home build ITB EFI need some assistancew
 

I'm building an ITB EFI system based on MV Agusta throttle bodies. Still, a few design points to work out and I thought I would ask the group to see what has been discovered.
Crank Trigger. I know that there are Clark pulley crank triggers and other brands. I would like to put it on the flywheel side. Has anyone done this or are there reasons not to do this?
My car is a '79 SC with a stock cross-over exhaust. i want to put an O2 sensor on each bank. Has anyone done it and has advice on placement? I'm also not 100% what material the exhaust is. A magnet sticks in some places but not others? Are there mixed SS and regular steel in the SC exhaust?
Thanks,
Adam

The cat is stainless on mine (stock 78), all the rest is coated steel.

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Im using Clewett cam and crank sensors with his front pulley , easy to install, great customer service from Rich..There are instructions on the AEM website for proper o2 placement..

If you don’t want to use a pulley wheel, you can use a flywheel with sensor teeth like that from the 3.2 and mount a sensor on the front of the motor. You have to notch the bell housing of the transmission for the sensor to access the flywheel, but that is easily done.

If you are going to use sequential firing and injection, you need a 60 - 2 flywheel (not a 3.2 flywheel) and a cam position sensor.

There is no practical advantage to using the flywheel vs the crank pulley/ trigger wheel to my knowledge with the exception of trying to keep the electronics out of sight...and the crank trigger is easier to install and get to the sensor etc. that's just me, i could be wrong.

Many have used the pulley end sensor. It works a dream and is easily accessible.

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Most Factory and professional EFI setups use the flywheel for crankshaft position.

There must be some advantage or some very good reason to use the flywheel as opposed to the pulley as all the Factory race cars I have seen use the flywheel as well. All the Porsche Cup cars use 60 -2 flywheels and, I believe, use some style of cam position sensor to figure out where the engine is in the cycle.

I bet belts coming off and destroying stuff might have something to do with it.

All the Porsche street cars that have EFI use the flywheel sensors.

In a perfect world, yes a 60-2 flywheel is the go but sometimes it just isn’t viable. I have a 60-2 pulley/Motec sensor and a distributor mounter CAS and it works a treat. You have to use what is best for the application. I wasn’t prepared to notch my bell housing to accommodate a sensor so this was the best option for me. Still works, just a different way of doing it.

Notching the bell housing is easy...

But, I was not saying that everyone should use a flywheel setup. I was just pointing out that the flywheel setup (or a trigger wheel on the crank near the flywheel) is the most commonly used setup by manufacturers and professionals and that there must be a good reason for that.

I a perfect world, yes a 60-2 flywheel is the go but sometimes it just isn’t viable. I have a 60-2 pulley/Motec sensor and a distributor mounter CAS and it works a treat. You have to use what is best for the application. I wasn’t prepared to notch my bell housing to accommodate a sensor so this was the best option for me. Still works, just a different way of doing it.

Great info, thank you!
I'm going to check in with Clewett tomorrow.

I have used both flywheel and crank pulley triggers.....and if sequential is desired a cam sensor is also installed. Both of these trigger methods seem to work equally well. Regarding the use of the toothed flywheel vs the crank pulley.....I suspect that some of the choice-making is/was related to the large diameter of the flywheel vs the smaller diameter of the the crank pulley and the ability of the sensors to discern between teeth and gaps at high rpms. The larger flywheel teeth and gaps do not require a sensor with the resolution/response time that is required for the smaller teeth/gaps of the crank pulley trigger. However. there are now many suppliers of both VR and Hall sensors that work great with the smaller diameter 60-2 crank trigger.

It's worth noting that EFI ECUs are going to have different pre-loaded flywheel configs.
They'll all work with a 60-2 or a 36-1, but they may not all will work with a 3.2 flywheel with 129 teeth.
Have to check compatibility before you start buying parts.