My car has 120,000 miles on her and I want to give her a real tune up before spring. The opti is stock and I know for sure it has to be worn by now. I was going to purchase a GM unit and replace it. While replacing the opti I was going to install and electric water pump. Is it a good idea to replace an opti thats working still? I've found that the car stumbled a little in cold weather before I put her in storage for winter.

Also.... does anyone know if I can still order O2 sensors from Sam Taylor? I got a set from him a year ago. Now I can't find his site.

Can't wait to get the bird on the road again

 

I replaced my stock opti around 130k although it ran good. I gave it a good tuneup like you mentioned and it ran much better. Got rid of my stumble also.

I say go ahead and change it, you never know when they'll go out. I would also go ahead and put a new timing chain and gaskets in it since you're already down there.

 

I was considering the timing chain. I've never replaced one so I don't know what to expect. Do I have to just line up the sprockets on the cam and crank? When I reinstall one.

One thing I'm kinda concerned about is the stock valve springs. I'm pretty sure I've got valve float above 5,400 rpm. The car kinda blows more black smoke out the exhaust above 5,500 rpm than a diesel truck does going down the drag strip. Could this be crappy valve float? Or a really rich condition from a bad tune?

 

I'm in the same boat. On a rainy day I did a quick rev up in first gear and the car started running terrible... like on 4 cylinders. So I bought an MSD Opti (8381 for a '94 non-vented) and started looking into what other parts I should replace.

Then the car went back to normal... and has been since... and the problem happened in the beginning of December. After I added MSD plug wires the engine runs better but it's developed a slight stutter off idle but it's only something I would notice since I drive it daily.

I'm still going to swap the Opti though. I've got a new Airtex water pump (looks like I'm the guniea pig for Airtex) and the gaskets & seals. Wouldn't you have to drop the oil pan to change the timing chain/gears?

 

You have to loosten the oil pan to allow the timing chain cover to clear the lip of the oil pan. Some times you can get away with snipping part of the corners of the timing chain conver, but it's still a pain. There are two timing marks that need to be lined up. I would also put the engine at TDC before removing the chain for safe measure.

 

My car always stumbles in the cold never in the summer. I have a new MDS opti and it will stumble in about 2 minutes after i take it out for a few secinds and not stumble anymore. If i warm the car up it doesnt stumble. Remember this only happens to me in the winter. Now as far as the electric water pump goes its not a good idea on a daily driver. One because if you drive alot and it goes bad you're assed out if you're not close to you're hose because you enginge will overheat and you can do some serious damage. They are rated only for a certain amount of usage so if you drive alot you will have to replace it like every year. If it is only a weekend driver then you can get away with it for a few years.

 

technically the opti will not wear out since the sensor has no contact with the disk, its just an optical sensor reading the pulses as the windows pass by.

The only thing that wears out is the cap and rotor.

but since we live in a real world the opti sensor can get mucked up by moisture and dust, but usually unless you car isnt wanting to run and its not the opti plug on the top, then just go with the cap and rotor replacement

 

If you doing all that might as well change opti. Also nice looking bird man.

 

So at a minimum I should replace the Opti, timing chain, and water pump. Whats a good timing chain to use? I'm still opting towards the electric pump, so the water pump gears won't be necessary. I figure if the electric pump goes out that it will be just as noticeable as the mechanical pump failing. I keep a pretty good eye on my gauges so if the temp goes up I can shut the motor down.

Is it really hard to swap valve springs and rockers? I've never done it before, but I'm willing to give it a try if its something that any weekend wrencher can do without alot of internal engine knowhow.

Also does anyone know if I can still buy from Sam Taylor?


Keep in mind that I have MSD wires, and NGK Iridium plugs with less that 15,000 miles on them. I figure I'm good there.

I appreciate all the help so far guys. I'll have some nice burnout shots in the spring.

 

I forget who a good mfg is, but someone will chime in. I would stay away from "double roler." chains because they are more prone to stretch and wear. A good single roller will do the trick. Valve springs are tricky. You will need a compressor and fitting to go in the spark plug threads to keep the cyl pressurized or else you run the risk of pulling a head.

 

I was told that springs aren't that bad if you bring the cylinder up and then rest the valve on top of the cylinder. The GM single roller timing chain is super expensive. Whats a different brand that I can use?