We will be starting season number three with the Monster in just a couple of weeks. With the new motor running well and a general spiffing-up of the car, I think we are ready to do battle once again.
After two years of sitting in our workshop, the four bolt main block was turned into a fairly healthy motor. We had previously bored the block .030" over, but unfortunately didn't check the machine shop's work before ordering the pistons and rings. We had never used this machine shop before, but since our regular guy was backed up with work and we had not heard anything bad about them, we let them do the boring. When we dropped off the block at our regular, trusted shop, we were dismayed to learn that the cylinders were badly tapered. One cylinder was tapered .006", which forced us to bore the motor to .040" over. Needless to say, the rogue shop will never have any of our future business. I guess a flag should have gone up when I picked up the block and found that they only accepted cash payment. Oh well, live and learn.
The majority of parts for this motor were purchased from Doug Herbert Performance Parts. We found them knowledgeable and easy to deal with. Their prices are good and they shipped promptly with nothing ever on backorder. I'm not so sure they hold me in the same esteem, as we ended up having to exchange items on three different occasions, due to no fault on their part. The first of course was the pistons and rings. We had ordered their 'Chevy Bracket' engine kit, which contained SRP 13 to 1 forged pistons, Scat 6" H-beam rods, Speed-Pro file-fit rings and Clevite H-series bearings. Naturally, I had ordered the kit .030" over, but now I needed to exchange the pistons and rings for .040" parts.
With parts in hand, the machine shop was now able to get to work on the block. We had it bored .040", decked .010" and align bored. The crankshaft journals were all cut .010" under, the floating piston pins were fitted and the whole assembly balanced. Assembly of the motor in our workshop went well. I purchased a manual piston ring filer and added a motor to it to make that job a little easier. I used a 180 rpm gear-motor and timing belt that I purchased at a surplus store to drive the cutting wheel. It worked very well, as each ring took little time to file to size. We are using a Herbert C6F solid roller cam that is a bit on the mild side for a race motor. The .625" lift is not overly abusive on the valve train. We plan to shift at 7200 rpm which shouldn't put too much stress on the rotating assembly and give us some reliability as well.
Because the roller cam has much steeper ramps than last year's hydraulic stick, the rest of the valve train needed to be upgraded accordingly. I machined the heads to accept Isky 9315 1.550" dual springs and used titanium retainers from Doug Herbert. I then used Comp Cams +.050" 10° valve locks to achieve an installed height of 1.950". Crane Gold Race rockers on 7/16" studs, Manley 5/16" 4130 chrome moly pushrods with guide plates, Herbert vertical-bar solid roller lifters and a Crane stud girdle complete the valve train. We are reusing the 2.02 / 1.60 Manley Raceflo valves from last year.
The finishing touches are a new Moroso 7 quart oil pan and Edelbrock Victor Jr. port-matched intake manifold. Click here for a complete list of the motor parts.
We ran two full seasons on our 14 X 32 Goodyear slicks and they easily would have made it through another, but the sidewalls were beginning to show some checking and I really wanted to try a softer compound, so we replaced them. This time I chose a Goodyear 1160 super gas tire. It is the same size but a much softer compound and our first test pass proved that it was a good choice, with a 1.47 60 foot time with no VHT applied to the track. I can't wait until the first points race to see how the car launches on a well prepared surface. While the car was up on jack stands to change the tires, I had an opportunity to inspect the brakes, rear end and sub frame up close. Everything looked great.
The final 'major' change of the off-season was to redo the electrical panel. After two years of additions and changes to the existing panel, it was time to start over and clean up the wiring. Not only is the new panel cleaner but I added a voltmeter to monitor the system, and by plugging in a test probe and throwing a switch, it doubles as a test meter. I also added high current relays to operate the fan, water pump and fuel pump, to take the load off the switches. We previously had the fan switch fail and luckily we were not at the race track at the time, so I feel the relays will add reliability to the system. I also built a fuse panel with LED indicators to quickly and easily locate a blown fuse. We once blew a fuse at the track and I had to get out the drawings to locate the fuse before I could change it, so this should make life easier if another fuse blows. Lastly, I added a rev limiter for the burnout. The MSD 6AL ignition has a built-in rev limiter that uses different value 'chips' depending on the rpm limit. The 'chips' are simply precision value resistors molded into rugged two-pin holders that plug into the MSD box. The values are such that the higher the rpm limit, the larger the resistor value. We have a chip installed to limit the maximum engine rpm to 8000, but I wanted to limit the burnout rpm to 5000. So I use a relay that is activated with the line lock button that switches another resistor in parallel with the 8000 chip to equal the value of a 5000 rpm chip. I did this because the rpm goes up very quickly during the burnout using the solid roller cam, unlike last season's hydraulic cam.
We finally got the car to the track on Wednesday night for some test passes. After an initial pass under 5000 rpm to check for leaks or any other bugs, Geoff made a second pass shifting about 6500 rpm. Since the track was only 'dragged' and no VHT traction compound was used, we wanted to keep the car tamed down somewhat. I had also changed the wickerbill on the spoiler from 1/4" to 1/2" to get more top end downforce and was hoping Geoff would be able run fast enough to test it out. Well he definitely ran fast enough with a 10.37 @ 132 mph! The car ran straight and true and Geoff said he could feel that the car was more stable than last year. So, we have two weeks before the first points race and neither one of us can wait!
Well, that was quick! We have completed the first two points races of the year and although we only have two round wins, we are definitely happy with the car's performance. After only a carburetor jet change the RX-7 runs steady 10.2's, with a best so far of 10.18 @ 134 mph. So I guess that means we'll have to try to run a nine second ET this year. It's fun to have something to shoot for. It also puts us at the top of our class, ET wise. At both races we were the quickest car in our class, which means Geoff plays catch-up each round. That can benefit us in two ways. First, Geoff's opponents are always in front of him, making the finish line judgment a little easier because he doesn't have to look back over his shoulder. And second, if all of his opponents leave the starting line first, they also have the first opportunity to redlight.
Geoff is getting more comfortable with each run and his reaction times are coming around pretty good. The car is much quicker than last year and that takes some getting used to. The 60 foot times are low to mid 1.40's with 1.41 being the best so far, so the car does put Geoff back into the seat when it launches. Seat time is the only answer now and we will be running twelve points races this year so hopefully as the season goes on, the round wins will start adding up, and who knows, maybe our first win will come soon.
Last but not least, I decided it was time to change the look of our website. It is turning into a little bigger job than I first expected. I hand coded our previous site in simple HTML, and I'm using a web page editor for this site. Once I fully learn the editor, things should go smoother and hopefully we'll have a better website.
Well, I guess that's it for now, I hope we have good news for my next post.
