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Discussion Starter #1
Anybody have any CHEAP ideas to get an rpm/tach reference for tach and stand alone trans controller? I was thinking crank trigger wheel..cut with a water jet (or bought on ebay) and magnet sensor from MSD.. any ideas? Alternator signal? Anything I'm overlooking? I saw that there is an available crank sensor for 4bt's for marine apps but can't find any part numbers! Chris
 

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Almost every possible way to run a tach can be found with this site's search engine, a whole bunch of threads about that. Check with tach, tachometer, pickup etc. and you should find what you're looking for.
 

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1995 12v out of a dodge will have a harmonic balancer with 2 slits in it and a sensor mounted to the front timing cover. I am picking one up on Sunday but i haven't figure out how i'm going to use it yet.
 

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1995 12v out of a dodge will have a harmonic balancer with 2 slits in it and a sensor mounted to the front timing cover. I am picking one up on Sunday but i haven't figure out how i'm going to use it yet.
I planned to use the same balancer setup with the hall effect pickup. Then I realized I put my belt tensioner too close. I don't know what to do now.
Does anyone have the outside diamater of the Dodge 6bt balancer handy???
I might be able to squeeze it in.
 

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vdo also do some hall effect and reluctor type screw in sensors. does anyone know what the thread is in the adaptor ? you may be able to screw one of these straight in.
 

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Advance adapters has an idea with the 4.2L/4.0L stroker builds/transmission swaps. Machine the CKP sensor triggers into the front harmonic balancer. Not alot of meat on the 4bt pulley to do this, but maybe weld a ring on and true it up on a lathe?

http://blog.hemmings.com/index.php/2007/04/11/hmx-one-step-forward/

These are the timing marks for a 6cyl, 4 pulses x 120°... 4Cyl (like my TJ was) has 4 marks at 180°. Haven't gotten into the specific spacing or clocking on it yet, but I'm going to end up doing something like this, so I can use the stock CKP and the factory tach.
 

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I think I figured it out..
Looks like I could just drill and tap a hole and have this sensor count the flywheel teeth.

I have that one. There is already the correct hole on the pass side, right above the starter, for the sender on my Ford block adapter. Right size hole and thread pitch, even. I the flywheel I have has 146 teeth.
 

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Discussion Starter #12
Lately I've been stuck doing other things.. BUT I wanted to let everybody know what I was up to..making a crank trigger wheel.

Last pics in my yahoo set at
http://4btswaps.com/forum/showthread.php?t=1894

I had a .250 thick aluminum plate spun on a lathe to 8" (just bigger then crank pulley) I'm going to thread 4 bolts into it (4 because the HEI dist. gave out 8 pulses fer revolution).

The spacer was made out of aluminum as well.. (3.5" x 1") (5/8" or 16mm center hole)

The magnetic sensor (VR) was found on Ebay for $20 (originally from a Onan/cummins generator governor). Sensor will be wired to an HEI module on a heatsink mounted somewhere in the engine bay. The reason for this is the magnetic variable reluctance sensor (as well as the HEI pick coil) put out an AC sine wave and the factory TBI ecm is looking for a DC square wave...the HEI module does this for us.

basically this will let me use my factory tach AND tell the TCI trans controller what RPM the engine is at to control the 4l60E.

Next up..TPS and fabbing a bracket for it.
 

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I had a .250 thick aluminum plate spun on a lathe to 8" (just bigger then crank pulley) .... The magnetic sensor (VR) was found on Ebay for $20 (originally from a Onan/cummins generator governor).
Sorry, but it won't work. Magnetic sensors won't sense an aluminum wheel, since magnets are not attracted to aluminum.
 

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Discussion Starter #16
Correct.. I'm drilling and tapping the outer edge side of the disc..
Here are some pics before final touches!
11-14-07_1757.jpg

12-04-07_1950.jpg
 

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You could mark every 90*, drill a 1/8" hole very close to the edge and epoxy in small pieces of 1/8" steel rod for the magnet to sense.
 

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how about thread the holes and insert setscrews?
 

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how about thread the holes and insert setscrews?
That works, too. Just make sure to epoxy them so they don't vibrate loose.
 
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