Actually it ran a few weeks ago but I was too busy working on it to post on the blog. As mentioned in the last installment we had a few problems with the rear diff. Well that turned out to be a saga, dragging what should have been a 2 hour job into two weekends. More rusted bolts were the culprit. After it was out there was a lot of work to do to repair the bolts we broke. One of the holdups was getting a new nut for the top of the power plant frame. It is a special nut with no hex on it. It has a splined area that is designed to grab on to a thick steel plate that prevents it from turning. The “nut” was fused to the bolt that we cut and we could not separate them. To make matters worse Mazda does not sell this part individually. They only sell it as part of the whole power plant frame!! Luckily the internet came to the rescue again. On a racing message board, roadrace-autocross.com, someone told me of a race shop that specializes in Miatas and sells a version of this nut that they make themselves. It wasn’t cheap, but it was a quality piece machined out of stainless steel with a big hex on the top to keep it from spinning. It didn’t have the spines, but a finely machined area that was a “tap fit” into the steel plate. It worked just fine. Edit: the shop is Advanced Autosports.
So while waiting we took everything off the old engine and transfered it to the new one. I broke a bolt on the alternator and when my dad tried drilling it out the drill it walked sideways into the softer aluminum of the alternator housing and ruined it. We split the cost of a new one. The rest of the engine accessories switchover went pretty smoothly save for a missing bolt or two, which we found later. I had noticed a difference in the flywheels. One was missing some material from the backside. After consulting the great internet again (www.miata.net) I found out one flywheel had been lightened. There is a ring of material on the backside about 3/8″ thick, that is easy to machine off and can shave 3 pounds from the otherwise stock flywheel. If you are doing a clutch job on your Miata and want to lighten up your flywheel for increased performance this is a good “cheap” option for you. Since SCCA ST rules require a stock flywheel I had to swap over the un-lightened one.
The diff wasn’t to hard to install. But the engine was. It was just a case of getting it lined up so the motor mount bolts would go into the holes. We had to swing the engine back like a pendulum on the hoist and we would always get stuck about 1/4″ from everything lining up before we ran out of slack. We played and played with the engine leveler, the chain slack, moving the trans around under the car. It took about two hours. This whole time my Dad and I are getting frustrated and barking orders at each other and arguing about how to make it work. Not fun. I think we finally took one of the motor mount brackets off the engine to wiggle it in there. Once we got the engine bolted down, got the powerplant frame hooked up, and the drive shaft in we called it a day and pushed the car back up the driveway to finish it the next weekend. Yes, another weekend spent working on the car. There would be more to come as you shall see.