CHRIS CRAFT COMMANDER FORUM ® .......A photo-intensive technical reference file and ongoing newsletter regarding the original fiberglass Chris-Craft Commander series. This is an independent not-for-profit and non-commercial web site, not affiliated with the Chris Craft Commander Club ~~ or ~~ Chris-Craft Corporation. Our mission here is to "have fun and share information" about the Commander series (and those associated fiberglass boats on the Chris-Craft family tree) for your individual personal use, and by doing so help promote the good name of Chris-Craft, and help preserve, restore, and appreciate Chris-Craft boats. The main reference feature is the ever expanding MASTER INDEX File which contains what we believe to be the world's largest collection of documentation photos and technical information on the Chris-Craft Commander line of boats, (like these original brochure scans, featuring the iconic first 38 Commander styled by Fred Hudson, and many of the great Dick Avery renditions that followed) , (a huge collection of Chris-Craft 427 tuning and specification information), and a few words about how to use the forum.

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Original Message
  • Stroking a 427
      • Randy (no login)
      Posted Aug 8, 2010 10:09 PM

      Gary,

      I used Scat 4.125" stroke crankshafts (Part # 9-FE-4125-6700-2200) and Scat 6.700" length connecting rods. The original FE rods will not work with the Scat crankshafts. As I have stated previously, I would replace the connecting rods regardless if I was rebuilding a 427. The pistons for this combination were custom made by Diamond Racing Products, custom dished FE pistons with a 4.250" diameter with the compression height adjusted to produce a 9.0:1 compression ratio with the original heads' combustion chamber volume. The complete rotating assemblies were balanced, which I highly recommend.

      For reference, a stock 427 FE has a 4.230" bore (largest of the FE family), a 3.780" stroke, and a 6.490 connecting rod length. My understanding is that it is not a good idea to overbore more than 0.030" (4.260") on a 427 FE block. I agree with Tom Slayton in that the 427 FE has a short stroke for its displacement compared to other big blocks of similar displacement. That is a characteristic common for extended high RPM circle track and road racing engines, not high torque work horses. Don't get me wrong, the 427 FE did a great job producing torgue in the CC application. I believe a 428 FE has a 3.980" stroke, and is externally balanced compared to the internally balanced 427. For reference, a stock GM 454 has a 4.250" bore and a 4.000" stroke.

      I don't feel I am pushing anything to the limit with this combination in a cruiser. I am trying to make a great marine engine even better by giving it even more torque. As much as I would like to, I have no plans to dyno these motors. I plan to tune the fuel injection systems in the boat where they will be used starting with the same 23x23 four blade props I used with the stock 427s. Based on the observed gains, I should be able to calculate a percent change in performance and fuel economy. I may change the pitch of the props and intake manifolds at some later date, we'll see how they do.

      If you live in the St. Charles, MO area, I will invite you out for a ride once I get my sh-t together and get these engines back in the boat. I have started some other painting, plumbing, and wiring projects in the engine room while the engines and generator are out, which have added to the delays caused by the high river levels. No sense in rushing restoring and making improvements to a beloved Commander.

      Where do do keep you boat on Lake of the Ozarks?

      Randy
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