Where do I get my crank balanced? need 86 small chamber heads

[BenKeith]

What's a good machine shop closest to middle GA that I can send my crank and flywheel to to be balanced. Can't find a shop that does outboard cranks in these parts.

Also, has anyone got a good set of 86 looper, small chamber heads for sale (at a reasonable price)

On an 89 Looper, open deck motor, how critical is the 1/4" of aluminum outside the steel cylinder area for gasket sealing. This block has three small places that, due to salt water use, the aluminum has corroded away almost all the way up to the steel sleeve. The metal ring on the head gasket does the lions share of sealing and normally the extra soft sealing area is just a buffer to keep corrosion from getting to it. I can have it repair, tig welded back and block decked, but unless it 100% necessary, I had just as soon not, trying to this thing to play with without a ton of money in it. Decking means having to mail the block off, no one around here can do that either.

[TTriton]

I've asked a similar quesiton to this before and from my understanding is that there is NO reason to balance a crank. They are balanced from the factory and so are the flywheels.

[racer]

Leave the crank alone, repair the edge of the block with marine tex. I have several small chamber heads in various depths. 200.00 for the pair.

[Craig Bailey F1]

Cranks can be balanced by -
Specialty Service Company,
1335 Rollins Road,
BURLINGAME, California 94010......(415) 348 1106.

In a standard application, don't bother.

[Jay Smith]

Ben ,
Don't waste your time or money !
If your flywheel has been cut on I would spend the money to have that done .


Jay @ JSRE

[us1]

Balance a crank is a huge mistake. At least for a Mercury.

[delawarerick]

US1 why is that a mistake to balance crank. Im not question your opion but why not. A friend here in delaware built a omc looper tricked to the max and that was one thing he claimed made a difference. Please give reasons for and against.thanks Rick

[us1]

I really can’t speak for an OMC but with Mercury’s it seems that when a crank is balanced it sets up a harmonic in the rotating mass that eventually brakes the crank. A friend of mine, a Formula One motor builder, had 3 cranks balanced and all three broke at the same race. I have heard other horror stories as well. There must be some reason the Mercury engineers design them so out of balance. I really can explain why it happens definitely but I do know of a few instances where it has created a problem. I don’t now any motor builders that recommend it. Again OMC may be totally different you will have to ask Racer.

[Robbie B]

I have had my OMC crossflow V6 crankshaft dynamically balanced. When I first installed the motor in the hydro, solid mount to the hull, every nut bolt and screw eventually came loose repeatedly, even though I couldn't really notice a vibration. The motor was in stock trim with stock flywheel at the time. Had Air New Zealand, engineering division do the balancing, they used a 50% balance factor when balancing (not really sure what this means, some sort of built in out of balance, I think ???) however 50% is the balance factor used for all 90 degree V motors. They had spun up a merc crank previously but could not get any sense out of the machine, couldn't find a standard balance factor that was even close. Told the guy to take it away as they would not attemt to do it. When the OMC crank was spun up, the balance was not far off using 50% so they balanced the crank at that. Runs very smooth right through to 8000 revs and no more loose bolts and nuts. That was about 1987 and I'm still using the same crank. Well thats my experience with crank balancing anyway, but its not your typical outboard set up either!! I would listen to the OMC guru's for your application, you may as well save yourself some bucks!!!

[BarryStrawn]

My limited understanding is that a 60 degree V6 can not be fully balanced without using external jack shafts. No amount of weight on the crankshaft will do it. Look at most current V6 cars. Four or two stroke doesn't change the balance and the automakers certainly would not spend one cent on the balance shafts if there was any other solution. A 90 degree V6 has different but less severe problems.

This all involves some complex monkey motion where the mass of one crankpin and rod big end is used to offset others and the counterweights add what is missing. Odd or even fire on the 90 degree motor also comes into play since that changes the relative timing of the crank pins on opposite banks.

I've got a textbook here somewhere that kind of explains the engineering complexity but it is hiding at the moment. For what it is worth, a straight six and a opposed or boxer six can be perfectly balanced on the crankshaft.

[BenKeith]

Racer,

I'm interested in a set of the heads. You mentioned you have several different chamber sizes, What would you recommend. I'm plugging the exaust reliefs, the block has not been decked, running STD bore and STD OMC pistons. I have reconciled myself to running 92/93 octane. Will be running stock exhaust port heigth. I decided against finger porting, for now, since I'm going to have to ship the block off and also get another set of pistons or have these drilled (if that can be done). I found out the pistons have to have the extra holes for fingerports that my pistons don't have. Ya'll talked me out of balanceing the crank, I am having the rods and pistons balanced (had to change out two rods).

My carbs measure 1.450" ID on the small (air baffle side) of the throat. Is this the same as the 225's?

My plans, for now, is to get the motor running and see how it pushes my boat. I figure it I can get 250 hp out of it, without a tremendous outlay, if that want get me to 70 MPH I need to start looking for another boat.

I still feel I need the flywheel balanced, five of the magnets have come loose and gonna try glueing them back in. Can you recommend a good epoxy?

You also said I could repair the block with marine tex. Is that a brand name, where do I get it, would Rickracer have it?

Email me with the info needed for getting the money to you. I might be next month, before I can get them, depends on how my money holds out getting the rest of the stuff I need.

[racer]

.700 chamber depth on the head. need to measure the venturie of the carb but your model numbers says they are. The factory makes a kit for reglueing the magnets. I also have the marine tex.

[B.Leonard]

I was always under the impression that balancing was primarily to remove subtle harmonic resonations from the crank not for removing severe out-of-balance vibration like a tire, that was needed as well of course but not the main reason.

The motor was usually smoother afterwards, but sometimes you couldn't tell a difference even when the machinist said it was way off.

Harmonic resonation can occur at a given rpm and then come back at a higher rpm and then go away again at an even higher rpm. So you balance for a particular range that the motor will operate in. It's the harmonic resonation that breaks cranks, cams and wipes bearings out.

I would balance a 90 degree motor without question since it seems to be fairly easy as opposed to the 60 degree motors. Why this is I don't know but would like to hear a good explanation.

-BL

[Superdave]

I used to work in an automotive machine shop that built engines for Darryl Waltrip when he raced at the Nashville fairgrounds. I did crank balancing, mostly 4 cycle engines. I did do one Merc in-line crank. It was off 2 whole grams!! An in-line crank is just spun up on the machine and metal added or removed from the appropriate areas.
However, a V engine (4cycle) has to have bob weights. The weight of one piston, one set of rings, one set of pin bearings and washers, two circlips, the weight of the small end of one rod, the weight of two big ends of the rod, and the weight of two sets of crank bearings (with cages (4)). All this is added together and bob weights are weighed to match and installed on the rod journals. Then the crank is spun up and metal added or removed in the appropriate places. Don't know if this applies to 2 strokes or not.
The reasoning is....the weight of the reciprocating mass (piston end), and the weight of twice the rotating mass (crank end) is need because there is one piston assy on the end of the rod, but two rods per journal. Can be confusing.
I would like to know if anyone has tried this, or if it would work. I read where somebody on this board had lost of Mallorry metal put in a V-6 crank and it was still out of balance. Was this just spinning the crank without bob weights. If so, would the bob-weight thing work.
Just looking at past experience.
Inquiring minds want to know!!!

[B.Leonard]

The inline six is the second most inherently balanced configuration, first being the flat six.

Statically, the bob weights simulate the rotating portion of weight of the connecting rod/piston assembly, so I would think the inline would need that as well.

-BL

[BenKeith]

Racer,

I still don't have the info needed to pay you for the heads and a total of how much to send. You can email me direct, I promise I want use your email address to bug you with questions directly once I get it, or give it to anyone else.

Those heads you recommended, about what compression will I be looking at. Will there be room left to have the block decked (just enough to clean it up) if I pull it back down in the future for boring and finger porting.

What's the max I should ever have for compression and running 92 octane. I use 92 as a reference because a lot of places in the small towns don't have 93.

[racer]

Holes pluged and .700 chamber heads, standard 89 gaskets should yield 135psi. Standard blueprint deck height is 9.320 plus or minus .012 so before you deck get an acturate measurement.

[BenKeith]

Racer

What do you use for a reference when measuring deck height on these motors. The bottom of the steel sleeve, the bottom of the cylinder next to the cylinder wall, the bottom of the cylinder in the center, near the rod slot.

Also, for the last time, I want to buy a set of heads, if you have a set (you recommended .700's)and want to sell them to me, please let me know where and how much money to send to pay you for them. If you don't have a set, I need to know that also so I can go looking else where. I had rather buy yours since you've given me so much help but I'm not familiar with a way to post money to this board and you get it.

Or, If this works:

Pay to: Racer $200 plus shipping for one set of .700 heads.

Ship to: Keith Jones
104 Pine Dr.
Jeffersonville GA 31044.

Home Ph (478)945-3880

[email protected]