Holley carb booster height

[pamotorman]

Cheated up short/raised booster air bleed to death 390 carbs are a joke. A stock '57 T-Bird carb calibration will run circles around that junk.

::: facepalm ::::

What you're almost describing (the "three-gauge" 390), is basically what the GN cars ran for over a half-decade before the 830-carbed "recipe" engine rule went into affect. Granted, there was one more part to that equation - open center boosters - but since a front row example of those engines was making about 745 hp at 8200 and over 565 lb/ft of torque from 355 cu in, even if you subtract 100 hp and call it 645 with full width cross-bar boosters, I'd still have to say that getting the booster discharge up out of the venturi...even the piddling little .045" that NASCAR allowed...on a 390 is worth doing.

The real key to why it works (if the necessary fuel metering changes are made along with it) becomes apparent when you consider that what the engine sees as min. venturi area is actually defined by the window created by the o.d. of the bottom edge of the booster and the closest radial distance to the venturi entry radius....not simply the curtain defined by the booster o.d. X the amount raised. Getting the booster up out of the hole adds a significant amount of area pretty quickly.

I built lots of cheater carbs in my day and the tracks figured out the best way to stop it was hire me as tech inspector. good move on their part because the racers knew everyone one was getting a far shake as far as carbs went. I made more $$$ building cheater carbs but I did sell a lot of legal modified ones after being a inspector. I DQ about 10 cars the first night as a inspector but I had told my customers I will bust you if you show up with one of my carbs.

[Warp Speed]

Homestead 1996!
That was the start of the NASCAR 390 carb tech/booster gauge debacle!
Booster design and placement was paramount that day!



Come into the pits leading, go out 21st, and be leading again in 5 laps..............
You know you were doing it when you could pass Mark Martin in the Wynn Dixie car like he was tied to a post! LOL

About that '57 T-bird deal?

[pamotorman]

a friend tom peck ran the busch series back then

[Warp Speed]

a friend tom peck ran the busch series back then

Yep, John Darby was the head of engine tech at the time, and Chip was the carb inspector. I still have the first booster gauges they came out with.

Bob Labonte (Bobby's Dad) was HOT that day!!! LOL

[140Air]

Ah so! I started to get an inking of this in your previous excellent post. Handcuffed by an engineering background, it never occurred to me that there could be a benefit to making a part worse at performing its primary function.

A Dilbert moment if ever there was one!!

From what Stanj said, controlling the booster height relative to any obvious reference point on the carb is futile since it appears they can also move the venturi height. Try measuring that to 0.005".

[Tuner]

Cheated up short/raised booster air bleed to death 390 carbs are a joke. A stock '57 T-Bird carb calibration will run circles around that junk.

::: facepalm ::::

What you're almost describing (the "three-gauge" 390), is basically what the GN cars ran for over a half-decade before the 830-carbed "recipe" engine rule went into affect. Granted, there was one more part to that equation - open center boosters - but since a front row example of those engines was making about 745 hp at 8200 and over 565 lb/ft of torque from 355 cu in, even if you subtract 100 hp and call it 645 with full width cross-bar boosters, I'd still have to say that getting the booster discharge up out of the venturi...even the piddling little .045" that NASCAR allowed...on a 390 is worth doing.

The real key to why it works (if the necessary fuel metering changes are made along with it) becomes apparent when you consider that what the engine sees as min. venturi area is actually defined by the window created by the o.d. of the bottom edge of the booster and the closest radial distance to the venturi entry radius....not simply the curtain defined by the booster o.d. X the amount raised. Getting the booster up out of the hole adds a significant amount of area pretty quickly.

I built lots of cheater carbs in my day and the tracks figured out the best way to stop it was hire me as tech inspector. good move on their part because the racers knew everyone one was getting a far shake as far as carbs went. I made more $$$ building cheater carbs but I did sell a lot of legal modified ones after being a inspector. I DQ about 10 cars the first night as a inspector but I had told my customers I will bust you if you show up with one of my carbs.

Aren't you a shining example of integrity. Provide people with cheater carbs and then piss backwards on them. You just described why a lot of people quit racing at tracks with such nonsense rules and people 'enforcing' them. This restrictor carb crap is like the crate engine debacle, the unintended consequences are doing harm to the sport.

I agree that on a large track where you can jet for best HP at maximum RPM, and the RPM doesn't get much below that, the short booster cheating has a purpose. On a short track it is easy to outrun them with the right calibration in a legal carb.

Raising the booster exit above the vena contracta, which is below the actual minor diameter of the main venturi, creates a carb which needs several jet sizes to provide satisfactory A/F over a wide range of air flow. The other pipe dream of lots of large emulsion holes, whether to please the fantasy that “more emulsion holes is better” or “cheat more air into the engine” or whatever other nonsense, just makes it for sure a carb that needs a different jet size every 500 RPM.

[treyrags]

Aren't you a shining example of integrity. Provide people with cheater carbs and then piss backwards on them. You just described why a lot of people quit racing at tracks with such nonsense rules and people 'enforcing' them. This restrictor carb crap is like the crate engine debacle, the unintended consequences are doing harm to the sport.

My thoughts exactly.

[140Air]

I DQ about 10 cars the first night as a inspector but I had told my customers I will bust you if you show up with one of my carbs.

Aren't you a shining example of integrity. Provide people with cheater carbs and then piss backwards on them. You just described why a lot of people quit racing at tracks with such nonsense rules and people 'enforcing' them. This restrictor carb crap is like the crate engine debacle, the unintended consequences are doing harm to the sport.

For integrity should he have refused the job of inspector? or should he have given a pass on the rules for his own customers? Should he have given them their money back (I assume their carbs could still be used at other tracks). IMHO, once having accepted the job, for integrity he did what he should have done.
It's like the former juvenile delinquent becoming a cop. The old gang resents it. JMHO.

[Tuner]

I DQ about 10 cars the first night as a inspector but I had told my customers I will bust you if you show up with one of my carbs.

Aren't you a shining example of integrity. Provide people with cheater carbs and then piss backwards on them. You just described why a lot of people quit racing at tracks with such nonsense rules and people 'enforcing' them. This restrictor carb crap is like the crate engine debacle, the unintended consequences are doing harm to the sport.

For integrity should he have refused the job of inspector? or should he have given a pass on the rules for his own customers? Should he have given them their money back (I assume their carbs could still be used at other tracks). IMHO, once having accepted the job, for integrity he did what he should have done.
It's like the former juvenile delinquent becoming a cop. The old gang resents it. JMHO.

So, you're saying it's OK to cheat in the first place.

[MadBill]

..So, you're saying it's OK to cheat in the first place.

Here's a real life example to pass judgement on: An eminently qualified Motorsports guru I know (consults for American Le Mans Series, Trans Am, Formula Atlantic, British Touring Car Championship and other international series teams, has written a much-acclaimed ~600 page book on Race Car Engineering, been crew chief on a number of championship teams, etc.) was asked some years ago to design and build a beyond state of the art car for a national Stock Car series.

With rulebook in hand, he optimized every possible element, nudging the grey areas where he thought it necessary and producing a really exceptional vehicle. His only mistake was not auditing a few races first. Even without turning a lap, when the team showed up for the first race he realized they were dead in the water. The competition was rife with the most flagrant violations of the rules; they all knew what was being overlooked in Tech and were taking full advantage of the slack system. The new car was a total turd, never got close to even a feature start. He cut up the chassis and started over, building to the accepted level of cheating and the new car was more than competitive.

So, was he wrong to 'cheat' or an idiot for believing the rules as written?

[Tuner]

..So, you're saying it's OK to cheat in the first place.

Here's a real life example to pass judgement on: An eminently qualified Motorsports guru I know (consults for American Le Mans Series, Trans Am, Formula Atlantic, British Touring Car Championship and other international series teams, has written a much-acclaimed ~600 page book on Race Car Engineering, been crew chief on a number of championship teams, etc.) was asked some years ago to design and build a beyond state of the art car for a national Stock Car series.

With rulebook in hand, he optimized every possible element, nudging the grey areas where he thought it necessary and producing a really exceptional vehicle. His only mistake was not auditing a few races first. Even without turning a lap, when the team showed up for the first race he realized they were dead in the water. The competition was rife with the most flagrant violations of the rules; they all knew what was being overlooked in Tech and were taking full advantage of the slack system. The new car was a total turd, never got close to even a feature start. He cut up the chassis and started over, building to the accepted level of cheating and the new car was more than competitive.

So, was he wrong to 'cheat' or an idiot for believing the rules as written?

The thread is about Holley carb booster height. Your example makes as much sense as have you quit beating your wife and other gotcha. The guru is an idiot because he didn't reconnoiter the field before he decided to play the game. It seems his eminent qualifications don't include common sense.

[MadBill]

So in other words cheating is now OK?

[Tuner]

So in other words cheating' is now OK?

If YOU think so, or you don't, you're absolutely right.

[140Air]

So, you're saying it's OK to cheat in the first place.

YES!!! If you don't bend the rules or build to the loopholes, you usually won't be competitive. You do your job to the max. BUT, if you are a tech inspector you have to do that job to the max also. The only question would be should a former competitor and "cheater" ever become tech inspector? I say there is nothing wrong with that. It's racing, not religion. However, his former customers and partners in crime have to realize he's going to do his job.

[Tuner]

What a sad outlook toward racing. Too bad you can't enjoy the satisfaction of winning and knowing you were legal when the losers were cheating. Losing a race with legal equipment is honorable, cheating is dishonorable, a cheating loser is pathetic. If you like to cheat to win you should go to 'Vegas and get rich.