Mr.Mouse

Just wondering whats involved to change a 92 LT1 and convert it to an earlier 1991 TPI setup with a distributor?
I have EVERYTHING from a 1991 TPI Vette.(parts car with 51K on it)
I searched and saw many articles on changing an L98 to an LT1 but not the other way around.
I dont give a rats *** about "less power".
I want to take the opti-spark out and beat some dumb *** GM exec over the head with it.

WVZR-1

You'll also need to go with the L98/TPI ECM and you mention having the parts. Does your collection include the ECM and appropriate harnesses?

I believe that there's also projects that have included changing to a conventional HEI for the LT1 but I believe for the '92 & '93 that would have it's own set of special circumstances.

You need to be a bit more creative in your search techniques. There should be a multitude of topics out there discussing it.

bjankuski

What about switching to a coil per plug design like the ls1, that will keep your power and eliminate the problem areas of the opti. Otherwise what you are asking could be done but you would need to follow the same procedure to concert a lt1 intake for use on a l98 except you would skip the water passage changes. This would allow you to use the lt1 intake and just add the distributer. (I missed that you wanted to add the tpi, i was assuming you just wanted to add the distributer to the lt1 intake.)

Mr.Mouse

I saw the multi coil setup.I would rather use what I have instead of spending a zillion dollars on more stuff,and besides that,you need a functioning opti-spark for that to work.

I also saw the "drill a hole for the distributor" deal but it looks like the guy who was doing that,no longer does it.I dont have a machine shop to create the parts needed.
I already checked out all the available options....and just want to know whats needed to run the 91 TPI on my 92.
Yes I have the computer and wiring harness.
As I said...I have a 100% complete 1991 parts car.

bjankuski

You still need a machine shop, the intake from the L98 will not fit a lt1, without some work to get the bolt holes to line up.

C409

......... Use the complete engine w/accessories , wiring harness , and ecm from your '91 ...........

WW7

All the dumb azz execs have been killed off years ago by LT1 owners before you.... If your going to all that trouble for an L98, why not just install a LS motor, way more reliable and even if you don't care, they have way more power..At least then you'll be moving forwards instead of backwards ...WW.
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Tom400CFI

I'd have the LT1 intake "converted" to run a conventional distributor, run it w/the L98 ECM w/a tune...keep the LT1 performance.


I also agree that the individual coil system does NOT "eliminate the problem areas of the opti" In fact, it maintains the two most problematic areas of the opti; the sensor and the bearing.

l98tpi

my suggestion would be to keep what you got and make sure you dont have a problem that seems like an opti but notthe opti. i had an issue with my LT4 and thought for sure it was the opti, ended up it was my connector to the coolant temp sensor.

dizwiz24

What is the goal of all this? To eliminate the optispark?

My optispark works like a dream (im not being sarcastic, i have had great luck with the optispark) because i know what to look for, added a vent harness and use high quality parts not $69 china specials.

Anyways, my favorite thing about the optispark elimination LTCC is it Doesnt eliminate the optispark!!!!!

So all these people spend bucks to add lsx style coils and still rely on the optisparks opticAl sensor - which is the most failure prone part if you have used a cheap optispark without the mitsubishi optical sensor.

Anyways the more i think about it, i assume this post is meant aZ a joke and not a serious question

bjankuski

I have had very few sensor failures. Most of the time the failures have been the rotor exploding on high rpm engines and coolant leaking on the cap causing misfires. The individual coils eliminate the misfires due to coolant leaking on the opti and arking of the wires and cap.

Mr.Mouse

The car in question only has 50,000 miles on it.It looks like a new vehicle.
The owner before me paid a Chevy dealer $1,400.00 to install a new opti spark,water pump and new plugs and wires.This was done a little over a year and a half ago.I saw the bill.
I have only put 2,000 miles on it since the new opti spark.
Never drive it in the rain,nor caught in the rain.
Never washed the engine.
No water pump leaks.
I never beat the car and drive it very conservatively.
I drove it for a few hours,mostly highway,the day before the failure.Ran perfect.
The next day,I put gas in it and shortly after that,it started missing.
I thought the gas was the problem,as I had no check engine light yet.
I siphoned the gas out,added a bottle of dry gas,and added new fuel from a different gas station.
Still missing,getting worse,bucking....then service engine light came on.
Checked the code....36
There was nothing wrong with the gas.I put it in my truck and no problems there.
Still thinking about the whole thing.
Was thinking about installing the L98 I have.
Am thinking about adding a distributor to the LT1 but cant seem to find anyone who modifys the manifold.
Was thinking of installing the 1966 Vette 327-350 I have.(Fresh rebuild,never fired yet)
The 327 has a set of 292 "over the counter" angle plug heads(Bone stock,Unmodified) and a 365 horse solid lifter cam in it.(I have the 350-350 Hyd. cam also)
The 327 would require a new flywheel and clutch (1 piece seal vs. 2 piece seal)
Wondering what else I have to change to pop that 327 in there?
Front dampner going to fit the frame?
All the brackets going to bolt up for the P/S A/C etc...?
The 292 heads have the bolt holes in the cylinder heads.
Wondered about the height of the 327 alum. intake,carb and air cleaner.

And no...this is not a joke post.

dizwiz24

My apologies mr mouse!

It sounds like you are at wits end here.

This type of sudden failure you are had is typicAl of a bad (or contaminated) optical sensor. Im going to guess whatever optispark they put in there did not have a mitsubishi opticAl sensor.

Opti problems on the cap/rotor side tend to manifest themselves as stumbling under load or stumblijg when lugging the motor

Ac delco new old stock is not available anymore so i used a. Delco remanufactured in 2012.

At first i thought i was good because there was a genuine mitsubishi optical sensor in there. However the car would run 3 minutes then die and not restart untjl the car cooled down.

I looked closer and the sensor looked fuzzy. Someone had put black spraypaint on the plastic to make it look new....

I took it back and found a new old stock one (obviosuly had the mitsu sensor) with 30000 miles on it and installed thT one. Works flawlessly.

These were gen 2 optisparks. I converted my 93 to gen 2 bc i was also doing a cam swap.

Its my understanding the delphi. Gen2 units are still high quality.

If you go with a gen 1 optispark you must add a custom vented setup like gen 2. You are doomed to failure if you dont do that

Now if you dont want anything to do with the optisparks anymore, go forwards with the lsx not back wards with a tpi intake

c4cruiser

I think you will find that trying to convert to an L98 setup will be difficult and fairly expensive to do. Trying to install the 327 with the carb will be a huge undertaking.

If the intent is to just have a nice driver and you want out from under the OptiSpark, then you may want to think about getting the car running and sell it. Then look for a 90-91. The 91 exterior and interior will look very much like the 92 and it will have an L98 motor.

When I had my '92, I never had one issue with the Opti. I sold the car in 2005 and the buyer never had a problem with the car. I wonder if the dealer that did the replacement actually used a new GM/AC Delco Opti or got a reman unit. Some dealers may not stock an Opti in their parts room and if that previous owner wanted the car right away, the dealer could very well have ordered a reman unit from a 3rd party source. You would be surprised to see how many times dealers order parts from 3rd party suppliers especially if OEM parts may be days away.

Tom400CFI

I'm sorry, but this IS a joke. It's insanity, is what it is. You can build/swap a 327 engine, but not change a distributor?? COME ON! Buy a new opti and put it in! You can buy them for less than $200 now days and install in about an hour, if you hustle. You posted a Chevy dealer's quote of $1400 to change one, but how is that relevant? All it "proves" is that the PO raped himself by going to a dealer for that work. You can do the job for less than $200.

OR install a "327" old skool, lose about 80 hp in the process (I hope you realize that "365 hp cam" won't be making any 365 hp...right?), lose EFI, drivability, fuel economy, etc.


The cheapest, fastest, and BEST way to fix your car, is diagnose, and repair the issue is has...then enjoy. Swapping in a destroked 350 w/a carb is



EDIT: If you want to convert your LT1 intake to a regular distributor, you can contact "David Frederick" on this forum. He does the conversion...though just that will cost you nearly twice what it should cost you to swap the opti (if that is in fact your problem).
.

aDigitalPhantom

Some people seem to forget how many things are perspective.


OP
It's all about how deep your pockets are, and what work you are willing to do.

WW7

I second Tom's suggestion on contacting " Dave Frederick"..Dave does excellent work and a manifold job from him would solve the problem alot cheaper then buying a new motor...He can probably use your manifold, he builds the aluminum up, then mills a hole in it for the distributor....."Good idea Tom".....WW

l98tpi

I would try to replace the coolant temp sensor and connector. Less expensive than the Opti and the new connector you will splice in the original harness. I'm telling you, the coolant temp defaulting due to a bad reading will make the car run just as an bad Opti will and kick and buck.

Mr.Mouse

"I would try to replace the coolant temp sensor and connector. Less expensive than the Opti and the new connector you will splice in the original harness. I'm telling you, the coolant temp defaulting due to a bad reading will make the car run just as an bad Opti will and kick and buck."

Would a bad coolant temp sensor and/or connector cause the computer to throw out a code 36?

l98tpi

I cant remember what code #'s came up. There were about 2 to three different codes and the LT4 (96) and maybe the 96 LT1 have different codes than earlier models. The one I remember most was for misfires. That is what made me think it was the opti. If we hadnt put it on the dyno with the data link showing all the properties and values at each sensor, I would have not know the coolant temp sensor was not reading and the ecm was sending it to default of -40degrees. That is how I found out the connector was bad. We could wiggle it and get a reading.