Incognegro
09-11-2011, 01:27 PM
I recently purchased a new Holley 750 Ultra Double pumper part #0-76750RD and installed in on my 355 small block that previously had a 4150 dominator on it. Here is a basic breakdown of the engine:
KB pistons
Eagle rods
Scat Crank
Luanti Cam 278/288 advertised duration 239* intake 249* exh at .500 lift
It has world 1 sportsman heads 64 cc (not sure on valves)
Basically the engine ran 12.0 deadly consistent in my race Camaro and was pulled to sell the car and was installed in a 62 Nova Gasser which is intended to be a street car. I selected the Holley Ultra Double Pumper cause it seemed more like a streetable carburetor with a choke. BOY WAS I WRONG!!
This carb from day one has ran like garbage, and I understand that it might need some minor tweaking to run good on my motor, but I did not expect this much fussing with it just to get it to run at all..
My first issue was loading up and fouling plugs before I even got it on the street. Turned out to be some debris in my needle and seat. (where it came from god knows cause my entire fuel system is brand new and I am running a filter, so I assume it was in the carb from the start).
Fixed that and on the road the car would bog when I went WOT, so I went from .28 pump shot nozzles to .31 with no luck then tried to go to .37 even worse...At this point the car idles fine, so I change pump cams from a green in front and white in back, to an orange up front and brown in the back, and down to a .31 pump shot nozzle. The car no longer bogged and took off like a bat out of hell but now at traffic lights it would load up and stall. Keep in mind I changed NOTHING but the cams and the car idles fine prior, but now will idle for a bit then after driving 10-15 minutes it wants to load up and stall at a traffic light..
So even with all the proper set up, the carb runs like dog *****, so I open the float bowls and find that the hole drilled for the accelerator pump is off center and crushing the gasket to the point it might be blocking fuel..
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4066.jpg
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4068.jpg
I also found that the O-ring on the front needle and seat was chewed up already possibly causing the loading up..
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4069.jpg
I really did not expect this lack of quality control from Holley and would expect that a brand new carb would not need to be opened up as much as I have already. I have sunk good money in purchasing parts for this carb and countless hours messing with it..
The carb has 72 front jets 80 rear jets and 6.5 power valve, and timing is set to 16* at idle to 38* at 3000 rpms with vacuum advance disconnected. With the vacuum advance connected the timing is around 20-24 idle.
Questions are:
What do I check next? Would the O-ring cause the loading up I mentioned?
KB pistons
Eagle rods
Scat Crank
Luanti Cam 278/288 advertised duration 239* intake 249* exh at .500 lift
It has world 1 sportsman heads 64 cc (not sure on valves)
Basically the engine ran 12.0 deadly consistent in my race Camaro and was pulled to sell the car and was installed in a 62 Nova Gasser which is intended to be a street car. I selected the Holley Ultra Double Pumper cause it seemed more like a streetable carburetor with a choke. BOY WAS I WRONG!!
This carb from day one has ran like garbage, and I understand that it might need some minor tweaking to run good on my motor, but I did not expect this much fussing with it just to get it to run at all..
My first issue was loading up and fouling plugs before I even got it on the street. Turned out to be some debris in my needle and seat. (where it came from god knows cause my entire fuel system is brand new and I am running a filter, so I assume it was in the carb from the start).
Fixed that and on the road the car would bog when I went WOT, so I went from .28 pump shot nozzles to .31 with no luck then tried to go to .37 even worse...At this point the car idles fine, so I change pump cams from a green in front and white in back, to an orange up front and brown in the back, and down to a .31 pump shot nozzle. The car no longer bogged and took off like a bat out of hell but now at traffic lights it would load up and stall. Keep in mind I changed NOTHING but the cams and the car idles fine prior, but now will idle for a bit then after driving 10-15 minutes it wants to load up and stall at a traffic light..
So even with all the proper set up, the carb runs like dog *****, so I open the float bowls and find that the hole drilled for the accelerator pump is off center and crushing the gasket to the point it might be blocking fuel..
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4066.jpg
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4068.jpg
I also found that the O-ring on the front needle and seat was chewed up already possibly causing the loading up..
http://i221.photobucket.com/albums/dd73/mrcmotorsportsLLC/CIMG4069.jpg
I really did not expect this lack of quality control from Holley and would expect that a brand new carb would not need to be opened up as much as I have already. I have sunk good money in purchasing parts for this carb and countless hours messing with it..
The carb has 72 front jets 80 rear jets and 6.5 power valve, and timing is set to 16* at idle to 38* at 3000 rpms with vacuum advance disconnected. With the vacuum advance connected the timing is around 20-24 idle.
Questions are:
What do I check next? Would the O-ring cause the loading up I mentioned?