I have a couple of 3 3/4 cranks and was wondering if this is still common and what the cost is. Is welding material on a viable option? In an old hot rod book I have a knarly picture of some guy building up the journals with a stick welder...it looked crazy but that's how it was done. Either one of these has to be cheaper than some new stroker crank, right?
Couple of ways to do it, Grim. You can either add material or offset grind to a smaller diameter using earlier rods. I have a set of pistons that are to be used with an offset ground Merc (4") crank that will give me 301". 3 3/8 +.030 X 4 1/8. I may save them for the Belly Tank. Wayno
Grim - prolly not worth it w/Ford crank - prolly need to start w/4" crank. Don't know going rates in your neck of woods, but you'd prolly end up money ahead w/a brand new SCAT crank...
Offset grind is still more popular than you would think. I haven't done one in a while, unless you count the indexing on my small block crank and its only .010 a very small edge in a world of strokers. But for my money the buildup and turn is the way to go. You'll have to find someone that is pretty savy, but I think I can hook you up when the time comes.
The big shift is that nowadays machine shop time costs more than parts... The 3 3/4 crank used to be stroked to 3 7/8 the same way 4" cranks were stroked later to 4 1/8, by grinding large journal cranks down to small journal off center. This stopped immediately in 1949, as a new Merc crank got you more for less money, especially since stock pistons were available. Displacement benefits are pretty small at this level of stroking, and both small journal rods and the bearings needed for them have gone up drastically in price lately. Another joker in the deck: Offset grinding requires a crank that's pretty close to full diameter to get the full 1/8". I think there's very little bang for the buck here...better to spend the money upstairs, or spend more for a bigger stroker. People are shocked by the climb of Merc cranks to 2-400 dollars, but add up special pistons, new rods, and rare bearings, machine work at $$$per hour, and that's chickenfeed. It's also not really much different than my $50 Merc crank from 1972, when you look at inflation and wage differences. Welded strokers are much less common now than in the fifties, but are still done. I have no idea if they are workable on iron cranks. Again, lots of skilled labor.
Two questions....1) How much stroke are the new Scat cranks available in?? 2) What rods are you talking about that are smaller on the big end than say a 8ba rod?? I have a Merc. crank that I will use in my next flat,but just how much cid does that 1/8th inch give?? OK sorry thats three questions.....
Welding should give you a stronger product,compared to offset grinding. But your faced with the cost of welding, straightening the crank after welding, rough machining, and final grinding. If you can find someone who would do it properly, I imagine it would cost almost as much as a new Scat crank. Maybe more. AV8 would know the score.
I'd buy a Merc crank every day if I could find them for $226, which is what the CPI pegs your '72 buy at, Bruce. All kidding aside, you're absolutely on target about the relative economics of having a Ford crank built up and offset ground vs. starting with a fresh stroker crank, whether a good Mercury casting, a new 4-inch French crank, or a new one from SCAT. Finding someone to do the work willingly and competently is only part of the problem; non-mainstream (read anything other than SBC) performance work often carries its own "surcharge," certainly in our neck of the woods. (One friend recently took a Mercury racemotor block to a well-known hi-po machine shop for an align bore of the mains, necessitated by the addition of a Tatom H-D center cap. He assumed that the price of the work would be the same or perhaps a little more than the $400 paid a year earlier on another block -- thought to be excessive even then. Imagine his surprise when he was handed a bill for $800 this time! Plug that into the CPI calculator and see what you get.) BTW, today's new $750 SCAT stroker crank (4-1/8 inches) would have set you back $106 in 1954 -- about the same as you would have paid at the time for an offset-ground 4-1/8-inch crank from C&T Automotive.
Hey guys, I don't know if it'll help or not, but there's a machine shop here in Flint that knows Flattys pretty damn well. it's called "Automotive Machine Shop" (fitting name eh?) I worked there for about a year, and George Sr. (the owner) showed me how to weld up cranks. (I've never done it, but he showed me what went into it) This guy knows his shit in a major way... I believe that it was the 60 degree v6 that GM couldn't get to run right... they brought the crack to him, and he cut it into like 6 pieces and put it back together and that's the design they chose to run!!! I'm not even sure that George Sr. is still alive, but George Jr. knew his shit pretty well too. For what it's worth, Sr was a "ol' skool" rodder. He was telling me all about how lame SBC's were.... flatheads are where it's at! (This was almost 11 yrs ago, before "RAT RODDING" was trendy!!! ) I was frightened more than once when he'd take a several thousand dollar billet crank and whack it with a hammer!!! But they always ended up straight!!! Might be worth talking to him anyway...
[ QUOTE ] 1) How much stroke are the new Scat cranks available in?? [/ QUOTE ] 4.000 4.125 4.250 4.350 And H-Beam rods to match... [ QUOTE ] 2) What rods are you talking about that are smaller on the big end than say a 8ba rod?? [/ QUOTE ] Early 221 rods w/floating bearings [ QUOTE ] how much cid does that 1/8th inch give?? [/ QUOTE ] 15-19 cu" depending on the bore
This needs to be an economic decision. A brand new 4.00 stroke SCAT crank is listed at Speedway for about 750 bucks. Do you think you can do better for less money? If you are or are in good with a machinist, you might be able to get it done for less. For those of us that have to pay for the core plus the machine work, a new crank looks like not a bad deal. By the way, I found a 5/8 stroker assembly (313 cubes) at http://www.flatlanderracing.com/ for about $2000 bucks. Pretty spendy, but if you really NEED the inches.......
What makes the SCAT cast F/H crank worth $7 to 800 dollars? It cant cost that much more to make than the $160 dollar SBC crank the same guys make. Hell theres two less mains to grind. I gladly pay that for a forged one. Oh ya like every thing else flathead, I forgot, people will pay it, so they can charge it.
That's a whole new concept, 296 V8. SBC parts are cheap because the buyers -- all 50 million of them are smart, while flathead parts are expensiive because the buyers -- several thousand of them are stupid. You've really sussed that for sure. You're a production/marketing wizard.
[ QUOTE ] while flathead parts are expensiive because the buyers -- several thousand of them are stupid. [/ QUOTE ] ...I like to think of it as, well, stubborn!
That Bruce guy is one smart feller. I've been thinkin about this also. I've got an extra 4" Merc crank and a set of early rods. Hmmmmm...might have to go talk to George Jr.
[ QUOTE ] [ QUOTE ] while flathead parts are expensiive because the buyers -- several thousand of them are stupid. [/ QUOTE ] ...I like to think of it as, well, stubborn! [/ QUOTE ] Aww gee, which one am I? 592?
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