I installed a new timing gear set in my 84 and need to set the timing, I hope its the timing. When I installed the set I made certain the markings on the cam and crank gear lined up and piston one was TDC on the compression stroke. The car will start right up and idle fine, but when I increase throttle the engine "pops" and "pops" again when I release the throttle, at idle all is fine.
My helms states to follow the vehicle emissions control information on the label on the radiator, only problem is the label is gone. What is the proper setting for the L83?
The helms also reads on vehicles with electronic spark timing to disconnect the EST connector at the distributor to cause the engine to operate in the bypass timing mode. Does the 84 have this EST?

 

You need to disconnect the tan wire (I believe with a black stripe). It has a square connector and is near the brake booster. I think your base timing is 6 deg but am not sure, Mabey CFI EFI will chime in if not I will try and dig out my old 84 manual. Once you have the base timing set, turn the car off and reconect the wire and thats it

 

yes its by the booster, when my motor was stock I ran base timing at 8 deg without any problems at all.

 

6 is proper spec by your label. Nice color by the way !!

 

Thank you, I'll check it in the morning, that is one nice car.

 

I just did my timing chain on my 84 a couple of months ago. When I was done, I set my base timing to 10 degrees BTDC. The manual calls for 6 degrees, but 10 gives it a little more low end grunt, and even running 87 octane fuel, it doesn't ping. Yes, it has EST, and you will need to disconnect the wire FD2BLK mentioned prior to setting the timing, and remember to reconnect it and clear the code it sets when you're done.

You say it "pops" at anything other than idle.....is it backfiring out of the intake or the exhaust? Now....why did you change the timing chain? Was it worn but running OK prior to the timing set change, or did the chain break while it was running? If it broke, have you run a compression test to rule out broken valves?

Now, are you 100% sure your timing marks lined up PERFECTLY? You say #1 was at TDC.....did you set the gears at the bottom of the cam revolution (crank at 12:00 and cam at 06:00) or at the top of the cam rotation (12:00 on both crank and cam gears)? If you set it with both at 12:00, did you verify the marks lined up at 12:00 and 06:00 also? Did you remove the distributor for any reason? If so, is it possible that it's a tooth off?

If your chain was sloppy when you changed it, the new tighter chain will cause your timing to be abnormally advanced (assuming the timing had been set with the sloppy chain). I had about 14 degrees of base timing after the change and was getting slight detonation....resetting to 10 degrees cured the problem.

Let's do a little troubleshooting....hopefully it's just ignition timing.

 

The car was running fine until one afternoon I was about to park it and have lunch, just as I was placing the shifter into park the car started to "knock". I drove the car home, about 20 miles at about 45 MPH. When I removed the timing chain cover I noticed the cam gear had one tooth while the others were gone causing the timing chain to slap against the inside of the timing cover.
I lined up the original cam gear at 06:00 and the crank gear at 12:00 then removed the old set and installed the new set. I then hand turned the crank and watched the cam turn one complete revolution at which time the cam gear was at 06:00 and the crank gear was at 12:00. I also removed the plugs so I could spin the crank easily. I placed a long screw driver into the #1 piston and it bearly won't into the cyclinder, just a hair, I'm sure it was at TDC.
I buttoned everything up and started the car for the first time yesterday, the entire job took about 3 weeks because of various reasons. The car did start right up and I let it idle for about 15 minutes. The temperature was 161 and oil pressure was about 76. As I increased throttle the engine did pop a couple times, not one after another just a couple. When I release the throttle the engine popped a couple times again.
Yes, the car was running fine until I heard this knocking noise which turned out to be the worn cam gear. There were also bits of nylon in between the teeth of the chain. I am absolutely sure the cam gear was at 06:00 and the crank was 12:00. I did not touch the distrubutor at all.
I've own the car for just under 2 years and the engine has always run well. I can't say what the previous owner did to the car, maybe the timing was changed to compensate for the cam gear/timing chain issue. I will locate the FB2DLK connector and remove it and time the car. I'm not sure if the pop was on the intake or out take, I'll check today.
Thank you kindly and to all have a safe and Happy New Year.

 

You need to make sure #1 cylinder is at TDC on the compression stroke and not the exhaust stroke. The easy way to check is to remove the plugs and rotate the engine manually with your finger in the #1 spark plug hole. When it pushes air you are on the compression stroke and then look at your balancer for the timing mark. You should at least see the mark. Continue to rotate until 0 degrees (TDC). If you can not see the timing mark your cam timing is off (probably 180 degrees) you will need to pull it apart and reset the cam. I hope this helps.

 

I set the timing at 6 and 8 degrees and the engine still pops on the exhaust stroke, (out the muffler). Regardless of what I set it at, the engine pops. I disconnected the EST connector, timed it to 6 degrees, turned the car off, connected the EST, started the car and as I checked the timing it jumped to 12 degrees and then off the scale. Any ideas?

 

that is normal. The ECM is controlling the timing from there. It should be around 23-25 degrees. That is what the prom says anyway. I would still check the cam timing. This is the type of problem that inorder to effectively troubleshoot you need to start discounting things..... eg cam timing.

I had a similar problem and it ended up being the dissy module. When they go bad they just go bad.

 

I crossed wires 1 and 3. I corrected the problem and all appears to be fine. Again I thank all who replied. Happy New Year to all.

 

I hate when that happens !!!!!!

Glad you got it figured out.

 

Me Too!

 

DOH!!!!!

I hate it when I do crap like that. Guess it proves we're all still human, right?

Glad it's fixed, and it was easy. It took me 3 weeks to do my timing chain as well, mostly due to my old aching back objecting to the positions I was placing it in.

Nothing would suck worse than having to pull it apart again. My original fear was that your chain had broken and you had bent a valve. Glad that wasn't the case.

Happy new year!

 

Glad to hear you're back on the road!

 

Brimis,

How many miles on your car? I have 98,000 and wondering if I need to change my timing chain and gears?

Pete

 

The engine has 166,000 miles and has always run strong. I guess after that many miles the stock cam had no choice but to disintegrate.
The job took about 3 weeks because I worked on the car in the evening after work in the cold. I was working in temperatures as low as 11 degress which did take its toll on my body. Not to mention I'm not the world's most prolific mechanic.
I must thank CFI-EFI for pin pointing the problem. Just a word for Pete, if its not broke, don't fix it!
Can you imagine if I removed everything and then found out it was a crossed wire!

 

Brimis.....with that many miles, it was only a matter of time. Generally, the chains on a SBC are good for about 120-150K before danger of breaking, but performance can fall off around 80K. After replacing my chain at 145K I noticed....

1. Smoother idle with no loping.
2. Better vacuum signal, picked up 2 lbs of vacuum.
3. Much stronger low end torque.
4. Quieter engine.

If you want to see how much play is in your chain, remove the distributor cap and turn the harmonic balancer with a socket and breaker bar to where the timing scale is visible. Stop at the 0 degree mark. Now, turn the engine in the other direction until you see the rotor move. Note the number of degrees it took for the rotor to move. Divide that number by 2, and that is how many degrees of timing you are losing from a worn chain.

84 WhiteVette, you are probably safe for a while, but at around 120, it would be a very good idea to change it out. It's not a particularly fun job, but if you take your time and have the right tools (and a warm place to work), it's not that hard either. Allow yourself 8-10 hours of leisurely wrenching.

Changing the chain can buy the motor another 80-100K of life. Breaking a chain can cause pistons and valves to collide in a most gruesome fashion.

 

Thank you for the explanation. I agree with the 8-10 hours . If I had to do it again I would have all the tools by my side. Take the A/C compressor for example, two 3/4" bolts, one 1/2" bolt, one 9/16" bolt and a 15 MM to boot!

 

Yeah....and a bracket that requires you to be a contortionist to remove and replace. Once you've done it a couple of times it's just a mere annoyance.....the first time it's a real bear.

Good idea about laying out the tools in advance. That alone could shave a couple of hours off the job.