Woody,
At the Coast High Performance website they have a press article explaining the reason why for the 347 "E" stroker rod/pin/ring/ combo:
"...George Klass of CHP explained to us their year-long effort to get the 347 "E" Street Fighter short-block legalized. Beyond applying with the difficult and necessary paperwork, getting assigned a CARB approval station, and getting the car tested (before and after), there was the actual process of reconfiguring the 347 Street Fighter for it's new "Emissions-Legal" status.
Remember, CHP already has an excellent 347 Street Fighter short-block (also available in kit form) so they didn't have to start with a fresh sheet of paper. Klass explained that one of the best advantages CHP had with the 347 in the smog fight was the Blue Thunder 5.315-inch rod, versus the 5.400-inch rod normally sold in 347ci stroker kits. With the shorter rod, Coast was able to place the wristpin underneath the
oil-ring land, allowing better
oil control--an important factor when you have a sniffer checking for burnt hydrocarbons. Klass explained that Coast still sells the 5.400-inch rod for non-emission-conscious applications, and that it's a good, strong, viable combination.
However, the shorter rod will provide better
oil control, thus increasing engine longevity and ring seal. Another less visible advantage of the shorter rod is that a longer, fuller piston skirt design was possible.
The 347 "E" short-block is only available with 9.5:1 compression, giving the piston a slight dish.
Of course, the really interesting thing about EPA and CARB legality is that a person can't see past cast-iron--meaning, how could anyone possibly know what kind of stroker or stroker short-block you really have under your hood? Well, a police officer, or visible inspection won't reveal the truth--but a smog test after 10,000 miles certainly can. The CHP 347 "E" has been tested and approved by CARB to be a smog-legal replacement for '88-to-'95 5.0-equipped vehicles.
When you buy a 347 "E" short-block, you also get an exemption sticker/certificate that you can present to anyone doing smog testing. As explained by Klass, there are some interesting aspects to the 50-state smog testing. Even if you purchase Coast's 347 "E" short-block, and bolt-on a set of 50-state legal TFS Twisted Wedge heads, GT-40 intake manifold, and smog-legal headers---the combination may not pass a smog test, although it's very likely that it will. The reason for this is because when CARB tests a part for smog legality (such as an intake manifold), it leaves the rest of the engine stock. So, by adding together combinations of emissions-legal parts, you are legal by the letter of the law, but it is no guarantee of actually passing a sniffer test."
On the 347" I built, I used the 5.40 inch rod.
Pete