Project 11.99 - 331 Stroker Track Results

Project 11.99 is back after nearly a year of hibernation.

Many months ago we embarked on a journey to revive our '67 Mustang project car. If you recall, a couple years ago we built up a 302 motor for the car, with the goal of hitting 11.99. We met that goal and, after a good two seasons on that motor, we decided it was time to think about another project.

The same block now houses 331 cubes, not 302. Same heads, intake, carb and exhaust. Other than the displacement, we now have a milder hyd. roller cam (226/230 .542/.552 110 LSA) rather than the solid roller used in the 302 (238/246 .560/.579 110LSA).

After debating about what sort of powerplant to build up, and what direction to take with the car, we decided on pursuing a 331 stroker buildup. Many of you followed along as we detailed the buildup of the motor. We did the shortblock and all machine work in part one of the article series, and then in part two we completed the top end. Anxiously you waited for part three... the results. As you noticed, we had delays in delivering part three. We made so many changes to the car (cable clutch, new steering box, detailed engine compartment, power brakes) that inevitably we had some glitches to work out before the car was track ready.

Well finally we have those long awaited results.

We found this twisted stock axle before we even left the garage. We'll be upgrading to hardened 28 spline axles before the next trip.

The last bug we had to work out before heading to the track was a nasty vibration which came on around 70mph. We were certain the vibration was in the driveline, not the motor, as it did not occur in neutral or while the car was at a stop. After several troubleshooting attempts, having the wheels balanced, and checking all the mounts, we decided to check the axles. Sure enough we found twisted splines on the driver side axle. This probably occurred the last time we had the car at the track and attempted a 5500rpm launch with the old 302 motor.

We stuffed in a spare 28-spline stock axle we had laying around and prayed it would hold on a couple easy launches behind the new 331. We're well aware that the 8" rearend and 28 spline axles will be a ticking time bomb behind the increased torque of the 331... it is something we will deal with soon.

At the track
We headed up to a test and tune session at our local track on a cool November morning. With temps in the low 60's and dry air the weather was decent to make a couple shake down passes, and then gradually tune the car for ET's. We trailered the car to the track just in case an axle, or worse - the motor- decided to let loose.

The first pass would be real easy. A 2000rpm launch, and slow shifts at 5500rpm just to ensure there were no more vibrations or other problems.
The results - a 12.49 @ 115, with a 1.84 sixty foot. Not bad at all knowing there was plenty more left.

Spec Stage 3 clutch is serving us well so far. It engages smooth and has surprisingly minimal chatter for a puck style clutch disk.

On the next two passes we raised the launch points to just under 3000rpm. Sixty foots responded with low 1.7's, but second gear was missed on both runs. The problem, our clutch cable was engaging too close to the floor and not releasing the pressure plate enough.
We dialed in the firewall cable adjuster to remove the slack out of the cable, most likely a result of stretching, and pulled back into the staging lanes.

On run four the launch rpm was brought up to 3500rpm, well below the potential of the ET Drag slicks (26 x 8.5 x 15), but probably pushing the ability of the 28 spline twigs in the differential. The 60ft flashed on the board - a 1.59, best ever for the car. The ET responded accordingly with a 12.04

We decided one more run was in order. Could we hit an 11 second ET on the first time out with this motor? We still had yet to check timing or even change a jet. The motor was running so well and smooth it didn't make sense to tune until we knew just how low the current setup would take us.

One last run... again a mild 3500 rpm launch, and like clockwork, another shocking 1.59 sixty foot. With no desire to powershift and bust up the stock 1989 T5 tranny, we simply made sure every gear was engaged at about 6400 rpm on the tach.

The results? 11.87 @ 117.5 mph.

Nothing broke. We're hitting 1.59 60fts with easy launches on stock leaf springs, stock replacement shocks, and Traction Masters. Yes, we're pleased with the results, and can't wait to get back to the track with some hardened axles. Perhaps Project mid-11's a better name for this car? F/M

Timeslip Log
  60ft launch rpm ET mph comments
1 1.83 2000 12.49 115.4 shift 5500
2 1.79 2500 12.80 116.0 missed 2nd
3 1.71 2500 12.88 113.5 missed 2nd (cable stretch)
4 1.59 3500 12.04 116.5  
5 1.59 3500 11.87 117.5 shift 6400



Related Articles:
Build a 302 Stroker
Part I: Introduction and Prep.
Part II: Assembly


Project 11.99


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