What is the purpose of using a paper clip in the ECM port?
Thanks for your info.

Shorts out the computer induced timing

Thanks, but is it a necessary step to correct timing?
R

It's necessary step if you're using a timing light to set the ignition timing.

Why do you ask?

If you're trying to set the distributer correctly, then yes you need to bypass the computer-controlled timing advance. That's what the paperclip is for. With the paperclip installed, ignition timing should be at or near 10° BTDC. If it's not, then adjust the distributer until it is. Then remove the paperclip, and you're done.

Thank you for the explaination. When my mechanic wants to know why do I have to do such a wierd thing just to time the engine I'll have an answer.
R

No problem. If your mechanic is familiar with GM HEI ignition, then he shouldn't have any trouble with it.

If your mechanic is an old guy, tell him that inserting the jumper is similar to disconnecting a distributor's vacuum advance prior to doing the timing.

Patrick: Now THAT'S something I remember my Father doing to his '65 Buick Electra 225!

quote Originally posted by RPYRAZOO: Patrick: Now THAT'S something I remember my Father doing to his '65 Buick Electra 225!

Exactly... it's an old guy thing.

If you’re trying to set it by ear then you don’t use the paper clip, right?

quote Originally posted by NiotaFiero: If you’re trying to set it by ear then you don’t use the paper clip, right?

Correct.

And after you do that, it might be a good idea to do the "paperclip trick" and use a timing light to see where the base timing ended up.

quote Originally posted by Blacktree: And after you do that, it might be a good idea to do the "paperclip trick" and use a timing light to see where the base timing ended up.

quote Originally posted by Blacktree: And after you do that, it might be a good idea to do the "paperclip trick" and use a timing light to see where the base timing ended up.

...although if the outer ring of the harmonic balancer has spun, the timing will appear to be way off.