How much total timing?
 

I was just wondering how much total timing everyone is running? Currently I am running 13 deg plus 30 deg of advance for a total of 43 deg, BTDC. With no knock retard.

I was just curious to see what everyone else is running?

nick

Where are you getting this 30' of advance figure from? That is way too much total timing, unless you're running a late 70s 7.8:1 compression motor or something. Most injected motors seem to make best power around 30' total timing

I am reading this on a TECH1.


thanks
nick

my Vette at part throttle has about 43* or so of timing, and around 30* at WOT. this was read on a Matco tools scanner. by the way, my base timing is 6*

Ed, that's very interesting. My 89RSconvt ZZ4TPI is set at 6 deg adv with the computer unhooked. I am showing abour 35 deg total advance under probably 45-50% throttle and less most other times. Is 35 deg adv timing too much for a TPI? I've always heard this was about right on.

The 30 deg advance I am reading is from the stock chip, so even with a stock base timing of 6 deg. I would have a total timing of 36 deg BTDC. So I think I would need more than 30 deg of total timing.

thanks everyone
nick

My car also advances the timing to 43 - 45 degrees at full throttle with no knock retard with the stock chip. I have recorded these numbers with my AutoXray scanner and I believe that is way to much advance. A typical small block ussually makes max power with total timing between 34 and 38 degrees. This week Wednesday I am taking my car to a chassis dyno and we are going to play with fuel curves and spark advance until the max power is reached, and a new chip will be burned. I expect the max power spark advance setting to be 34 to 35 degrees with the Vortec heads.

bjankuski
 

Please let me know what you find out at the dyno, I am very interested to see some real data on where you get maximum power.


thanks
nick

The engine in my Jag has the base set at 6 and shows a total
up to about 45 or 46 with a Snap-On scanner with no retard.

Bjankuski
 

Did you ever make it to the dyno? What kind of results did you get?

thanks nick

The dyno operator canceled the trip for last Wednesday and rescheduled it for this wednesday, I will post my results when I receive them.

As stated earlier, I did make it to the dyno on Wednesday for a chip tuning session and listed below was the results of the tuning and what was needed to make maximium power with my combination. I was mainly concerned with tuning the fuel curve and ignition curve. The fuel curve as provided by the stock chip was pretty close. I needed to richen the low end below 3000 RPM by roughly 5% and lean the top end above 3000 RPM by roughly 2.5% to acheive maximium power numbers. Overall I was surprised by how close the stock chip fuel curve and spark curve was to what my engine wanted. The spark curve was then tuned to acheive maximium power and surprisingly the maximium power was provided by the stock spark curve tables. The total spark advance that the engine needed to make maximium power was 35 degrees and this was the advance curve that the stock chip had programmed at wide open throttle. One interesting note was that the engine was very indifferent to the spark advance that it needed to make max power. We ran the advance anywhere from 30 degrees to 39 degrees and the power curve looked almost identical. At the low of 30 degrees and the high of 39 degrees the power curve did drop some but it was almost not worth worring about.

By the way the combination is now making 255.3 RWH and 314 RWTQ. One other interesting note was that the power really holds on after its peak. The HP peak (255) occured at 4800 RPM and at 5750 RPM the HP number was still 237.4.

Thanks for the info, it is greatly appreciated!

nick