R.Brown":1iq430m4 said:» Post Fri May 20, 2005 11:10 am. I have flowtested all types of jets, and have used many different methods. I found with the difference approach and exit angles on the jets that pin gauging them did not lead me in the right direction. You can to it for dirt cheap if you have a gram scale, and a stop watch, and some type of a fuel pump. Build a jig to hold a jet, make the entry and exit angles in the jig as large as possible so you do not influence the flow of fuel to the jet, then machine in a pressure tap right at the upstream side of the jig, near the jet. Plumb the tap to a 0-15 PSI gauge. Run the pressure to 6PSI, or whatever you dream up for head pressure. I use stoddard solvent .786 SG fluid. Get the jet flowing at the right pressure into one container on the bench, and have another sitting on the scale. Start the stop watch and move the hose into the container on the scale simultaneously. Flow for 1 minute. Record the weight.
I wrote a simple excel program to do the math, type in the weight and it converts to lb/hr.
This worked well when I was trying to prove to myself that this was a worthy endeavor. Now I sell over 500 flow tested main jets a year, so I built a flow stand with a high dollar flowmeter and a "quicker" way of testing, but the results are the same... just takes one tenth the time.
Feel free to ask any other questions about this, although I do not get a chance to surf very often these days. You can email me directly thru the link at:
http://www.ryanbrownracing.com
xctasy":1iq430m4 said:the chart that shows all them plotted. Disregards the units. The chart should read 150 microns is 1.5 mm
And specifically:The earlier standard jet sizes for Holley Webers are:-
103 cc/min=105 microns, or 41.34 thou
128 cc/min=110 microns, or 43.31 thou
152 cc/min=115 microns, or 45.28 thou
178 cc/min=120 microns, or 47.24 thou
201 cc/min=125 microns, or 49.21 thou
225 cc/min=130 microns, or 51.18 thou
251 cc/min=135 microns, or 53.15 thou
275 cc/min=140 microns, or 55.12 thou
298 cc/min=145 microns, or 57.09 thou
325 cc/min=150 microns, or 59.06 thou
346 cc/min=155 microns, or 61.02 thou
375 cc/min=160 microns, or 62.99 thou
400 cc/min=165 microns, or 64.96 thou
425 cc/min=170 microns, or 66.93 thou
450 cc/min=175 microns, or 68.90 thou
475 cc/min=180 microns, or 70.87 thou
525 cc/min=185 microns, or 72.83 thou
There are some common misconceptions about Weber IDAs. I recall when I was designing the motor for my Cobra replica I was talking to a gentleman who is very highly regarded in the industry about my carburetion options. I told him that I was considering Weber IDAs. He was very adamant that the IDAs were a poor choice and went on to explain why. For my application (a 331 stroker small block Ford) the “traditional” carburetor might be a Holley 650 CFM four barrel. This carb has 4 bores that are approximately 43mm in diameter. A Weber IDA system for the same motor might use 8 bores that are maybe 40mm in diameter. He explained that the Webers would fall flat on their faces when nailing the throttle because they would suddenly be opening up nearly twice the throttle area of the Holley 4-barrel. This, he reasoned, would kill air velocity and therefore performance.
At first glance, his reasoning seems sound. But it’s actually not, and the reasons become clear if you think about it a little bit more. A motor demands air only one cylinder at a time. In a traditional 4-barrel setup, the carb is essentially only serving one cylinder at a time, and each cylinder “sees” all 4 barrels plus the entire manifold at WOT. In essence, this is just the opposite of what the expert explained to me. An engine with conventional carb sees far more area when the throttle is nailed than an engine with Webers. Consider an IDA on an individual runner. Each cylinder only “sees” its dedicated barrel and a very short manifold runner. It certainly doesn’t “see” any of the other independent barrels. This results in a very fast-moving air charge. Torque is a highly dependent on air velocity and high velocity increases torque. Since the runner is so short, the air can get moving very quickly, increasing throttle response. There is a reason that the Weber IDA on an independent runner manifold was the carburetor of choice for race cars prior to the advent of fuel injection. It provided the best torque, and throttle response – essential for a race car.
chad":3236grww said:agreed Econo.
Tuning (syncronising) them is no big deal with a hose, but there is a gadget called the Unisyn that takes all the guesswork out of the job.
But now I hear there's a Carter YH side draft (an early '60s thru '66 I've heard) that's reliable (just so many sizes it's hard to assure/ID the right one) used on early vetts too.
"...thought it may be helpful…"
Not ramblin. Like I said, it ALL helps !!!
chad":2s6kt8o4 said:can the main jet @ .802 tell us anything about how this YH might perform a sextet on our motors? (or R we back to trips but side draft)?
U or Mike's Carbs sez this Carter wuz used on 'Vetts - 1 per 2 cylinders...
Is it a good option for the "1 per cyl" falcon motor? if so which of the 6 motors...
"...many little Ford six boat engines..."
chad":2s6kt8o4 said:I grew up on the Chesapake Bay (1952 - '80) and saw some teake, mahogony and brass outfitted "skiffs" with motors
like those in the area. I wonder if there is a connection. The engine pictured is the 200?
ludwig":3um9q53j said:I wonder why that low-slung big block never caught on? That would make an awesome street fighter. And what a conversation piece when you pop the hood.
X-man - you need to collate all this arcana. What a trove of cool stuff!!!
http://m571.com/yblock/intake.htm":31zie3w5 said:Interceptor
Interceptor
This marine manifold used Carter YH sidedraft carburetors to keep the installed height to a minimum. Some installations used only one carburetor. YH sidedrafts were also used on turbocharged Corvairs, 215 F85 Oldsmobiles, Corvette “Blue Flame” 6s, and Nash Le Mans 6s. Exhaust heat is passed under the cross runner of this unit.
Interceptor on Thunderbird
This beautiful Interceptor intake installation on a Thunderbird was accomplished by Gary Hartzell of LA Mesa, California.
In Gary’s own words:
“Wanted to do something out of the ordinary. Went to the Goodguys show at Del Mar last weekend (first show) and stumped a lot of Ford know-it-alls!!!!! One guy asked if I had to do anything special to make it run right and I told him I had to fill the radiator with salt water!! I had to fab my own necks to the radiator, but the installation wasn't too difficult at all and the results were well worth it.”
Primarily to look cool, and mess up show goers.chad":138pjv9d said:i no they circulated sea water but Y did the auto (T-bird) need to use it?
chad":2pmvgf5j said:re-viewin da pic in ur #26 post above, X, I C a way 2 use the YH in "1 per cyl".
(They use a side draft like a down draft - to me, anyway. Again may not have the proper nomenclature).
If placed on a 90* adapter (like on the #26 post) the log could B retained. The carbs could B arranged left/right/left, etc all the way down the log.
I believe this may take up abt the same hight as my RBS (or the other low mount carb: 1100) plus___?___ inches.
Linkage? wtf? a buncha cable throttles...