Building a Stroker Crank on YT

Some get welded the other direction, meaning around the crankpin rather than across it as in those pictures.

But yes, they are not pretty during the process.

Some cranks will have a small pit left in the crankpin where the weld meets the parent material. Doesn't hurt anything. By welding a little further around the crankpin, those bottom welds are gone as it's offset ground in "deeper" during the offset grinding.

I'l give a little explanation of the process. Lots of welding, straightning, and more welding and straightnong involved. Typical on a 4 cyl they may weld 1, 2 or 3 crankpins. Straighten and then index off the original un welded crankpin and grind the welded ones oversize, say .100" from finished diameter. Then the last crankpin or crankpins are welded, straighten and index off one of the prior ground pins. Straighten again after roughing in and then ready for the final grind. Carbon plugs are used to fill the oil passage during welding.

My sd card isn't working on my phone so I can't take pics right now but when I get it fixed I'll post some pictures for you. I like to see some welding on the bottom of the crankpin blending it into the throw. It's extra work but most of the strength in the crank is in that area. By filling it and tapering it to the crankpin the crank is much stronger when done. In the first pic there you see that welding done so after roughing in they can taper the throw to the crankpin. It's more work but makes for a better product when done.

Edited by wi50 - 02 Mar 2013 at 8:34pm

How do they stay straight??? Thats looks like a very rough process!

That's why it's about $200 per cylinder typically to weld and offset a crank. It really doesn't matter if they weld a little or a lot. The welding isn't that much work difference from a little welding to a lot, but the rest of it is the same. Then let it chung away offset in the grinder doing an interrupted cut and it's hard on grinder ways and stones compared to grinding concentric.

With the time and materials involved, welding and strokeing cranks is about the least profitable jobs for a machine shop. Don't complain about the price. Of they were reconditioning heads or boreing blocks they'd make 4x the money at the end of the day.

One thing I should add is that I say "index" off from a crankpin. Sometimes the stroke gets moved far enough that thr oil passage can be exposed on the bottom side of a crankpin. To avoide this, the welding is done to a different angle, or "clocked" differently on the crankpin meaning that rather thAn going straight "up" it may be moved to the side just a bit. Index, change rotation a bit and then grind.   Then grind other crankpins according to the first one.

The timeing marks on the crank gear will have no value once this is done.

Edited by wi50 - 03 Mar 2013 at 7:13am

i've been waiting for the "keyboard commando" to tell us it is ugly because they used the wrong kind of welder

Edited by Mrgoodwrench - 03 Mar 2013 at 8:43am

Not exactly on topic, but my question for Marty is,  is there ever a need to weld up the crank nose and install a harmoic balancer rather than using the stock front pulley? would this ease some stressess ,  or contribute anything to smoother rotation, better balance? thanks, Gary

Excellent information guys! really enjoy reading these and trying to learn a few pointers. Keep up the good work!

Just curious if you grind the mains undersize before welding them? I've heard various opinions on welding them. I've heard of some roughing the crankpins in undersize and then welding all the way around them before a final grid, but that seams like a lot more work for no reason, other than if the forging has some issues in the first place.

Some guys want heat on the crank, to straighten and I've heard some guys don't want to press them but cold hammer them.

I just had a Leroi crank done and that crank had some pits in the parent metal, no welding on the mains but grinding exposed some in the thrust surface as well as a few other areas so it took a bit of tig welding to fix. The forging just wasn't the nicest one.

What do you think of welding a crack in the front main of a 226 Allis crank where it meets the throw?   I've had a few of them cracked there and I just welded one for a low hp engine.......we'll see if it works out. Everyone I asked for more opinions said the same thing. It'll work.   A friend broke a MM crank in the front main, welded with a draw bolt through and never failed after that, it was one of those deals where there was to much in it to throw awayand he wasn't out much to try it.

Edited by wi50 - 04 Mar 2013 at 4:22am

here we go....

Glockhead SWMI wrote: here we go....

Edited by wi50 - 04 Mar 2013 at 8:16am

Now we also see why wi has been going through the deal to add counterweights by his own admission of having crank problems he is looking for answeres .

mlpankey wrote: Now we also see why wi has been going through the deal to add counterweights by his own admission of having crank problems he is looking for answeres .

Where did Wi say he had crank problems?? He said he REPAIRED a MM crank. The definition of repaired is: to fix or mend. Reading comprehension, try it sometime.

LARRY GREAT POST AND GOOD TOPIC OF IDEAS .. THANKS

How would cracked core engine cranks have anything to do with someone's skills as an engine builder?

Why is pankey a crank expert when he's looking for someone to do his crank work for him after breaking a few? The timeline of events and his story do not add up. Lies never make sense.

http://speedtalk.com/forum/viewtopic.php?f=1&t=22323&start=15

In this age of modern technology why don't you set up a video camera and make us a short condensed video of you welding and grinding crankshafts in your shop?

I have some video from the balancing class you guys missed. I will try to post them soon. I know some will be mad rhey didnt come to it and some will come just watching the video