A Tempest on the Track (Part 4)

To preface my last post in the series, this is not a current build. It is only a dream. No Tempests were harmed in the making of this series.



When I ended yesterday’s post, I promised my next missive would cover mods I would make to the body. Let’s get going with the interior since it’s easy – everything must come out. Okay, not everything – I’d keep the headliner, any good interior vinyl panels, and the dash. Factory carpet with its layer of sound deadening is dead weight, so it’s out to be replaced by clean, painted metal surfaces. Stock seats weigh a ton and are completely incapable of keeping you firmly behind the wheel when pulling a 1G turn so they’re out to be replaced by a couple of lightweight racing buckets. Two instead of one because I’m smart enough to know riding along with a good driver at the helm is great way to improve one’s driving abilities. No back seat since I don’t want any backseat drivers along for the ride, and the racing seats and rollcage I’d install will make getting into the rear nearly impossible. The aforementioned rollcage would have a horizontal bar behind the seats to mount the shoulder belts of two five-point harnesses (driver and passenger).

Finally, I’d want to do something with the exterior. The car must be orange…., or red……, or beige with an orange stripe or two. If you’ve read any of my blog posts right before this series, you’d know I’m struggling with what color to paint my ‘65 LeMans. Picking a color for this car would be just as difficult for me. Maybe I’d just ask the lovely Loriann (my wonderful wife and talented artist) to make the choice for me.

Yesterday I posted a photo-shopped image of Keith Collier’s very nice ’61. I showed it lowered with bigger rims and low-profile tires. Today, I added a front splitter and racing seats to the photo, which I’d also do to the real thing. I’m on the fence regarding a rear spoiler since part of my attraction to the ’61 is the down-sloping rear end. The ’62 with its fins and the ’63 with its more square-ish rear end might get a spoiler though.

So that’s it. A Pontiac that could take on the twisties with plenty of aplomb. Will I ever build it? My previous daily-drivers were Corvairs modified for time trials. I loved them and I miss them, so chances are very good I’ll have a vintage track car again, and it may as well be from the Wide-Track brand.

A Tempest on the Track (Part 3)

Credit for original photo: Thomas A. DeMauro / High Performance Pontiac / Hot Rod
While my first two track-car posts haven’t elicited any comments here, they have sparked some conversation on the Facebook posts I made to drum up readership. Jon Wood replied with the following: “The torque tube wall thickness was increased from .050 to .090 for the 326. The rope shaft and torque tube were used with the SD421 Tempests, and they held up fine. The automatic transmission is pretty sturdy, the 3 spd manual leas so but suitable for a stock 326. The 4 spd manual was not very sturdy.”

So, the ’63 drivetrain is the only one designed to be robust enough for the three-hundred plus foot-pounds of torque the LS1 would output. Would I then opt for the ’63 over my previous choice of a ’61, or would I stick with a ’61 and swap in the beefier torque tube? Since I’m dreaming, I’ll go with the latter.

As promised, I’m moving on the wheels, tires, and suspension with this post. Interestingly, according to Wikipedia, the first-gen Tempests all came with a unique-to-GM "four-on-four-and-a-half" bolt pattern. Fortunately, this is pattern is the same as that found on early Mustangs, so the aftermarket supports it. The stock Tempest could be had with a six-and-a-half inch width if you ordered air conditioning. The stock tire on these was called 6.5X15. This system has gone the way of wide whitewalls, so the modern equivalent is P175/75R15. I’m going to want to keep the same outside diameter (25.3”) since I like the fit in the wheelwell and the speedometer will still be accurate. I’ll go a little wider than stock (7”) and much larger in diameter (17” - shorter sidewall for good handling). With a fender massaging and the right offset, I’m figuring I can get away with 205/50R17 tires. It’s a popular size with plenty of high performance options out there.

On to the suspension. The front end is pretty straightforward sixties’ GM with unequal length a-arms. I’d put in stiffer springs that lower the front a couple inches, bolt on performance shocks, and fit a beefy sway bar. The rear, however, is a bit trickier. The trailing arm suspension was only offered on two American cars, the first-gen Tempest and first-gen Corvair. The design is basically the same as that used on VW Beetles and, with much success, on early Porsche. GM improved the scheme in the Corvair for 1964 by installing a transverse leaf spring and softening the coils at each wheel. What this did was tie the left and right side wheels somewhat together to minimize the tuck-in that could take place under adverse cornering conditions. There’s a lot written out there about the Corvair suspension, but suffice it to say the transverse spring is an improvement, and I’d implement on my Tempest somehow. The rear end would also be lowered with the overall spring stiffness (coils plus transverse leaf) being higher than stock.

I’ll finish up my dream build in the next post where I’ll address body modifications.

A Tempest on the Track (Part 2)

Continuing yesterday’s dream, I’ll now pick which Tempest from the first three years I’d have and follow up with how I’d make it track-worthy.


Credit: Thomas A. DeMauro / High Performance Pontiac / Hot Rod

To me all three years of the first-gen Tempest (also known as GM’s Y-platform) have attractive styling details, but I’d prefer a ’61 for a few reasons: the split grill, the ribs down the center of the hood; the side “swoop”; the lack of rear fender fins; and it’s from my birth year. Honestly, though, I’d try to find the most rust-free example from any of the years.

On to the modifications. At the end of the last post, I shared that the stock manual drivetrain will handle the 352 foot-pounds that the 326 V8 was rated for. I also mentioned the ideal 50/50 weight distribution of the car, however, that was with the base 196 cubic inch Trophy 4. Bumping up to the V8 brought with it an additional 260 pounds (roughly 650 pounds versus 390 pounds) all on top of the front wheels. So I need a lightweight engine that puts out around 350 ft-lbs. Lo-and-behold the LS1 engine weighs roughly 390 pounds, and, depending on what vehicle it came in, puts out anywhere between 335 and 365 ft-lbs. So an LS1 it is. Hopefully, a bellhousing adapter and a custom coupler to mate the crankshaft to the torque shaft don’t add too much weight. I’m going to have to use the torque shaft as-is, so the engine mounting location may have to change, but this can be accommodated with the required custom engine mounts.



Okay, the GO has been dealt with; let’s turn our attention to the STOP. From what I’ve seen in photos and read on the web, Pontiac used Corvair-style car half-shafts to spin the rear wheels. The small nine inch diameter drums only accommodated one and three-quarter inch wide shoes. An upgrade the Corvair folks make to their first-gen cars is to convert to truck half-shafts and drums. This gives a two inch increase in brake shoe diameter and a quarter inch more width. I’m not sure if this is an option for the Tempest. With the swing axle rear suspension (more on this later), I’m very limited on swapping in disc brakes. There is a Corvair guy that’s making rear disc setups for the Corvair car, and the images I’ve seen of the Tempest brake setup look a LOT like a Corvairs, so maybe this is the way to go. The fronts should easily accept a disc brake swap, so I’m not worried about that. Stock wheels would not fit over the calipers, but the stock stamped steel wheels were going to be swapped out for something larger and lighter anyway. I’ll address that in my next post.

The other end of the braking system is the master cylinder. Back in the day, you could only get a single reservoir master cylinder. I’ve done the easy conversion from single to dual on Corvairs, so I’d do the same on the Tempest. Regarding power brakes, I don’t think it was available. The same was true for the Corvair, so I’m not surprised. The light weight wouldn’t really necessitate the added braking pressure.

That’s enough for today. The next post, where I talk about suspension and wheel changes, may not appear until Monday.

I’d love some feedback on what I’m dreaming about here, so feel free to comment.

A Tempest on the Track (Part 1)

Wow; nearly two hundred reads of my last post in roughly twenty-four hours; and one of my recent posts is up to 500 views. I am humbled. With that in mind, A few someones are finding my missives interesting, so I’ll try to be more verbose – i.e. more posts. What to write about? Here’s a diversion - building a race-ready Pontiac. Not a NASCAR high banks runner or a quarter-mile burner, but a nimble Poncho for road-course track-days and autocrosses.

My previous car life had me immersed in all things Corvair. This included restoring one with each of my four daughters. Also, since they were considered a poor man’s Porsche, I took advantage of their inherent good handling and built a ’62 two-door sedan into a hot daily-driver for me that was a blast in the curves with cut off front springs, front anti-roll bar, relocated battery, and a custom exhaust. I sold that car and proceeded to turn a plain Jane ’68 two-door hardtop into something track-worthy with the same sort of modifications. This car was a little more challenging since it started life with an automatic transmission, so I had to swap in all the bits necessary to make it a manual. When I decided it was finally time to turn my attention to the LeMans, I sold all the drivable Corvairs to focus on only one old car.

Since the ’61-’63 Tempest is much like the Corvairs with a transaxle in the rear, an available four-speed manual transmission (starting in ’62), four-wheel independent suspension, uni-body construction, 50/50 weight distribution, and only 3000 pounds in curb weight, it would be a great platform for a corner-carver.

What I wouldn’t want to build is a car that was constantly breaking. I’m thinking the week link would the drivetrain, specifically the torque shaft and transaxle. I love this photo I found on HotRod Magazine’s website. It shows the independent rear end, the transmission directly in front of the differential , and the infamous rope drive bringing torque to the trans from the front-mounted engine. The most powerful engine you could get in an early Tempest was the 1963 326 cubic-inch V8 rated at 352 ft-lbs of torque. This was quite a bump up from the 235 ft-lbs. from the 215 V8 available in the 1962’s. I read that GM did not bother beefing up the transaxle or torque shaft for the 50% increase. Hmmm.

I’ll continue this "drive"train of thought tomorrow.