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Updated - 10/13/18 - 1/18 1969 IMSA Big Block Road Racing Camaro

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Taking an inspiration from Gene Felton's efforts in road racing in his 1969 Camaro.

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In the rough and tumble early years of "run-whatcha-brung" IMSA road racing, Felton stuffed a Big Block Chevy engine into it, with moderate success.

Taking that concept to the workbench, here are the early results.

1/18 scale GMP Streetfighter body and chassis, and some custom 3D-printed Corvette wide-body fender flares.

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Putting a Big Block from a Carousel 1 L88 Corvette, with crossflow 4x2 Webers (I think from a GMP Lola).

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Quick Change rear end from a GMP Winged Sprinter, which will require a custom drive shaft (details on that later).  Wheels and tires from a GMP Can Am McLaren, as well.  Going to be an interesting build to get the wheels and tires to mount, but I think I have that already figured out, just waiting for some parts to arrive.


Stay Tuned!

Edited by ibj40

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Nice!   Keep it coming.

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Made some progress on fabricating the driveshaft.

Took delivery of several sizes of aluminum and brass tubing.


Measured the OD of the original driveshaft, and the ID of what appeared to be the most appropriately sized tubing. In this case, a brass thin wall.


ID needs to be 5/32, so I chucked the front and rear u-joints up in my "lathe", and dispatched the appropriate machine tool.





And now here's the front and rear, ready, and then jointed with the brass tubing.



Attaching the wheels to the front and rear axles next.

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Okay, got into fabricating the front axles with which I will be widening the track to get the tire out to the edge of the flare.

So, this is the stock stub axle coming off the upright. Remember we are trying to accomplish two things here, widen the track, and locate a set of non-standard wheels onto the model.



I am going to create a two piece apparatus. One to fit over the stub axle.


The other to fit into the wheel (although I did drill out the wheel to allow this piece of tubing to fit inside the stub axle piece.


The wheel adapter is about the same length as the stub axle adapter, owing to the amount pressed into the wheel being about the same length as the stub axle.

Going to run a screw down through the center of the wheel into the original plastic stub axle, so that the wheels will roll.


Next, moving back to the rears.  Here's a teaser.

Edited by ibj40

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So, working up a fuel filler set up. Many of the 1/18 scale GMP 60's Trans Am Camaro models have a quick fill device in the middle of the rear deck lid.

Here's one, for example.


The GMP Street Fighter Camaro body donor for this custom didn't have the deck lid cut-out, so I thought I would create a filler similar to the one on my first '69 Camaro racer. Picture's a little grainy but I think you can make it out.


Here's a picture of that same rear spoiler, now painted flat black, hanging in my garage/workshop.


I took the fuel cell body, and added a center section  (resin cast by Mike Kotwick - Swede70).


Fabricated a neck out of aluminum tubing, and added a flip-type fuel filler cap (attached it to a smaller piece of aluminum tubing for ease of installation and positioning).



Then took a Dremel to the deck lid until I had enough clearance for it to sit flush.




Might shorten up the neck just a bit when everything is final, but right now, we've got it pretty much roughed in.  Also need to add a vent, pondering a combination of aluminum tubing and shrink wrap (like I used on my custom dump cans).


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Clearly this was going to be a problem.

So, while waiting for the new bodywork to show up, I have moved the engine back about .25" (in reality, which would equate to about 4.5 inches in the real world).

Re-established the front mounting point for the engine, and very glad I had not glued the custom driveshaft together yet.

Had to cut some firewall and transmission hump for clearance, which will require some cosmetic fabrication, but did manage to improve front/rear weight distribution.


Played around a little more with the fuel filler, more pictures tomorrow.

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Not sure how clear these pictures will be, but I found another fuel filler cap (in a lot better condition, and made of chrome-plated diecast in lieu of plastic).

This picture, more or less, tells the story.


From left to right, original cap, original adapter, original ID of fueling tube, sourced brass tubing, revised ID of fueling tube (with brass insert), and new cap.

The new cap fits perfectly into the brass tubing, and with a heavy duty pin vice, I "drilled" out the fueling tube to accommodate a brass insert.

Here's the two, more or less, side by side (old on the left, new on the right).


I think it makes for a better looking detail.


Still waiting on the new flares, so started working on repairing the firewall after I moved the engine back. Might have some pictures tomorrow.

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Now,the firewall.

This is what a stock GMP Trans Am Camaro firewall looks like.

44414698984_ae5c9de793_n.jpg     44414695494_fdc51c66a4_n.jpg    43322383470_995ec952d7_n.jpg

This what it looks like when you put a Big Block in the engine compartment and then move it back a scale 4.5 inches.


I had to cut it in the middle to allow a more simple means of grinding away the plastic.  I knew that the middle was going to get really thin, and wanted a controlled cut, versus a jagged break.  The problem, then, is how do you reconnect the two sides, and then also, how do you seal the hole.

I decided I would use a technique that I developed when building my custom race trailer, so I got some 1/8 inch square styrene shape, and formed a channel using a Dremel plastic cutting blade.

45135450241_f64e462996_n.jpg      45135447411_ac70f44cd9_n.jpg                                                                                         43322240570_ee256daa4a_n.jpg      45135442031_6af670981e_n.jpg

I then Superglued that piece across the top of the firewall.



And now the fun part.  How do you fill in that hole, but also making sure that you don't impose into the passenger compartment and interfere with little things like the driver.  I decided that I would try to create the new infill by laying in JB Weld, knowing that it will adhere to the plastic of the original firewall (but also knowing that it will take quite a bit of grinding to smooth it up).

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Test fit of the body to make sure it will all work.

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And ready for the JB Weld.



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And now the grinding starts.

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Okay, so back in the day, when I was working on real racers, one of the things we had to focus on was getting water to and from the engine and radiator. On my first racer, a converted '69 Z28 Camaro, running a stock radiator and engine, it was easy. You just had to go down to the local car parts store, buy upper and lower hoses and you were done.

As we got into semi-tube frame, and tube frame, things got a little more difficult. Our second racer was a C3 Corvette, on a semi-tube frame (front clip was stock, rear clip was fabricated to hold a Franklin Quickchange center section with a coil-over suspension). When we got it, it was set up for a Small Block Chevy engine, with the radiator in the stock location. Well, in order to improve cooling and air flow, we decided that we would lean the top of the radiator forward, in lieu of how the stock configuration was, therefore setting up the challenge.

Once we got the aftermarket radiator located, we then set about trying to figure out the best routing for the hoses. Clearly, stock hoses weren't going to work, so what we did was eyeball the route, and sketch up a solution. I had a buddy who's Dad ran a couple of car parts places, so once we had a design in our head, I'd go over and stand in front of a wall of hoses, and do "research". The conclusion to that process is the inspiration to a solution for this model.

First, I knew that the hoses from the Carousel 1 Big Block weren't going to be a direct match to the GMP Camaro radiator, but then moving the engine back a scaled 4.5 inches added a degree of difficulty.

Here's how they sit.


And here's the solution, again, straight from my racing days. On the racing Corvette, we decided that we would fabricate two aluminum tubes, and connect them to the radiator and engine with very short pieces of hose. In that case (as opposed to what I have fabricated for this model), we welded a bead around each end of the aluminum tube to give the hose clamps something to capture. As you can see here, I have captured the hose inside the piece of aluminum, but I am using a fabricator's license to say that's okay for this model.


Hard to see the lower hose, but it's there, and connected. These are just on there loose for now, as there is still a lot of detailing to be completed before final assembly.

While I was in the shop last night, I also shortened the drive shaft brass tube, so that it is now the correct length.


Worked some on the Blob, and still not satisfied with that solution, and the new bodywork came in, but not enough time to fab it up onto the Camaro body and take pictures (plus, I had to break away frequently to watch the Red Sox/Yankees game).

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To misquote an oft-used line from the Old West: Meanwhile, back at the firewall.

Clearly, the Blob was not going to be a workable solution. While it was fun, it did not prove to be functional,

So, back the the drawing board, or in this case, the cardboard.

I took a piece of cardstock and started cutting away everything that didn't look like a firewall. After a few starts and stops, here's where we ended up.

30307586767_c2843f275f_n.jpg  30307586687_fb8ca0b96b_n.jpg  30307586457_c577d52851_n.jpg  

This is what a stock, unadultered firewall looks like.


This is two GMP Camaro chassis, side by side, just to show how far back the new one has to be to clear the relocated Big Block engine (the piece of styrene is just there as a point of reference).


I will use this pattern to produce a new firewall out of styrene sheet, which will be this weekend's fun and games.

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New bodywork came in, and I fooled around with some test fitting. Remember, these were intended to fit to a 1/18 scale Carousel 1 Corvette, so some modification will be required for a final.

This is with the body sitting on a stock chassis, with standard width wheels and tires.


his is with the wider wheels and tires , loosely fit under the final chassis.


Now here are some other profile shots.

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44324723355_dac0dfb69a_n.jpg 30296092077_187defa116_n.jpg  44324814345_fe4085b96e_n.jpg

Going to be an interesting process getting the flares to blend into the Camaro bodylines (and I also have a Vega sitting in the wings, for a similar exercise).

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