Help! Ignition timing help needed.

[dap220]

Hi All,
Hope someone has some advise to share on my timing problem.
I have a 81 with the standard 350, quadrajet carb and original equipment distributor.
I just dd a tune up, plugs, wires, coil, rotor and cap. When I finished putting on all the new parts but before setting the timing it was giving a little backfire through the carb when I revved it. So today i reset the timing to 6 degrees ATDC like the tag under the hood states. So now what is happening is that when i rev it up I hear a noise that sounds like a metal on metal clank and if I drive it I hear the clank and then the engine bogs down.
I hope I given given enough information for someone to be able to throw a couple suggestions my way.
Oh, one other thing I did was claen up the inside of the distributor. The little weights and springs were all rusty so I hit them with some sand paper and WD40 although everything in there seem pretty hard to move.

Thanks, Dale

 

[frank_nesta]

Pinging

The sound I think you are hearing is the engine pinging.

When you set the timing did you block the Vacuum to the distributor vacuum advance canister? It sounds like the timing is to far advanced? My $0.02...

 

[bill81vette]

The timing should be BTDC not after.
did you unplug the 4 wire plug from the distributor???

 

[Antz81]

The sound I think you are hearing is the engine pinging.

When you set the timing did you block the Vacuum to the distributor vacuum advance canister? It sounds like the timing is to far advanced? My $0.02...

May be pinging, but no vacuum advance on the 81.


must unplug the 4pin plug as bill said to set timing

 

[Ruckus42]

Check wires , 18436572 ..any ignition noise is dangerous
The plug for computer is in rear of dizzy ..stop driving it till noise is gone ..the plugs installed may come into question. .reach , gap , heat ?

 

[dap220]

There looks to be a vacuum advance on the distributor and I did not disconnect when setting the timing.
I did check the firing order and it is all lined up.
I am confused about this 4 plug wire being mentioned. Can anyone elaborate?
I checked that i did indeed set the timing before top dead center.

Thank you all for your input, I'm just glad no one said "you destroyed your distributor...replace it!".

 

[Ruckus42]

If I could get a pic to upload I'd show you .The 81 didn't have a vacuum advance from the factory. 1981 was the first year for a computer control carb and dizzy..if yours has a Vacuum advance someone installed it . Your car might have a cam try adding some timing , push it up to 10 degrees..if it hard starts back down to 8 degrees , if it starts fine try adding more ..12 deg..you can keep adding till around 18 deg ..if you have a digital timing light .set it at 36 deg ..unhook vac advance ..start motor with light on ..run motor at 2800 rpm while at 2800 rpm set timing at 36 deg ...base timming is nowhere near as important as total timming. .do not exceed 38 deg total..make sure vac advance is disconnected while your doing this

 

[dap220]

Adding 10 degrees would explain why when I first marked up the balancer to adjust the timing it looked to be off the chart!
I will pull out the timing gun and give it a bump up.
Thank you!

 

[Antz81]

There looks to be a vacuum advance on the distributor and I did not disconnect when setting the timing.
I did check the firing order and it is all lined up.
I am confused about this 4 plug wire being mentioned. Can anyone elaborate?
I checked that i did indeed set the timing before top dead center.

Thank you all for your input, I'm just glad no one said "you destroyed your distributor...replace it!".

If you have a vacuum advance unit then your distributor has been replaced, so no need to look for the 4 wire plug.
as long as the carb has been replaced to a standard quadrajet and isn't still the E4ME that the 81 was fitted with then no need to change it back.
easy way to check is the E4ME has a plug for the solenoid on the top at the front right and a plug for the throttle position on the front left.

 

[Vettehead Mikey]

Adding 10 degrees would explain why when I first marked up the balancer to adjust the timing it looked to be off the chart!
I will pull out the timing gun and give it a bump up.
Thank you!

If the engine is already detonating/pining, advancing the timing even more will just make it worse.

 

[dap220]

All better now!

Thank you all for your input, I have corrected the problem.
I did advance the timing 10 degrees and it ran very much better but still had some popping and bogging under acceleration. I took one more look at the wires and found that I had switched #4 & #8. Didn't see this when I double checked and then checked a third time!!

What a great bunch of members in this forum. I really appreciate all your responses.
Until we meet again, be well.
Dale