Crank trigger EFI help

Are you really arguing about the time precision of micro seconds? In micro seconds the engine is hardly moving at all and easy to calculate the speed of past teeth and predict when the next would arrive.

This is for the Megasquirt 1, the 2 &3 runs twice as fast and the Holley like 8 times faster than that. The ECU has plenty of computer time to calculate, re-calculate and re-calculate the spark timing way before it fires the spark plug.
"The main loop (the area of the embedded code where the fuel pulse width is calculated) for MegaSquirt-I normally runs at about 1500 Hertz (1500 times per second) and can wander a couple hundred Hertz either way depending on whether you are in cranking mode or whatever else is going on and needs attention (these are called interrupts). For MegaSquirt-II, the main loop runs about twice as fast.

For example, in a pretty reasonable worst case, 1500 Hz is about 4 times the IRQ ("interrupt request") rate (6000 RPM * 8 cyl = 400 Hz). So on a V8 at 6000 rpm, the fuel pulse width is updated 4 times between each spark event (and 8 times between fuel injection events, if running 2 squirts). MegaSquirt-II doubles these, as would running a 4 cylinder (since there are half as many events at a given rpm). At 600 rpm, you have 10 times as many updates per ignition/injection event."
https://www.megamanual.com/v22manual/mfuel.htm

I'm out, only so much water I can put in front of the horse.

 

Here's the instructions for the setup your doing for the crank and cam sensors

https://forums.holley.com/forum/hol...1-magnetic-hall-effect-crank-cam-sensor-setup

 

Maybe I'm not thinking this through in my head correctly, but what's to stop someone from creating and adapter that mounts onto the front of the OEM crank pulley, and then has the SBC (or other off the shelf wheel) bolt pattern on the other side? It could be just long enough to place the trigger wheel flush or close to the outside edge of the pulley. This way you wouldn't need to space any accessories, you'd just need longer pulley bolts. It would actually as a pulley washer. It would essentially look like two pucks with a shaft in between them. You might need to back off your sensor to swap belts.

Would this work?

 

I could see a spacer in the center of the stock pulley then adding the buzz saw blade to the front of the pulley. Its what I did on my '69 Firebird engine, but that one has a flush front that makes it easy to do. The down side is the sensor has to be removed to change belts, but how often do you change belts?

 

That's such a rad looking engine! That a straight 8 or 6?

Maybe I'll draw this idea up in CAD just for the hell of it!

 

1969 Pontiac inline six. The spacer design is simple enough. Just needs to be thick enough to clear the pulley and wide enough to run bolts through.

Just to re-post, I'm happy with my 36-1 wheel behind the stock pulley with just a little clean up. I did this in 2011. A new ~1992 Ford Escort harmonic balancer is like $50, or get a used one from the junkyard, and tap the trigger wheel off. Then machine open the the ID to match a machined flat Buick crank pulley. $50 for the wheel, $28 for the sensor, $15 in aluminum pieces, and was like $50 in labor to true up the pulley surface and match the trigger wheel ID. No pulley offsets, tucked safely behind the balancer, etc.







After 4 years I ended up changing out the roll pins (4) for screws from the inside as the centrifugal forces and vibration finally worked some pins out.


I don't have the fuel pump anymore, but the bracket never moves. A $25-$30 hall effect sensor.

 

That idea seems like it would work. I believe i should be able to modify the bracket that blocks off the fuel pump to make it work with that wheel. As long as the holley system will registers the wheel (which i dont see why it wouldnt) what did you do to secure the crank wheel to the pulley. You mentioned screws?

 

It looks like he originally started with roll pins and then changed to set screws or through bolts, see his pic above. I suppose you could also tack weld it? Not sure what material the trigger wheels are.

 

Im not sure of tack welding it either. Im leaning towards using some small allen headed set screws, i wouldnt want those pins coming out going down the road. I think set screws maybe the ticket here. I never wouldve thought to use a 92 ford escort crank pulley (robbing the trigger wheel off of it). Thats slick

 

As mentioned, I drilled 4 evenly spaced holes and put roll pins in (pictured before), but after 4 or so years of being fine, multiple Drag Weeks, etc, then three drag strip passes in at Drag Week 2015 and shifting at 6,100 rpm and they ALL left town when I was going down the track! I got it lined back up and put screws in from the bottom, where the heads can't pass through the hole.

I know people that have tack welded these wheels and the wheels came apart above 7,000 rpm, but whose to say if they'd come apart below that rpm, idk. Its a sintered iron wheel and I chose to secure with drilling holes.

I recommend getting your trigger wheel fixed up in place first, that way you can secure the wheel with the sensor pointing at the tooth an appropriate number of teeth before the missing tooth.

 

Will get it set up before i secure it to the pulley. What size of screws did you end up using to secure it?

 

It was so many years ago I don't recall.

 

Had the crank pulley and the ford escort pulley machine and pressed together. I think im able to modify the Holley bracket very slightly to permanently line it up and set the clearance between .062 and .080. Doesnt look bad should be functional atleast.

 

This setup looks very similar to what my shop does for a crank trigger on Pontiacs. Quick question do you run an LS harness and ecu for your port injection or is everything after market like mega squirt. Is there any benefits of using an aftermarket ecu or is it just preference. I want to run a port injection setup on a BB Buick (hopefully in this lifetime) and have been trying to gather information. I am still in the learning phase of all of this so I hope to get a more comprehensive understanding and pick your guys brain while avoiding asking stupid questions and making a fool of myself. Anyhow hope all works out with your setup!!

 

Yes for this system im running an ECU and a universal main harness holley part# 558-117. I bought this system slightly used from another board member here. Im completely new to this port injection myself, and am learning as i go as far as installation goes. Then i will learn the tuning aspect. There are few members that are pretty knowledgeable of port injection, tuning. And so on. Dont feel like any questions are stupid, plenty of guys are willing to help no matter what it is. Thats why i asked the question that started this thread, and had many good board members that helped me get to the pictures i sent in my post a little earlier today

 

Thanks you! Im very grateful to have found this forum and the fast information it has on these amazing engines and cars

 

Nice! Those hall sensors are pretty forgiving on the tolerances, so it doesn't have to be perfectly centered on the trigger wheel.

My work here is done

 

To be sure its all set up correctly, you need the sensor pointing at like the 3rd tooth AFTER the missing tooth when the balancer timing mark is lined up with the 0º mark. That way the sensor sees the missing tooth before TDC. I use 30º (3 teeth) at a target offset.

 

I should be able to rotate the pulley and I have a little bit of adjustment on the bracket as well so i can get relatively close to 3 teeth. I really liked that ford escort idea. Saved a ton of headache with this