Man, the offseason is short here in Florida, but we're almost ready to get at it again. We pulled the motor and transmission right after the final race of 2003 with intentions of freshening everything up for this season. Initially we had planned to build our 4-bolt/steel crank motor, but the cost of doing it right would be easier to bear if we stretched it out over a longer period of time. So we rebuilt the 2-bolt/cast crank motor that we ran all last year with some nicer parts. Actually, the only things from last year's motor that we re-used are the block,crankshaft,carb and intake. Upon inspection of the motor during disassembly, it was found to be in excellent condition. Almost seems a shame to tear a perfectly good motor apart, but it's all in the name of quicker ET's.
We started out by boring the block .030" and decking it .010" to clean it up. We installed a set of SpeedPro L2256F30 forged flat-top pistons on a set of Chevy 'X rods' that I reworked by grinding the beams and balancing. The 'X rods' are stock Chevy rods that have gone through additional scrutiny at the factory, and are generally considered a better rod. They are easily identified by the 'X' on the rod. We had the rods resized and installed ARP Wavelok bolts. Finally, we sent the whole rotating assembly to the machine shop for balancing. We assembled the block using Hastings chrome moly rings and Federal-Mogul bearings.
We decided to get a new cam for this year, but since a new torque converter would cost around $700, we stayed with a hydraulic grind. We chose a Comp Cams Xtreme Energy XE284H. It has a nice wide power band that will work well with our 3000 rpm torque converter and still have some rev capability to put us across the finish line in the mid 120's mph. We also got a Pete Jackson gear drive for the motor, the noisey model of course. I'll admit that the only reason we got it is because Geoff likes the sound. And it may add a small intimidation factor at the race track. In any case, it does sound cool.
The biggest single horsepower-adder we got are the heads. Last year we were running stock, untouched 1.94 Chevy passenger car heads. For this season, we bought a set of World Products Sportsman II heads. These are essentially updated versions of the Dart Iron Eagle, with 2.02/1.60 valves, 64cc chambers and 200 cfm runners. We installed Manley Raceflo valves and Crane H-11 springs. They have screw-in rocker studs and guideplates. As soon as we pulled the bare heads from the boxes there was no mistaking these as reworked stock heads. Everything is machined nicely with no casting flash to be found anywhere. The ports are big and match the Fel-Pro gaskets perfectly. We simply assembled the heads with a 1.750" spring height and bolted them on. I calculated the compression ratio to be about 10.5 to 1.
Because the ports matched the gaskets so good, we assumed the intake manifold would be real close because it is an aftermarket part also. I was dumbfounded to see how poorly the intake ports matched the gaskets. These things are cast in molds, I can't believe they are so far off! Geoff ended up spending four nights grinding on the ports to smooth and match them. I'll never buy another intake manifold without first checking the port match.
We finished assembling the motor with a new ProForm electric water pump, Comp Cams yellow polymer valve covers and Moroso Blue Max ignition wires. We installed the new MSD HEI terminal cap on our Pro Billet distributor and chose Autolite 24 spark plugs. We also got a new Professional Products 90000, 6 3/4" damper that is SFI approved, just in case we close in on 10.99 and it becomes an NHRA requirement.
While we were building the motor, the transmission was being refurbished by the local tranny guru, ex-supercharged gasser national record holder Tommy Shinholster. New racing clutches and sprag were installed and Geoff machined a part to allow an additional clutch be added to the high gear pack. Tommy said the clutches that he removed from our transmission were pretty much used up, so I'm glad we decided to have it gone through.
Last Friday we finished assembling the motor and installed it on Saturday. We set the motor back another 1 1/2" to get a little more room for the new water pump and that required a relief in the firewall for the distributor and a new transmission crossmember that we easily fabbed. On Sunday we fired the motor for the break-in. If we need to run the motor for any more than about a minute, Geoff will go door to door to warn everyone. Our neighbors are great and don't complain, and we run the motor only when we have to, so I hope we can keep this fragile treaty in place. After setting the valves and timing, the motor sounded GREAT!
On Wednesday we went to the track to put some easy passes on the motor and see if we have any big bugs. The first pass was limited to no burnout, an easy launch and 4000 rpm shift points. Geoff gradually floored it in high gear and ran a 14.35 at 106 mph. The second pass was an easy burnout, a harder launch and a 5000 rpm shift point. That produced a 12.54 at 105 mph. Everything looked good with the motor and tranny, so the last pass would be harder yet. I was a little apprehensive about a full-blown pass because the track wasn't in the greatest of shape. They use very little VHT on the Wednesday night sessions and most of the other fast cars with slicks were having trouble at the top end. So I backed the timing down to 33 degrees total to tame it down even more and we limited this pass to a 6000 rpm shift. Geoff did a normal burnout and launch and ran the RX-7 through, straight as an arrow, at 11.22 at 122 mph! Oh man, talk about surprised. I haven't even touched the carburetor yet, it still has the jets from last season. The timing can still go another 5 to 7 degrees, and our normal shift point is going to be 6200 rpm with this cam. And oh yeah, the car spun the slicks at the launch. This thing is going to run 10's probably the next time out!
This car continues to amaze me. The new motor is by no means a full blown race motor. It could be driven on the street. But when the car weighs only 2365 pounds, it doesn't take a whole lot of motor to go fast. We will get the car back to the track a couple more times to fine tune it, then start the 2004 season. We plan on racing more this year and we will probably hit a few more tracks as well. I'll try not to go the whole season without an update, like I did last year. Until next time, see you at the races!