Mercury 3.0 efi Balance formula.

[Dirty Dodge]

I've spent t hours I've searing this site and the web with little results. I was hoping someone here could help.

I'm looking for the balance formula to set up bob weights to balance my crank. All I can find is the 2.5, which states 30% standard and 50% for the racing motors. Y'alls assistance is greatly appreciated.

Btw, it's a 2003 3.0 225 hp efi, if that matters. It has a 60* block, like I believed all post-70's Merc V6's.

Thank you
Jesse

[rgsauger]

Welcome to scream and fly!

[powerabout]

I've spent t hours I've searing this site and the web with little results. I was hoping someone here could help.

I'm looking for the balance formula to set up bob weights to balance my crank. All I can find is the 2.5, which states 30% standard and 50% for the racing motors. Y'alls assistance is greatly appreciated.

Btw, it's a 2003 3.0 225 hp efi, if that matters. It has a 60* block, like I believed all post-70's Merc V6's.

Thank you
Jesse

Where did you find that info?

[Chaz]

If you are reading from the Hines balance chart, you will see that for most 120* three or six cyl. engines ... no bob weight is needed.

Being a bit old school, I make up bob weights for my 3.0L builds that are 52% just like all the car engines I have done in the past.

After all is said and done .. I spin them without bob weights .. pretty much the same as with bob weights .. LOL

Loxahatchee .. humm, TEC or Little Johhny .. ??? :D

[Dirty Dodge]

Yes, I got that info from Hines a d Aera. Thank you very much for the information. Do you usually need to add a bunch of weight to the crank?

[powerabout]

when the manufacturer changes the rod and piston weights on the same crank in various models you know its not like a 4 slug

[Chaz]

No , I usually just use a flapper wheel to slightly "aero" the rear counter.

The factory later put a big piece of Mallory in the front counter of the 3.2L stroker.

Which tend to come loose from time to time ...

https://i.imgur.com/oqolVRkl.jpg

I had to make up a set of inserts for the bob weight frames. Otherwise you need a set for a motorcycle type crank that will go down to 1.000" to fit the outboard journal. A set of light pucks is needed also.

https://i.imgur.com/tH15jRdl.jpg

The pistons are heavy. I get them down to around 500 g. Coat the tops with Ceramic and the skirts with dry film.

https://i.imgur.com/VdqJoqZl.jpg

https://i.imgur.com/8zTBTQ9l.jpg

I put rods in groups of six .. that are with-in 10 g (sad) of each other. Then drop the rest down to the lightest one. Then shot-peen, coat and then a cryogenic bath.

https://i.imgur.com/lqvjQTKl.jpg

https://i.imgur.com/Adp9Podl.jpg

https://i.imgur.com/sHdQ4U1l.jpg

https://i.imgur.com/tLy1Dkbl.jpg

Todd T. is a good dude .. fair price and easy to work with ..

https://i.imgur.com/3QpX5Ywl.jpg?1

Like I said before .. this crank was checked with no bob weights after it was balanced. Wanted to jump out of the V-blocks before .. pretty smooth after ... Makes it easy to get it in the ballpark .. then fine tune it once it's close .. :thumbsup:

https://i.imgur.com/m86G8oJl.jpg

[hooken203]

Chaz this balancing work and piston coating is this something you do only for yourself or outside customers also?

[Chaz]

203 ,

Yes I work for others.

PM me with an idea of how far you want to take it.

I will give you a price and time frame to get the work done.

Thanks .. Charlie

[hooken203]

PM sent.

[Dirty Dodge]

Wow, that's awesome information Chaz! I wish I saw this before. I'm right down the road from you in Palm Beach.

My machine shop couldn't drill the crank, so I skipped it.
I just got it running the other day. With just the piston and rod balancing, it idles like a sewing machine. Hopefully I'll get it in the water this weekend to start the break-in.

[Chaz]

The cranks are carburized 8620 or 9310 . Same stuff they make rear end and transmission gears out of. They get it to 60 - 62 on the Rockwell scale. Which is hard as a (&*%^*() #%^5 rock .. LOL
Only thing I have found that can break thru the boundary (aprox .060 deep) layer is carbide. There's no need in ruining a $150 Kennemetal cutter. I just buy a few of these two flute concrete (tapcon) bits. Cheap, turn it slow, lots of pressure, keep if flooded with coolent, sharpen it on a green wheel a couple times .. throw it in the garbage when your done. ;)

https://www.lowes.com/pd/Tapcon-8-in-Carbide-Masonry-Drill-Bit-for-SDS-Plus-Drill/1000009386

Like I said , I'm a 50 - 52% old school guy. If you look at the header on this link .. they say .. If you don't see your motor listed, 50% reciprocating is the default .. go to number.
I like some of the old British twin's .. 80+% .. LOL I remember riding some of that stuff when I was a kid ... I think my eyeball's are still rattling around in my head from those days ... :D
Detroit Diesel ... 200 / 200% :eek: :leaving:

https://www.hinesindustries.com/images/pdf/reciprocalmass_2023.pdf

I just sent a few cranks + flywheels out to spin up. And rod sets to be put on ice. :smiletest:

I'll see if they will send me some pitch-erz to post up .. :thumbsup:

[Dirty Dodge]

Thank you. You are an absolute wealth of information!

So far, the motor is running great, with just the pistons and
rods balanced, except it's not refilling the oil tank on the motor. Probably a small leak at tbe tank. I did cut the flywheel down to just over 12 lbs, did some porting, and added Chris Carlson fiber reeds. Super smooth and responsive. I only have about 2 hours on it now though.

I just got a rotator cuff surgery, so it ma be a bit before I dive in it.

[Chaz]

The check valve on the starboard side of the block get dirty and stick , or the cap could have been overtightened and cracked. Those are the only two things I have seen that keep the oil bag from filling ...

I didn't want to do the rehab time. I just had them vacuum the trash out of the joint.
Scheduled to have the other one done towards the end of the year .. :thumbsup:
Isn't growing old .... fun. :o

https://i.imgur.com/KUBPetDl.jpg

[Dirty Dodge]

Damn! I wish you a speedy recovery. I am fortunate that my job can put me on light-duty. A buddy is coming over today to help me check the system for leaks or cracks.