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Carburetor change in GCR
http://prodracing.com/viewtopic.php?f=7&t=18518
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Author:  Brett W [ Wed Apr 10, 2019 7:07 am ]
Post subject:  Re: Carburetor change in GCR

Agreed, clean up the arbitrary language to remove the confusion.

Author:  Protech Racing [ Wed Apr 10, 2019 7:13 am ]
Post subject:  Re: Carburetor change in GCR

Maybe the first line word should be changed to "powertrain" from "drive train". Clearly the GCR list "drive train" and under the heading has the rest of the" powertrain " with all of the dos and donts.

Using "Powertrain" as we define it, lets all of the things that have been done, still happen.

1. Drive Train Level 1 a. Drive Train Component Modification 1. Stock and permitted alternate components of the drive train can be modified by any mechanical or chemical means. Modification of a drive train component does not permit relocation of that component. 2. No material or mechanical extension can be added to any stock or alternate component, unless specifically authorized by these rules. Repairs to a stock or alternate component are permitted, provided the repair serves no prohibited function. 3. Stock and permitted alternate components of the drive train can have thermal barrier and friction altering coatings applied. b. Induction System 1. All inducted air must pass through the venturi(s) of the car’s carburetor(s). On cars where the use of one (1) 40 DCN, DCNF, IDF carburetor is required, can fit one (1) of the following permitted optional carburetors: 1. Weber 32 DGV/DGAV/DGEV 2. Weber 32/36 DGV/DGAV/DGEV 3. Weber 32/36 DFV/DFAV/DFEV 4. Weber 34 DAT/DATR/DATRA/DMTR 5. Holley-Weber 5200. Carburetor jets, jet needles, metering rods and needle valves are unrestricted. Choke mechanisms

Author:  dhrmx5 [ Thu Apr 11, 2019 7:56 am ]
Post subject:  Re: Carburetor change in GCR

You guys are all late to the game. I noticed this 2(?) years ago when the carb rules were being modified and made 3 points to the PAC: a bunch of current carbs were going to be illegal, it was going to hit rotaries hardest, and why was the rule change needed given that the vast majority of races are won by fuel injected cars these days. Were carbed cars some unseen threat to the class parity?

The loss of the generic "auto type 2 barrel" caused me to park a 1st gen EP RX7 that I was building at the time. And I had to junk a thousand dollar carb that was built specifically for the class.

Author:  Brett W [ Thu Apr 11, 2019 3:46 pm ]
Post subject:  Re: Carburetor change in GCR

Floor pan rules were more important.

Author:  TED HEINRITZ [ Mon Apr 15, 2019 4:09 am ]
Post subject:  Re: Carburetor change in GCR

The level 2, limited prep carb rules actually make sense. Some of the choices are somewhat limited.

The SPEC line lists a carb and "choke" size, at least for some of them. For example one my old fiesta, I could run one of the listed single carbs, or a pair of weber DCOE (or similar) with a specified choke size (to limit the intake size). Now if the intake size is limited by a specified choke size, why would I be allowed to modify the carb? The original carb choke size is being used to limit the intake size.

It's an attempt to limit the intake flow, while giving us some options for carb choice. If we start modifying carbs we will need a SIR like GTL.

Author:  Dan DeRosia [ Mon Apr 15, 2019 5:25 am ]
Post subject:  Re: Carburetor change in GCR

I'm going to jump to the Mazda stuff specifically because they're an easy example to find for me. The level 2 99-02 Miata in EP has an option of "2 Auto-type sidedraft w/28mm chokes" for example. Prep level 1 defines what an "auto-type" carb is. Level 2 does not. There are a number of listed alternate carburetors - the standard little Weber list - none of which are sidedrafts.

I know what the intent of the rule of restricting venturi size is and have no issue with it. I know what has been run in the past (I'm building an RX-7) and have no issue with that - for that matter it didn't seem like there was an issue with the cars running away with the class. With the current state of the language, it seems that the intent of the rules and what has been run in the past do not jibe with the letter of the rules.

Author:  Al Seim [ Mon Apr 15, 2019 6:53 am ]
Post subject:  Re: Carburetor change in GCR

Al Seim wrote:
Hi Jim -

Have a look at GCR_-April_2018.pdf (page 458 of the .pdf file, page 456 printed at bottom of page)

E. Authorized Modifications

__1. Drive Train Level 1

____a. Drive Train Component Modification

____b. Induction System

____c. Fuel pumps etc

____d. Emission system etc

____e. Cylinder Head


etc etc

Only sections n. and o. are "Drive Train" ie transmission and final drive.

It is absolutely plain to me that "1. Drive Train Level 1" is a typo and should read "1. Power Train Level 1". Otherwise why is the entire engine and Drive Train called out in section 1? (Power Train = Drive Train + Engine)

Same issues apply in the "Drive Train Level 2" section.

Given that, it also stands to reason that "a. Drive Train Component Modification" is also a typo and should read "a. Power Train Component Modification". For instance, this section allows thermal barrier coatings, which are commonly applied to piston tops and combustion chambers but seem mostly useless in the Drive Train.

Al Seim


As I posted a year ago and Mike Ogren last week, this all stems from what logically HAS TO be a long standing drafting error / typo in the rulebook. Think about it, look at the rules and I bet you'll agree.

Author:  Protech Racing [ Mon Apr 15, 2019 8:24 am ]
Post subject:  Re: Carburetor change in GCR

Anyone put in the letter for correction?

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