Something funny...[Nitro Funny Car build thread]

Chevyonfuel

Tubes...

To start at the beginning on this bit, ordinarily a Funny Car chassis has asymmetrical tubes immediately in front of the engine, the reason being the oil pump on a 426 Chrysler pokes out the bottom of the engine and fouls on the tubing spanning the bay immediately in front of the motor plate ears.

In its previous life, this chassis used a 417 Donovan with a tri-drive setup meaning the oil pump went straight out in front, driven off the camshaft. For that reason the chassis was built with symmetrical tubes. Having installed a 426 based motor back in the car, some work was required...

                                                                                                                                                 

It's not immediately obvious from the above photo, such is the tidiness of the amended tubing, but the vertical bar to the left of the shot used to be cranked over, as visible in the photo below.

                                                                                                                                                 

With the flexibility in the chassis, it needed the motor to be removed and the chassis locked up with some temporary tubes to stop it springing loose. All sorted now so it's onto the body mounting.

Speaking of which, the body is hanging off a ceiling mounted rig to allow easy vertical movement for lowering it and marking out panel placement before lifting it clear of the chassis. In the next few weeks the tin work should go in. I'm waiting on a replacement wheelie bar kit to arrive from the US. These aren't pricey but have a fair chunk of CNC work required for the brackets that hold the wheel - fingers crossed it arrives in a few weeks.

A proper full beans update should follow soon .

Chevyonfuel

         
Dipped beam? MOT fail for certain...

                                                                                                                                                 

The frame, or 'bath tub' as it's called that sits around the cockpit and provides the base to mount the body tin work, is almost complete. A steering linkage box has been added - normally these are just a notch made into the tin work itself, but there was the option to build a box for it instead.

                                                                                                                                                 

The advantage of this is some protection to the steering linkage and just tidies that area of the car up a little bit.

                                                                                                                                               

In theory the wheelie bar assembly will be winging its way across the pond in a week or so. The bulk of the tin work will become an easier task to put in now the bath tub is complete. So in about a month most of the major stuff will be finished on the tin side .

Chevyonfuel

Picture the scene, you're in your workshop, it's measuring -3 degrees indoors because the heating doesn't work, and then it snows, indoors, because there's a hole in the roof...

Race cars are still built in humble surroundings, it would appear

To ensure the body sits right on the chassis, further body amendments were needed. These went beyond the fore mentioned cutting in a new bonnet line (because it was wonky) but also re-cutting under both A-pillars to correct the roof height. There's a lot of glass work to do, but when it's done it's done, and we can start tinning inside.

                                                                                                                                                 
Inside the cockpit, the bath tub and fire wall mount is located.

                                                                                                                                                 
Still need to address the roof area where the cage protrudes, but only barely - a small bubble will fix it (similar to GT40's back in the day).

                                                                                                                                                 
To get an arrow straight line on the bonnet, aluminium strips that are folded and used to glass into. It'll be sharp and clean once re-glassed.

                                                                                                                                                 

                                                                                                                                                 
The makings of the final stance; as low as practicable and period correct as much as it can be within the rules. I'm pleased with it.

                                                                                                                                                 
An incision to open things up and get the A-pillar and roof properly straight, not nearly straight.

Onto paint... sort of. Having decided on a painter and letterer, the quote took some digesting, but you get what you pay for. With one eye on the maintenance side of the paint (accidents do happen), I wanted to swing away from House of Kolor as although they're wonderful, you have to use their primers and lacquers and suddenly the cost becomes eye watering.

A more economical way of getting a colour you like, is looking at production cars. In this case, I'm known for an involvement with Aston Martin, so that's helped, and also some fingers in pies at Audi. The final decision on paint looks something like these (remembering the original rendering I had done, so so many years back - time flies).

                                                                                                                                                 
Audi Sonoma Green

                                                                                                                                                 
Aston Martin Diavolo Red

The lettering will all be done by hand, not in graphics as I'm a bit of a purist and a Nostalgia Funny Car should have paint not stickers (IMO).

I'll try and post a full fat update after the coming weekend, slight lack of internet at home might scupper things though.

Chevyonfuel

I cannot recall if I went into detail about wheelie bars on Funny Cars, so assuming I didn't (and with a visual aid below, now that it fought its way through the snow), wheelie bars...

                                                                                                                                                 
Wheelie bar kit assembly. The turnbuckle to the left is adjusted to raise of lower the ride height of the wheel.

In a regular drag racing application where the car (or bike) runs on slicks and has a chassis setup enabling it to providing maximum traction to the rear wheels, the wheelie bar is used to limit the amount of vertical lift of the front end. If it's going up, it's not going forwards...

In a Funny Car (and Pro Mod to a similar degree), the wheelie bar has a different function. Running on 34.5" diameter tyres that are 17" wide, you have a fairly wide contact patch, which under compression from drive train forces at launch, can be adjusted depending on track conditions.

How this works is fairly simple, but not obvious upon first inspection. While the wheelie bar does prohibit the car from flipping over, you generally find with a chunk of horsepower, the tyre slip at the hit doesn't work the tyre in the same way (not as much instant grip). On a good track, where you're not clawing for as much traction as you can muster, you run the wheelie bar wheel clearance to the track as small as you dare. The result is the hit on the wheelie bar is quite quick, and the car then 'gets up' on the rear tyres as they're not scrabbling for grip. As the tyres centrifugally expand with speed, the contact area becomes more and more narrow:

                                Slow motion video; you can see the wheelie bar touches down a couple of times. This is caused mainly by the initial tyre deformation (going out of round as it squats) and then as rotational forces kick in, it starts to bounce back into shape as it gains traction.

On a poor track, you'd raise the wheelie bar which allows the rear tyres to squat more, leaning on the sidewalls and allowing a greater contact patch with the surface. The trade off is the risk of the front end becoming light or getting more air than you'd like, but it's sometimes necessary if you're struggling with a cold or marginal track.

Hopefully I'll have a full size update to put together next week (Monday night in theory). It's getting there slowly.

paulyoung666

Awesome posts , keep em coming !!

Chevyonfuel

You're too kind! I try and make it interesting, hopefully the next month or so will bring some updates that make all the dithering and baby steps to this point, make a bit more sense...

paulyoung666

Still hoping to see this in the flesh this year , part of my 50th birthday celebrations , Japan first though !!!

Chevyonfuel

I'll keep you posted as things progress, I'd hope to be getting some testing in (albeit the body in primer and not finished paint) somewhere between June - July. Too many toys occupying my time at the moment, so it needs a solid month on the Vette to get it back on course

Chevyonfuel

Firstly an apology for the lack of updates - it's been a busy time, things just haven't stopped. Like many things on the car, it looks a bit tardy until it's finished so we're trying to limit the number of photos. These will look infinitely better once they've been powder coated, but in any case...

                                                                                                                                                 

                                                                                                                                                 

Re-worked fuel and oil tanks. They might not look like much, but these were a pig to sort. The Corvette body's nose sits much lower than the previous altered body, and being a chunk shorter some trimming was required. This is what they used to look like:

                                                                                                                                                 

The overflow breather pipes were re-positioned, along with re-jigging the internal baffles in both tanks. The fuel tank has quite an intricate assembly of trap doors and shelves. The oil tank is just a shelf with some holes in it. In both cases it's simply to stop fuel surge under g-force. For aesthetic reasons, the filler caps were moved back, it just looks a bit nicer now. The tank strap of course needs replacing, but that's far more straightforward than all the Kellogs box templates required for measuring the tanks to get them re-shaped

We haven't measured the fuel tank capacity. At a guess although it's smaller, it's probably still around 15 gallons - more than enough for our needs, but you want to have 5 gallons left at the end of a run to ensure you don't starve the fuel pump. When the parachutes deploy the car would see a -5G force and subsequent fuel surge forwards, so having something means the pump's fed at all times.

Next up - tin work. The body is about to get glassed up and the dashboard is now in its final location, meaning the bulkhead can go in. Hopefully in a few weeks there'll be some decent photos to explain what all the fuss was about.

paulyoung666

Loving it [emoji106][emoji106][emoji106]