Tips For Starting Up A Rebuilt Engine With Sniper Efi

The little burrs in the holes are Lead-ins and outs as the laser can't just sit and fire thru it's got to keep moving. A drill bit will take care of that.
The outside finish just needs tumbled or sand blasted.

 

Good call. Yeah I know they are lead-ins. This is a commercial mail-order metal cutting production shop in Reno. If I paid the operator to fine tune the toolpaths or slow the beam travel rate down I'm sure they could be minimized...but then it wouldn't have cost $25. So as you said - a drill bit!

 

We use lasers to cut the parts at work. If you put a little v or u on the circle you force the laser to start there with the lead in rather than the little spin from inside to circumference.

 

I’m actually super curious about this, I might send you a DM with the part file so you can show me what you mean. I teach on the laser and CNC plasma at our makerspace but I am by no means an expert and I would love to help people solve this problem.

 

Do you have the part number for the sensor you are using?

 

https://www.summitracing.com/parts/hly-554-124

 

first time reading through this thread...
I just installed a holly sniper on a land rover 4cyl..
cant say good enough things about it, but they are finiky and dont have a lot of room for error, especially with the TPS...
Do you have the 02 sensor in a good place?
you should really have it 18" back from the collector, not just measuring 1 bank of cyl...
might be wonky with the odd fire

 

Each bank is an even fire 3cyl. But together the 6cyls are odd.

Take that math geeks!

 

I have read through this whole post. I’m thinking of getting a sniper for my odd fire. My questions is about the rpm signal. I have a tach installed on my engine now. The tach reads rpm just fine with no bouncing around. Why wouldn’t the sniper have the same reading.

 

Is there enough gap on the inside of the trigger wheel to allow the outer portion of the harmonic balance to move as it should?

the wheel should only need 3 equally spaced sense points for the rpm input. Or simpler just 3 equally spaced notches.
Not to make this expensive but lighter bolts may assist (titanium or possibly aluminum) if there is a balance issue created by current bolts.
Dennis

 

The issue with the sniper is the computer processes fast enough to see the ignition firing 90,150,90,150 90,150 degrees of crank revolution and not blur it together. So the crank position sends a 120,120,120,120,120,120 signal to the unit for the tbi to control fuel without thinking its rapidly going from say 600rpm to 900rpm and back in a fraction of a second when it's actually running 750rpm
The tach needle has enough mass to not move fast enough and shows 750rpm

 

One could fix that by making the V at 60 instead of 90 degrees. This oddness comes from turning a 90 degree V8 into a V6 - the 225 is 3/4 of the Buick 300 cid V8. Or you could split the crank journals by 30 degrees, as Buick later did for the even-fire engine.

 

Chevy also had a compromised semi-oddfire 200 and 229 with a split crank that was something like 105/135 deg they look nearly identical to the 85 and 86 4.3 which is even fire
Get those semi odd distributors mixed up with an even or odd and it will drive you nuts

 

I like the term "semi-oddfire". it's sort of like "semi-dead".

 

Or semi-boneless.

 

… or PZEV. Part Zero Emissions Vehicle. Heaven help us.

 

Can you elaborate on what you mean by the harmonic balancer to "move as it should?" Doesn't it just rotate....?

Good suggestion on the lighter bolts. I was planning on securing it with three bolts spaced at even intervals around the circumference of the balancer to try not to throw off the balance.

Folks over on the Holly Sniper EEFI forums suggested having only three "teeth" at 120 degrees....I figured I would try the larger # of teeth first since the wheel I designed is patterned after the Holley generic one with 35 teeth...you can specify the # of teeth in the ECU. If that doesn't work I will pull it off and grind off teeth, leaving three spaced at 120 and try that. Worth a try. All I think the sensor needs to really do is sense the speed of the teeth passing by to get a valid rotational signal to feed the ECU.

 

The harmonic balancer is made of 3 parts, hub, elastomeric compound and “outer” ring. The elastomeric compounds gives a little bit and the outer ring moves a little to help damp some level of vibration- therefore needs to be able to “move a little” to be effective
Dennis

From the web
The harmonic balancer helps minimize torsional crankshaft harmonics and resonance. The damper is composed of two elements: an inertia mass and an energy dissipating element. Most often made of rubber, this element may be composed of a synthetic elastomer, a clutch, a spring or fluid. The mass counteracts the torsional crank motions and in concert with the energy dissipating element absorbs the harmonics vibrations.

 

Is that true for the balancers on our Jeep Dauntlesses too? I’ve got a few on the bench from prototyping and all I really see is cast iron (but not sure where to specifically look….)

 

On most of them, there will be a big "rubber band" between the inner hub and the outer ring, I'd have to go look at mine, but I'd guess about maybe .125" thick or so, if it's been slathered in paint, it can be easy to miss.