New Cast "Steel" Stroker Cranks Arrived: Initial Inspection

[RobMcQuarie]

Well, After three years of waiting, the first of the new "cast steel" FE stroker cranks arrived today!

Pulled the first one from the box for an initial inspection-a 4.25" stroker. NOTE: This is a sample of ONE-it may or may not be indicative of the rest of the cranks.
Overall, looks pretty good. Same appearance as the other cast stroker cranks: small block and 460. Polish/finish looks good except for a few minor blems that will clean with a quick polish. Chamfers look good. Stroke is ok, runs from 4.243"-4.246".

The grind is not quite as good as I had hoped. Main journals varied in size from each other somewhat: 2.7482 smallest to 2.7490 largest, with two journals showing .0004 taper, three no more than .0002. The rod journals were better with small to large of: 2.1990-2.1994, and no more than .0001-.0002 taper, but they did show up to .0003 out-of-round.

On average, pretty good. Similar to what we see in the other cast cranks for the small blocks & 460's. You just have to remember that these are not high dollar billets, and they need to be checked closely. If you want more exacting tolerances, you will have to plan on having it ground by a top notch grinder-which we have had to do with numerous small block stroker cranks in order to have them exactly how we want them.

Of course, many are already aware by now that three strokes are available in these new cranks: the std 3.98", 4.125 and 4.250" strokers. We have previously used a 4.125" billet in a cast iron block, and a 4.250" billet in the Shelby aluminum block for customer's Cobra motors. But now we will try one of the 4.250" cranks in a 428 block. Scat doesn't know what clearancing issues might arise, so we'll just have to see.

As there has been almost no interest in the std 3.98" stroke crank, we are just going to stock the 4.125 & 4.250 stroke cranks for now. Should be interesting to see what stroke ends up being the most popular. Now all we need is for the new iron blocks to get into full production.

BTW-For those wanting the strength of the billet stroker cranks, but not the extensive time in production or high price, we will have a high quality, U.S. produced, FE Forged stroker crank available, hopefully by late winter. Tooling is being built now. Costs will be 30% less than the billets, they will be much more readily available, and the forgings are every bit as strong as the billets.

Rob

[Bob Putnam]

With those clearances, maybe they should offer +.010" journal so that the customer can do the final finish to stock bearing specs...

[RobMcQuarie]

We had a chance to check a second crank and it was even better. Mains showed .0005 from smallest to largest main jounal, with only .0002 taper. Rods showed .0003 size variance and up to .0003 taper. Stroke was right on with 1.249-4.250. Actually pretty darn good. I don't see many crank grinders that can hold their tolerances any better. It is generally accepted that "stock" grinds are acceptable with + or - .0003 and a high performance/high tolerance grind is held to .0002 variance. This is what we see with the high dollar billet cranks, but it is rare with your typical crank grinders out there.

I did check w/Scat, and oversize cranks are not available, so if you are looking for an absolute spot on grind, you may have to grind .010 under. But, don't expect that just any crank grinder will be able to do so.

We are going to be able to polish the "large" mains on the first crank to bring the sizing in pretty close. With only a two crank sample so far, I would advise checking closely, but you should be able to use these cranks as is. These cranks will be a nice addition to the FE builder's war chest.

NOTE: This whole discussion is based on the assumption that the block has been properly line honed, with new ARP hardware, and you are using Performance type high quality bearings. If not, your tolerances in the bearing housing bores will be off far enough that an accurately grond crank is a moot point. And that includes any block that the machinist has passed jugdement on as NOT needing a line hone. Rubbish, after 40 some years, EVERY performance block needs new hardware and a QUALITY line hone.

Rob