Tips For Starting Up A Rebuilt Engine With Sniper Efi

Looking at your picture from post # 73, directly above the arrow cast into the hub, you can see the elastomeric material between the hub and outer ring.

 

Interesting. So what impact am I going to have on the intended functionality of this mechanism by adding a “gear” disc that fits flush around the outer disc where the 12 holes are?

 

Nothing at all, unless its affixed in such a way that it's being bolted to the inner hub, in addition to the outer ring.

It's *possible* that if your balancer is old, and the outer ring starts slipping due to the rubber de-bonding, that it could move the timing points, but for your application? It'd really have to be slipping a serious amount for it to cause you issues.

As long as the rubber remains bonded to both pieces, the movement is extremely minimal, it isn't as if this is an application where the rotational direction is changing, ever, unless you've done something *really* weird and somehow managed to rig up a way to make your dauntless rotate backwards at the flip of a switch.

 

Just need enough room that the outer ring can move in concert with the balancer. Suggest that the design have a gap of XX and not be pressed on/centering the hub portion of the balancer. Remembering steel rusts and a small gap could shrink from the moisture at the front of the engine compartment. A gap plus a rust proof coating?
Dennis

 

I made it 0.05” larger than the inner hub. I tried one where it was exactly the same size to help it be centered but thought a gap would be useful… We will see after it gets painted if I need to make the gap bigger.

i’m going to have to crank the engine around by hand and make sure I’ve got the required 40 to 80 thousandths between each tooth and the sensor…

 

How is your project going? Hopefully all is heading toward a robust solution!
Dennis

 

I’ve been head down trying to get the wiring done. After that is troubleshooting leaks in the brakes. Then I’m going to focus on this crank trigger, since the Jeep should theoretically be driveable.

I’ve got a good discussion going on the Holley forums with some experts there:


https://forums.holley.com/showthread.php?52107-Sniper-on-fresh-rebuild&goto=newpost

I think the one thing I’m concerned about now with my trigger wheel is how it would adversely impacted balance of the crankshaft. Kind of wondering if maybe going back to the three bolts is a better option.

 

Three lightweight bolts (non ferrous such as aluminum or an exotic like titanium), centered in three notches at 120 degrees (if sized appropriately) should balance.
For a “RPM only” signal that does not use multiple pulses for timing you only need a count of three pulses per revolution vs the higher count. So three notches and three protrusions.

Though with three bolts at 120 degrees they are balanced.

The “damping” may change as you adding some more inertial mass to the outer ring.
Putting bolts in each hole would add a lot of mass.


Dennis

 

I thought your trigger wheel had uniform teeth and holes. If so it shouldn't have enough variance in material to matter. It'ld be no worse than a missing tooth on the ring gear of the flywheel.

 

The missing tooth is too small to matter for balance as noted, the attachment mechanism (bolts) are more significant.

Unless used for timing purposes a missing tooth does not assist with a RPM only input for the 225.

noting the total inertial mass change also for ring and “ bolts”, minimized by only three lightweight bolts

 

OK so begging everyone pardon cause I’m way out of my depth here, I think the issue with my trigger wheel (as currently designed) working with the Sniper is that I was wrong - one cannot specify the # of teeth on the wheel in the Sniper ECU menu.

I think the wheel needs to have only three teeth, spaced at 120 degrees, in order for the computer to get an accurate signal. This is what others have done with steel bolts with added metal on the heads bolted through the existing holes in the balancer.

This was posted on the Sniper forum:

Regarding balancing the trigger wheel on the balancer, I do have three titanium bolts for this purpose.

 

Grant
Once you get a 3 tooth design let us know, thinking there may be several on the forum who would like one for their system!
I know I would!
Dennis

 

It’s super easy for me to order another version with three teeth, they’re only $13 laser cut in steel. I think I might take mine to the belt sander and take it from 35 teeth to three teeth, and see how that works and report back.

 

You still need 3 evenly spaced teeth so 35 not being a multiple of 3 will still be an issue. So you might want to get a 3 tooth made and try selling the 35 on ebay or something.

 

Each of the “teeth” being 60 degrees with the attendant 60 degree gap seems like a good idea

Lots of saturation time!

Dennis

 

What if I removed all the teeth, but these three spaced at 120°, and attached with three titanium bolts to maintain balance?

 

A few questions that I think needs to be addressed. I see the comments about using titanium bolts and I believe a trigger wheel made of 5051 aluminum. I don't know what type of sensor you intend to use, but if the wheel doesn't have implanted magnets or isn't made from a ferrous material, how do you intend to trigger the sensor? How are 3 short steel bolts installed equally spaced around the harmonic balancer going to upset the balancer of the engine? Your trigger wheel needs a total of three teeth. Your ECM is only looking for three pulses per revolution, 6 per combustion cycle for this engine, fuel only and no ignition control which it is not designed to do on the oddfire.

 

I think your overthinking this.
Grind your trigger wheel down to 3 teeth and run it. I can guarantee you that your crankshaft pulley is more out of balance than that trigger wheel.

 

The sensor mount (bolts to fuel pump mount) is 5051, trigger wheel is laser cut mild steel. Bolts attaching wheel to balancer are titanium.

Alternate idea to wheel is to use three steel trigger bolts with added-material heads through balancer (pic in post #28) instead of trigger wheel (like @Norcal69 ).

 

Grant
Should work- three teeth at 120 and the bolts at 120 in between the teeth.

the ferrous iron should be sufficient at the tooth width you have, if the signal is erratic then making the tooth longer would help.

Looking at with a storage scope will show how steady it is

Dennis

Because the 225 is externally balanced I am leaning toward being conservative with the rotational mass changes.