mrestrictrplate

iTrader: (2)

Hello. I am installing a new jet chip (until i can afford a custom one) in my 305 converted to 350 tpi. The car has had the timing advanced. Do i put the timing back to stock before putting the new chip in? Thanks. Chris

AlkyIROC

Best base timing depends on the cam grind. With a stock cam, you can use the factory spec or bump it up a few degrees. Most people find that around 12* advance is a good base timing with a basically stock engine.

The computer will control the timing curve, total timing etc.

sofakingdom

iTrader: (1)

This is true, but ONLY TO A POINT.

All the computer can control, is the OFFSET from the instant the distributor sends out a pulse. All of the "offsets" are stored in the "chip".

So for example, if the chip mfr concluded that all of the factory's "offsets" were all late (retarded), they could have designed their chip to be installed with the stock setting, and then the "chip" would apply the new "offset" to the incoming pulse from the dist at EVERY SINGLE set of conditions. In that case, the stock setting is probably OK.

OTOH they MAY not have done that. They MAY have designed it with the initial setting at some OTHER point besides stock, and then programmed in all their "offsets" from there.

For any given chip, it's impossible to know, except by asking.

But EVEN BETTER than asking the chip mfr, try asking THE ENGINE. THE ENGINE knows, in no uncertain terms and better than ANY mfr (including GM) will EVER know, WHAT TIMING IT LIKES THE BEST. All ya gotta do, is set it somewhere. Drive it. Make mental notes of how it acts; get some track times; in general, just gather some data about how THE ENGINE likes it at that point.

Then adjust it.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Better/worse?
Better: adjust it some more the same way.
Worse: adjust it back to where it was, then about the same amount the other way.

Presently you will get it to a point where NO MATTER HOW YOU ADJUST IT FROM WHEREVER IT IS, it gets worse. At that point, no further improvement is possible. It is as good as it can possibly get by adjusting that particular adjustment.

"Better" in the case of timing might include more power, better gas mileage, freedom from pinging or detonation, cooler running, snappier throttle response, and so forth. YOU get to be the judge of what "better" means to YOU, in YOUR car, driving it where and how YOU drive it on the fuel YOU can buy in the place YOU live.

We call this "tuning". Live it, learn it, love it.