Holley FR-80805HBX

[ChevyTS]

Hi. A friend of mine just purchased a Holley FR-80805BKX and everyone is telling him that that carburetor is "worthless". Their words, not ours. I'd like to know the truth. Thanks.
tandkperformance@gmail.com

[ChevyTS]

I'd really like to know about this carburetor. I refuse to believe that Holley would sell a component that's "worthless". We're being told that this carburetor doesn't work and can not be made to work. Some details would be great. What was this carburetor designed for? Is there an optimal application? Should it be avoided in certain applications? Thanks.

[Gaz64]

Everybody has opinions about many different engine components, carburetors are no exception.
I built my own based around a 80804 850, converted to 12 hole annular billet boosters.
Looks like an Ultra XP to the casual user.
Mine has all of the great features of an XP, than many other carbs don't have.
These guys that ridicule an XP probably haven't used one.
An Ultra XP is really meant for race applications. The fuel curve is fairly rich, and not tuned for street fuel economy.
The throttle linkage is devoid of unnecessary linkage metal, since more than likely not to be used with an AOD transmission, or needing an idle stop solenoid, etc.
The camshaft and rest of the engine combo will be the deciding factor as to whether this type of carb is suitable. They're a good value for what you get. Gary

[ChevyTS]

Thank you for the reply. We've contacted some custom carburetor shops and they're basically telling us that this carb is designed incorrectly. The bores on the main body are machined too large and do not provide enough vacuum signal. Because of this the fuel circuits have to be jetted excessively rich making the carb have poor idle and part throttle characteristics. The engine that this carb is on was built and purchased from a company that's one of the best known in the business for Ford performance engines. I'm trying to solve the driveability concerns. Idle, run-on, and poor fuel mileage. So my question is should we purchase a new carb?

[Gaz64]

I don't like the 950 myself for the large venturi. Either have it converted to annular boosters, or go for a smaller venturi carb.
There are many specialty carburetors out there, but be prepared to pay for them. Gary

[ChevyTS]

Thank you for your help. I just spoke with the customer. Considering what I have discovered so far, I suggested that he should contact Shelby and let them defend their decision to use this part number carb. He purchased the engine as a crate engine through them. The engine was built and tuned by Roush Performance. I suspect that they will either send him the correct carb or pay for one of their tuners to come to East Texas to solve the problem. I am a nobody, involving Shelby & Roush, questions will get answered. By the way, I see that you are in Australia. Are you a 351C builder?

[Gaz64]

Glad to help. I'd say Roush has gone for a carb that produces the customers desired power on an engine dyno. Outright power is not everything in a street car. I would trade 20 HP for 20 ft/lb of torque. I'm a GM trained tech since 1980, so I concentrate on our Australian Holden V8, and small block Chevy. I mainly dabble in carburetors, I have nearly all the Holley tools. I like to use parts from from BLP as well. I like their Rapid Jet blocks. I also deal with Troy from TMP carbs. Gary