Does someone out there know what the timing should be set to on an 81?
Seems I read somewhere 12 BTDC? Don't know at what RPM though.

Thanks!!

 

6 degrees BTC

:)

Kevin

 

A stupid question. BTC = Beyond or Before?

 

Before,otherwise you will have very nice red glowing headers...And it will run like crap.. :yesnod:
Btdc..Before top dead center :smash: :smash:


[Modified by BB wowbagger, 3:48 PM 7/1/2002]

 

K guys, at lunch, I went out to set the timing and I have a couple questions. Should I see the timing mark every time the strobe flashes? If I should, what would cause this to be inconsistent? It may take me 10-15 seconds to see the mark again. To breef you, I am trying to fix a sputter in the engine (like a miss). I have replaced plugs, plug wires, rotor, dist. cap, and rebuilt the carb. Still this thing is acting like is is missing out. I plan to attempt to check for vacuum problems, but am working on being sure these other things are right too.
Thanks for any info.

 

you should see the line the whole time the light is flashing. Make sure your on the # 1 plug wire (driver side, one closes to the radiator).

If this doesn't help with the timing, it's way beyond me but I'm sure someone here will have the answer.

 

I am on the #1 plug.. OH NO, now I really need some help.. SOMEONE, ANYONE, PLEASE HELP. What would cause this to happen? Is it something I can fix? Do I need to take it somewhere?? HELP :confused: :confused:

 

You could have a failure in the HEI module but it's really a little tough to tell. Generally, the module is like a light switch...it's either on or off. Does it seem to run worse when it gets hot?

 

gerry,
Yes, the hotter it gets, the worse it runs. Excuse my ignorance, but HEI = ? Something with the ignition? If so, where is it located.

Thanks for your help!!

 

It's under the distributor cap...under the rotor. It sits on the distributor timing plate. Looks a little like a funky boomerang. Not too difficult to replace.

 

The wires coming out of that seem to be a little worn. Actually the insulation is cracked and somewhat gone. Could this thing be shorting? If I replace it, what do I ask for and HEI or does that stand for something else? Any idea on cost?
Thanks!!!!!!! :cheers:

 

HEI stands for High Energy Ignition. Should be around $80 or so. I would also check to make sure that your spark plug wires are all wired correctly. Check that your firing sequence (located on the front of the manifold) is right.

 

OK, Figured out why it wasn't working. Optical illusion. I was on the wrong plug wire.. :mad . Anyway, I think I have the timing set close. One question I have is how many degrees is each tooth on the timing gauge? In addition, I recently rebuilt the carb and was wondering if anyone has some instructions on how to fine tune this thing. Smells rich, but not really sure what to do to make it better.

Thanks for any help..

P.S. Still seems to have this miss when it get hot. I will get back to that when I get this carb thing worked out.
THANKS!!

 

Have you still got the computer hooked up?
If so then you need to disconnect the connector coming out of the dist cap when setting the timing (4 wires on the connector? I can't remember). If you don't then them timing will have a slight advance.
Paul

 

No, I have unhooked the computer. I thought that if a sensor went this thing was trying to adjust the engine. If I disconnect the dist wires, wont this cause the ignition to not work?
Thanks!

 

With a computer in place those wires feed the advance signal to the HEI, so if they aren't disconnected the computer will be feeding a small advance request through while you're trying to set the base timing. Without a computer in the system I think you time it up with all connections in place.
Did everything work OK after the computer was disconnected? Was anything done b4 the car started playing up, or did it happen for no apparent reason?
:cheers:

 

When you say you have the computer unhooked, where is the computer unhooked from? Is it unhooked from the ECM, (the computer itself:)) or is the carb unhooked or what? Paul is correct in saying that the connector that goes to the distributor, I think it's a 6 pin, or maybe 4, needs to be disconnected, but I think this is dependent on what the computer is still hooked up to.

 

Hi Justin (the Vettes looking good :) ),
Glad you asked about the computer as I wasn't sure what disconnected meant either.
So..... is the computer completely out of the system & has the carb & dist been replaced by non-computer ones, or is it just unplugged from the harness, or.....
:cheers:

 

I disconnected the two plugs at the computer.

At lunch, I plugged them back in, and checked the timing, it was out, but the dist. plug was still plugged in. So, should I unplug the dist. Plug in the computer, then set the timing? Question - Before top dead center. does this mean in the rotation of the pully. i.e. if I am looking down from the front, the thing is turning clockwise, so 6 degrees BTDC would be to the left or toward the top?
I also found another thing at lunch.. When the car is at idle, and seems to be missing, I removed the connector to the MCS(mixture control sensor) and the thing seems to idle fine. Is my MCS the original real problem?
Thanks guys, this thing is getting so bad, not sure if I will be walking soon or not..

 

Hi again,
If I've got this right, the computer (ECU) still controls the car. It should be controlling the carb primaries mixture, the spark timing & the TCC lockup. So if you unplug it the TCC won't lock up (no biggy), there will be no spark advance (bad running) & the carb will be, I think, in the full rich position for the primaries. So you'll be running over rich (really noticeable when hot) with no advance. It will run like a dog.
To set the timing leave the ECU in the system & disconnect the multi-wire connector coming out of the dist. Mark the timing line on the harmonic damper with some white paint/typist correction fluid/something light & connect a strobe set to 0 degrees advance to the No. 1 plug. If the timing is correct you'll see the line on the damper lined up with the 6 BTDC mark on the timing tab which is connected to the top d.side of the timing cover (BTDC & ATDC should be marked on it). If you then plug the connector back in to the dist and stobe it again you'll notice that the timing will be slightly advanced from 6 (even at 600rpm the ECU is giving a bit of advance).
If you do time it up without unplugging the connector, then as long as you do it at low rpms, the extra bit of advance won't hurt (you'll probably find it beneficial).
Once the timing is set & the ECU plugged in, then it's "just" a case of finding out what system, sensor, etc is playing up!
Was the Check Engine light on when you had the ECU unplugged? Does it come on with the ECU connected in the system & the engine running? If so then the stored error code(s) are great for helping find any problems.
Good luck,
Paul