SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: steele211 on February 18, 2008, 05:56:44 PM

Title: holley carbs
Post by: steele211 on February 18, 2008, 05:56:44 PM

anyone out ther know off hand the difference in bore size of a 750 cfm and an 800 cfm is and what probs it might cause going from one base plate to another (800 to 750)

Title: Re: holley carbs
Post by: crewchief22 on February 19, 2008, 06:31:05 AM

Without knowing what list #'s you have its impossible to guess.

Here are the differences in the 4779 (750)     and      4780 (800)
    venturi diam. primary           1 3/8                        1 3/8
    venturi diam. secondary       1 3/8                        1 7/16
    throttle bore diam. pri/sec    1 11/16                     1 11/16 

My old Holley catalog shows different throttle body & shaft assemblies for these two carbs.

Get the List #'s and I'll check by book.       

Title: Re: holley carbs
Post by: speedymopars on February 19, 2008, 06:37:58 PM

Larger baseplates on 50-100 CFM smaller carbs usually work well.

Title: Re: holley carbs
Post by: steele211 on February 23, 2008, 06:23:45 AM

thank you for that crewchief. the base plate that im looking at isnt a holley and says it fits all holley 4150 carbs. to the best of my knowledge holley no longer makes the base plate for my carb.