Re: 393W not running up to expectations
Here is to reviving an old thread, again, but who doesn’t want an update or closure. As you have already read last year, the 393W was not running up to expectations. Over the past year, there has been a lot of head scratching, consulting, and analyzing. This was in an effort to make the Fun Ford Weekend event this year at Famoso. The payoff was more than satisfying, but another problem arose. We’ll talk about that later. The end result was a small list of things that needed attention. First off, the camshaft seemed a bit short and was changed to another solid roller:
• 258°/266° @ .050”, .672”/.656”, 108° lobe separation and installed at 105° intake centerline
• Matching valve springs, 1.6 ratio shaft rockers and .116” wall pushrods
• Lowered octane to 100 (compression was later found to be 10.54 to 1)
• Replaced the stock Ford vacuum advance distributor with a mechanical advance MSD
• The converter was replaced with another that flash-stalled at 4700 (it was not designed for this car. It was tried over the original lower stalling 3700-3900 converter)
• Raised shift RPM to 6800
• Replaced the open-hole spacer for a one-inch, tapered four-hole
Over the weekend. the car ran a best of 11.50 at 119 MPH. A marked improvement over last year, but there was a small hindrance as mentioned earlier. 60’ times were horrible at 1.68 -1.72. These times were associated with what looked like Pro Stock “tire shake”. The tires looked like they were hopping all through first gear. After the shift to second and third, the car stopped hopping and turned into a monster and took off like it had never done before…MASSIVE ACCELERATION! It is now a completely different car. It runs great and HARD after the tire shake. A variety of tires pressures and launch RPMs was tried. Everything netted the same hop. Although, with the higher the tire pressure (20 PSI), less hop was felt/observed.
Some of the launches were videotaped and after some slow-motion examination, we could see the traction bar bumpers were literally slapping up & down on the spring eyelets during the hopping phenomenon. I remember something like this before with another car that had the same problem that had a manual transmission. The phenomenon was call leaf spring ‘S” shaping or something like that. We couldn’t actually see the springs, but this thought was based on the way the tractions bars were moving up and down during the launch, tire sidewall distortion and an old racer that observed it and said, “those rear springs are worn out, you need new ones”. We are pretty sure it has something to do with the rear springs or simply the wrong traction devices. I’ve seen the same exact setup on another car that was running 1.40/1.50 60’ times with no hop so it is possible it can work. Along with the stock rear leaf springs, it has 50/50 drag shocks with extensions and aforementioned slapper/traction bars. The car is consistently pulling both front tires evenly about six-inches during the hop and the slicks seemed to have really good bite. If the hopping can be cleared up, I’m sure the 60’ times will decrease as well as the ETs considerably. Anyone else out there have this problem?
A while back, I mentioned grafting Cleveland headers to fits a Windsor, but I never backed it up with pictures. Here is a set of Hooker Headers that were originally made to fit a ’69 Mustang/Cougar with a 4V Cleveland. They show some surface rust, but the metal beneath was good to work with. With a few u-bends, a pair of flanges by Stahl, and a few weekends of test fitting, I have a set of, don’t laugh, custom headers that fit my car and engine requirements. Perhaps a bit cheezie, but it kept me busy by practicing my welding and metal work and it was cheaper than buying a real custom set.
Racing Cougars (the other Mustang), for four decades...
Last edited by k718cougar; 09-19-2016 at 01:05 PM.
Reason: Photos added.