I know that you can do this, but i'm just making sure that i'm doing everything right. I have a 93 engine, so that means that i need a electric water pump a 95-97 timing cover, and a 95-97 vented opti spark. Thats all I need
I have all execpt the timing cover and the water pump. I'm going to buy the water pump from NAPA but I'm in the need for a cheap timing cover. Please Help
Thanks
Andy

 

The gear drive is very noisey and will generate false knock (knock sensor). You will need to "defeat" the knock sensor if you choose to go this direction.

 

it will also take up to 18hp from the motor.there is no real advantage to running a gear drive other than the fact that the timing will stay accurate!

 

LT1 timing is already more accurate than other smallblocks because of the opti vs. rear mounted distributor. What exactly do you think you would gain with a geardrive?

 

The gear drive assembly, minus the chain, and it's stretch properties, may very well have more accurate timing, than oem style assemblies, with their larger number of variables (components), but this is not to state it will indeed be 'spot on' accurate, which I highly doubt. OK, that being stated;

I obviously disagree with the above quoted statement, because I challenge anyone (including 96capricemgr) to prove to me the LTx timing mechanism is more accurate than any preceeding sbc. The opti/pcm communication has no bearing on the accuracy of the mechanical opti spark distributor assembly. The distributor is STILL driven from the cam. The chain driven camshaft STILL has the crank and cam gears, crank gear located with key in a keyway, and cam gear located to cam via the dowel pin. The lone difference between the two, is with the actual connection of the distributor. The opti is located from cam gear locating dowel pin, and convertional sbc is driven off a gear located at the rear of the camshaft. The mechanical components today, are still manufactured with inherent tolerances. Unless the following is your sole 'defense' of your statement (to which I would concede), to simplify discussion, we could dispense with the high rpm 'spark chatter' and camshaft twist symptoms, both known negatives of conventional chevy cam driven ignitions.

As with a typical error graphing, analysis will show assemblies will be off a degree or two, and some will be (close to 'spot on') accurate, as well as off by 3-4 degrees. But vary, they will, and off, a representative nmber will be. Anyone who has degreed in cams, is aware of this.

So, given the above, again, I challenge anyone, show me, with stats collected, from actual physical checking via proper procedure, a trend, verifying the accuracy of drive mechanism, and prove to me, how the LTx series of crank to cam connection, is any more accurate than any other sbc, and thus displays fewer, of the tolerances in the assembly. Internet hearsay, and opinions containing what a person thinks, do not count, and need not be included here. Too much of that quality of info, is spread on this forum, the way it is. Happy new year!

 

It would be speculation that the short, inline drive mechanism of the opti, would be more resistive to error from twisting than the long, driveshaft of a conventional SBC distributor, but seems compelling.

Whether or not this link has any of the convincing data you seek, it is good info.

 

who makes the gear drive for our motors? do you lose the use of the opti? just curious.

thanks
taner

 

Hi Rob. HNY! I consider that article, good, and well written. Quote "In conclusion, it is the author's opinion that the Opti-Spark is an excellent design that has been a victim of misunderstanding and poor mechanical procedures."End quote
Some of those that own an 'opti crap', may also benefit from reading this article.

Quote"Reading the leading (rising) edge of the low-resolution optical signal along with dual knock sensors (some models), the ECM is able to identify detonation on individual cylinders and offer timing correction to those in need."End quote

Hmmm, was not aware pcm was able to do that. Anyway, to the subject at hand.

Quote"Accurate drive positioning directly from the front of the camshaft",End quote
AFAIC, does not address the mechanical linkage prior to actual drove pin to opti link. The actual contact of the two noted, would be the result of any tolerances B4 it. Benefit here, would be in regards to shaft twist. The article focuses on advance rate and amount, and it's ability to recognize varing conditions, via the software. (Article) does not address mechanical issues, however. AFAIK, PCM has no way of knowing whether of not, the crank gear is off the width of the keyway, using this to dramatize, of course.

Quote"Prior to the development of the Opti-Spark the exact position of the crankshaft was never recognized by the ECM, that data was not available. The input of data in one-degree increments of crankshaft rotation into the ECM's programming now allows for more accurate control of engine functions. In a standard L98 ignition, which is an electronic-spark-timing high-energy system, control of the spark advance curve is handled by the tables in the PROM once an engine speed of 400 rpm was surpassed. Below that rpm the control of the ignition timing was independent of the ECM and was a function of the module and the installed position of the distributor." Also...."This is the result of knowing the exact crankshaft position..."End quote

(putting emphasis on this phrase: Quote"the exact position of the crankshaft was never recognized by the ECM.."End quote

So how does the pcm recognize the actual position of the crank/piston?

Quote"The Opti-Spark not only paid dividends in decreased assembly time during engine manufacturing, but also removes the inherent tolerance that a mechanically adjustable distributor creates during engine build procedures and infield service."End quote

I'll concede to being 'all wet', and silence will overcome me, if anyone that has installed an opti, with the drive dowel in a slot other than the correct one, can verify the engine ran fine/normal (state of tune) prior to developing the obvious mechanical durability issues. This would prove, to me anyway, mechanical position of the opti rotor, is accounted for, within the electrical engineering parameters.

 

Thats a very technical post above and i had trouble following all of it, but i "think" this may be the answer to your question. First post, made by me.
http://web.camaross.com/forums/showthread.php?t=310918

Basically as long as the high and low res wheel are where the are supossed to be, the opti rotor itself wont effect spark timing.

 

How do you KNOW the h/l res wheel is where it is supposed to be? More importantly, how does the PCM know? How would you know the timing chain was off by one tooth, without ckecking?

 

I guess my and the ECMs assumption would be that the cam dowel is at 3 oclock when motor is at #6 TDC, and from that it knows within 1 degree of the cranks position. That would also assume that your timing chain and gear set is 100% true in alignment, both in tolerances and install.

As for the post i quoted, the opti h/l wheel was aligned as the ECM thinks it should be, and then the igntion timing pretty much takes car of itself regaurdless of where the rotor is.

If the h/l res wheel is moved also from its "home" position, it loses its perspective by the amount its moved, AFAIK. (run into the age old argument about injector phasing etc with mechaincally advancing/retarding your cam)

However, isnt that true with anything? A ruler is only as good as the person measuring with it right?

 

Hopefully, you now understand, where I am coming from. You, and more relative to this topic, the PCM does not know, it assuuumes it is mechanically properly aligned.

If someone can present the case, the PCM can verify the proper alignment of the cam/crank linkage hard parts, I can no longer present a case, from my present perspective.

Yes, but does the pcm know this?

 

I was running a Pete jackson timing gear set in my LT1. I have a 97 with a CSI elestric waterpump. The timing cover will need to be milled to accomodate the idler gears. The setup ran well, but I had other issues with the motor (not timing gear related) I'd be interested in selling the gears and the modified 97 timing chain cover if your interested. $130 for both the gear setup and timing cover. Was run for about 300 miles.

Bill

 

Arnie i think i misunderstood what you were saying from the beginning when you said
I took opti rotor to mean the front half igntion portion, not the high/low res wheel out back.

I would think like you, that the opti itself needs a reference point to start from.

However, ive seen cars run with mechanically advanced cams and run well (my buddies 396 6 speed went 10.7 and was fastest 6 speed for over a year until tanner just went a touch faster last month).

Also on my car, i had kinda sorta put the cam off a tooth on the timing chain. The car ran and drove fine, just didnt make any power. (ran 14.00 at like 98 with bolt ons plus 847). Only other symptoms were very little vacuum and running hot.

However im still not convinced about about moving the resolution wheel out of where it thinks it should be matters, or if the above examples are a big enough change to be able to notice. Without drilling a new cam dowel hole 45º off and installing like that, im not sure you would be able to tell either way.

I know I am contradicting myself somewhat, but i can see both sides of the argument.

 

Yes, you are on the right track! What I was referring to, with "mechanical position of the opti rotor", was the position rotor is put via the cam drive dowel. For instance, if the drive dowel were put in the incorrect notch, would the pcm recognize such?

However, I've seen cars run with mechanically advanced cams and run well.

They very well may have. That method of altering cam timing, is done to fine tune a given combo, for a particular application. Also, injector timing may not as well, have been altered enuf negatively, to verify, without dyno or track testing. I made reference to screwing up the opti install, in dramatic fashion, to emphasize pcm's role in recognizing such. If it were not off enuf to undeniably recognize, how could anyone recognize, whether pcm was doing any compensating?

...sorta put the cam off a tooth on the timing chain. The car ran and drove fine, just didn't make any power....Only other symptoms were very little vacuum and running hot.

By my definition then, it was then not running fine, or in tune. This would tell me, the pcm was not compensating for inaccurate physical setting/install. Again, I figured it was necessary to dramatize/magnify the amount of error, to verify. If the amount of error was only 3-4 degrees, which I consider normal/common, and which is my original argument, it would be difficult to note how well/poorly it ran (or didn't run, without dyno test), without pcm intervention, let alone be able to compare, to verify, if indeed pcm actually intervened.