Thread: Tuning a Holley

More than likely the LPG has backfired, and destroyed the power valve diaphragm. This will cause all sorts of overfuelling issues. Try also removing that large flat blade screwdriver screw in the side of the float bowl while idling. The fuel level should just start to spill out if it is right. (Vehicle must be on level ground). If it gushes out then that is the first place to start. Remove the float bowl and make sure the needle and seat isn't faulty or got dirt lodged under it, or the float isn't porous or damaged and sunk to the bottom.

If all OK, reassemble and adjust float height by undoing the locknut ontop of the float bowl housing and screwing it in or out (Can't remember which way now...) to alter the height of the needle assembly.

If all this fails, its emulsion block off and clean thoroughly, replace the power valve (Take note the numbers on the side) and all should be OK.

PS, a 500 CFM carb is a little too big, a 350 Holley would be a better unit.

If you can post up a pic or two we can help describe it all to you.

There is also some youtube tutorials on holley carb repairs. [ame="http://www.youtube.com/watch?v=6vKlAnKdcB4"]Carburetor Power Valves Video - Holley Carb Tuning DVD - YouTube[/ame] for starters

JC

Also the holley will just flood the motor either up hill or down which ever way it is fitted , Thats another reason why the Su carb is better Sorry but for off road use with out spending good money after bad you holley will just be perfect for a paper weight
I know some love holleys they have their place i just cant think of one right now

Originally Posted by rangieman

Also the holley will just flood the motor either up hill or down which ever way it is fitted , Thats another reason why the Su carb is better Sorry but for off road use with out spending good money after bad you holley will just be perfect for a paper weight
I know some love holleys they have their place i just cant think of one right now

Extend the vent as high as possible in the air cleaner and add a whistle in the fuel bowl vent, problem solved

Good place for bits

Hume Performance, Carburettors Rebuild, Air Filters and Cleaners For Sale

Thanks for the input guys,

The power valve information is very useful, I've put a new power valve in it but have no idea if it is the right type for this motor. Once I've put the fuel tank back in (fixing the fuel sender) I'll check the manifold vacuum and research this some more.

I've checked the float level and it is spot on up to the viewing hole.

As mentioned, I'd prefer not to change the carby if possible, this car is being done on a budget to save money for all my other toys!

Rovercare, would you be able to elaborate on extending the vent? Is this a vent from the float chamber up into the inside the air cleaner?

Cheers,
Steve

Classic Broncos .com - Tech: Carb vent tricks for your Holley - 66-77 Early Ford Broncos

Easier for me to find a link rather than explain

Originally Posted by Mister_white_keys

Thanks for the input guys,

The power valve information is very useful, I've put a new power valve in it but have no idea if it is the right type for this motor. Once I've put the fuel tank back in (fixing the fuel sender) I'll check the manifold vacuum and research this some more.

I've checked the float level and it is spot on up to the viewing hole.

As mentioned, I'd prefer not to change the carby if possible, this car is being done on a budget to save money for all my other toys!

Rovercare, would you be able to elaborate on extending the vent? Is this a vent from the float chamber up into the inside the air cleaner?

Cheers,
Steve

Justinc. is right about the Holley 500 being to big, it is essentially a race only carb designed for racing classes that only allow 2 barrel carbs. Everything is too big, accelerator pump and cams, jets, power valve, etc.
Go back to a SU carb, or put an off-road kit in a 350 Holley and don't make the mistake that most people that hate Holley carbs do and that is rebuild with any parts other than genuine Holley.
Aftermarket gaskets, esp. those on the metering block and float bowls shrink and cause chaos, Power Valves with no numbers stamped on the sides are totally useless. The numbers on Holley Power Valves indicate in inches of mercury the point that the valve opens and enrichens the fuel mixture transition. You don't want a power valve that is open at cruising speed, as it will enrich the mixture too much, when you don't need it.
The off-road kit includes spring loaded float needles, extensions for main jets, baffles for the fuel bowl internal extensions for the air vent and external, etc. The accelerater pump cams and the pump would need to be changed to the standard size also and the fact that even a 350 Holley would be at the size limit for a 3.5L engine would suggest that LR knew what they were doing when they fitted the SU type carbs, Regards Frank.