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MISTRAL V-TWIN BOOST

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The secret to the vacuum secondaries on a Holley is to plug the air bleed from the vacuum diaphragm chamber into the secondary venturi, leaving the bleed into the primary venturi open. Some soft solder tapped into the passage with a pin punch does the job nicely. Then, you can get the vacuum secondaries to operate virtually identically to the gear-drive secondaries on the double-pumpers. With the correct diaphragm spring, you can get them to begin opening at about half throttle once past about 4K. Feels a bit like a turbo kicking in, as you need not move the throttle for them to open. The secondaries stay closed when intake velocity is low or manifold vacuum is high. 

Had a Holley 4239 (700-715 cfm depending on source) on my hot-rodded 283. It was half of a big block chev dual-quad setup. No provisions for choke, power valve, and it had the "whistle" vent in the primary float bowl. Man, when that engine came on the cam and the secondaries opened, life was good!

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On 11/7/2019 at 7:09 AM, LowRyter said:

Remember the Fish Carburetor?  Those things would double both power and mileage. 

The oil companies bought the patents and kept them off the market. 

Wink wink. Back in the day, I helped a couple of fellow wrenches who were campaigning an "Econorail" - a dragster chassis with a single 4bbl V8 engine. They tried a Kendig carburetor - a perhaps too-radical design that was extremely simple but as difficult to tune as a Weber. Talk about stack fires! Here's a link to the Kendig Variable Venturi Carburetor: http://www.tlawebstuff.com/kendig.htm

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On 11/7/2019 at 6:19 PM, gstallons said:

Oh , they are righteous , with a few problems . I had one on a 70 Mustang 351c 4spd . I had a 600 cfm double pumper with a chrome dual line I installed on it .

 I was George Thorogood in that car !

 

On 11/7/2019 at 6:39 PM, Chuck said:

^^^^^I built a 351 Cleveland, turbo charged it, and had a 600 Holley double pumper. It wasn't enough carb. (!) Ended up with a 750. Bad mofo, that was.. :grin: Used a primitive water/alcohol injection into the secondaries metered with an aquarium needle valve. :rasta:  Used a windshield washer pump triggered with a pressure gizmo (technical term) in the intake manifold when the manifold came up to 2 psi positive. 

Cleveland people . . . I knew I loved you guys! :grin:

There are times the way the sport comes on reminds me of the 4bbl Cleveland in my '70 Cougar Eliminator.

Some mysterious combination of factors just takes over . . .

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The Ford 351 Cleveland V8 is what made me a motor head. The torque, the way it came on the cam, the exhaust note. Holley, Edelbrock, Hooker Headers® (that's just fun to say!) . . . :sun:

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All of that seemed cool, but did not make the motor appreciably better. Some of it was detrimental.

This all reminds me of not understanding fuel injection and, thinking the system was simply lean, winding up the TPS to "richen" the "mixture."  This is, of course, flawed as the TPS has to index the throttle plate(s) to  the ECU mapping. Done precisely, this makes a critical difference in performance.

 

 

 

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2 hours ago, gstallons said:

the 351C is the best engine FoMoCo ever produced !

Please define "best"

Ciao

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5 minutes ago, gstallons said:

Well , my favorite ! I will leave it at that .

I was going to liken it "likewise" to the V11 motor being the "best" Moto Guzzi has ever produced.

Really, just my "favorite." :sun:

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1 hour ago, Lucky Phil said:

Please define "best"

Ciao

For making horsepower per cubic inch. Back in the day, the Cleveland ruled..

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Just thought, Ford has made quite a few good engines, 429 The Cosworth/Ford DFV. I know not strictly a Ford the DFV but they financed it and owned it so us Ford guys can claim it surely:)

Ciao 

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Quote

few good engines, 429

The 429 was an up sized Cleveland. After all, an engine is just an air pump, and those Cleveland heads were really good at it.

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Back on topic. We have a Griso in at the moment for rollerisation. It's been running a finbau forge O2 sensor fooler. 27,000 km and the tappets are some of the worst we've seen and the camchains are utterly rooted. Tops of the pistons are washed pretty clean so it's rings are history too. Why people fit these bits of shit is just beyond me.

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