Holley and fresh air?

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Ironracer

Gearhead
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Hi, I hope everyone is doing well this evening. I have a 74 Duster,came w/ a dual snorkel scoop. I'm cutting the diamond area out of the hood, and sealing it to an offset base bottom and an 18x2 cake pan,with a gasket. Any recommendations on a good Baseline for jetting? Carb is a 3310-12 # under ( think its a date code (1020) never been rejetted. Its kinda weird. No idle air mixture screws or 1/2" or so block in the secondaries. 48 MP cam, old strip dominator, worked j heads.
Thank You!
 
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3310 is a vacuum secondaries carb. They can be converted to run a metering block in the back but most of them (and how they are set up stock) use a metering plate for the secondaries. There is no jet changing back there. In the front it should be somewhere around 72s and that’s a good place to begin.
 
I think I would use it as is to start. That's your baseline right there. Changing it right off the bat I don't think is a good idea.
 
3310 is a vacuum secondaries carb. They can be converted to run a metering block in the back but most of them (and how they are set up stock) use a metering plate for the secondaries. There is no jet changing back there. In the front it should be somewhere around 72s and that’s a good place to begin.
I was thinkin with the scoop sealed to the hood, I would need the bounce up a few jet sizes? So there's really no way to adjust secondaries on that other than maybe drilling out the built-in Part?
 
I was thinkin with the scoop sealed to the hood, I would need the bounce up a few jet sizes? So there's really no way to adjust secondaries on that other than maybe drilling out the built-in Part?
Correct. You can buy different plates I think but I’m not positive on that. You may need to jet up or down depending on your specific combination but I would start with the factory calibration and read the plugs.
 
I think I would use it as is to start. That's your baseline right there. Changing it right off the bat I don't think is a good idea.
Dig that. I was always assuming it needed to be bumped up a little bit just because of work I did on the motor. And now I'll be sealing the scoop ( as soon jam the LCAs back in) Its always ran good. I built it about 10- 11 years ago. Bougbt the carb then. Plugs are really light grey tho
 
Don’t jet your engine by anything someone tells you. Let the plugs tell you what the engine wants. There is no better way.
 
Don’t jet your engine by anything someone tells you. Let the plugs tell you what the engine wants. There is no better way.

Puzackly. That's why I think he should leave it as is and then read the plugs.
 
Puzackly. That's why I think he should leave it as is and then read the plugs.
Yessir, Understand. I just always figured she needed more fuel .. pure asinine assumption! The only thing I did was change it to the light yellow spring, make sure the float level was right, and made sure that the proper clearance with the feeler gauge was going going to the accelerator pump
 
Yessir, Understand. I just always figured she needed more fuel .. pure asinine assumption! The only thing I did was change it to the light yellow spring, make sure the float level was right, and made sure that the proper clearance with the feeler gauge was going going to the accelerator pump

No, I think you're probably right, but IMO, if you change now, you'll kinda be lost. If you wait and read the plugs AS IS, then you'll have a better base line. .......course, I could be stupid.
 
Don’t jet your engine by anything someone tells you. Let the plugs tell you what the engine wants. There is no better way.
Hmm. Yall might be teaching me something. I was kind of digging around and for the same elevation comparatively 35 degrees to 70 degrees you should get down one size for the temperature change. I'm thinking down here in lovely sunny humid rainy Hav a Tampa, the air coming in the hood will definitely be cooler, maybe offsetting the extra air forced in by the sealed scoop. I'm not to that point yet and I thought about maybe grabbing a couple different pairs of jets to alleviate any possible issues
 
No, I think you're probably right, but IMO, if you change now, you'll kinda be lost. If you wait and read the plugs AS IS, then you'll have a better base line. .......course, I could be stupid.
Definitely having a solid base when trying to dial anything in is a good deal. Heck, even on big commercial framing jobs, back in the day, we'd Mark the center of the building and then clear coat it if there was ever an issue months later go back measure off that to see who messed up where
 
Hmm. Yall might be teaching me something. I was kind of digging around and for the same elevation comparatively 35 degrees to 70 degrees you should get down one size for the temperature change. I'm thinking down here in lovely sunny humid rainy Hav a Tampa, the air coming in the hood will definitely be cooler, maybe offsetting the extra air forced in by the sealed scoop. I'm not to that point yet and I thought about maybe grabbing a couple different pairs of jets to alleviate any possible issues
Having a few jets in stock is a good plan, but IMO a street car will not notice one jet number. You have to be really proficient at reading plugs or really consistent at the drag strip to dial one in that far. You aren’t looking for 1/10s or 1/100s here. The fresh air and scoop might make a slight difference but probably not enough for a jet change.
 
Having a few jets in stock is a good plan, but IMO a street car will not notice one jet number. You have to be really proficient at reading plugs or really consistent at the drag strip to dial one in that far. You aren’t looking for 1/10s or 1/100s here. The fresh air and scoop might make a slight difference but probably not enough for a jet change.
Ok. Dig that, I'm probably wasting a lot of my time and y'all's to then I'm trying to squeeze every little thing I can out of this thing! Lol.
 
The sealed hood scoop will provide cooler air, but not enough change to start resetting the carb. Think of it as running on a cool Spring day.

The scoops don’t provide any ram air effect. You have to get to 100 mph for the dynamic air pressure to add just 1 psi of increased boost pressure. Not enough to change the A/F ratio requirement for the carb setting.
 
The sealed hood scoop will provide cooler air, but not enough change to start resetting the carb. Think of it as running on a cool Spring day.

The scoops don’t provide any ram air effect. You have to get to 100 mph for the dynamic air pressure to add just 1 psi of increased boost pressure. Not enough to change the A/F ratio requirement for the carb setting.
Ah, now I'm getting it. Once you speak it out in Layman's terms and smack me with a pipe wrench....
 
All I heard was "keep it above 100 mph'
Not hard. But still to close to the histle and bustle of the city for me. Then again I've been looking for a rivet gun out this way for 3 days and I can't seem to find one. Guess the country folk ain't allowed to have no chinese-made garbage..
 
The sealed hood scoop will provide cooler air, but not enough change to start resetting the carb. Think of it as running on a cool Spring day.

The scoops don’t provide any ram air effect. You have to get to 100 mph for the dynamic air pressure to add just 1 psi of increased boost pressure. Not enough to change the A/F ratio requirement for the carb setting.
Got it. So, the engine won't make more power, but the cooler, slightly denser air ( if that possible in Tampa) may make more power available?
 
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