Ferrari 250 GTO / Pontiac GTO-powered

[Pierre Rivard]

So boring when everything fits on the first try. I suspect this one will be a bit more interesting.  ?

[Gramps46]

Appreciate the update.

[larman]

This is another really cool project, very nice work on what you have done so far!

[Scott8950]

I just picked this kit up friday I'm planning on a hemi or nailhead gasser.

Your build awesome I'll be following.

[89AKurt]

Just saw this, will be following.  The wheels really work well.  So how do you craze the paint, the dash would look perfect with that texture.

[gotnitro?]

Fantastic theme build 

Looking forward to your progress 

[89AKurt]

I looked through the other thread, saw that hot primer crazes the plastic.  I saw that Spot Model was selling red paint that has a texture, for the Testa Rosa valve covers.

[larman]

As far as the hood, perhaps you could cut the blister out, make it a little wider and raise it up? 

[Ace-Garageguy]

On 4/26/2023 at 2:10 PM, larman said:

As far as the hood, perhaps you could cut the blister out, make it a little wider and raise it up? 

I'm going make a mold of the original hood, then make fiberglass a copy and do essentially what you suggest to the copy, then make a mold of the modified copy, and then make another very thin copy of the modified hood in the second mold.

Stay tuned. All will be revealed.  

[cobraman]

Oh, I am liking this !

[Ace-Garageguy]

If there had been sufficient hood clearance with the engine located as shown earlier, a bit too low, I would have gone ahead with it in the "it's only a model" frame of mind. But because I'm going to have to do a custom hood anyway, I decided to put the engine at a realistic height from the road surface, so if this thing was a real car it would be entirely drivable. I made up mounts that will pick up the block in about the right places, and hold it at the right height.

From the side, we see we now have plenty of room for speed bumps, etc. We also have worsened the interference between the carbs and the hood, causing the huge gap at the rear.

As the original kit was intended to be a curbside, the front frame is simplified and not very correct. Also, I want to do pose-able steering, and there will need to be provision added for some kind of upper suspension lateral links (control arms) to accomplish that.

The ancient 1/25 Aurora 250 GTO kit has its share of problems, but the front frame is more representative of reality than the Gunze design. If it hadn't already been heavily glooed together, I could probably have adapted the crossmember and all the suspension.

I liberated the Aurora front crossmember after removing the glooey suspension mess. The old gluebomb Aurora 1/25 kit is slated to be rebuilt as another "what if" M/SP drag car, with a straight front axle, so it graciously donated the IFS crossmember it won't be using.

Next trick was to laminate a .020" styrene face to one side, for additional strength and thickness.

The first rough position fit of the new crossmember. I've looked at photos of bare 250 GTO chassis, and there seems to be some variation from car to car. So this isn't going to be anything like a rivet-counting exercise, and the story if it misses the mark of perfection is that the car had been wrecked, acquired cheap with no engine, and the forward frame section and suspension were rebuilt by a competent fabricator, but not following the original blueprints. This is entirely feasible in reality. The lower control arms as supplied by Gunze will remain, but everything forward will be pretty much scratchbuilt. This also lets me make upper control arms that will hold spindles for pose-able steering. The edge of the laminated rear face is visible here. A curved crossmember between the engine mounts has also been added, to lessen the torsional loads on the frame tubes, and stresses at the mount locations on the block (thought out in advance, so the pan could be dropped with the engine in the chassis it it was real).

. Everything forward of the control arms carefully removed, and additional .020" styrene laminated to the front face of the new crossmember, with appropriate "lightening holes" added.

 

[NOBLNG]

Cool project.? I will follow along.?

[chris chabre]

making me want to dig out my ferrari drag car!

[Ace-Garageguy]

On 5/1/2023 at 7:31 PM, NOBLNG said:

Cool project.? I will follow along.?

Glad to have you aboard, sir.  

On 5/3/2023 at 5:40 PM, chris chabre said:

making me want to dig out my ferrari drag car!

I hope you do. That's one of my favorite builds on this board.  

[chris chabre]

On 5/7/2023 at 12:41 PM, Ace-Garageguy said:

I hope you do. That's one of my favorite builds on this board.  

thank you!!! I should update you on what I have going on!!!!

[Ace-Garageguy]

Nothing too thrilling, as my bench time is severely limited. But I DID finally find a cast-iron Pontiac exhaust manifold with close-to-right port-spacing to match the engine I'm using, and started making flanges for custom headers.

 

 

[Ace-Garageguy]

Hit a wall on this one, as none of the headers I have here are even close to workable. I don't want to use solder, my alloy welding rod that works great for under-car exhaust parts is too hard to form the tight bends for headers, and so far, nothing else I've tried is really acceptable...including insulated 16 gage wire that almost does it, but won't hold bends permanently.

I started making up some primary pipes from hot-bent styrene rod, and it looks good so far. Problem is, the area I have to fit the pipes into is difficult to access for full-scale hands, they have to be quite accurate to do what I want, and I don't want to bugger up the engine in the process.

But I think I have a solution. I'm in the process of making a fixture that represents the engine, with the heads at the right angle, drilled to slip the styrene rods into during bending, a rod that represents the frame tube they have to clear, as well as a target where the pipes need to terminate to hit the collector correctly.

PITA, but pretty much like building custom headers on a real car where I would have good access.

We'll see...   

[Ace-Garageguy]

Finished up a reasonable fabricated front crossmember, and got it in place. Also shown are the closest header sets I have here, none of which are workable. Hence, the need to scratch 'em.

[Scott8950]

?

[Ace-Garageguy]

^^^ Obviously Photoshopped, but yeah, I have one of the misshapen Aurora 1/25 kits to do something very like that...actually, the one I'm stealing a few parts from to do this one, though I'll fix the awful proportion and line issues.  

Too bad what's in the box looks nothing like what's on it.

Edited June 2, 2023 by Ace-Garageguy

[Ace-Garageguy]

Finally moving again... The Pontiac V8 engine has similar exhaust port spacing to several other engines, but the angle the ports exit the heads is very different. Hence no kit headers come close.

After a fair bit o' head scratching, I figgered I could rework some 427 Cobra headers to work, though there's a lot of cut and paste involved. Still, it's easier than completely scratching a set.

Also, because of the lowered stance I'm going for, the under-car exhausts have to go. Ray Kurn (Cobraman) to the rescue with a set of Cobra side-pipes that otter look pretty good.

I have a thing for poseable front wheels, believing they add more realism to a model than most other mods. This kit is essentially a curbside, with a straight plastic rod for a front axle. To get some steering action, it's necessary to make up a set of upper control arms that can support spindles. They need to be square and symmetrical.

Measuring the existing lower arms gave me a baseline, but I realized that the new front crossmember I'd made wouldn't let me use arms that long ...without introducing excessive positive camber.

The slop on top of the frame tubes is putty to finish up the fill job on the previously somewhat hollow sections. Curbside kit, remember?

Setting up a measuring jig let me get an accurate overall dimension for upper arms that would fit the available crossmember mounting location (black dot).

 

 

 

Edited October 3, 2023 by Ace-Garageguy

[Ace-Garageguy]

As we get closer, final clearances get tightened up. Floor (and tunnel, of course) had to be reworked a little more than originally planned to clear the shifter linkage. Firewall step needs a little more too, so it's time to look at everything around the engine.

I drilled the front of the timing cover and added a rod to the back of the lower pulley so I could mock up where the pulley face would end up relative to the crossmember. Turns out the engine needed a little additional setback too, so the clearance hole at the driver's footbox got hogged out more (it will be closed with plastic sheet stock). The black radiator and its support to its right are from the ancient Monogram 1/25 kit, and might be used. The white rectangular part is the frame front from the Gunze curbside, which won't go back in. There are variations of these cars as-built, and this model represents a car that's been hit hard and repaired, so representing functionality correctly is more important to me than rivet-counting accuracy to any prototype.

One thing I noticed about the Gunze kit...and other 250 GTO kits, oddly...is that the floors don't always end up in the right place, spoiling the fit of the body to the frame, and ruining the stance. While I was working on the firewall, I shaved about 3/64" from the bottom of it where it contacts the frame molding. This gets the rockers parallel to the frame all the way along, which they weren't as-molded. There is just no substitute for measuring and test-fitting.

Since we're getting rid of the under-car exhausts, we don't need the big ol' klugey rings it mounts to. They're easily shaved...carefully...with an X-Acto chisel-tip blade, and any errant divots get fixed with a couple dabs of Tamiya white putty. The 4.175" note refers to how far it's s'posed to be to the very front of the frame where it used to contact the body shell. Keeping measurements like this handy helps to keep the wheels centered in the wheel-arches.

Photo below shows the first side-pipe assembly in place, the start of the modded big-block Cobra headers, and the junkyard Ford 9" diffs I'll be choosing from.

Up close and personal on the side-pipe assembly, pinned to the rocker, and feeding through a new hole in the fender. I like it. 

Edited October 3, 2023 by Ace-Garageguy

[Scott8950]

Glad to see you back on this awesome build. This build is gonna help me tremendously with mine.

[NOBLNG]

Nice work! I like the side-pipes too.?

[ea0863]

So sacrilegious. I love it!