273 Supercharged...ITS HAPPENING PEOPLE!!

chrissock said
Well I have some information to share. First thanks for all the interest. I know we haven't made great progress yet so it not exciting but I promise it's coming. Should have the block and parts back next week to start assembling the bottom end. As long as I can find a crank!! Still looking for a forged crank so that might hold us up a bit. The assembly WILL BE BALANCED. I was able to "negotiate" the price down to a point where it makes sense and we decided to just do it. Cometic is making a set of head gaskets that are the correct bore and are set up for the boost. They are not cheap but I didn't want to skimp on that. I wasn't aware they offered that service but it's good info for anyone doing weird bore sizes. I am getting anxious to start getting this thing together. I have so much to do!! Don't want to rush the machine work though. Stay tuned!!!

You probably already know this, but here's some info on the crank just in case. All 68-72 340 cranks were forged. 73 340 cranks were not forged, but were shot peened for extra strength- not quite as strong as forged, but stronger than cast. Also, the 273 cranks were supposedly forged 64-66. There were also some 318s that came in trucks with forged cranks.
The way to tell by looking, besides knowing the casting numbers (which I do not) is to look at the casting or forging flash on the throws. On a cast crank, the casting flash is 1/4" wide; forged cranks have a 3/8" to 1/2" flash on the throws.
It might be hard to find an original forged crank, but you should be able to find an aftermarket forged 340 crank pretty easily. They have them at Summit, Jegs, Mancini, ebay, etc. for around $750.