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Question: Holley 80555C

Vette79

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Jan 23, 2007
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1979 L-48 Black Coupe
Will the Holley 80555C 650CFM Q-Jet Replacement be adequate on a 355ci with AFR 180cc Cylinder Heads, 218/224 CompCam, Edelbrock Performer Intake, 1.6 Full Roller Rockers, Headers and Dual Exhaust. I am thinking of switching and would be going from the 750cfm Q-Jet to the 650cfm Holley. I'm not concerned with MPG.
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
Will the Holley 80555C 650CFM Q-Jet Replacement be adequate on a 355ci with AFR 180cc Cylinder Heads, 218/224 CompCam, Edelbrock Performer Intake, 1.6 Full Roller Rockers, Headers and Dual Exhaust. I am thinking of switching and would be going from the 750cfm Q-Jet to the 650cfm Holley. I'm not concerned with MPG.

What's your objective for the swap, or what specific problem are you trying to solve?
 

Hib Halverson

Technical Writer for Internet & Print Media
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CenCoast CA
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71 04 12 19
What's the rpm range of the engine? What's the axle ratio? Which transmission is in the car?
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
What's the rpm range of the engine? What's the axle ratio? Which transmission is in the car?

I have decided on the 0-9895 Holley (4175). I have an automatic tranny with original rear end 3.55. The rpm range would be up to 5500. I have been experiencing a fuel leak at the fuel inlet and a bog at full throttle. After two q-jet's and two rebuilds and a considerable amount of cash I'm ready to move on to something hopefully more reliable and easier to tune.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,457
Location
CenCoast CA
Corvette
71 04 12 19
I have decided on the 0-9895 Holley (4175). I have an automatic tranny with original rear end 3.55. The rpm range would be up to 5500. I have been experiencing a fuel leak at the fuel inlet and a bog at full throttle. After two q-jet's and two rebuilds and a considerable amount of cash I'm ready to move on to something hopefully more reliable and easier to tune.

With the engine configuration you list, you are better keeping a Quadrajet on the engine. A QJ is a better carb for your engine, especially the driveability. Edelbrock makes a good Quadrajet clone. That said, it's clear your QJ experience has been "dirtied" perhaps by poor-quality rebuilt carbs. A 650 Holley would be a good choice, but don't believe that a Holley is any easer to tune than a Quadrajet...well...it depends on what "tuning" means to you. In fact, a Quadrajet is more "tunable" than is a Holley because it uses metering rods. On the other hand, Holleys are a little easier if "tuning" means just changing jets.

Good luck and Merry Christmas.

Don't be surprised if your bog at fill throttle remains.

If it is still there when you're done with the Holley swap, start troubleshooting your fuel supply system. Inspect for restricted fuel lines. Pull the sender and check the "sock". Change the fuel filter. Test the fuel pump and replace if necessary.

Also, what your spark timing is doing may affect how the engine runs at WOT. You may want to make sure the distributor advance is working right and that the timing is set properly.
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
With the engine configuration you list, you are better keeping a Quadrajet on the engine. A QJ is a better carb for your engine, especially the driveability. Edelbrock makes a good Quadrajet clone. That said, it's clear your QJ experience has been "dirtied" perhaps by poor-quality rebuilt carbs. A 650 Holley would be a good choice, but don't believe that a Holley is any easer to tune than a Quadrajet...well...it depends on what "tuning" means to you. In fact, a Quadrajet is more "tunable" than is a Holley because it uses metering rods. On the other hand, Holleys are a little easier if "tuning" means just changing jets.

Good luck and Merry Christmas.

Don't be surprised if your bog at fill throttle remains.

If it is still there when you're done with the Holley swap, start troubleshooting your fuel supply system. Inspect for restricted fuel lines. Pull the sender and check the "sock". Change the fuel filter. Test the fuel pump and replace if necessary.

Also, what your spark timing is doing may affect how the engine runs at WOT. You may want to make sure the distributor advance is working right and that the timing is set properly.

No doubt my Q-Jet experience has been tainted. Timing is set correctly. There could be an issue with the fuel pump (stock) but that was replaced during my top-end rebuild a few years back. How do I test the fuel pump? I could have a vacuum leak I suppose? Would that cause the bog at initial full throttle? Emissions components have been removed and the headlight vacuum system has been disconnected. The Holley 0-9895 is a great replacement for the Q-Jet. Merry Christmas To You as well!!!
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,457
Location
CenCoast CA
Corvette
71 04 12 19
No doubt my Q-Jet experience has been tainted. Timing is set correctly. There could be an issue with the fuel pump (stock) but that was replaced during my top-end rebuild a few years back. How do I test the fuel pump? I could have a vacuum leak I suppose? Would that cause the bog at initial full throttle? Emissions components have been removed and the headlight vacuum system has been disconnected. The Holley 0-9895 is a great replacement for the Q-Jet. Merry Christmas To You as well!!!

Now that you specify that the bok is at initial full throttle, it is unlikely the problem is the fuel pump.

Good luck.
 

Vette79

Well-known member
Joined
Jan 23, 2007
Messages
1,392
Location
Millersville, MD
Corvette
1979 L-48 Black Coupe
Now that you specify that the bok is at initial full throttle, it is unlikely the problem is the fuel pump.

Good luck.

Holley 0-9895 delivered today. Looking forward to the swap. Looks like I just need to modify the fuel line or create a new one.
 

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