KEITH BLACK PISTONS!!
Run #3 should be in stock June 25th!
A few minor changes. No valve relief's, for one. This extra feature proved more trouble than it was worth, and of actual benefit to a tiny minority of users. A slight modification at the pin bosses, is another. Unknown to most of us, there are two major casting differences in 64-69 rods. A minority of them (fortunately!) have a slightly heavier crossection at the rod cap. In three instances we know of, this caused an interference with the KB's. A very small amount of filing fixed it in all cases, but we will correct this issue on the next production run.
Well, they're two pistons in one - In the 1960's Chevrolet and Yenko put their minds together and came up with a piston that incorporated several unique design features that were absolutely necessary in the survival of the Yenko Stinger prepared racecar.
Now jump to the present.
Keith Black, the leader in aftermarket performance pistons, has developed a number of designs that are proprietary to their successful products.
We asked them to make a special piston for the Corvair utilizing modern manufacturing materials and techniques.
The result is the all-new KB Corvair Performance piston!
Let's look at the features of the new Keith Black piston -
The Keith Black Piston is a super hypereutectic alloy, with 6 expansion struts - designed for ultimate strength and life. The design allows for the running of very tight clearances, as expansion of the alloy is almost negligible. That means that you have greater control of compression and oil consumption.
The special gap between the top compression rings is to give optimum gas control under compression. The narrower stock 1964-69 Corvair rings are used in this location because of better survival under high revs. The oil control ring assembly is of the 61-63 Corvair design because the wider spacing between rails gives better oil control. (We realize that some of you racers may want to further modify the tension assembly to reduce side pressure)
As noted the pins are designed so as to allow for the use of the stock pressed on rod OR for a full floating design (Retainers are included - simply have the rod eyes honed out slightly).
NOTE - Full floating is not recommended for stock engines.
The pistons are calibrated to give stock compression ratios.
Oil holes are drilled for added strength. Slotted oil passages have traditionally been a serious weak spot in other designs.
BORE SIZES AVAILABLE - .020, .030, .040, .060 Std sizes are not available because we strongly advise against using these pistons in old re-honed barrels. Doing so reduces many of the special features as proper clearances are not possible.
WEIGHT - .020 piston - 515.2 grams. Weight differential between pistons will be VERY close
MATERIAL - 16-19% silicon alloy (HyperEutectic) w/six expansion struts
MARKINGS - "KB" cast into one side - "SL" cast into the other. Look for those markings! Only real Keith Black pistons have these markings. Don't accept inferior foreign manufactured copies!
AND HOW HAS THE FIRST RUN OF KB'S FARED?? - We sold 50 sets of KB's on the initial run. They have been used and abused in almost every way you can imagine. We have been impressed with the results. Only two users have lost a piston to disintegration - and in both cases we believe it was due to neglecting to open the top ring gap (as in the instructions) and/or not compensating on the timing (should be retarded 2-3 degrees from the previous setting).
It is imperative to remember that these pistons are being used is some of the most extreme environments. One engine is a full race job running 11 to 1 compression with 28 lbs boost at the turbo (no I'm not making this up). At least half a dozen other sets are in full race engines - without any problems. Remember, that forged pistons have not traditionally held up as well as these KB's. ANYONE can destroy ANY piston, if they are misused enough. The real question is what pistons will hold up the best overall in extreme use - and not cost $600.00 (or worse) a set!
We are convinced that these pistons are, at the very least, a match for forged (in strength and durability) and only time and further testing will prove if they are
vastly superior as well. Well, if they are at least equal, then why not just buy forged? Because our KB pistons run much tighter tolerances (.001-.0015) and can
actually give you slight increases in horsepower and efficiency - owing to their design alone. Remember that forged pistons require a loose clearance fit (.0035-.005). That means more noise, more oil consumption and more lost compression.
Special Moly ring sets for the KB pistons - $104.50 - state overbore size. Note - Several of you have questions about the rings. Our KB's use the old ForgedTrue practice of using 1961-63 Corvair oil control rings but 1964-69 Corvair compression rings. We've already had these special sets made up for us by Hastings.
TO ORDER BY PHONE - 503-434-1648
TO ORDER BY FAX - 503-434-1626
TO ORDER BY MAIL - PO Box 339 Dundee OR 97115