Check this out!

My car took a major dump on me about 4 or 5 weeks ago. One second it's idling at the grocery store gas station, the next second it's coughing, misfiring, and backfiring in a serious manner. I was only about a half a mile from home and barely made it with a plume of black smoke behind me and sparks shooting out my exhaust. I was pretty sure my opti had gone south so I found a new AC delco on E-Bay, and within days I had it installed. The car would then run, but only for 10-15 minutes at a time, and then it would start puking, coughing and backfiring again… If I let the car cool down, it would usually run another 10 minutes before acting up again. After a few times of doing this it would not run at all. I then found that I had a mangled cap/rotor in my rear distributor (the previous owner put a traditional dist. in back to simply distribute the spark as the opti rotor has a reputation for dissintegrating at high RPM). Then the car actually started and ran pretty well….. for about another 10-15 minutes. Then it was dead again. Thinking that the guy on E-bay sold me a bum opti, he sent me a replacement. I also got the place (All Ignition) that sold me the first bad opti (I installed it last fall) to me to also send me a replacement. So, after installing a total of three different optis, the car was dead, dead, dead. It would crank but sounded like it needed more timing to start. It would pop and fire, but no start. So, I pull out my trusty GM Service Manual and start running through the varous tests. It told me that my PCM was faulty. Being at the end of my rope and knowing that my new: opti, coil, ECM, and MAF (It actually needed a new MAF) were ok and all of my sensors seemed to be working, I order up a new PCM from Bryan Herter at PCMFORLESS (probably not a bad idea anyway as my current tune sucks). Still, no start. I just happened to reach back to the rear distributor and turn it as far as I could to the left. Suddenly, the car would start but would pop and crack at the slightest opening of the throttle. This got me thinking that something was pulling timing out of the PCM. After asking around I determined that a bad knock sensor could not pull enough timing to prevent a start.

Ok, I was pretty sure that the vented opti can only go on one way since the other two slots are "pinched". Nevertheless I was very careful to align the elongated slot with the cam pin. Well, I was wrong!!!! I had installed the vented opti in the wrong slot!!! This leads me to conclusion that you should always put #1 cylinder at tdc before installing the opti. In this position it's just much easier to slide the opti into the correct slot with the crank hub in this position. You can slide it right on without twisting it. Also, it's a good idea to mark with a marker the outside hub (the wheel part that inserts into the timing chain cover) at the elongated slot. This ensures that you keep alignment of the elongated slot with the cam pin. So, I get the opti installed and decided to move the plug wires to the opti instead of the rear dist. Now the car runs and actually sounds pretty good (I have a pretty radical cam). With that in mind, I decided to go ahead and change the oil pan gasket since I had torn it trying to sneak the timing chain cover back on last fall (with the oil pan still in place) after replacing the timing chain cover seals and an opti. Changing the pan gasket is of course a hellish job at best without a lift.

So, I let the pan down as far as I could after hoisting the engine off of its mounts. Of course I couldn't see inside of the pan, so just for the heck ot it I put a magnet down there and fished around…. What do you know, up came two big pieces of pushrod…!!!!!!!!!! I figured it was from a prior engine catastrophy…nope, a search of my valves revealed a broken #3 intake pushrod. So, I ordered all new pushrods. We'll see if I have any bad damage when I get them installed later this week. I'll perform a compression test to see what's up.

I think what was happening is that my engine would run until the #3 intake runner filled up with gas and drained into #5 intake runer. This would make the right O2 sensor go bazerk. Either that or the extra gas just made the air-fuel ratio so rich that it wouldn't run. All I know is that I am glad I checked the rocker arms. I almost didn't check the pushrods since the motor sounded pretty good...

 

wtf??? a front and a rear distributor??? umm never heard that before.

 

This can't be for real.

 

i stoped reading

 

No, it's absolutely for real. The electronic guts of the opti are used to drive the computer. The rotor in the rear dist. is simply phased with #1 cylinder at tdc. Instead of feeding the coil wire to the opti cap, it goes to the rear dist. The spark plug wires come off of the rear dist cap. I simply capped the plastic coil and spark plug connectors on the opti. The question I always had was how in the world did they get the rear dist dea nuts on 0 degrees btdc. It has to be zeroed or 6 degrees advanced, etc. The PCM does all of the spark adjustment. The electronics in the rear dist. are not used, only the cap and rotor.

 

There is only one distributer on the lt1.There is no rear distributor.

 

Normally, but my manifold has been converted, as have many... All you do is remove the oil plug under the intake manifold and slide a dist. in it's place, after of course milling a hole in the intake and welding a 4 degree wedge to angle the dist. correctly.

 

tony.....shut up please.

 

You are obviously a novice.....

 

I want to see photo's.

 

seems like hes talking about basically it had a half assed "opti delete". using the optical sensor/pickup wheel to fire the injectors and the high res fires the coil and the coil wire was ran to the back to the HEI cap and rotor. his manifold has the hole drilled in the back with the distributor drive shaft (usually what single plane guys use).

previous owner wouldve been better off with the LTCC.

 

You are absolutely correct. They did it simply to avoid the inevitable opti rotor explosion... What does LTCC mean?

 

It's nothing special to look at. I think someone would do this if they wanted to control their LT1 via a FAST box or other aftgermarket EFI box. You would set the crank reference angle by running the motor to #1 TDC. Then making a timing tape for the LT1 balancer, and mark it off at 6 degrees so you can set the FAST HEI crank reference angle. As easy as falling off a log. As a matter of fact I was very close to doing just that, and getting rid of thje opti and factory PCM all together! If I ever put a turbo on the car that's exactly what I'll do, jjust use the electronics and the cap and rotor of the rear dist. It's just a typical HEI dist. out of a newer truck (I think).

 

http://www.bailey-eng.com/LTCC.html

 

yeah im a novice, i have owned 6 LTx powered cars and im a novice. i have a 95z28 and it has a ford dist in the front and a chevy dist in the back and a opti and it makes good power

 

I don't see why people think this is so far fetched. I believe completely lacking a number three intake pushrod would cause your problem. It was basically flooding the intake with fuel as it was not opening the valve. All the black smoke and popping you're talking about would just be the unburnt fuel igniting in the exhaust.

 

I think the black smoke and popping were the result of a combination of the opti going bad and the missing pushrod.

You know, I rarely post on these forums and now I am reminded why. I simply took my time (which took a while) to type my story hoping that maybe it would help others... instead, a few have chosen to be complete idiots. Take it or leave it, I really don't care.

 

oh ok ya i have seen this setup before. you dont need to to keep the opti at all thou. i thought you could just plug the hole in the front. you could use a standard chevy dist. with a low rise cap. i have seen it before thou. it was the way you were typing it that it sounded fubared

 

I thought you had to keep the opti because the standard HEI dist. does not send the correct signals to the stock PCM. That would be great if I could dump the opti all together.

 

I have seen some people convert to an MSD crank trigger setup. One guy even used a system off of a Ford Tempo (essentially a crank trigger) that had 32 tabs that counted out near perfect timing. The only real advantage of the opti is that it is accurate +-1º of timing.