You guys need to practice some safe downwind sailing tactics. With the 250 and parts back up from CI, you save because you have the best transmission, ease of installation, power per cubic inch, you maximize torque and seam to still get great fuel economy. A zero deck 250 is a match for a very well spec'd 302 Windsor, and goes a lot harder with the CI head and Clay Smith cams than the same components on a 200. Just having a 250 is a privilege. The pluses have only one minus...expensive pistons.
Proper management for a nominal 55 (50 to 60) cc chamber is a 15 cc dish piston or more.
The parts you are using force you to steer clear of cast flat top pistons, and its much better to spend most of your budget on good aftermarket US custom forged pistons deep dish pistons, rather than the suspect cast flat top replacements. 14.5 cc is just about ideal. A set of six forged pistons cost US $575 + freight from RaceTek Pistons. With that cost, comes a huge saving on forged factory rod choices. The 5.99 2500 cc or 300/4.9 I6 6.21/6.24" Items
Down here in Australia, Ford Aussie used several deep dish pistons, 15.5, 22.9 and 27.9 cc, and have stayed with that bigger dish from 1971 to date, because it works prefect with our 239, 243 and 250 cube I6's with a 3.91" stroke. We often use 6.27 tall deck 200 pistons from the short stroke version of the 1971 to 1992 cross flow 250 six. Even a stock 5.88" rod high compression Aussie piston for a 250 won't ever be less than 8.5 cc in dish. We tend to use very durable Repco sourced stock 1.531" tall Mahale, Duralite high silicon or CP forged pistons, but US suppliers are the best in the world, and you can't go wrong with saving a little more for the best pistons for a US 250.
Re-read 62Rnachero200's post. In his instance, he went down to 1.300" tall pistons from the stock 1.500" aftermarket2.3/2.5 HSC or 200/250 piston. As a rsult, he was able to swap in the early 300 rod, as it is pretty well as bullet proof as the 5.99 2.5 hsc is reputed to be. You can re-bush the later big wrist pin rod to suit the small Ford Six 0.912" wrist pin. I think the oil pickup bolt fouls the larger 300 rod cap base on one cylinder, but nothing an extra washer can't fix.
https://imageshack.com/i/mk6ba4j
Here are his states after hours an hours of long consideration and darn hard work.
Mike didn't have a choice to make a whole amount of redundant alloy on the CI head. The compromise on combustion chamber size is the right one, as most performance Fords tend to favor the more common 200. The 250 solution is deep dish pistons, because the flat top HSC/HSO four cylinder pistons aren't always reliable in service, and have a lot more wrist pin off set. They have been noted to freeze in service and sometimes crack skirts under load, two instances here on FordSix Performance.
With 250 Ford I6's Ford US decided to run those over 100 thou piston to block shortfall, and economize on the stock 22 thou 200 gasket, 200 large chamber head, and then used very conservative cam timing, then retarded it even more later on.
In rebuild situation, even expert 250 punters s like Gene Fiore or Does 10's can't get the stock cam gears degreed right, and in stock form the two 250 US cam gear packages slips in service from the ideal figures listed on the cam placards.
This means the modified US 250 with changes like long 6.21" 300 or 5.99 2.5 liter Taurus rods, zero deck, bigger gasket and smaller combustion chamber and smaller dish pistons is a problem.
My solution is the same as 62 Ranchero 200's, and that is to use deeper dish RaceTek pistons which are still 1.5 or less so on deck height from wrist p to piston annular top.
His sig details
62 Ranchero, 252 cid, 300 rods, RaceTek pstns, ARP mains bolts & studs, balanced & blueprinted, CI AL head, 1.6:1 adj rckrs, Smith Bros, 274/274/108 cam, CI int, Holley 500, DUI, CI SS hdrs, PowerMaster strtr and 1W alt, Optima, V-8 rad, CF C-4 with B&M ClickShift, 157-T FP, TCI 2500, orig 7.5" diff with 3.50, four wheel drums. Next planned upgrade: front disc brake conversion.
