Will this Renault PRV flywheel work (on an oddfire)?

[Matt Cramer]

This is an old fashioned engine with the cams driven by a chain inside the engine. There are no external pulleys or anything. All I have is crank and distributor.

So the Renix 6-2-2 is a "special" mode by the sounds of things. Can I combine Renix mode with a distributor wheel and oddfire?

Yes. Add a one tooth distributor trigger if there is not one already present.

[dieselnutjob]

During the next month the engine is coming out of the 604, and I am planning that it will go back in with a flywheel with teeth on it.

I had the idea today that maybe the mechanical fuel pump could be replaced with a sensor that could pick up the cam that currently drives the fuel pump.
Here is a pic of the cam and the pump


I am guessing an inductive proximity sensor like this one http://www.ebay.co.uk/itm/112335865769 could give me a once per 720 degree pulse?

I could replace the mechanical pump with an electric one for now to fuel the carbs, and get the megasquirt doing the ignition timing and then once that is done do the fuelling as well.

[rickb794]

You could grind that fuel pump lobe into a tooth and shove a sensor in the hole.

Chopping off all but one tooth on the distributor would be easier.

[dieselnutjob]

My distributor doesn't have any teeth; it has contact breakers.

[rickb794]

Section 5.2.9 of the fine manual covers points input

[robs]

dnj:

I'd have a go at using the contact breaker points. The MS just samples the cam input at a particular point on the toothed wheel to decide whether it's the 0-360 or 360-720 rev. For an ordinary missing-tooth wheel it's first tooth after the gap IIRC. Not sure when it is for the Renix, but I'm guessing you'll be able to leave the three lobes on your dizzy cam.

You have to contrive it that one of your sets of points is open at the psychological moment, and will be closed when the distributor has turned another 180 degrees. You'd want to drive a bit of current through the points (to keep them clean -- say through a 5W 47 Ohm resistor) and sample that through the opto input to the MS2.

With my own 604 I went with a 36-1 wheel at the crankshaft pulley, but that doesn't keep the factory look. Is running rather nicely though. I did post here a while back about my own cam sensor questions. You can see from the size of my optical slot (getting near 90 distributor degrees) that this doesn't call for great precision. (I have fixed up the wiring since this posting, and it's all potted in polyurethane and has been reliable so far).

At least With the dual coil arrangement, you'll be spared the distributor phasing hassles I had.

Have fun,

Rob.

[dieselnutjob]

I did post here a while back about my own cam sensor questions. You can see from the size of my optical slot (getting near 90 distributor degrees) that this doesn't call for great precision.

Thanks for that Rob. An interesting thread.

I am coming to some conclusions.

Because I am so slow at doing this, I want to pull the engine, fix the problems that I have with it (rust in the chassis rail, blown crank oil seal), fit a crank wheel and sensor inside the bell housing and then get the car running again as-is. This means that I will have to leave the distributor alone. However this is not a problem as I have another idea (see below).

Also the Renix flywheel that I have isn't actually that useful as it won't mate with my torque converter. It would be much safer to fab a 60-2 wheel onto my spare 604 flywheel / flexplate, so I think that it what I will do.

The plan:-

1. Get the engine running with an electric pump on carbs.
2. Pull engine, fix issues, fit 60-2 wheel and sensor inside the bell housing.
3. Get the engine running again on carbs and points.
4. Chop up the mechanical fuel pump and use the sliding pin inside it to interrupt a photointerrupter/detector.
5. Install megasquirt ECU and see if it can sync from 60-2 and photointerrupter.
6. Migrate ignition from points to megasquirt.
7. Migrate carbs to throttle body.

Probably it would all work with Renix, but it seems less risky to go with 60-2 and probably not that much more work.

If putting a photointerrupter inside the fuel pump doesn't work then I can use your way as a plan B.

I think that this thread has probably served its purpose. Thanks for all the replies folks.

[robs]

Plan sounds reasonable. Just to be clear though, I wasn't suggesting you need any distributor mods, just a bit of external circuitry to the existing points. Something like section 5.2.9 of the MS2 Hardware Manual as rickb794 said, but targeted as cam sensor, not tach.

A word of caution too on using the fuel pump eccentric -- make sure you position your tooth #1 synchronised with the high point. Since MS will only sample your photointerrupter around tooth #1 you want to be sure it's not sampling half way up on one rev and half way down on the next.

Have fun,

Rob.

[dieselnutjob]

make sure you position your tooth #1 synchronised with the high point. Since MS will only sample your photointerrupter around tooth #1 you want to be sure it's not sampling half way up on one rev and half way down on the next.

Noted. Thank you for that.