[johnnyt5646]

I have done much searching on this but found nothing but every other combo (ie. 950 is a 850 base with a 750 main body.)

I am wondering if you can put a Holley 850 main body on a 750 base plate. Reason for this is i have a holley 650 (4777-2) carb. From what i read the 650 base plate is the same as the 750. I would use the holley 650 base which is the same as a 750 and put a 850 main body on it. Probably be a 780-800 cfm. Can i do it

I have a sbc 414 with afr 195 heads, comp cam intake 234 @ .5 exhaust 244 @ .5, holley 650, 11:1 compression, air gap rpm. I believe i can do better with a bigger carb. I can get my hands on a proform 850 main body for cheap. i just need to know if it can be done, if it can be done what do i have to do to make it work, and is worth it on my combo.

thanks for your help

john

[bubbahotep]

Not 100% sure but I think its the same. They're all considered 4150/4160's?

[bigdog7373]

If it were me i would just put the 650 on until you get enough money to buy a bigger carb. I wish i had a 650 for my 350 but i currently have a 750 which just dumps way to much fuel in the motor. But you have a bigger engine so you could use a 750. But yea, put the 650 on until you can buy a complete carb instead of trying to rig different parts together to make a bigger carb.

[1BAD80]

I read it wrong, thought you wanted to put a 850 base plate on a 750 carb, that would work.
Its still a 750 using the 750 base plate to a 850 body,
because of the butterfly size.

[bubbahotep]

Costwise I think it cheaper to buy the correct carb in full but in the end I think its all the same if you have the right parts. The 850 probably has different jetting and possibly (youd have to check) accelerator pump sizes? Its mechanical secondary so theres not too much to worry about there.

Might be doable assuming the plate is the same which as far as I can tell they are.

[ericnova72]

The bottom of the carb venturi bores on the 850cfm main body are 1/16" bigger than the throttle plates on the 650-800cfm base plate. The 850 has 1-3/4" throttle plates and the 650-800 have 1-11/16" plates. You end up with a mismatch in the wrong direction if you do what you are planning, not good.

Just putting the so called "750" HP style main body from Proform with the base plate from your 650 will result in a 780 cfm, you can increase this to 810cfm by thinning the throttle shafts of the 650 base plate to streamline them when at WOT. I've done this several times, makes for an awesome responsive carb.

If you can get a really good deal on the "850" HP main body you can buy a new "850" baseplate for around $100, check Ebay, with some shaft slimming you can end up with a true 925-935cfm carb.

The so called "950" Holley made from the 850 baseplate and 750 main body doesn't come anywhere close to the 950cfm it is called, more like 830cfm at best, and this has been proven. Talk to anyone who does custom carbs and they will tell you, the 950 Holley is not what it is cracked up to be.

[cobalt327]

What is the difference between the 3310-1 (4150) @ 780 cfm and the 3310-2 (4160) and up @ 750 cfm- I guessing the boosters (-1 has downleg)?

[ericnova72]

Originally Posted by cobalt327

What is the difference between the 3310-1 (4150) @ 780 cfm and the 3310-2 (4160) and up @ 750 cfm- I guessing the boosters (-1 has downleg)?

That is correct, downleg on the -1 and straight leg on -2 and up. The HP style main bodies have downleg, plus the streamlined and raduised air entry area.

[bubbahotep]

Originally Posted by ericnova72

That is correct, downleg on the -1 and straight leg on -2 and up. The HP style main bodies have downleg, plus the streamlined and raduised air entry area.

doesn't the 4150 have secondary metering block but not the 4160?

[ericnova72]

Originally Posted by bubbahotep

doesn't the 4150 have secondary metering block but not the 4160?

That is also the correct terminology. All Double Pumpers are automatically 4150's because of the rear block, but Vacuum Secondary carbs can be either 4150 or 4160.

There are also two discontinued since the 70's 3160's , these are 3 barrel vacuum secondary, came in 950(List# 3916) and 1050(List# 4604) sizes. They have one big oval blade and venturi in the rear with the same two boosters, the result of Holley removing the divided area between the rear barrels. No DP 3150's were ever built.