I’ve done a EFI conversion on my 69 Olds Rocket 350 and used the TBI setup from a late 80s GM truck, a 307 Olds electronic distributor from the 80s and then modified the ECU using one of DynamicEFI.com EBL Flash daughter boards and software to tune etc.
Everything work great and the motor runs nice but I’m now using the WBO2 to tune some more and I’m noticing WOT is a bit sluggish. I think the timing tables are out or I don’t have enough advance during WOT.



One thing I’m not certain of is what to set the base timing at using the 307 HEI distributor? Someone suggest that like the Olds 307s from the 80s the base timing on the HEI unit needs to be 20 degs. Granted the 80s 307 is a different emissions based motor and mine is not. It has the number 5 Olds heads. The ECU controls advance and timing but needs to know the base degs to operate correctly. I’ve got it at 10 deg now but wonder if it should be at or closer to 20 degs?


Regards,
Kris.

 

The base distributor timing affects two areas:

It sets the at-cranking spark advance. Cranking is at a base timing. Which 20° is usually too much.

It affects the minimum and maximum possible spark advance when running. Only so much retard or advance can be programmed into the distributor before the cap/rotor cross fire.

RBob.

 

Thanks for the reply, so basically if the car starts fine at 10 deg base there is no reason to change it.


So is there a separate SA table for WOT I should look at?

 

Correct, no windmilling when cold, and no hard cranking when hot.

There is the PE adder table:

SA - PE Adder vs Gear/RPM

RBob.

 

Thanks again for the info.


What do you recommend for proper idle speed in park/neutral and drive? I've read conflicting info, only reason I ask.

 

I don't really know what th, hang on, I've got an ancient Chiltons manual. OK, in '69 there were three different 350 Olds engines with different HP ratings.

250 HP: stick: 400, auto 400 RPM. This is low, but i has to do with how the carb idle mixture screws are set up.
310 HP: stick: 675, auto 575 RPM.
325 HP: stick: 850, auto --- RPM. Guess this engine wasn't offered with an auto (no surprise).

Just tweak until the engine is happy with the idle speed.

RBob.

 

So I'm running to another issue. I'll do a good basic VE learn with the NBO2 in closed loop, then I'll switch to open loop and do some VE learns with WBO2 to get WOT etc but the WBO2 adds a lot to most areas that the NBO2 has already learned. The car like it better obviously with what I assume is a richer tune throughout but when I change back to closed loop with the NBO2 the car doesn't like it and if I do some VE learns it leans out a whole bunch in ares the WBO2 added. I end up chasing my tail so to speak and I'm not sure what the solution is. For the moment I'm running in open loop with the WBO only but MPG takes a hit.

The same thing is happening to my friends GM 350 we installed in hos 87 Monte Carlo. Fresh crate engine with s few bolt on's. His is a day driver in the summer this issue is more of a problem I need to solve for him. Any thoughts or advice???

 

1. I don't know dick about EBL. Keep that in mind for the remainder of this post.

2. The late-'80s swirl-port 350 almost certainly has a faster burn rate than the Olds. The Olds is going to need more spark advance than the Chevy. MAYBE all you need to do is to advance the base (initial) timing, and let that add to the timing curve programmed-into your computer.

3. Olds did use tremendous initial advance--20 degrees or so--on various engines. But you're not using the same computer-programmed timing curve as those engines, even if you're using the same distributor. Olds was also infamous for specifying spark-plug gaps of 0.080 on some applications, due in part to the very lean and EGR-polluted fuel/air mixture. You wouldn't use .080 spark plug gaps, either.

4. I would "map" the existing spark advance at various RPMs and loads, using a reliable/accurate timing light and reliable/accurate tach and vacuum gauge, to see if it passes the "Giggle" test. For example, if you're seeing less than 30 degrees at 3000 rpm, you can be entirely assured that there isn't enough advance--in fact at light load/high vacuum you'd want more like 45 to 50 degrees. 3K RPM with heavy load/no manifold vacuum, you'd want ~35 degrees. I'm not sure how you'd separate the computer version of "centrifugal" advance from the computer version of "vacuum" advance--perhaps by pulling the vacuum hose from the MAP sensor and using a hand-held vacuum pump to "trick" the computer into accepting light-medium-heavy load. That's going to affect fueling, too--but all you care about is spark advance.

5. I got a (partial) education about "Latency" in GM HEI ignition modules and computers; and I have no idea how the Olds (7-pin) module compares to the later 8-pin jobs, of which there are numerous part numbers which vary from one another in terms of "Latency". The whole "Latency" issue was a mind-popper for me. But for your purposes, I think a timing light, tach, and vacuum pump/gauge would tell you all you need to know, provided the light and tach were accurate from idle to the end of the timing curve, whatever RPM that turns out to be.

 

You need to correlate the target VE in both modes, otherwise one will pull from the other whenever you do a VE Learn in either mode. It would be in your best interest to run Closed Loop, but with an Open Loop idle, just be sure to set the same air/fuel target for your idle RPM during OL, this way it will not deviate when you do your VE Learns. Don't get into the habit of constant VE Learning though, once your VE is tuned for a specific temperature range, leave it alone. It will always vary and correct depending on temperature, and this is where you will chase your tail, so choose a window your happy with (RPM and Temp), and move on to the next part of tuning...

- Rob