About 12 years ago I bought a 1973 340 from a guy parting out his collection he had stored at a local machine shop that was going out of business. From what I know, the motor is bored .030 over and the cast crank turned .010 over. I have a current set of heads with large valves, mild porting, and a fresh valve job.
Here is what my motor looked like when I brought it home from that machine shop. Since then it has sat, wrapped up except for a two year trip to someone's house who promised me they would build the motor for me... Sorry it took showing up at the door and a threat to call the Sheriff to get my parts back.
May, 06 2010 - I have delivered my motor to P&M Performance Racing Motors in Richlands, NC. My idea is to improve performance as much as I possibly can without sacrificing drivability. So, my current plan is to buy a 416 stroker kit. I have an Edelbrock LD340 intake, a Comp Cam XE284H and some chrome goodies. However, it will be the results of the machine's shops assessment that will determine the direction I go. Here is how I left it.
November, 11, 2010 - Motor is mostly assembled. It is now a 416 stroker!!! I had to take a few parts (carb, hoses, plugs, etc.) by for the break-in and dyno pull we are going to do there. Here are a couple of shots so far. I am to get a call when the engine has been broken in and they are preparing for the dyno pull. I am using the original 318 manifolds for the break-in and then bolt on the TTI headers for the actual hp check.
UPDATE! December 07, 2010 - Well, machine shop called!!! Couldn't talk long since I was on the way to a Christmas program at the school. They have broken in and dyno'ed my mild stroker I had them build. My goal was a nice torquey 400+ hp motor for the street (727 tranny, 3.23 gear) that looked pretty stock. I think I did a good job predicting the outcome.
Here is the rundown:
1973 340 block- .030 over
360 heads, mildly ported with 2.02 standard valves (keeping cost of motor down)
416 stroker kit- cast crank and pistons (machine shop dished them a little to get a better compression for pump gas)
750 Edelbrock carb (may also be holding down power)
Comp Cam XE284H
Windage tray and stock pan
Old set of Comp cam steel roller rockers
So from what I heard, it made 420 HP 475 ft lbs torque somewhere around 5200 RPM (with a modified set of small block Chevy headers needed to get it dyno'ed. The TTIs wouldn't fit on the dyno.) They pulled it up to 6000, but I didn't get the results on that. It will idle down to 650 which is good. I wanted to make sure it was easily streetable.
I'll find out more tomorrow. I know I could have gotten a lot more out of this motor with better heads, but right now, that really wouldn't be worth the extra cash. I am going tomorrow after lunch to see it run before they unbolt it from the dyno to bring it home. I'll take pictures and post a YouTube video later.
December 08, 2010- Got to hear it run and do an easy dyno pull. This one was with a air cleaner. Still made around 412 hp! This will be a fun motor!!!! I do have to get my chrome valve covers on it though!
January 01, 2011- HAPPY NEW YEAR! I took a moment today to mock up the engine with the chrome goodies... Looks good doesn't it?