bought a mystery 850 double pumper...

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mbaird

mbaird

mbaird
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I didnt need this but curiosity got the best of me. And for 100$ what the hell.
First the shaved airhorn caught my eye.... Then the large boosters.... Then the drilled (and filled) throttle plates....
Guy said it was on a Indy headed dart he bought from a Pro-Mod racer (not the dart ) out of Colorado and it ran great. He wasnt trying to sell it to me... It was just sitting there.....
I havent opened her up yet...

What do you see?
IMG_20170611_094355.jpg
IMG_20170611_094431.jpg
IMG_20170611_094614.jpg
 
Do some measuring. I'd bet that's an early 830. I have one of those main body's for sale here on FABO that I changed to down leg boosters. If no one buys it, I'm taking it to the range and I'm going to blast it to bits.

I'd bet if you do some measuring you'll find it's a 750 base plate with an 850 body. I hate them. I know profession carb guys who won't touch them. I fought mine on and off since 1989.

Buy a billet main body, base and metering blocks and sell the rest. Better yet, sell that and put the money towards a BLP B4X. You'll be happier.
 
Thats not the reply I was looking for.... Lol

I have a slew of carbs including several Dps so I really didnt need it. Just got impulsive.
I figured it had been old school modded.
 
It's a 9380 you can look it up summit sells them I have had a few and they work great if you can tune a holley.
Good score!
 
brian6pac said:
It's a 9380 you can look it up summit sells them I have had a few and they work great if you can tune a holley.
Good score!
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I can say it again, call BLP, or Braswell, or Book, or Cubic, or or or and they will tell you the same thing. They won't touch it.

Holley designed that carb for a NASCAR class back in the day. They were meant to be modified. Holley was behind the 8 ball in the industry so they marketed this pig and let the chips fall where they would. I got burned by it. Over the years I changed boosters, several times. It was best with a down leg. I made the air bleeds and emulsion changeable. That helped. I tuned and tuned and tuned. Always had a hole in the fuel curve. If you filled the hole it was pig rich. If you made it the correct A/F ratio it had a hole in the curve. I eventually bought BLP metering blocks and BLP baseplate. It helped. Finally, I was sick of screwing with junk and bought a BLP B4X and ended the torture.

Just because they keep selling it doesn't make it good. Junk is junk at any price.

I don't me to pee in your lunch but truth is truth and facts are facts.

If you can make it work, I'll send you my carb and you can fix that one too.
 
Like I said.. I just bought it as a curiosity.
At the very least I got a set of 50cc pumps and other various parts.
I have another 850 DP and it seemed to work fine for a street motor.
My favorite though is a 600 DP the was modded by a buddy in the 80s... Seemed to make any engine run just a little better
 
mbaird said:
Like I said.. I just bought it as a curiosity.
At the very least I got a set of 50cc pumps and other various parts.
I have another 850 DP and it seemed to work fine for a street motor.
My favorite though is a 600 DP the was modded by a buddy in the 80s... Seemed to make any engine run just a little better
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That's what I'm saying...it's not an 850 it's an 830. Two entirely different things. I could be wrong but I don't think so. The only way to know now is to measure the base plate and the Venturi. I think you'll find it's a 850 main body with a 750 base plate. Even if you blend the two at the base plate, it causes fuel curve issues. The only way it's an 850 is if someone installed annular boosters in an 850. Otherwise it's an 830.
 
mbaird said:
Like I said.. I just bought it as a curiosity.
At the very least I got a set of 50cc pumps and other various parts.


That's the way I look at it!! I'd pay 50 bucks for a junk Holley if it has an electric choke on it because you get the electric choke assembly and a bunch of spare parts.

Treblig
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The guy I got it from has been racing around here since the 70s and made no claim to knowing anything about it. He just said the guy he got the car from ( Indy headed big block Dart with. 700 solid roller) ran a promod car which lead me to believe the carb was probably done right. He also said the car ran great. He had sold the car years ago.
 
if it ran in Colorado, you can bet the air bleeds were altered. First thing I would do is get it all back to stock Holley. Then start fiddlin'. Butterfy size should be square 1 3/4. 1-9/16 bore on a 1 3/4 base is a true 850 across the board. Holley (R80509) 830 (NASCAR mandated 1-11/16 butterfly class) uses 1-9/16 (750-950) venturi and 1-11/16 (750) throttle bores so you can write that off if your butterfly is a 1 3/4. .
http://documents.holley.com/techlibrary_carb_numerical_listing.pdf
 
Well Im in Idaho so if I run it I will be close to 3000 ft.
When I get home I will tear it apart , check the metering block #s and measure bores
 
I guarantee it's 1.56 venturies 1.75 throttle plates.
the story is 850cfm w/downleg boosters 830 cfm w/annual boosters because the annual's are bigger and restrict the air flow a little. Now they just rate them 850 because the actual cfm varies from CU.IN and RPM. If you read the specs it says 800-899 cfm rating.
 
brian6pac said:
I guarantee it's 1.56 venturies 1.75 throttle plates.
the story is 850cfm w/downleg boosters 830 cfm w/annual boosters because the annual's are bigger and restrict the air flow a little. Now they just rate them 850 because the actual cfm varies from CU.IN and RPM. If you read the specs it says 800-899 cfm rating.
Click to expand...


I'd bet whatever you can lose if it's a true 830 annular booster carb it will measure 1 9/16 ventures and 1 11/16 throttle bores.

OP are you going to measure it for us?
 
mbaird,
Please measure the throttle plates so we can put this thing to rest.
By the way it is a great carb.
Thanks
 
there were 3 annular carbs, 9379, 9380 and 9381
the 9381 is the 830cfm carb
based on the secondary linkage i bet that carb is a 9380, 850cfm, whats the number stamped on the throttle plates? looks like 1.75" plates to me...

also might wanna check all the bleeds in the carb, looks like it might be missing some idle bleeds.
 
cookietruck said:
there were 3 annular carbs, 9379, 9380 and 9381
the 9381 is the 830cfm carb
based on the secondary linkage i bet that carb is a 9380, 850cfm, whats the number stamped on the throttle plates? looks like 1.75" plates to me...

also might wanna check all the bleeds in the carb, looks like it might be missing some idle bleeds.
Click to expand...


I have a 9381 with overhead linkage on it. But mine is old. I think it was bought in 1989. Maybe 1990. The original base plate is long gone. It was one of the first changes I made to try and correct it.

So it may be a 9381 even with that linkage on it if it's old enough.
 
9379 is a 750. I have one that's been on all kinds of engines over the years. Right now its on a mild small block ford. Killer carb. Very responsive. Annular boosters have their place
 
It's a 750, 93 being annual booster 79 being 750 4779 downleg booster 750
4780 downleg 800, 4781 downleg 850, you know how it goes,
 
the first pic is good the second pic is the outside of the booster, you need to measure the smallest part of the bore, the venturi. It's hard to measure but if you have one of these its very accurate.

5180541b-7d4a-4f97-bea1-f552d8790db8_1000.jpg
 
You can also use a small piece of coat hanger of welding rod to measure the inside of the venturis if you don't have a set of inside calipers.
 
Ok... Didnt realize that...
I do have a set . I have all kinds of tools that I dont know how to use.... Lol

Will measure tonight.
 
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