I remember when my mother bought an 82 Cadillac Sedan Deville with the 4100 v8. It was our first fuel injected car. My father called it a wire carburetor. I used to take the air filter lid off and stare at the fuel being injected into the engine.
I tried many carbs on my 383 stroker in my camaro, nothing worked better than an old 650 holley dp with down leg boosters. Tried 3310s, 4779s,, demon 750 annular mech, 850 dp heavily modded. Ran 12.33 @116.98 on street tires and a 4 speed with a stock clutch with an old crusty 650dp, stock fuel pump too! Was thinking about trying annular boosters again on my next project.. Now I know Demon carbs suck..
One of my all-time favorite carbs is 9381 (830 annular) used to buy them new for $379 for ever then the prices just crept up. That carb worked good on a built small block or a moderate big block. Recently had trouble with a 9379 (750 annular) on a 383 with vic jr that had an off idle hesitation that just didnt improve satisfactorily no matter what I tried, then I just swapped everything onto a 4779-6 mainbody and the issue was resolved. It seemed like the engine liked having the booster closer to the venturi and gave much better response. That was the first time I had an engine combo that was happier with the downleg booster vs the annular.
There is a rule of thumbs with boosters. Most active booster is the annular. It will atomize fuel the best and start drawing through the mains a little sooner too compared to straight leg... Less active and dont atomize as well. Annular=small particles Straight=large particles Large particles of fuel work better on a factory/heated type intake manifold Small particles doesnt need as much heat on the manifold There is a "optimal droplet size" you just have to pay attention what works best on your setup. But thats about where my knowledge ends as of now... Pretty much you could end up using the wrong booster chasing power over-atomizing the mix (on a heated manifold more commonly)
Its all a balance for sure. A lot of edelbrocks run annular boosters standard. I've also heard guys say they they tend to run richer on the top end as well, kind of like a siphon. All 3 of my blow through carbs are down leg but maybe on my next one, I'll build annular booster carb 👍
Annular boosters. Make sure everything is clean. I’ve repaired performance cars where one or more of the fuel delivery holes in the boosters. That sucks. And you can’t compare each of those with actually flowing them. Then run a Dino sheet. This is basic.
Several companies sell them in different styles. Dambest and BLP off the top of my head but the tool to actually install them is expensive. Also, a lot of custom carb builders can install them for you, cheaper than it would be to buy everything yourself. PRC carbs is one of those guys
Most off the shelf carbs are straight leg boosters unfortunately. If you want something with downleg, you're gonna have to pay a premium. I wouldn't say theyre "not recommended" but if you have the option to go downleg or better yet annular, I'd definately jump on that instead.
Yes it will. Just make sure you get the right one(Mechanical secondaries or vaccum secondaries). If the idle holes dont line up, I have a video about that. Its not a big deal
@@NightWrencher I've been rebuilding carbs for a good 30 years. All sorts of applications. Racing, street rod, economy etc. Have a large collection. More curious if changing boosters will increase miles per gallon. I'll get around to it once I get the right carb to test. This summer I'm going to run an engine on the dyno and do some testing. I'll have to find that right carb.
It should, anything that increases horsepower without adding fuel should be better for MPG. People claim annular boosters take less fuel to make the same horsepower so thats where I would start 👍
