Add crank and cam pos sensors to BB (for Megasquirt)?

Posted By: JimG

Add crank and cam pos sensors to BB (for Megasquirt)? - 09/19/12 10:50 PM

Well, I've now bought enough hardware that I'm comitted to a Magasquirt installation.

I have a 3.57 with the MS3X board. I'd really like to do sequential injection with Chevy LS coil-near-plug sequential ignition. To do this, I'll need a crank position sensor and and cam position sensor.

The crank sensor seems easy enough: just buy the proper diameter 36-1 trigger wheel and adapt it and the sensor to the harmonic balacer/front of the engine. That I can handle.

The cam sensor looks like it'll be the challenge. I could use a lean burn distributor for cam positioning only, but then I'd have distributor with no ignition wires bolted to the front of the engine. I'll save that as the drop-dead option. Somehow imbedding a magnet into the upper timing chain sprocket and installing a sensor through the timing cover crossed my mind, but I'm not sure my fabrication skills are up to the task.

So here we are. I'm open to ideas.

Thanks,

Jim

Posted By: haddixj

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/19/12 11:55 PM

I have a aquatintance who has done this same thing to a bbm. Ill see if he is ok with giving out his email.

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 12:40 AM

Thanks, haddixj!

Posted By: jcc

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 01:06 AM

Quote:

I could also cheat and fabricate a second trigger wheel with 2 teeth, and somehow attach it to the crank snout. Then I'd have no way to compensate for timing chain stretch, so that seems like a cheesy plan as well. Somehow imbedding a magnet into the upper timing chain sprocket and installing a sensor through the timing cover crossed my mind, but I'm not sure my fabrication skills are up to the task.

This more of a bump then an answer, but I don't think timing chain stretch is an issue period, its mainly for reference to start the timing sequence, and I don't believe to two tooth wheel solution works, period. I sure others will elaborate. i like the magnet imbedded in the chain sprocket though.

Posted By: astjp2

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 01:58 AM

A dual sync distributor will keep you from modifing things like balancers and timing covers. Tim

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 02:08 AM

Quote:

This more of a bump then an answer, but I don't think timing chain stretch is an issue period, its mainly for reference to start the timing sequence, and I don't believe to two tooth wheel solution works, period. I sure others will elaborate. i like the magnet imbedded in the chain sprocket though.

The timing chain stretch comment is my own ASSumption, and not anything that I've ever read or heard.

Thanks,

J

Posted By: 1_WILD_RT

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 02:22 AM

Your gonna have to plug the dist. hole somehow & it's gonna have to be set up to control axial thrust on the oil pump driveshaft... So take lesson from Ford & create a stubby housing to mount a cam sensor...

Attached picture 7386597-$(KGrHqZHJB!E-EfS1P36BPv8MFqR1!~~60_1.JPG

Attached picture 7386597-$(KGrHqZHJB!E-EfS1P36BPv8MFqR1!~~60_1.JPG

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 03:08 PM

1 Wild RT:

I had already envisioned something like that when I was thinking this through, I just had no idea that it already existed. Thanks for posting.

Do you know what it fits? I need to find out if they're plentiful in junkyards. It might be possible to graft the top of this thing onto the bottom of a Mopar distributor.

Thanks,

Jim

ETA: Google is my friend! It looks like these things are common on late 90's 5.0 Ford Exploders and Mountaineers.

Posted By: DaytonaTurbo

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:02 PM

Quote:

A dual sync distributor will keep you from modifing things like balancers and timing covers. Tim

Yes that would work, but the OP specifically said he wanted to run coil on plug and not have a dummy distributor sitting around. I suggest just forgetting the COP setup and running a distributor. It will save you all this fabrication work and headache and I don't think will have any measurable difference in performance vs the COP system you are envisioning.

Posted By: astjp2

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:15 PM

Fastman EFI has already done the big block conversion to COP, it uses a dual sync distributor without a cap and rotor. It acts as a cam and crank sensor in one. He has pics of it in his hemi book if I remember correctly. Tim

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:25 PM

Quote:

I suggest just forgetting the COP setup and running a distributor. It will save you all this fabrication work and headache and I don't think will have any measurable difference in performance vs the COP system you are envisioning.

Yes, I'm considering doing just that - getting it going in "fuel only" mode (with the existing ignition system) at first, then looking at integrating the ignition later.

The downside to running the existing ignition system is that I see no way get the equivalent of ported vacuum to keep the vacuum advance working as it does today. But, with all the fuel only systems available today, someone has probably come up with a workaround that I haven't stumbled onto yet.

One other startup option is to run COP in wasted spark mode and to run the fuel in batch fire rather than sequential - both possible without a cam sensor.

Thanks,

Jim

Posted By: astjp2

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:30 PM

Run something like this without the cap and rotor. With a little fab work you can make a phenolic cover to replace the cap.

http://www.ebay.com/itm/Accel-Mopar-Chry...s-/360448958181

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:34 PM

Quote:

Fastman EFI has already done the big block conversion to COP, it uses a dual sync distributor without a cap and rotor. It acts as a cam and crank sensor in one. He has pics of it in his hemi book if I remember correctly. Tim

Good to know, thanks Tim!

I was unaware of this, and also thought you were referring to a "standard" dual sync distributor.

I'll definitely check it out.

Jim

Posted By: 1_WILD_RT

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:44 PM

Ford also used a setup like that on 3.8 & 4.2 V6 engines, there are many ways to do what you want, personally I like the idea of a very minimal sensor housing, it would look cleaner...

Posted By: gtx6970

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 04:54 PM

EFI late model 4.0 Jeeps had a cam sensor where the dist USED to be (no idea if the OD the base is the same as LA or B motors )
Looks like this

http://www.ebay.com/itm/Wrangler-Grand-C...9e5&vxp=mtr

might be able to adapt something over , or at least use it to design off of

They have a crank sensor positioned on the back of the block that reads crank position off the windows on the flywheel

Posted By: IMGTX

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 05:49 PM

Can you just convert a small block Magnum distributor's trigger wheel to a Big block and use that?

Of so a little time and epoxy can make a cover to replace the cap.

Save $
Maintain stock easy to find parts.
Keeps the distributor to oil pump shaft in place.

Just curious

Posted By: DaytonaTurbo

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 06:25 PM

Quote:

Quote:

I suggest just forgetting the COP setup and running a distributor. It will save you all this fabrication work and headache and I don't think will have any measurable difference in performance vs the COP system you are envisioning.

Yes, I'm considering doing just that - getting it going in "fuel only" mode (with the existing ignition system) at first, then looking at integrating the ignition later.

The downside to running the existing ignition system is that I see no way get the equivalent of ported vacuum to keep the vacuum advance working as it does today. But, with all the fuel only systems available today, someone has probably come up with a workaround that I haven't stumbled onto yet.

One other startup option is to run COP in wasted spark mode and to run the fuel in batch fire rather than sequential - both possible without a cam sensor.

Thanks,

Jim

Megasquirt can control ignition timing without doing COP. Take a lean burn distributor or a stock electronic ign distributor(with the advance locked out) and throw it on. Megasquirt can control your entire ignition timing curve. From the outside it will look stock - distributor, wires, etc, but it's all computer controlled. That's why I say I don't think you will see any difference between this and COP. Generally I would not suggest going through all the work to go EFI just to leave a mechanical/vacuum distributor there.

Posted By: dogdays

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/20/12 10:09 PM

Using my Ford MPFI experience, the cam sensor only tells the engine which of the two revolutions is happening. On my SHO car, the cam sensor was a small flattened C shape that went over a rotating cylinder with half of the cylinder cut off. So half of the revolution there was metal in the sensor and half of the time there wasn't. No way did it resemble the tooth counting crank sensor or the 8-pulse-per-revolution distributor pickup assembly.

R.

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 12:35 PM

Thanks for all the info (so far) guys. A lot of new ideas for me to ponder!

Posted By: Swedcharger67

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 03:45 PM

Jim, stick to your original idea with a crank sensor and tooth wheel, you don't want the bad precision from a distributor signal.
The cam sensor on the other hand can be something simple like was suggested above.
I have the same idea as you, if you know where I can get the good coils at a reasonable price, pm me...
Martin

Posted By: 1_WILD_RT

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 04:18 PM

Guy in my industrial complex does allot of EFI conversions, for a crank signal he's adopted the Ford strategy of a toothed wheel with a tooth every ten degrees but with one tooth missing to ID TDC of #1 & 6 cylinders... It's referred to by Ford a 36 minus 1... He sandwiches a 36 tooth bicycle sprocket with one tooth removed between the harmonic balancer & the crank pulley.... He still needs a Cam sensor but as mentioned all it does is tell the computer whether cyl 1-8-4-3 or cyl 6-5-7-2 is on compression stroke..

Posted By: JimG

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 04:51 PM

Quote:

Jim, stick to your original idea with a crank sensor and tooth wheel, you don't want the bad precision from a distributor signal.
The cam sensor on the other hand can be something simple like was suggested above.
I have the same idea as you, if you know where I can get the good coils at a reasonable price, pm me...
Martin

Martin, at this early juncture, I only know what I've read. Having said that, I have read that some guys have had trouble with noise when using OEM Mopar distributor pickups integrated to Megasquirt.

Thanks,

J

Posted By: Swedcharger67

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 06:16 PM

Quote:

Martin, at this early juncture, I only know what I've read. Having said that, I have read that some guys have had trouble with noise when using OEM Mopar distributor pickups integrated to Megasquirt.
Thanks, J

Noise is always a potential problem, no matter what system you are using. It usually pays off to plan the electrical system carefully, think shielded cables for sensors, one common grounding point for all signals and ECU. Never use engine and/or chassi as return path for the ground.
Noise is somewhat complicated, and can create lots of problems, I think careful/early planning will make it less painful...

Posted By: furious70

Re: Add crank and cam pos sensors to BB (for Megasquirt)? - 09/21/12 09:29 PM

I use a lean burn 400 dizzy in my 383 with my classic FAST efi doing fuel and spark, sending the trigger to an MSD 6a box. I have the sequential box, but didn't want to go through the extra work/cost of the cam sync to use the seq mode. It's been running for 3.5yrs now and I don't see any drivability issues where I'd take the time to go seq. I run 37lb injectors and 5lbs of boost right now. A heavy hitter running big injectors may see a benefit.

One other option a guy showed me was taking the 2nd pickup in the lean burn dizzy and grinding off part of the pickup and then grinding off parts of the paddles to allow it to 'see' whatever events you were looking for.