weber ida
My rx has a large streetport 13b with a 51ida. Im just wondering what jetting everyone are using such as idle, air, main etc, as im trying to re-jet my carb due to a flatsport up to 3000 rpm. Otherwise, it haul ass with no problem
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your flat spot is probably due to the 51ida having such big chockes and at low rpm there isnt enough air speed. many people call that the undrivable part of a weber as you said as it hits 3000 rpm's it takes off, that is the air speed building up. I havent heard of any one that uses a 51 ida on a street port. try going down a few sizes in the jets
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Wacky,
What size venturis do you have in your carb? Is this a street car? Chuck |
The 51IDAs are usually reserved for bridge and peripherial port race motors.
For a 48IDA on a street port, Racing beat recommends Venturi: 38mm Fuel jet: No. 190 Air jet: No. 160 Emulsion tube: F-11 Needle valve: No. 250 Cody |
this car is a daily driver with a 13b-4port monster streetport. its true that the 51 is set up for higher up portings but when i switched from a 48 to a 51, i noticed an improvement on top end. my prior 48 had 43 venturies with 240 main but not enough to give me goose bumps. At the moment, I’m using a 40 venturies and playing with different settings. I’ve also tried the racing beat’s recommend setting but I felt that its not sufficient for large ports since rb template is smaller.
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Wacky,
If you're going to run larger chokes and try for more peak HP, you're probably going to have to live with that flat spot. Personally, for a daily driver, I would go with smaller chokes to give it more bottom end, but that's just my personal opinion. My race car engine is a 12A with what would be considered a monster streetport and a 48IDA. The rules of our class limit us to 38mm chokes, so that's what I run. I have F-11 emulsion tubes, 185 air, 195 fuel jets (most of my races take place at about 1,000ft above sea level) and a 300 needle and seat. It makes great top end power, but it's a pig under 6,000RPM. At 8,400RPM, it produces 196 RWHP. At 5,400RPM, it makes a pathetic 107 RWHP. One thing you might try if you don't want to go with smaller chokes, is larger idle jets. |
thanks for the info everybody. i appreciate it.
btw chuck, what idle jet do you use. |
Wacky,
I'll have to measure them to tell you. I had F65s in there, but we ended up drilling them out at the track one time to make them larger. Chuck |
i've got the same thing. drilled out f65 but dont even remember the size. basically, what i am getting into is that im planning to lower the idle jet just to see what if the performance will change.
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