351 Windsor carb to EFI done

TR,
I am enjoying the questions and am very pleased to be being able to share what I have learned, but I'd like to start this reply off by reminding everyone that I am basically self taught in many aspects of this. Engine mechanics is a serious hobby of mine, and I do a lot of research, but I don't want to come across as someone who knows all the answers. There are many ways to tackle problems. I know what has been working for me from practical experience, which I'm happy to share, but I don't want to offend anyone by coming across too strong.

There. That's out of the way.

Now, rotor phasing. In a distributor you have a rotating element, the rotor, and the distributor cap, which has equally spaced terminals for the individual spark plug leads. The centre terminal on the distributor is for the output from the coil. It is in direct contact with the rotor by a carbon brush and spring steel contact. There is no direct contact from the rotor tip to the individual cylinder terminals so the spark is forced to jump across this gap. You want to keep this gap as small as possible which also means that the rotor must be "phased", meaning "aligned with", as close as possible, to the appropriate terminal. This isn't an issue with a conventional distributor with mechanical and/or vacuum advance because the advance mechanism also changes the position of the rotor relative to the distributor shaft.

With electronic spark timing you don't normally use any mechanism at all because a wider rotor tip and more space between terminals can compensate it for. If you use a small diameter cap, as I have done, then the centrifugal advance mechanism can be used to your advantage. The rotor will be perfectly phased probably over a very narrow range of your spark map. Most of the time it will be either retarded or advanced from the ideal position. It's certainly not ideal, because the mechanical advance curve is fixed, but it's usually close enough to prevent cross firing and makes no significant difference to the actual time that the spark arrives at the plug.

How to best set the phasing of your rotor is pretty much an educated guess subject to fine tuning. The best information I was able to get, if I recall, was off the SDS EFI web site, which suggested setting it at about half of your advance range. I was aiming for a static timing of 10 degrees BTDC crank, and didn’t expect to have a total advance under any condition of any more than 40 degrees. Because I wanted less error to be on the high speed loaded part of the map I decided on 20 degrees as a starting point. I rotated the crank so it was at 20 degrees BTDC for number 1 cylinder. Because it’s pretty hard to get at the distributors in my engine room I had to make an aligning jig of some sort. I had an old distributor cap which I butchered so the only thing left was the base and the number 1 terminal. This would allow me to see when the rotor tip was aligned with the terminal. With the crank at 20 degrees, and the distributor hold down clamp loose, I just rotated the distributor until the tip and terminal were aligned as close as I could see. So far I have had no reason to change this position.

Skifitz,
Good for you! Nice to see someone else venturing over to the dark side.
Now the questions:
Is that a GM throttle body set up?
If so, what manifold are you using?
I've never studied the GM TB system but I think they run on lower fuel pressure than the Ford port injection does. What fuel pump do you use and is it return to tank or something else?
What version board and firmware do you use?
How about tuning software?
How about O2 sensor, how did you handle that and do you run open or closed loop?
What kind of boat is the engine in?
What's your normal cruise RPM?
Any significant differences in power, economy or just plain manners?

Skifitz,
Thanks, but you're doing just as well yourself.

So, with no O2 to give you an indication of what your A/Fs are, how did you tune your fuel map?

I'm with you on the Holley, but to be completely fair they always started extremely well for me. It was just the warm up phase and low speed low load range that I couldn't get from being over rich. There was nothing wrong with the 2900 to 3300 range either. I had another 351, 4160 with a Jacuzzi jet on a smaller boat for a very short period of time. It was the same way, an excellent starter. I swear it would fire when the first cylinder came up on compression, or almost that good any way.

My set up starts good too, but not that good. I think it is because my code needs 3 trigger signals to confirm that the RPM calculations are valid before things completely stabilize. TFI doesn't need any input from Megasquirt at cranking revs so I didn't think that would be an issue. Perhaps it just needs a bit more fine tuning. That never really ends, at least not for me.

You are not hijacking at all. This is what I hoped my original post would accomplish. I'm so glad you chimed in because I've been scouring the net literally for years trying to find someone else who's experimented with programmable EFI on boats. Well done and keep the information coming.

Fascinating! I always suspected that at least a certain amount of "generic" tuning would be possible between engines of relatively similar size and design. You've proven the theory.

Are there provisions with Megasquirt for a knock sensor? From what I remember reading about the EEC-IV, it wasn't available through all the years on the stock Ford setup.

E4ODnut wrote: Having said that I did come up with one mention that there is a boss about mid way down the left side of the lower intake manifold that was for a knock sensor. The fact that the PCM EFI engines have them was news to me.

Actually, all PCM motors equipped with the Protec ignition system (which debuted in '91) have knock sensors as well. This includes carb and TBI boats, not just the GT40 multiport (95+).

I'm curious about this Protec ignition. Is there any information about it anywhere?

The PCM engines (or at least the ones I have looked at) use knock sensors screwed into the heads, with open loop control and the varying quality of gas available on the water it is a very nice thing to have. PCM might have found that they needed it to have both a well tuned and warranty safe engine:

The manual states :

When spark knock occurs, the Knock Sensor produces a pulsting electrical signal. This signal is put through and amplifier and then sent to the ECA. The ECA then immediately retards spark timing until knock is no longer sensed, or up to a maximum of 8 degrees retard. The engine will return to normal spark advance after the MAP sensor detects 3-4in. Hg. Change in engine vacuum.

The 5.8 liter PCM setup (ford marine setup) was definitely more similar to the 5.0 automotive setup than the 5.8 truck setups. Upper intake manifold, throttle body, maybe knock sensors... all 5.0 stuff.

How do I tell what kind of Ignition system I have on my 96 176? It has a single coil, the distributor doesn't seem to have a point set in it, unless it's under the metal plate. The distributor has a toothed wheel that I would guess is an actuator of some sort. I can't find a control box or ECU. Any suggestions?

Enut
My feeling is that if somebody wants stock, then they can look elsewhere. Somebody who values what you have done will welcome the changes you have made. An old girlfriend once said "if they don't like my house, then they don't have to buy it. But I'm not going to change it to suit them"

Don

TX Foilhead wrote: Something I've wondered about that hasn't been discussed yet is how reliable is all this stuff. It's interesting from the standpoint of the person who understands and likes to tinker, but what happens for the next owner who may not feel the same way. I can see this being an issue when its time to sell.

Going back to 2003, I have built, installed, tuned, and driven 4 Megasquirt processors and have never had a component failure. I had a throttle position sensor and an Idle Air Control stepper motor fail, but those were stock sensors and would have failed regardless what computer was using them.

But that doesn't really answer your question about how reliable all this stuff is. On a forum where electronic ignition is regarded as questionable, unproven technology, I doubt it would be possible to give a satisfactory answer, but I'm saving the crappy Holley for the next owner if he or she is of a similar mind. ;)

skfitz wrote: TX Foilhead wrote: Something I've wondered about that hasn't been discussed yet is how reliable is all this stuff. It's interesting from the standpoint of the person who understands and likes to tinker, but what happens for the next owner who may not feel the same way. I can see this being an issue when its time to sell. Going back to 2003, I have built, installed, tuned, and driven 4 Megasquirt processors and have never had a component failure. I had a throttle position sensor and an Idle Air Control stepper motor fail, but those were stock sensors and would have failed regardless what computer was using them. But that doesn't really answer your question about how reliable all this stuff is. On a forum where electronic ignition is regarded as questionable, unproven technology, I doubt it would be possible to give a satisfactory answer, but I'm saving the crappy Holley for the next owner if he or she is of a similar mind. ;)

I think TX raises a valid point. An EFI conversion involves much more than just the brain running it all- I dont think anyone here knows enough to seriously question the Megasquirt's reliability. The other sensors and components are also part of the overall system though, and as you stated, parts can fail. When theyre assembled in a custom manner (which will usually lack the full up documentation/definition that a factory EFI set up would), you darn well better know how the system works in order to be able to troubleshoot it. Are any of the aftermarket EFI brains capable of running diagnostics (OBDI or II type stuff)? I dont know the answer to that, but they would be fairly sophisticated, if they are.

Most non-original modifications wont be met with a positive reaction by potential buyers when it comes time to re-sell. Such an EFI set up will undoubtedly fall into this category- moreso because it has a serious and direct impact on how the boat functions (not just how it looks) should it malfunction. I know I would most likely be uncomfortable buying a boat so equipped without being very familiar with how it was put together. I would think most buyers would be even less excited about such a conversion.

But, I dont think many people considering such a project are doing so with resale in mind. Like Robert said, its not like the changes are irreversible- and it may need to done to appease new potential owners.

As far as electronic ignition conversion kits go, I for one, maintain that their cost/benefit doesnt outweigh the downsides they offer in an otherwise stock engine. That doesnt mean I (or anyone else who agrees with me) has a fear of technology in general... so that comment is a little silly. An EFI conversion is likely in my future... but dont count on my installing a standalone EI kit anytime soon.

Robert, thanks for the explanation on phasing- makes perfect sense now.

I would go so far as to say that when the Megasquirt is plugged into the laptop, the laptop is an OBD tool. It allows you to see every input and output value any time you'd like -- in real time or in a data log. You would know, for instance, that something is wrong with the throttle position sensor when you see an erratic needle or, in my case, a static number as the value for % open when you are working the gas.

Most aftermarket ECU/management will have diagnostic of some kind as described above, MS is a great way to start putting your toe in the water.......less $$$ if resale is a worry to you it’s not for you....but if you like messing with stuff fill your boots as most that mess will keep the old parts and swap back to sell keeping their hoard of EFI parts for their next project or sell.   

Your specialized equipment comment reminded me of something: MS uses bluetooth so that I get real time display of all engine parameters on my cellphone in real time, along with GPS speed. It's pretty sweet. I'll take a screenshot next time I have it plugged in in the car.