Holley Strip Dominator angled carb base...

Dear Mooso,


I have a Holley on top of a Holley Strip Dominator with the stock carb pad. It has run fine since installation in 2006. With the higher rise of the HSD, the angled appearance of the carb attitude is more obvious. I was as sure, as an amateur can be, that the angled mounting of the carb *must* be detrimental to power. As I inquired, I discovered the same handful of options to attain a level carb. I inquired of a friend with decades of experience in NASCAR, drag racing, endurance road courses, etc, who is also a Pantera owner. His succinct advice was I could level it, but it wouldn't change the performance. A level carb only affects the appearance.

I haven't changed it. The car was driven to Phoenix two or three times and then to Houston followed by the only dry day on the TWS track.

Chuck Engles

I personally had difficulty with the fuel levels in the Holley carb using the angled intake manifold.

Just adding a Moroso angled spacer helped me and it will reduce or eliminate that issue.

Besides uncovering the jets the real issue is that if you set the floats according to the Holley instructions, on a steep grade you will be spilling fuel into the throttle bores.

Conversely your fuel level will be low where it shouldn't be.

Keeping the carb flat keeps all of the "factory' float levels valid.

I don't know what the maximum angle is before they spill but at least make sure the vents have the extended tubes on them.



Depending on whether you are climbing or descending a grade decides if the carb will flood or starve.

As an aside, when I was going through 'tech inspection' some make you run the car hard then hit the brakes as hard as you can. With the Holley, for me, that always stalled the engine because the fuel sloshed away from the primary jet system.

The 'Tech guys' always loved that. I didn't.

When transitioning from split plenum dual plane to open plenum single plane manifold topped with a with mechanical secondary carburetor, I have experienced serious lean condition bogs on aggressive acceleration. To remedy the bog, required changing to larger pup shooters and 50cc accelerator pumps.

Leveling the carburetor via machining of the mounting pad creates a bit more air cleaner clearance below the engine screen, most noticeable at the rear of the air cleaner. Leveling the carburetor with a wedge shaped spacer does not improve clearance. There is no performance advantage in leveling the carburetor ... as long as the float levels are adjusted properly in either situation. If the additional air cleaner clearance is desired, I would have the carburetor mounting pad machined, if not I would use the manifold as-is. I wouldn't use a wedge shaped spacer under any situation.

Tim Meyer, who has been posting here lately, is a good machinist, he's capable of performing the machine work to level the carburetor base if you want to go that route. And to answer another question, yes if I were having the carburetor mounting pad leveled, I would have the holes for the carb studs re-drilled as well ... by the same machinist leveling the carb mounting pad. There are a couple of different ways to approach that issue, I'd leave it up to the machinist to make that choice.

As John has indicated, I would expect some re-tuning of the carburetor to be necessary when swapping to the strip dominator manifold.

I've been contemplating this swap as well. By adding another 1000 rpms, I would assume that the 650 carb will need to be changed to a 750?

Jon, a dual plane manifold needs the larger carburetor more so than the open plenum manifold. I would start with the 650 carb you have now, and only go to a bigger carb if you're unhappy with the upper rpm performance of the smaller carb.

Footnote:

I feel compelled to write this footnote here. Not necessarily for Michael or Jon, but for anyone who may be reading this thread. I ask the long time members to forgive me for being redundant ... or "preachy".

Before an owner goes revving the motor in their Pantera above 6000 rpm, please make sure its got ARP nuts on the rod bolts, replacement valves, a replacement crankshaft damper, and sturdier push rods. The engine should be retrofitted with the Cobra Jet oil pump suction tube and a windage tray if it is not already so equipped. It would be reassuring if a strategy for controlling the amount of oil flowing to the valve train were also implemented.