Reply to "Thoughts on bottom end rebuild and or stroker kits"

Jack

on the subject of aftermarket stroker kits, the inexpensive crankshafts found in the stroker "kits" are Chinese made. They are notorious for very poor quality control, and the machine work is just as notorious. There are a few businesses here in the US which purchase Chinese cores and then do their own machine work, to a much higher standard. These businesses are also very picky about which cores they use, the poor castings and the ones with poor metallurgy are rejected, sent back to the distributor, they only use the cream of the crop. One such business is Scat, Scat has developed a fairly good reputation within that market.

If you must use a "kit", save yourself a lot of grief, and do business with one of these companies, like Scat, that do their best to maintain a decent level of quality control and precision machine work. Remember the castings which Scat rejects are sold to others, and then passed on to the public at a lower price. You do not want to put yourself on that end of the "food chain".

If you price the US manufactured crankshafts you'll likely skip a heart beat, they are pricey. They are worth it in my opinion, but not everyone's budget can take a hit like that.

The oil passages in the oem crankshaft are an integral part of the Cleveland lubrication system, if you are going to use an aftermarket crankshaft, it is in my opinion imperative to install bushings in the lifter bores, set the lifter bore to lifter clearance between 0.0007" and 0.0012", and drill a 0.040" orifice in the bushings for supplying oil to the lifters & valve gear. That hole may need to be a bit bigger if you plan to use a hydraulic cam & lifters, we can cover that later.

Another bit of advice, steel cranks are harder on the block, if you're gonna use a steel crank, invest in a "good" balancer. The common balancer I hear mentioned among experienced Cleveland racers is the ATI balancer, it seems to help the thinwall block survive a lot of abuse.

A 4" stroke and 6" rod will put the wrist pin in the oil ring groove, which normally results in oil burning. A contact at JE pistons tells me it is possible to spec a piston & ring combination that will not burn oil with the wrist pin in the oil groove. So if you decide to go that route I can put you in touch with him also.

I like the idea of the 400 cubic inch Cleveland, it wakes up the 4V heads and makes it possible to make big power over a reasonable, street-able powerband. But knowing how much the parts in the 351C are inter-dependent, I've never been 100% happy with the situation.

Which brings me to two alternatives.

Fist alternative: the 351C was designed by Ford to make 500 BHP at 7000 rpm, that's plenty of power in my opinion. The 351C is designed to be very durable at that RPM, the motor likes to rev. So instead of building a stroker, just build the 351C the way it was designed to run.

Second alternative: Off set grind the oem select grade 90% nodularity iron crank from stock 1.75 inch throws to 1.85 inch throws, reducing the diameter of the rod journals from 2.31 inches to 2.10 inches. The 2.10 inch rod journal allows you to use readily available 6 inch long I beam connecting rods designed for the SBC. SBC rods are lower priced than comparable Clevo rods (I beams weigh less than H beams). Choose a nice light, forged, full round skirt piston, compression height = 1.330 inches. After offset grinding the rod journals have the crank tufftrided, have it straightened, chamfer the oil holes, micro polish the journals, have the reciprocating assembly dynamically balanced.

3.70 inch stroke with 4.030" bores increases the displacement to 377 cubic inches. Everyone likes what that small increase in stroke does for a street motor with 4V heads. The oem iron crank is a very durable part. The iron is gentler on the block, the iron surface also retains oil better than steel. The oem crank also has the right oil passages and the standard 351C crank snout. A lot of the aftermarket cranks have Windsor snouts which requires a specialized hybrid timing set and a crank spacer. By using the Ford crank all 351C parts are used, no spacer is needed, etc.