Moparts
Holley Carb Gurus-Help Needed
Posted By: G-Money1320
Holley Carb Gurus-Help Needed - 05/30/11 12:16 AM
A friend of mine hooked me up with a 750 double pumper and I need a little advice as to where to start with it. First it has 32 shot in the front and 42 in the back, with 82 jets in the front and 71's in the back. Now I know this probably is way off for my application so what would be a good base to start with?? Im switching from a 750 vacuum secondary that has a 25 shot with I believe 72 jets. Im running a good 340/auto,3.73 gears in a 3100# 69 Dart. Also shouldnt the idle adjustments be in the front metering block? They are in the rear block?? Im not good with carbs so I would appreciate some advice. Thanks1
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 12:25 AM
Go to the Holley web site and set it up back to standard...
you gonna need the numbers off the carb.... yes the
primaries are in the front... thats the idle plate...
you sure you dont have it turned around backward...
because the jetting is backwards also
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 12:32 AM
I put new gaskets and diaphrams on it today and while I was assembling it I noticed the blocks didnt look right, thats why I asked just in case, but the front one has the power valve in it-im so confused,
The way I took it apart and reassembled it was the way I got it. Hi Mike
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 12:36 AM
Yeah, sounds like your looking at it backwards, the mix screws should be up front, most 750dpers are jetted 70/80 PV up front.
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 12:39 AM
Quote:
I put new gaskets and diaphrams on it today and while I was assembling it I noticed the blocks didnt look right, thats why I asked just in case, but the front one has the power valve in it-im so confused, The way I took it apart and reassembled it was the way I got it. Hi Mike
I would install 31 squirters front & rear, 42 will be too much. You can get away with the 32 out back, just install a 31 up front. you can get away with the 71/82 jets for now.
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 01:00 AM
Quote:
I put new gaskets and diaphrams on it today and while I was assembling it I noticed the blocks didnt look right, thats why I asked just in case, but the front one has the power valve in it-im so confused, The way I took it apart and reassembled it was the way I got it. Hi Mike
Take it back apart... throttle linkage is on the left
(drivers side)... idle metering block goes in front
and so should the PV if running one... if using the
PV you will be about 8 jet sizes smaller on the front
than the rear... no PV in the rear... I tried to
pull up the specs for the different 750DP but the
Holley site isnt working right now
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 01:43 AM
You didn't post your list number so here are all of the specs for 750's i have: (all powervalves are in the front)
4779 c 750 (F)75,(R)76 8.5 4150
4779-1 750 (F)70,(R)80 8.5 4150
4779-2 750 (F)70,(R)80 6.5 4150
4779-3 750 (F)70,(R)73 6.5 4150
4779-4 750 (F)70,(R)80 6.5 4150
4779-5 750 (F)70,(R)80 6.5 4150
4779-6 750 (F)71,(R)80 6.5 4150
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:09 AM
Well theres no choke horn on it to get the numbers from it, on the base it had 47708 and I just went out and took it apart again to verify the blocks are on right and now im even more baffled. The front block is indeed on right as it has the PV but no idle screws or even tapped for them, and the back block had the screws but not drilled for the PV.
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:15 AM
Quote:
Well theres no choke horn on it to get the numbers from it, on the base it had 47708 and I just went out and took it apart again to verify the blocks are on right and now im even more baffled. The front block is indeed on right as it has the PV but no idle screws or even tapped for them, and the back block had the screws but not drilled for the PV.
hmmm sounds like it was thrown togehter with mismatched parts. Might be better to move on if you don't know about carbs.
Oh and rear blocks did come with powervalve holes but were plugged on some carbs.
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:18 AM
I missed the suirter question. most early ones with the small pumps used 25's and 28's the -1 and -2's used 28 and 31
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:19 AM
Quote:
Quote:
Well theres no choke horn on it to get the numbers from it, on the base it had 47708 and I just went out and took it apart again to verify the blocks are on right and now im even more baffled. The front block is indeed on right as it has the PV but no idle screws or even tapped for them, and the back block had the screws but not drilled for the PV.
hmmm sounds like it was thrown togehter with mismatched parts. Might be better to move on if you don't know about carbs.
Oh and rear blocks did come with powervalve holes but were plugged on some carbs.
Yep, sounds like a mix and match pile of parts...
you dont need the PV in the front BUT you do want the
mixture screws in the front.... the PV will help when
cruising
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:23 AM
Quote:
Quote:
Quote:
Well theres no choke horn on it to get the numbers from it, on the base it had 47708 and I just went out and took it apart again to verify the blocks are on right and now im even more baffled. The front block is indeed on right as it has the PV but no idle screws or even tapped for them, and the back block had the screws but not drilled for the PV.
hmmm sounds like it was thrown togehter with mismatched parts. Might be better to move on if you don't know about carbs.
Oh and rear blocks did come with powervalve holes but were plugged on some carbs.
Yep, sounds like a mix and match pile of parts...
you dont need the PV in the front BUT you do want the
mixture screws in the front.... the PV will help when
cruising
I use a power valve on all cars in the front even the blowthroughs. Tons better driveability.
10 jet sizes makes for a fat low and midrange!
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 02:30 AM
I use a power valve on all cars in the front even the blowthroughs. Tons better driveability.
10 jet sizes makes for a fat low and midrange!
Yeah they do help driveability, I usually run 8 jets
different then tweek from there
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 03:46 AM
If you can find a metering block with the idle screws & a PV provision you'll be good, then stick the one with no idle screws in back, You need to find a metering block off a DPer or at least a 3310 750, the 600 1850 will be too small for the metering, If you feel you don't want to tread in this area, just get another carb (preferably new) & move on.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 03:49 AM
If this is a mix-matched carb, then why does the front have a PV and not the idle screws? I can understand the rear having them since it could have been a 4 corner idle carb. I do have a 650DP I could take the block from.
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 03:51 AM
because its a rear meetering block
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 03:53 AM
Do the rears have PV's also?
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 03:58 AM
Quote:
Do the rears have PV's also?
on some models they were drilled but plugged.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:05 AM
So if I use the front block from the 650 with idle screws and PV and the rear block from the 750 with the idle screws would I have a better tuneable carb? In your opinion is the front block I have really a rear that someone drilled and tapped for the PV? Thanks for your help
Guess I should have stayed in school longer
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:09 AM
Quote:
So if I use the front block from the 650 with idle screws and PV and the rear block from the 750 with the idle screws would I have a better tuneable carb? In your opinion is the front block I have really a rear that someone drilled and tapped for the PV? Thanks for your help Guess I should have stayed in school longer
You "probably" don't have 4 corner idleing, so having rear idle screws will do you no good, Yes, it is a rear MB.
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:10 AM
your asking a lot from a conversation on the internet. I have no clue what baseplate you have what center section or what blocks you have. At this point i don't even know your engine/trans rear/use of your car. Its looking to me like you need to walk away from this carb or get somebody who knows holleys to go thru it for you.
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:12 AM
Quote:
your asking a lot from a conversation on the internet. I have no clue what baseplate you have what center section or what blocks you have. At this point i don't even know your engine/trans rear/use of your car. Its looking to me like you need to walk away from this carb or get somebody who knows holleys to go thru it for you.
, but it never hurts too learn.
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:14 AM
Quote:
Quote:
your asking a lot from a conversation on the internet. I have no clue what baseplate you have what center section or what blocks you have. At this point i don't even know your engine/trans rear/use of your car. Its looking to me like you need to walk away from this carb or get somebody who knows holleys to go thru it for you.
, but it never hurts too learn.
I agree but at least post pics and some dimensions!
Posted By: RAY1969CARS
Re: Holley Carb Gurus-Help Needed *DELETED* - 05/30/11 04:21 AM
Post deleted by RAYS_W-5_69DART
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:30 AM
Quote:
WHAT IF IT WAS A PROFROM MAIN BODY ??? WHAT WOULD THE JETS BE ?? BUT WAS A 4779-7 2679
I had my PF MB jetted 73/82 on my 451, but you can start out with the jets that come with it, then jet for "best" MPH.
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:34 AM
Quote:
So if I use the front block from the 650 with idle screws and PV and the rear block from the 750 with the idle screws would I have a better tuneable carb? In your opinion is the front block I have really a rear that someone drilled and tapped for the PV? Thanks for your help Guess I should have stayed in school longer
Greg, if you look at the rear see how many bleeds are
on each side of the vent tube... even if you put
the metering block on the rear with the mixture screws
they wont do anything if its not set up for it...
put a 650 front metering block on the front and you
would have a good start
Posted By: RAY1969CARS
Re: Holley Carb Gurus-Help Needed *DELETED* - 05/30/11 04:36 AM
Post deleted by RAYS_W-5_69DART
Posted By: RAY1969CARS
Re: Holley Carb Gurus-Help Needed *DELETED* - 05/30/11 04:42 AM
Post deleted by RAYS_W-5_69DART
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:52 AM
Quote:
Quote:
CAN YOU FIX A BROKEN booster ???? AND DOZ IT HAVE TO B A 750 ONE OR CAN IT COME OUT OF A 650 ???
PLUS WHERE DO I GET ONE ??
You should start your own thread, they call this high-jacking 
.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:58 AM
I tried to post some pics but they are too big for this site.
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:02 AM
Quote:
Quote:
So if I use the front block from the 650 with idle screws and PV and the rear block from the 750 with the idle screws would I have a better tuneable carb? In your opinion is the front block I have really a rear that someone drilled and tapped for the PV? Thanks for your help Guess I should have stayed in school longer
Greg, if you look at the rear see how many bleeds are
on each side of the vent tube... even if you put
the metering block on the rear with the mixture screws
they wont do anything if its not set up for it...
put a 650 front metering block on the front and you
would have a good start
Mike, why should he need to know how many bleeds are on each side in the rear, its still 2 on each side whether its 2 or 4 corner idle, what he would need to do is look at the underside of the MB to see if the idle feeds are drilled through, but thats an area for someone who knows what to look for, i did advize him to buy a holley tuneing/perf. book so he can get a better understanding.
Posted By: Labratt
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:05 AM
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:15 AM
pics
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:16 AM
#2
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:18 AM
#3
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:24 AM
Greg, thats an 800 DP. Most likely the jetting is 70-71 F/85 R, 50cc pump out back.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:29 AM
It did have the 50cc in the back and the rear block has brass screw ins in the passages. This will be way too much for my car then wouldnt it?
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 05:41 AM
Greg if you read all of this you will get a pretty
good idea how they function
http://www.holley.com/data/TechService/Technical/Carburetor%20Tech%20Info.pdf
Posted By: RAY1969CARS
Re: Holley Carb Gurus-Help Needed - 05/30/11 06:16 AM
sorry guys
Posted By: Cuda367
Re: Holley Carb Gurus-Help Needed - 05/30/11 07:03 AM
Many truck holleys had the idle screws in the rear metering block.
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 11:59 AM
Quote:
Many truck holleys had the idle screws in the rear metering block.
And what would be the reason for that 
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 05/30/11 04:15 PM
Quote:
Greg, thats an 800 DP. Most likely the jetting is 70-71 F/85 R, 50cc pump out back.
The Holley 8156 used that linkage and it was a 750.
Posted By: RemCharger
Re: Holley Carb Gurus-Help Needed - 05/30/11 07:41 PM
The metering blocks should have the list # on the top. If you could take a pic of that # we can read what it says.
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 05/30/11 08:15 PM
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 05/30/11 10:41 PM
Quote:
Quote:
Greg, thats an 800 DP. Most likely the jetting is 70-71 F/85 R, 50cc pump out back.
The Holley 8156 used that linkage and it was a 750.
What are the chances of it being a 8156 but you could be right, I'm bettin its a 4780 myself, but i've been wrong before.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:00 AM
First thanks for the helpful info
Here are some #'s the PV block has 7047 then 47812 on top and the rear 1 has 1116t with a deep 3 underneath. The base has 12R-4770B and 4895. The butterflies are 172's. Can I use the 800 base on the 650 with all the rest of the 650 parts and have a decent carb?
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:20 AM
Quote:
First thanks for the helpful info Here are some #'s the PV block has 7047 then 47812 on top and the rear 1 has 1116t with a deep 3 underneath. The base has 12R-4770B and 4895. The butterflies are 172's. Can I use the 800 base on the 650 with all the rest of the 650 parts and have a decent carb?
My best guess here is its a 8156 and it does have the proper rear metering block and wrong front block. Have you looked to see if it has the rear idle circuts drilled?
If all four butterflys are 172 or 2 are 173's the base plate is a 750. 800 and 850's used 180's.
I'm still thinking your 650 is much better than what you are showing us here. Why don't you do some mods to the 650? like cut the air horn, blend the top and then do some tuning with the pumps, cams and squirters.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:25 AM
Thats probably the way im going, the horn is already cut on the 650 so I guess a good cleaning and tweaking is in order. The carb in question was just in better overall shape and looked like a better starting point, but now appears to be more of a hassle
Posted By: bigtimeauto
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:28 AM
save it though. When you learn a little more or can get somebody to help you its a nice carb.
Posted By: G-Money1320
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:33 AM
Thanks, too bad all you carb experts are days away
Maybe Raff will put his touch on it when I see him
Posted By: MR_P_BODY
Re: Holley Carb Gurus-Help Needed - 06/01/11 01:56 AM
Quote:
Thanks, too bad all you carb experts are days away Maybe Raff will put his touch on it when I see him
That can happen
Posted By: joedust451
Re: Holley Carb Gurus-Help Needed - 06/01/11 03:38 AM
Quote:
Can I use the 800 base on the 650 with all the rest of the 650 parts and have a decent carb?
Yes you can, 650-800 use the same base
That 47812 metering block is from a 4781-2 850dp. Both metering blocks on the 850dp used PVs, so if it has no idle mix screws, its a rear MB.
