Help. I rebuilt my Holley 4600 1850-3 600 vac sec and installed it back on my truck. When I started it there was gas gushing out the tube sticking up in the just behind the bowl on the front of the carb. It is amazing that the 390 was able to run at all.
Any suggestions? Do I need to adjust the float?
Thanks, Ray.

 

OK, got the float adjusted. No more spewing. Now the truck runs really rough and has slight surge. Will only run with choke part way and at around 2000 to 2500 rpm. When I push in the choke, the rpms drop off immeadiatly and the engine dies. Sorry that it is taking so long to respond to your help, I am by myself and need to lay down at times (cronic pain issues from military). I may be slow but I do questionable work.

 

Sounds like you idle mixture is adjusted too lean. Turn the screws on both sides of the metering block in all the way untill they GENTLY seat. Then back then out 2 to 2.5 turns. Connect a vacuum gauge to a manifold vacuum source and adjust the idle mixture screws to achieve the highes vacuum you can. After adjusting, you may have to reduce the low idle speed.

 

Thanks, I have the mixture screws turned out 1 1/2 turns right now. I will try bringing them out some and see what happens. I do not have a vacuum gage, but I do have a rpm gage on the steering colum. I will also check the timing once I can get it to idle. I will let you know.

 

You can use the tachometer to adjust the mixture screw. Adjust the mixture screw for highest rpm (what do you think causes the increase in vacuum?) After you get it, reduce the idle speed with the idle set screw.

 

I still can't get this thing running. It will only run with the choke partly closed and about 2k rpm. The idle mixture screws do nothing (rpm too high?). I took the carb off and reset the floats and made sure no passages were blocked. When I move the throttle there is a squirt of gas from both holes. The dist. vac. is blocked off and I can't find any vac. leaks. If I put my hand over the primaries, it will rev up. I know it is lean, but can't for the life of me figure out what I am missing. Any help would much appreciated. I am real close to chucking it and buying a new one.

 

If the choke has to be half onto make it run then that is probably making the idle to rich. You can not have the choke on at all when adjusting idle mixture screws. Keep disconnecting and plugging vacuum lines until you find it. Make sure none of the nipples on the carb are unplugged.

 

Well, I gave up. I got a new Holley 1850-7 from SHUCKS for $240 out the door. Bolted it on, made some minor adjustments and she is running fine. I will continue to play around with my old one to learn more about the carb. Thanks for all your help.