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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": https://lh3.googleusercontent.com/-t...-rw/timing.JPG 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. |
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?
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Originally Posted by indysupra
(Post 4490463)
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?
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! |
I'm 10 deg out of gear. I can send you a timing table email address?
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have any of you tried adding a little fuel in the rpm dip area to help bounce the rpms back up.
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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" |
Originally Posted by Tibbstoy2
(Post 4490455)
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": https://lh3.googleusercontent.com/-t...-rw/timing.JPG 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. 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. |
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.
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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. |
Originally Posted by Tibbstoy2
(Post 4490519)
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. 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. |
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