Holley 850 HP carb - Page 2 - Ford Truck Enthusiasts Forums



1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Holley 850 HP carb

Reply
 
 
 
Thread Tools Search this Thread
  #16  
Old 08-13-2017, 07:29 AM
Franklin2's Avatar
Franklin2 Franklin2 is online now
Moderator
 
Join Date: Jan 2001
Location: New Market, VA
Posts: 39,326
Franklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant future
I can slam a vacuum secondary carb open and it will run fine.

Slam the double pumper open you will get a immediate surge from both accel pumps dumping the fuel into the engine, but after it uses that all up and the engine is still not turning fast enough to pull fuel through the venturi, you will get a bog. He even admits that.

Quote:
Yes, if you mash it to the floor at 900 RPM in 4th gear putzing around town it'll accelerate more slowly than if you roll into it. That's normal and to be expected when you lug the engine, though this torquey engine doesn't really "lug" per se.
The original poster can run one of his double pumpers and probably be fine, might even like it. But it's not going to be the ideal smooth running setup that a vacuum sec carb would be.
Reply With Quote
  #17  
Old 08-13-2017, 08:16 AM
CountryBumkin's Avatar
CountryBumkin CountryBumkin is offline
Posting Guru
 
Join Date: Apr 2011
Location: Orlando area
Posts: 1,572
CountryBumkin has a very good reputation on FTE.CountryBumkin has a very good reputation on FTE.CountryBumkin has a very good reputation on FTE.CountryBumkin has a very good reputation on FTE.
Quote:
Originally Posted by FuzzFace2 View Post
Beside a carb is not just idle & wide open you know?

Dave ----
That's the difficulty with the DP - it's getting the "transition" from idle to cruise and cruise to WOT, correctly setup. IMO.
Reply With Quote
  #18  
Old 08-13-2017, 08:39 AM
FuzzFace2's Avatar
FuzzFace2 FuzzFace2 is online now
Postmaster
 
Join Date: Nov 2015
Location: Angier, NC
Posts: 4,783
FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.
Quote:
Originally Posted by CountryBumkin View Post
That's the difficulty with the DP - it's getting the "transition" from idle to cruise and cruise to WOT, correctly setup. IMO.
On a Holley that is the job of the power valve (PV) and the VS carb also has a PV.


What I see you guys saying is the VS carb can be run on anything and just run, be it right or not where a DP is just a PITA if not right and takes someone who knows how to tune them.


To tell the truth I have not run a Holley DP on the street and the only Holley was a 2300 v2 500cfm on a 304 v8 and even it had a PV I had to "dial in".
All the DP (HP's) were on race motors for drag so if it idled and went to WOT good I was happy. Not that I cant turn it for street just never had the chance to.
Dave ----
Reply With Quote
  #19  
Old 08-13-2017, 12:44 PM
Franklin2's Avatar
Franklin2 Franklin2 is online now
Moderator
 
Join Date: Jan 2001
Location: New Market, VA
Posts: 39,326
Franklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant futureFranklin2 has a brilliant future
No way can a power valve overcome all 4 butterflies opening wide open all at once at low rpm. It has double accelerator pumps(double pumper) to try to shoot fuel in there mechanically to overcome this, and it will if the engine is free to rev in a lightweight car. A very high number in the rear would help on a truck.
Reply With Quote
  #20  
Old 08-13-2017, 01:34 PM
Jake.schmale Jake.schmale is offline
New User
Thread Starter
 
Join Date: Feb 2017
Posts: 7
Jake.schmale is starting off with a positive reputation.
Quote:
Originally Posted by Franklin2 View Post
No way can a power valve overcome all 4 butterflies opening wide open all at once at low rpm. It has double accelerator pumps(double pumper) to try to shoot fuel in there mechanically to overcome this, and it will if the engine is free to rev in a lightweight car. A very high number in the rear would help on a truck.
I think if the DP is tuned properly it would work fine on the street in any vehicle. I know a lot of guys that run DP on the street with no issues accept probably gas milage.
Reply With Quote
  #21  
Old 08-13-2017, 07:02 PM
FuzzFace2's Avatar
FuzzFace2 FuzzFace2 is online now
Postmaster
 
Join Date: Nov 2015
Location: Angier, NC
Posts: 4,783
FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.FuzzFace2 has a very good reputation on FTE.
Quote:
Originally Posted by CountryBumkin View Post
That's the difficulty with the DP - it's getting the "transition" from idle to cruise and cruise to WOT, correctly setup. IMO.
Quote:
Originally Posted by Franklin2 View Post
No way can a power valve overcome all 4 butterflies opening wide open all at once at low rpm. It has double accelerator pumps(double pumper) to try to shoot fuel in there mechanically to overcome this, and it will if the engine is free to rev in a lightweight car. A very high number in the rear would help on a truck.
The PV is does "the "transition" from idle to cruise and cruise to WOT" as you posted and that is what Holley says it does.


Who said they open all at once? Again the carb on the street is not going from idle to WOT like it does on a race motor and even more so if it is a 460.
If your 460 is that weak you need to go from idle to WOT you got bigger issues with the motor than running a DP carb.

Quote:
Originally Posted by Jake.schmale View Post
I think if the DP is tuned properly it would work fine on the street in any vehicle. I know a lot of guys that run DP on the street with no issues accept probably gas milage.
You are 100% right.
Would a VS carb be easier to tune? Maybe but only because you can be off on the tune and it will still run pretty good.

If all I had was a DP carb sure as heck I would give it a try and tune as needed.
Let us know what carb you go with and how you make out.
Dave ----
Reply With Quote
  #22  
Old 08-13-2017, 07:40 PM
matthewq4b matthewq4b is online now
Posting Guru
 
Join Date: Feb 2008
Location: St Albert, Alberta
Posts: 1,082
matthewq4b has a very good reputation on FTE.matthewq4b has a very good reputation on FTE.matthewq4b has a very good reputation on FTE.
Quote:
Originally Posted by Franklin2 View Post
I can slam a vacuum secondary carb open and it will run fine.

Slam the double pumper open you will get a immediate surge from both accel pumps dumping the fuel into the engine, but after it uses that all up and the engine is still not turning fast enough to pull fuel through the venturi, you will get a bog. He even admits that.



The original poster can run one of his double pumpers and probably be fine, might even like it. But it's not going to be the ideal smooth running setup that a vacuum sec carb would be.
Sorry got to call BS on that. It that was the case then no one would use DP's as a drag carb. It all comes down to proper tuning and that means accel pump cams/squirters as necessary to tune the pump shot curve and adjustable progressives linkage for the secondary's . Most all DP's are progressive secondary's, and really only hard core race DP's are 1:1 ratio on the primary's and secondary's

Just cause you have no idea how to tune a DP carb does not mean it is not viable option for street driven vehicles. NO vac secondary carb will out perform a DP in terms of flat out acceleration. Either from a standing start or part throttle.
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
F-850 history/info.? 1OldFordMan Large Truck 7 08-17-2017 06:44 PM
1979 Ford F250 460 Holley 850 Carb Correct Jetting??? nitro1207 Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460) 1 09-29-2016 01:54 PM
holly 850 cfm carb to big for a 302? fordman1986xlt 1973 - 1979 F-100 & Larger F-Series Trucks 4 02-21-2013 06:37 PM
What size carb? dgparsons2 Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460) 10 04-20-2009 03:41 PM
Holley Carb Identification 77f2504by4 Fuel Injection, Carburetion & Fuel System 3 07-05-2008 07:48 AM


Go Back   Ford Truck Enthusiasts Forums >

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -5. The time now is 07:45 AM.