MercRod????

[Dave S]

The rod to have.... was 5250..... them Merc went to 1881 then...…. drumroll....141 …..52s wreck havick…...1881s break at the crank... o holes…. 141s bend…..So in merc carange…. which is best?????

[FUJIMO]

their all good dave...but u know that. ...its just like everything else in life though, you have to recognize & respect, through experience, each one's limits...

[Chaz]

The Cosworth 3.4L rods ...

[Dave S]

Darn.... I was hopeing I could start a long thread with a bunch of way out ideas......tired of BML riots and conv19......HeeHee

[LakeFever]

What comes in the FF block 200's?

[bullet123]

What comes in the FF block 200's?

fishing motor 8141's

[Chaz]

Beam's ground , weight matched , shot peened , next two processes ... to follow

[FUJIMO]

...never let a set of bad rods go to waste...

[capteliminator]

Whats the application Dave?

[Dave S]

Rod RIOT stopper...….Just starting a funn thread . Just pulled a 150 optiBOOMer…… The wrist pin pulled out of the piston....pinna spinning.... puttinh holes where Merc didn't....Hee Hee. Then the rod snaped in 2.... no more fissing that day. Not my motor.... some gave it too me. 100 LBS of bull crap on that nice 2.5......Back half of block is good.....getting carb/ ports and a new life...….Merc in their wisdooom…..put 3.0 wrist pins in the 2.5 opti…….that's why they pulled JMO.....Didn't even stick … just broke. Hey Chaz do you think it is nessary to have them shot peened? Thanks everyone...….for posting.....

[capteliminator]

I have run both 5250s and 841s. 841s are obviously lighter but supposedly the bigger 5250s have a greater stuffing effect. Cant say ive ever noticed a difference. Both style Ive ran were big bolts. If breaking is your concern due to running over rioters, Id go with the 5250s, lol.

[Chaz]

The 3.0 / 3.2L rods are pretty weak as far as I'm concerned . Kind of reminds me of back in the day running Chevrolet's . You couldn't buy aftermarket rods that look like jewelry , like you can today . So I just went back to what we did back then .
Grind and polish the beams ~n~ blems , shot peen , hone the big end and send it .
I've been working with two company's for a while now , that have helped me step into the new millennium (old dog new tricks .. LOL ) . I've got 4 sets to finish up , and then I'll post up some pics of the finished product .

The housing bores of the rod is the outer race for the needle bearings , so they have to be carburized to get them to 60 ~62 on the Rockwell C scale , yet the beam needs to stay softer and more malleable . So they copper plate the rod except for the areas to be hardened. Hard to believe it doesn't melt away from the intense heat , but it stay's put and does it's job.

Since you can't run similar metals together , OMC and Merc (bottom guided) use a etched side thrust face and plate it with silver . Merc paints ( "powder-paint" I think they like to call it ) most of the rod black , anywhere the acid etch or silver could / does come in contact . Good stuff if it just rolls right off. But bad , that it can and does hide surface blemishes and irregularities .

I know ya asked about shot peening ..

Shot peening knocks the black coating off easily , and while it won't get thru the copper on it's own , it will flatten out the surface of the rod , anywhere the blast stream comes in contact .



Not wanting to take the silver off , I made a set of "blast bushings" that protect the thrust faces and housing bores .
Check out all the left over slag around the oil hole and sharp edge around the counter bore for the bolt head … mass production parts ..



High Tech honing …
Actually , does a good job of touching up the surface , the rods are so hard you would have a difficult time removing any material . Of course , the best part is it provides a good tooth for the … ahh .. oil film ..

[Capt.Insane-o]

Ugh 3 liter rods..just did a pair. One motor was a **** reman . 80 grams was the spread from the lightest to heaviest. Yes 80. ...but Chatfields are the answer.

[Capt.Insane-o]

Chaz have you tried DLC yet on the thrust surfaces like we were mumbling aboot some time ago

[Chaz]

The Chatfield's won't fit in the Styrofoam motor's … And Mercury Racing makes decal's and car motors these days , unless I'm looking on the wrong page ..

Yes sir , the rods all have the same part number , then "A - 1 thru 12" updates. All are pretty much … weak , with no visible change .

I try to start out with twenty or thirty rods. First thing I do is see if it fits on the "go ~ no go" fixture I made . I can live with .005" ~ .010" diff in length , No sense in using a rod that the small end's hole is shifted .060" to the side ..

Next I pair them up by overall weight , then each end. I haven't seen 80g .. yet , but most seem to fall in the 340~350g big end and 170~185g little end .



I'm not finished with the rods yet so I didn't want to get to deep into that .. but I can say , I have been coating piston skirt's and crown's on rotating assemblies that I put together for almost a decade now. Cant really see putting one together without it ..