supercharger carb info needed

[Pete]

Originally Posted by JWL

Unfortunately many of these posts have lost sight of the OP request and established standards. This was not, I thought, about what to do for maximum HP. But rather, a request for the best combination for the small cube engine to torque up a hill. I have provided the appropriate suggestion to satisfy the sought after information. There are several options for what would "work out" here but the optimum would be nearest to what I suggested. There is a very wide range of A/F mixtures and CFM options which seem to work just fine with our Flathead engines because the torque curve is flatter than most other engines. But, in many cases these are "seat of the pants" assessments which are not quantified, realistic, evaluations. Just because something seems to work "OK" does not indicate it is the best.
I do not make suggestions just to be talking. I present only the facts. People can choose to learn or not.

As Joe Friday used to say, "we just want the facts, man".

[V8COOPMAN]

Originally Posted by Pete

As Joe Friday used to say, "we just want the facts, man".

More closely......."Just the facts, ma'am"

[tubman]

"Dum-Da-Dum-Dum"

[Bored&Stroked]

There is more than one way to skin the cat . . . and I'm not about to say what the "perfect" carb is for his car. It depends on a lot of things - not just CFM. It depends on whether or not it is a square bore, spread bore, vacuum secondary, double-pumper, gearing, complete engine package, RPM range he wants to run in, etc..

Another factor is his ability to actually "tune" the thing - versus popping a carb on it out of the box. I can make a "bigger" carb work well on a smaller engine via how I configure and tune the thing. Lastly, there are quite a few aftermarket folks that modify Holley carbs and adjust the various circuits to achieve better AFRs under the various load conditions (using custom components in many cases). Truth be told, almost any of these carbs can be made to work a LOT better than out of the box - in the hands of somebody who really knows them and does it for a living. This is especially true for a boosted application. There is not ONE single best solution.

Also, a lot of engines are over-carbed (especially on the street) . . . as many folks were led to believe that "bigger is always better" - simply not the case.

If I had BOTH carbs - 465 cfm (model 0-1848-2) and the classic 600 cfm (0-1850C), I'd try them both. If I only had one to buy/try, I'd probably go with the smaller carb first, spend time tuning it (power valve, jets, etc) - before I'd try the 600.

In a perfect world, I'd put the car on a chassis dyno and work with somebody who really knows how to tune these carbs for your specific combination.

Enough outta me . . . the coffee has kicked in!
B&S

[21stud]

Dale, well said.

[vincent]

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Maybe a little more information is needed about me and the abilities here.
Having built a supercharged Triumph drag bike where I needed to make my own jets, needles and float for the SU carb, I am able to find out what an engine needs, not only on the strip but also on a Schenck dyno which is suitable up to 600hp. Having made my own moulds to cast crankcases, cylinders and heads for a Vincent engine with 1835cc, all those cast parts were machined in my shop as well. Another project was the hop-up of the classic Norton twin where we cast new crankcases, modified the crank heavily and made our own pistons and conrods. Of course we made new camshafts and developed a lot different profiles to find the best cam for this engine layout. Talking about cams - another bike that got my cam installed after modifying the head a lot to make it go round at all ;-) had to be converted to one of my dry clutches as the oilbath clutch could not hold the power. I have made my own flatslide carbs for a racing bike, build my own dry clutches for various bikes, have built Egli and Dunstall frames for road- and race bikes etc,developed and produced a complete 3-speed gearbox, shafts, gears, forks, airshifter within 4 weeks! The gearbox held up no problem to the 600hp of the Vincent streamliner. Of course I am aware of the pitfalls when developing an engine. I managed to get my french flathead running good without the rich smell that it had when I fitted those two Strombergs as they came. I asked for advice one of the carb gurus here that said that he does not give advice on the GB replica carbs. So I asked the maker in GB, some of his advice helped a little bit but in the end I made my own experiments and found a solution. I just asked here what carb would be a good starting point as I just started working on a car and until now have limited knowledge about car carbs and especially US car carbs but now that Ronnie is taking my hand I think I will learn a lot very quick.

[Bored&Stroked]

If you're going to be purchasing a new carb, you might want to call the guys at Pro Systems and have them custom configure one for you. There are a lot of tricks that can be done in the metering plates, the air bleeds, accel pumps, throttle plates, etc - to give better performance for your specific application needs. I've had them build multiple carbs for both track and street - including blower carbs. Worth a call . . .

https://www.prosystemsracing.com/

[vincent]

Thanks B&S - just what I need! The blower is now on the way and as soon as I have made the bits and pieces to install it I will give them a call as well.

[Bored&Stroked]

Also, really consider what you're doing on the ignition side of this. If this is a street car, then you'll probably want the ability to have some level of "timing management" - to pull timing out under boost. There are multiple ways to achieve this - though it seems a lot of us end up with MSD type "boxes" of some sort. I'd probably go with a MSD ignition/distributor and the appropriate timing controls (various options). Personally, I like to have the higher-end boxes, where I can hookup my computer to set the curves, can see the ignition running in realtime, etc.. (Kind of the racer part of me!).

[vincent]

Yes, I was thinking about this and might use the lever of the vacuum device to push (retard) ignition. I could use the boost of the blower to move the lever.
I have a good ignition man here that can build me what I need but making it yourself is more fun.