Guys
can anyone tell me if they did the 30cc to 50cc pump mod on the holley 4160 4 barrel 600 cfm carb? did it make a difference or not?
regards
ben

 

Ford_nut,

I have not made this conversion, I was just wondering what kind of trouble you are having with your carb that this may fix. Do you have a "bog" off the line?

 

Ben,
I was having a problem with bogging off-idle with my 4160, and went thru all kind of gyrations, including bumping up to the biggest shooter available and Reo pump conversion. Nothing seemed to "quite" do the job, until a nice guy on this forum told me that I needed to go SMALLER on the shooter! This is because a heavy truck, which mine definitely is, needs a longer duration accel pump shot to carry it past the slower acceleration period, as opposed to a light truck or car, say, which will pick up revs more quickly. The smaller shooter nozzles will lengthen the time that the extra gas is made available until the main jet system can pick up the slack. Make sense? Anyway, that's what did it for me. Actually, I just left the Reo pump on (lazy) for as long as I used the Holley even with the smaller shooter, but have gone to an Edelbrock now. Good Luck! Steve

 

Guys
I apologize for not being more specific with my problem. First, the truck is a 1975 F250 4x4 with a 360. I have what seems like a bog or misfire? right off idle to part throttle if i get aggressive with the gas pedal. at 3/4 throttle to full throttle it takes off. Its really annoying because anything more than 'easing into the gas slowly", the truck hesitates! I am ready to rip this damn 1850 holly off and go with an edelbrock performer.
Steve, like you, I have tried LARGER and LARGER shooters and accelerator pump cams---black, blue, red ect in both positions one and two. Heck, I even bought the hollow screw bec i was up aroung a #40 or so shooter!
My carb also has a metering block conversion on the secondary side. In addition, I have a yellow vac secondary spring in the housing. All that I have yet to do, is try the 50cc kit. I ordered it from summit and it should be in soon. I dont want to have to yank the carb off and install it if i can get away with a simple fix. So, the question is, where do I go from here? smaller shooter? What color cam should I be running and in what position? For what it is worth, my gas mileage is TERRIBLE!!!! HELP!!
thanks guys for the insight!
regards
Ben

 

It sounds to me like you need to look at two things. You would do well to, first of all, check your timing and make sure you aren't retarded. That can cause a bog as much as the carb. Plus that might explain poor fuel economy to some extent, tho FE's were never noted for economy! I would also suggest that you go to the smallest shooter, I think it's a #25, and match up the cam that will give you the most sustained volume, and give that a try. I'm not sure I could dig out my Holley manuals without upending something right now, but I recall that there was a good explanation of which cam does what packed with the cams, and in the Holley manuals, or you could pick that off their web-site too.
Finally, just for kicks, take a look at www.bob2000.com and scroll on down to the bottom to "Tuning Your Carburetor the Scientific Way", or something like that. A lot of things made more sense after I looked at that when I was trying to figure out which way was up on my 1850.
Good Luck, Steve

 

hey steve
after i posted here, i installed a #25 shooter with the orange cam in #1 position. well, the darn thing really runs like crap now. all this is with a 30cc pump too. i cant mess with it now bec its dark not to mention freezing cold! ill see what i can do tomorrow. until then, thanks again. Ill post back what i find!
Ben