IP gear tooth count?

[averagef250]

How many teeth are on a 7.3 injection pump gear? I'm playing with the tach sender on a cummins and the number of teeth would be very helpful. Thanks!

 

[71cc]

Here is that info, finally

221-2242S includes: 3342 Cam Gear - 106 teeth (OEM #E3TZ-6256A) and 3341 Crank Gear - 53 teeth (OEM #E3TZ-6306A).

The IP gear runs 1:1 with the cam so it is 106 also. However it is running at 1/2 the engine rpm so your pulse count should be 53 ?

 

[averagef250]

Thank you! Just mounting the sensor to pick up off the crank. We'll try 53 teeth on the crank and see what happens.

 

[71cc]

Thank you! Just mounting the sensor to pick up off the crank. We'll try 53 teeth on the crank and see what happens.

I am confused, no maybe not...OK My thinking may have been off here on the pulse count.The IP gear must make TWO REVOLUTIONS PER CRANK REV.. So wouldn't it see 212 pulses ?The more I think about it , the less I am sure.. OK your choices are 53,106, and 212.

Let us know what works.


after re-reading it appears you are picking up directly from the crank gear?

 

[THECACKLER]

I/P & Camshaft run at half speed of the crankshaft. Crank does two cycles to the I/P & Cam's one. One revolution of the Crankshaft exposes 53 teeth to both the Cam and the I/P gears turning them 1/2 a revolution. 53 pulses or 53 teeth of the I/P gear = 1 revolution of the Crankshaft.

 

[averagef250]

I'm not picking up off any gear. I'm milling slots into the harmonic balancer. I've seen several guys drill and tap the cummins timing cover to run the ford sensor off the power steering pump gear, but I don't have the opportunity to do this. The engine is already installed.

In factory ford cummins installs the dash uses a different tach insert and reads directly off the flywheel teeth.

In a 4 stroke engine the cam turns 1/2 engine rpm. In one crank revolution the cam turns 1/2 a revolution. 1/2 the teeth on the IP gear would be 53 so 53 slots in the balancer should do the trick.

 

[Chevyboy_0]

I'm not picking up off any gear. I'm milling slots into the harmonic balancer. .

Correct me if im wrong but won that mess with the balance?

 

[averagef250]

Using a dividing head on a milling machine, it should not alter the balance. Furthermore this is a 3000 RPM diesel. The Cummins 12 valves are factory balanced with pistons within a gram and rod big ends within 10, but that's considerably closer than is even remotely necessary for a long happy life on a 3000 RPM engine that spends 95% of it's life below 2000.

These engine's don't see damaging harmonics until 4100 RPM and are rated for continuous 3750 RPM use at full rated load WITHOUT a harmonic balancer. The on the road engines have them to make owners happy, they're likely for looks more than anything in a stock or mild engine.

This particular engine already has 390,000 miles on it with very poor maintenance, fram filters and fueled to around 300HP since it was just a pup. It runs better than new, doesn't leak and if by some miracle it manages to come apart or start using oil in the next few hundred thousand miles I'll replace it with another $500 12 valve.

 

[Chevyboy_0]

Why thank you for clearing that up for me. I really have spent to much time working on my gas motors....

 

[6.9poweredscout]

i thought i read somewhere it was 52 teeth.....?

-Jon