has any one used a 780 single pump vac sec carb for racing with any success ? going on a duster 372 small block small covertor 456-1 spool whats the tricks ? i have a like new one thats the only reason iam considering it what do you think ? thanks

What model, the early style 780 with downleg boosters and a secondary metering block, or the later 750 with straight boosters and a cheap metering plate?

#3310 780 early down leg booster and sec metering block

I know stick shift racers that used them as well as automatic tranny guys back in the day Try it How are you ever going to know if it will or not if you don't try it

A long tome ago, I used one on my 440 bracket car with some success. Easy to drive, but eventually I worked up to an 850 DP and achieved that cars best ETs and speed. Still a good place to start and you can use the same fittings and linkage on a bigger carb.

My first year bracket racing, 1983, I was runner up in the sportsman class for the season. Second year I won. 780 vacuum secondary.

Used one on a 383, I set it up like the old DC book showed. They work great with tighter converters, street-strip type. Takes a while to get it fine tuned, but you'll be happy with it.

I would go with a double pumper for racing. #3310 was made to be a super inexpensive (Super Shops) street carb. Easily tunable (read sell more parts, pump cams, springs, vacuum diaphragms) and safe for street use.

2970 total, stock stroke 360, X heads, 4:56 gear, 5100 flash, .557 cam, 1.50 60's, well thought out, hundreds of passes. A B A, each jetted over hundreds of passes, no difference in R4780 and R3310. (780, down leg boosters). It depends on the motor. Enough is enough. Anecdotal opinion from a dumb A@@!

what jets, 50 cc pump, what power valves ? my set up real close to yours

thanks for all the comments

Junkyard! Do I know you? Just my opinion shat slinger! Get on with your bad self...

If you can tune a carb and the carb is sized right for your combo, then you can make most any one work. Some will just take more work and require more changes than others.

In other words, the tuner is more important than the carb. I personally like the 3310. A lot. For street cars, it and the new Street Demons are my go-to carbs. But it would not be my first choice for a track car. But that doesn't mean it cannot be a winner in the right hands and on the right combo. As has been noted in a previous post.

I'm sorry, that was 33 years ago! I do remember that combo needed more pump shot, so I used a 50 cc pump. A different cam, converter, manifold combo probably wouldn't need it.

My old RR with a 440, 4 spd with 4.56 gears used a 780 carb on top of a M1 single plane and liked it a lot. The trickest part on the whole carb was the .31 squirter.

Found this one in a carb junk pile at a swap meet. $25. Works great. The 3310 is one of the all time best street carbs Holley ever sold - and they sold plenty.

Even though I like and have them on street engines, a vacuum secondary carb is not the best for the track. They aren't as quick to react. You will never get the car to 60 as good as a double pumper. my

Agree, and I don`t use a vs on anything ever and can get a dp just as clean on the street...........

I ran a 3310-1 for years and liked the adjustability. It did take a 50cc pump for best results. Won a few track championships using it. DP's will 60 better.

A 780 is just as easy to set up as a DP, air-fuel bleeds and jets. Block the air bleed on secondary opening passage then adjust the spring to your engine. Unlike the dp that dumps a pile of fuel into the intake, overkill. 60 ft times is just a meaningless number, other then being the same every time, the one on the windshield is the only one that counts in bracket racing.

thanks for all the comments that helps

Interesting...........The dp`s can be clean n mean and even get mileage when tuned properly and don`t "dump" fuel except from the squirter to over come the momentary lean spot from the secondary butterflys opening. And 60 ft`s are meaningless?

heavy B-body, tight conv,stock size valves, low 500 l cam...low 12s easy, consistent also....ran one for many years ,,,the old standby

When I changed the gear in my rearend from 4.10 to 4.86 pro gear, the car launched way too violently, adjusted shocks and ladders and still did a 2-foot wheelie. Put a VS carb on it and it calmed it right down. More consistent for bracket racing. I think I have the silver spring in it. 42 squirter.

To answer the question, I would estimate that more than 100,000 3310s have been used on drag cars since it was introduced on the 425hp 396 in 1965. Many of these cars have been winners.

The downleg booster carb is the only 780 in the series, everything else is a 750. If you look at the boosters some of the carbs have little tabs sticking out on the outside of the booster, those were there to correct fuel distribution problems in the 396.

Holley switched to straight boosters with the 3310-2, IIRC, and that was a long time ago.

If you're after that last tenth a double pumper is probably better. If you are after consistency, like bracket racing, the 3310 can be a very good carb.

If you're looking for a strictly street carb the 80508 is a newer version of the 3310 and I believe it has better metering.

R.

I'm sure there are some 3310's going down the track in NHRA stock class since the carb came on different muscle car engines. Guys are probably running 10's with them.

I have one sitting out in the shop that I haven't used in 30+ years. It was the first hot rod part that I bought. I think I bought it back around 1978 or so but I don't remember for sure. I ran it on the 351C 4bbl engine in the '56 Ford F100 that I drove when I was in high school.

IMO a tight converter will like the vacuum carb over the D/P. The only dislike I ever had with a 3310 was actually on the street and roll racing - the slight lag before the secondaries rolled in that a D/P doesn't have.

doood you need a dp on top of a dp with a 'y' shaped manifold on top of that with two more double pumpers! Then maybe...just maybe... it will be enough fuel for your small block!