I just bought a 94 camaro with an LT1 5.7. Supposedly the opti spark was replaced, I see evidence of new water pump gaskets so I am going off that. It wont start, and back fires. Sounds like a timing issue. I have never worked on an LT1. So I am wondering if the opti was put in wrong. I check the plug wires and they seem to be in the right places on the opti. The only codeIam getting on my scan tool is for the MAP censor. What next?

 

I guess if I am going to have to take the front of the engine apart, I may as well check the timing chain

 

In theory the Opti can only be put on one way. The splined shaft drive on the 93/94 units has an odd tooth in the splines that can only be inserted into the cam sprocket in the correct position. Unfortunately, it doesn't always work that way. Being on this site for 25 years helping LT1 owners, seems to me that about 10% of the installs end up with the splined shaft misaligned = incorrect timing. I think people force the shaft into the cam sprocket by pulling it down with the bolts.

http://shbox.com/1/93-94_opti.jpg

One possibility is that the splined shaft is not indexed correctly. Unfortunately, there are more possibilities. Cheap Chinese rip-off Optis are sometimes not assembled correctly, with the disc that rotates through the optical pickup not aligned correctly when assembled. Another possibility is that the rotor screws have come loose, or the rotor has come apart.

Do you know what brand the "new" Opti is? As noted above the less than $100 Chinese crap is often defective right out of the box. Most of the auto parts store brands are not very good. Even the expensive MSD Opti has its problems. Seems like only the unit sold by Petris Enterprises is reliable.

https://petrisenterprises.com/collections/frontpage

Also check to insure the plug wires are connected to the correct plugs. And in the dark with the engine running look for arcing, indicating failed wires.

 

Why are you going to have to take the front of the engine apart?

Removing the timing cover gets messy, because of the gasket between the oil pan and the bottom of the cover. Also requires removing the crank hub, which often results in damage to the bolt/threads. Neither has to come apart to replace the Opti.

You also need to track down the problem with the MAP sensor. The PCM uses the MAP sensor reading and the engine RPM to look up the advance in the timing tables.

Plug wires:

http://shbox.com/1/opti.jpg

 

I am 60 yearsold, so I am old school, never mess with any thing after 1970s until I got this 94 , just though maybe I would check the timing chain but I guess it is a lot harder to do than the old school small blocks. I have no idea what brand opti is in this thing...

 

after taking the water pump off I see new gaskets behind the timing chain cover..this tells me some one put a new timing chain in and did not get the timing set correctly, I think it probably is 180 degrees out this why it back fires like it does.

 

Incorrect install is probably the more common problem. Otherwise excessive wear, or the mythical “timing chain jumped a tooth” are not common problems with the LT1.

 

Could be not installed correctly, but the "180° out" scenario does not apply like in the old SBC rear distributor days. You could possibly tell about the timing gears by turning the crank to 1 or 6 TDC and looking at the dowel pin position on the cam. Might be hard to tell if just a tooth off, though.

http://shbox.com/1/cam_timing_ani.gif

 

After I got the balancer of I noticed there is no front oil pan to timing cover seal and the oil pan bolts are not even tight... man some people.

 

1994 factory service manual, free download, courtesy of member GaryDoug:

https://www.mediafire.com/?40mfgeoe4ctti

 

ty Gary