pick up water pump gaskets, so please respond asap. Thanks.
Le Mans Master
Joined: Jan 2003
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From: Portland Oregon
Originally Posted by RichS
DEFINATLY Check the pin length. If it is too long the Opti will push back on the cam pin, pushing the upper gear into the cam retainer plate. This will grind down sending metal into the motor.
I had this problem with my Comp cam when I first built my 396. After that I only replced my opti once just for preventive maint reasons last winter.
I had this problem with my Comp cam when I first built my 396. After that I only replced my opti once just for preventive maint reasons last winter.
If you install a Comp Cam, the definitely check the dowel pin length. Every Comp Cam I have every received for an LT1 be it an off the shelf or a custom grind, they have come with extra long dowel pins. Some as long as .750" from a GM spec of .620"
Thread Starter
Le Mans Master
Joined: Feb 1999
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From: South Carolina
St. Jude Donor '03 & '05
Originally Posted by tjwong
If you install a Comp Cam, the definitely check the dowel pin length. Every Comp Cam I have every received for an LT1 be it an off the shelf or a custom grind, they have come with extra long dowel pins. Some as long as .750" from a GM spec of .620"
I am just wondering what other things can be measured and fixed to alleviate stress on the Opti. I use a Delteq(so the Opti is only used for a reference, per say), but shouldnt be breaking Optis(broke one with Delteq, one Dynaspark broke becasue of Reluctor ring/balancer loose fit casuig vibration issues) with all the different components that I have.
Last edited by steve40th; Oct 16, 2005 at 10:04 PM.
Drifting
Joined: Dec 1999
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From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Originally Posted by POLOVETTE 94
How crucial is it to remove the rotor, or to loctite the rotor bolts, for 6000-6300 rpm? I have a 383, LT4 heads, vortech s-trim, and the Delteq opti direct system. Did the stock LT4's have a problem with opti rotors, as there redline was 6300? I am installing Greg Carroll's 8 rib setup, and right now I am ready to bolt the crank pulley to the ATI hub, then reinstall the rack (I got the bushings out, and the poly ones in---see my other post), then bolt up the new bracket, and so on. This would be a good time to address the rotor, as there are only 6 bolts and one hose attached to the water pump, and the crank pulley is off. I wanted to get this running again today, but if I need to do something with the rotor, I'll need to go pick up water pump gaskets, so please respond asap. Thanks.
Safety Car
Joined: Sep 2002
Posts: 4,030
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From: Maryland
Originally Posted by POLOVETTE 94
Anyone? I would like to get this up and running this week, but need to know what to do about the opti. Thanks.
I asked RichS about the Opti before. He has the LT4 but his is now a 396. He road races the car so you better believe it is run hard and in the high rpm range for a long period.
Anyway--he has not had trouble with rotors going up all the time. Based on that, I'm not doing anything to my '95 style opti.
Based on this thread though, I'll go check my cam dowel pin length.
Drifting
Joined: Dec 1999
Posts: 1,330
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From: Waynesboro, PA
Co-winner 2020 C4 of the Year - Modified
Well, I took it off to check. The depth of the drive hole in the opti was .430", and the length of the cam pin (measured from the tip to the cam gear--I'm not taking it apart to measure to the cam) was .400", so I still have .030" of free space in the hole 
. I called Delteq, and they said if I'm only turning 6000-6300 max rpm, I shouldn't have any rotor problems. They did say, however, that they've seen the rotor screws come loose, even in a brand new opti! So, while I have it off, I'm going to put some red loctite on the threads. Does anyone know the size of the torx screws holding on the rotor? The smallest I have is T10, and that's too big. I was thinking maybe T5 or T7? Should I use any type of sealant on the opti cap seal, or is the rubber gasket enough? Thanks.
. I called Delteq, and they said if I'm only turning 6000-6300 max rpm, I shouldn't have any rotor problems. They did say, however, that they've seen the rotor screws come loose, even in a brand new opti! So, while I have it off, I'm going to put some red loctite on the threads. Does anyone know the size of the torx screws holding on the rotor? The smallest I have is T10, and that's too big. I was thinking maybe T5 or T7? Should I use any type of sealant on the opti cap seal, or is the rubber gasket enough? Thanks.