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Accurate Miniatures Corvette Grand Sport


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Funny. I always thought that the kit Webers were overscale - but the photo suggests that maybe they are accurate - do you have the MFH fuel line - that would work better - hard to source but the .018 is great for this scale …

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Gotta love the side draft weber, small block Chevy engine. It is so badass looking. That's a great ref picture you have there to follow. Traco squeezed a lot of power out of it for its time back in the sixty's. I believe they ended up with 377 cubic inches. i studied up on it back when I did mine but have forgotten most of what I learned. There is a you tube video of the guy that was one of the main guys behind the Grand Sport project and he goes around one of the remaining Grand Sports explaining a lot of things about it . A video well worth watching. I will post the link if I can find it.

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I decided that the molded fuel distribution is a no go.

Gluing small ferrules on the fittings at the end of the molded hoses, chop them off and glue to the 4 carbs to create fuel inlet fittings to carbs.

Fuel manifold scratch built with the fuel in line and the four out to carbs.

Why yellow? Cuz I like yellow...

 

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Then I had this silly idea to check engine integration to the chassis and body.

I have to admit that at this point I got close to shelving this one.

Got back to it after thinking it out. Main interference is right forward carb to hood as well as the newly added oil fill to hood.

Engine was sitting high overall but more so on the right side. I slowly lowered rear mount by removing material on the tranny (not visible once built) and I bent and sanded the 2 engine mounts to lower the front. Some finessing of hood profile and thickness helped too.

 

 

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I figured I should check the rad clearance. Not even close. 1/8 inch interference.

First picture has an X where the rad inlet was on top of the rad. Chopped that and making a new inlet lower.

I also lowered the lower rad support.

2nd pic show the engine in it's new position. You can see I created some relief on the firewall wirer the distributor will be.

I also added the engine coolant out where there was none in the kit design (?!). All these port location adjustment will require making my own coolant hoses.

I would love to get to final chassis/engine painting and assembly but one more task awaits me. Exhaust system...

My apologies if I am covering this with too many details but I plan to use this as a logbook to help me with my next GS build.

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On 6/3/2022 at 11:53 PM, absmiami said:

Funny. I always thought that the kit Webers were overscale - but the photo suggests that maybe they are accurate...

The side-draft Webers most people are used to seeing are 40 DCOEs. Each venturi is 40mm.

BUT...Weber also made 45, 48, 50, 55, and 58 DCO-series side-drafts that look like 40s, but bigger. (NOTE: those are the only sizes I'm certain of; there may be more)

They were seen on exotic production and racing engines in the '50s and '60s.

The Grand Sport engine ran four 58 DCO3s.

https://www.jalopyjournal.com/forum/threads/chevy-4-x-58mm-sidedraft-weber-inlet-manifold.1002358/page-2

Edited by Ace-Garageguy
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Some Indy cars - im thinking the climax engined Brabham Cooper of 62 also used 58’s - and some of the Lotus Climax engines ran the large Webers - like the climax engine im making for my dormant Lotus 32B build - the photo w the mic is very instructive - but fitting a scale correct engine w

scale correct carbs into a 24th sc Corvette w NOT scale body panels is ….   Builders purgatory …

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Wow!

I'm amazed by all the fit conflicts this kit has and by your skill in overcoming them.

I'm curious, did the kit designers ever build one of these, or are the fit issues due to gradual mold degradation over the years?

David G.

 

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David and Len, here's my take on the fitment issues.

I don't see any mold degradation, the parts are crisp and straight. A homerun compared to old AMT/MPC kits for example.

What I see is that AM tried to create very precise assemblies that cannot live with the realities of tolerance stack ups.

As for lowering ride height causing the engine to crash into the hood all I can say is that I removed interferences until the chassis could mate to the underbody as it should (ie no gap to attachment points). I did allow some lowering of the front wheels to wheel hub interface but this should not have an impact.

Perhaps I did cause some of this, not sure...

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1 hour ago, David G. said:

...are the fit issues due to gradual mold degradation over the years?

No.

The size and shape of mold cavities carved in heavy steel blocks don't change appreciably over time.

"Degradation" appears as "flash" as the tightness of fit of mold elements to each other is allowed to loosen, and molten material squeezes out the resulting gap. Degradation also appears as misalignment of mold elements, resulting in exaggerated or "stepped" parting lines, caused by uncorrected wear of mechanical alignment pins and other alignment means. On model car bodies, misalignment of mold elements can manifest itself as slightly different body thicknesses from side to side, and in worst cases (probably where "repairs" have been made incorrectly) as misshapen roof pillars and sail panels.

Exaggerated "ejection pin" marks are also caused by wear of moving mechanical parts within a mold.

"Sink marks" aren't due to mold wear, but are caused by slight short-shotting (not injecting quite enough material during production), running molds slightly too hot, or de-molding too early.

Early de-molding is also what causes "warping", not mold wear.

Edited by Ace-Garageguy
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1 hour ago, Pierre Rivard said:

David and Len, here's my take on the fitment issues.

I don't see any mold degradation, the parts are crisp and straight. A homerun compared to old AMT/MPC kits for example.

What I see is that AM tried to create very precise assemblies that cannot live with the realities of tolerance stack ups.

As for lowering ride height causing the engine to crash into the hood all I can say is that I removed interferences until the chassis could mate to the underbody as it should (ie no gap to attachment points). I did allow some lowering of the front wheels to wheel hub interface but this should not have an impact.

Perhaps I did cause some of this, not sure...

I take back what I said now. You were going to have fitment issues whether you changed the ride height or not. They need to rename these kits "Some What Accurate Miniatures"  If these are just a repop of the revell kit that seems odd that revell would have so many issues. They are usually pretty good about fit.

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31 minutes ago, MarkJ said:

...If these are just a repop of the revell kit that seems odd that revell would have so many issues. They are usually pretty good about fit.

It's the other way around. The Revell kit is the repop.

Accurate Miniatures was a vary small company making very ambitious, highly complex, and beautifully detailed models.

For my money, they did a great job in spite of the issues, and the necessary corrections aren't seen as being "necessary" to the vast majority of builders.

But this build highlights the fact that a spectacular and accurate model can be built from a "difficult" kit with some applied intelligence, effort, and skill.

Edited by Ace-Garageguy
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Pierre, is there a way you could raise the engine mounts (on the block) allowing it to sit lower in the chassis? I had this issue years ago when I was building the ROG Jaguar XK-SS and converting it to a D-Type. The engine sat too high making the hood stick up, and not sit flush with the cowl.

I remember not only shaving the mounts, but moving them higher up on the block to get it to sit lower, and also shaving the inside of the hood for that extra half mil or so clearance. At least you're finding all this out now, and it's the reason I constantly reinforce to novices to NEVER paint your car first until ALL the fitment issues are handled if there's any at all.

Painting IMO should be one of the last things done in building a model.

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Mark, I like the new name haha! Parts are beautiful but integration is lacking hence all the reworks needed. This one is fighting me all the way but I'm not giving up. Not even close.

Bill E, I could not agree more with your statement. I love this kit but it is a big test for my skill level.

Bill G, thanks for the comments about the XK-SS. Looks like similar challenges.

Started work on exhaust system. Oh la la!

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The last delicate part of chassis fabrication is the integration of the exhaust system

I should have invested in HRM exhaust manifolds which must have been designed to clear the chassis tubes...but did not so I will have to manage with the kit parts.

Instructions call for headers to be attached to the engine after the engine is installed to the chassis. Makes sense because of the width of the engine/header combo would not clear the rails. Plus it's  very tight to the steering box and there is slight contact to upper A-arms and a significant interference to the chassis rails.

First I removed the little pegs supposedly fitting into the heads and made flanges, choosing not to use the kit's PE flanges.

 

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At some point I will need to integrate a wider cross section to the exhaust dumps to replicate the unique setup of the car I am modeling. This is fine because I wanted to break up the side pipes. The front half of it will mate to the manifolds with a flanged joint. Not exactly accurate but it looks better than butt gluing tubes.

The back half of the exhaust I will build and integrate after chassis is integrated to the body.

Lots of fiddling but happy with the look...and it comes out straight!

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