Tibbstoy2

This is what I needed to hear!

I actually had been increasing my timing below idle, and noticed it helped... but only by changing columns (not rows relating to MAP pressure changes).
Here's the "basic version":


I haven't seen any tables/global folders with timing at 8 degrees at an idle? I use cranking timing of 15 degrees and idle around 28.5 degrees at 950 rpm. If the rpm drops at that RPM, I ramp up to 31 degrees by 800 rpm and 35 if it stumbles to 400.

Should I be drastically changing my idle timing? My engines seem to like high idle timing, will retarding the timing this drastically help the engine cope with the load? I assumed 30+ degrees under the load of shifting was a good thing based on how it likes to idle there.

indysupra

I run as high as 35 deg in gear idle. The bigger the props/load the more it helps. What is your iac percentage at idle in neutral?

Tibbstoy2

IAC % at hot idle is ~3%. I've actually programmed in an IAC kick (originally intended for AC fans kicking on) to work in time with my shifter mechanism. I use a limit switch with a cam that rotates to give the IAC a heads up that I'm shifting. This worked pretty well with Bravo drives since the cone clutch had a delay, but I pretty much can't get it to react fast enough with the BAM tranny. It makes complete sense that timing could be the answer since the Holley system is intended to trim timing instantaneously - instead of waiting for an IAC motor.

35 Degrees of timing in gear makes sense... you're still getting the reduced cranking timing to help the start, but it sounds like I'm not giving it enough timing fast enough.

I read your post above that you "run more than 22 deg in gear"... how low do you run out of gear? Can you possibly post a picture of your timing table? I guess what I'm looking to see is how fast your chart changes and by how many degrees. Thanks!

indysupra

I'm 10 deg out of gear. I can send you a timing table email address?

kvogt

have any of you tried adding a little fuel in the rpm dip area to help bounce the rpms back up.

Tibbstoy2

Thanks In advance for sending your info. My email is jtibbe13 <at> Gmail dot com.

I have tried adding fuel and no longer use closed loop at low rpm. How much percent extra do you guys use in transition to in "in gear"

hadleycat

I originally was running about 20 degrees of timing at idle out of gear because that is what my engine liked. But I could not get into gear without stalling.

Once I reduced this to 8 degrees of timing at idle out of gear I had to readjust my idle screw a fair amount to add more air at idle and get my IAC back to approx. 5% at hot idle.

I have the cell I am in at idle out of gear at 8 degrees. I also have the cells surrounding that cell set at 8 degrees.

The cell I move into when I shift is up and to the left. That cell and the cells around it are at 22 degrees.

So in my situation yes I did have to drastically reduce the timing at idle out of gear. Once I reduced this timing I had to add a fair amount of fuel and air to keep the engine running.

I am at work or I would send you a copy of my timing table.

hadleycat

I was surprised to not find any timing tables with 8 degrees at idle also. But that is what Merc sets the stock 502 at.

Tibbstoy2

Ok, since my engines seem to like 30-35 degrees, I'm thinking i'll try out of gear idle at 20 degrees and bumping up to 35. How rapidly do you change? In other words, what rpm is the cells that are out of gear vs rpm in gear? The difference in advance vs change in rpm is probably the key.

Also, now that yours is well tuned, do the rpm even drop in and out of gear?

If anyone can send me a global file to compare, that would be extremely helpful: jtibbe13 <at> Gmail dot com.

hadleycat

I hardly notice a change in RPM when I shift into gear now. I cant remember what my RPM is in the respective cells but will try to forward you my Global Folder tonight when I get home.

I am running a Procharged 509 with a 525 cam. Bravo drive and a 30 pitch prop just to give you an idea of what I am working with.