i have a 71 challenger with a 383 and an automatic. i believe the rear has 3.55 gears and a suregrip. right now i'm running a carter 625 cfm carb and i've never gotten it to run right. i was thinking of getting a holley 750 double pumper but ran across a 650 over the weekend. obviously i know 650 will let it run, but i want to get some more performance out of the car. future changes are calling for a cam swap and to get the heads freshened and home ported. the engine as far as i can tell is totally stock and i would like to keep it looking that way. so there won't be any headers aluminum intakes (unless i can hid it) etc. just looking for some opinions.

thanks

jerry

Jerry,
If the 650 that you found has the tuning "bells & whistles" on it for tuning your short term modification goals, then that might work. But if it is a basic 650 with no extra tuning capabilities, then I would suggest looking into a larger carb with tuning "bells & whistles" so that you can tune it through your short term and your long term performance changes.

If it has the tunable air bleeds in it, the 650 will work better than the carter. Same goes for any Holley type, get one with changeable air bleeds.

how far off are your heads and cam?

that tells me that you should wait and spend money for a bigger carb instead of buying this one now that you're going to have to replace again later after the head/cam swap.

but...if it's going to be several years before you do the heads and cam, then go ahead and get the smaller carb now and get the car running right.

I think that you will be surprised at what well tuned 650 will do for you on that engine. You may loose some top end with it over a 750 but you should have good low end.

If I wanted to make power I'd go with an 850.

On a basically stock 383 with manifold heat the 650 dbl pumper will be good choice. Stick with 68-70 jets frt and no more then 76-77 rear the pump shooters are good as is in most cases unless the car is heavy. I try to tune at the track with that issue. Don't start screwing with the air bleeds unless the car is modified or you cannot get it to run right, or you got the dough to blow on th cost of the carb

If you're keeping the stock intake a 650 Holley will be about all the intake can use. Back in the day I'd go to the drag races and look at the carbs on the cars and they were much smaller than I would have guessed. These weren't bracket racers, they would have run a bigger carb if they could. But obviously the slightly smaller carb gave better ETs.

If and when you get your "new engine" figured out it will be time to go bigger on the carb. But you have to realize that 383s came stock with carbs that weren't much bigger than 500 cfm. It used to be that putting on a 440 carb would help out quite a bit, and those 440 carbs were in the 600-650 cfm range.

I can see some big corks in your engine's performance and the carb ain't one.

R.

Not the best example but my buddy has run a 650DP on his 55 Chevy for years, it's a 427, turbo 400, 4:56 gears, 9x28 DOT slicks, he drives the car quite a bit & around town the small carb really helps drivability, at the track with the 650 he's run consistent 12.0's... With a 850 & lots of tuning he's run a 11.92... Personally I think a 650 would be fine for a healthy 383....

Many people overcarb...I've run a 12.40 in my Duster with a stock stroke 340 and Holley 650 carb.

Jerry as has already been mentioned, most people tend to overcarb their engines, particularly street engines. For what I presume you're planning to do with your car the best thing you can do is go on the small side for a carb. You'll find it to be more responsive, particularly at low rpm's where you're likely to be spending most of your time. The reality is 6500-7000 rpm runs won't be happening so much for you that you'll miss the extra capacity.

I've been through this myself many times over the years, and in each case have found myself happiest with a street car running a 600-650 cfm vacuum secondary carb. I'm partial to Holley's myself. I've struggled with a few Edelbrock's and AFB's. I think the Holley's are easier to understand, particularly for an idiot like me.

Realize you're not talking that much money that you can't upgrade later on when you re-do the engine. There's always a good market for used Holley's. Once you've done the top end work, sell yours and go for a 750.

This car is my 71 challenger vert driver. i've got a built 440 going into my 73 for when i really want to get on it and go. so for the driver i was thinking the 650 would be fine as well, figuring it would be close to what the factory used. when i do rebuild this it won't be much more than 450 hp or so and i don't plan on racing it as thats why i'm building the 73.

Buy it. Something to keep in mind, the 650,700 and 750( 4777,4778,4779) all have the same size throttle plates. If you decide you want a bigger carb later, swapping to a Proform or Holley main body makes yours a 750. Those main bodies also have removable air bleeds. IIRC, changing the primary metering block is a good idea if you swap to the bigger main body. I believe the emulsion tubes are different in most of the 650s.

The 650 will run fine.It will give great low end and midrange punch falling off slightly on the top end.Buy it and try it.
A well tuned 750 vacuum secondary would be better for overall performance but not a bit better on driveability.

I have a 650 DP on my warmed over 383. I also have a 750 DP which has been rebuilt by the guy who did the 650 DP for me. For some reason my car loves the 650. With the 750, it's harder to start, and just seems "off." Put the 650 back on, and she's ready to burn the tires off.

AMEN pro 650 guys. Bigger is not always better.

i'd get the 750.