Join Date: Aug 2016
Location: Minneapolis, MN USA
Re: FITECH EFI TUNING tips, info sharing, ideas, settings, etc...
The FiTech 'base' setting does not play into total timing. The timing number displayed on the handheld should always be the actual timing on the engine, you don't add that base number to it. If the display says 10 the engine should be 10, if it says 50 the engine is at 50, forget about that base setting number.
The idle setting is the lowest the timing will ever go and I am told can not be set lower than the base setting. IF the base setting ended up at 20, you can't set idle at 15. I have not experienced that myself but someone else mentioned that 'feature' here. Must have to do with the way they wrote their software and do there timing references. There is no conceptual reason that has to be like that and there are other systems out there that don't have that limit.
If your readings with a timing light match the displayed timing on the handheld forget about that base number. The display on the handheld is the number that varies, you can find it in the long list or bring it up in the large gauge feature. If it matches you are good. If not that is how you get it to match. If you do have to change it you need to check your rotor phasing because changing that number will change the phasing.
So assuming that matches and you are phased you can move on. I think idle defaults in the teens somewhere? Which should be fine for most motors. If you and your builder thing 35 was all it needed set your max and wot to 35 and pick something in between the idle and max for that mid setting. You also want to think about the break points. From memory they default to 3 and 6 k? If you have a higher revving engine those may be fine but if you have a high torque low rpm motor you will want to drop those so you actually get into the curve in normal driving. If your full timing doesn't come in till 6k and you have an OD trans and cruise at 2k its not going to be a great performer. A street build will usually have full timing or very close to it at its cruise speed. If you are at 30 at cruise you are probably close but if you are at say 25 you need to look at your settings and overall setup. If it was working with a carb and conventional distributor then the overall setup must be fine its just going to be settings. If you didn't have it running before you may have a mismatch in your gearing vs power vs weight.
What I did on mine was took readings before I pulled the original distributor. I used a hand vac pump to pull and hold full vac and revved the engine high enough to see where and how much the mechanical was adding so I knew what the total was and roughly what the curve was. I then used those notes to get me a starting point on the FiTech. At first I didn't change the break points so I was not able to get to the same max timing, I have high torque low r engine. I wanted say 40 for a total but it would only get to 32. I first tried setting the max to 50 and that helped a bit but I still didn't get to my 40 and then was worried if I ever did get the R's up it would be way too advanced. That is when I figured out changing the break points which really let things fall into place. I had some electrical issues I didn't get worked out till near the end of the driving season so I didn't get a chance to really play with the curves but I plan to tinker with them next summer. I have a low compression engine so I should be able to run 87 gas. Historically I have never been able to get decent performance without detonation so I have had to run better gas. That was a major reason to go to EFI, I should be able to tweak the curve so I get performance on regular gas. With the mechanical I was never able to get the curves just right for all conditions. I spent a whole summer trying, wrecked lots of weights and other parts trying to get different curves.
I'm going from memory at the moment so I may be a little off on some of the numbers. I also tend to forget details about the setup I am talking about, been in too many threads or crazy long ones like this so if yours is a track build some of my numbers don't work, my experience is on the mild street builds which I thought was what you had but am too lazy to try and sort back through this thread to see which build was yours.
Sorry no Chevelle, 73 Cadillac Eldorado - Fairly stock low comp 500cid.
FiTech Go4 600 - Timing control via gutted 7 pin large cap HEI - Fuel RobbMc Powersurge with returns.
Previous system was Megasquirt w/Holley TBI so I am not new to DIY EFI