R. Bruno

I have a '71 pickup small block with a 2 barrel Rochester carb. It has a classic case of a nice heavy bog at take off. It idles fine and runs fine otherwise. I did a tuneup and rebuilt the carb and replaced float - accelerator pump seems to be working fine as I can see streams of fuel shooting into carb throat.

I see some stuff in the archives regarding fuel pump as a possible problem. Anyway to check this? Any ther ideas?

Thanks in advance guys :cheers:

mfgaffney

I would point you in a couple of directions: First, do you have any rubber fuel hose between tank and pump? It can suck closed. Second: you may not have the correct advance on ignition timing. If your distributor is original, the bushing may have too much play and is not feeding the correct mech advance as you try to accellerate. Check this with a timing light and dwell meter by just plotting the degrees of advance at 500 rpm increments from idle to say, 3500 rpm.
I think that when you rebuilt the carb you may have gotten part of your fuel/ignition system renewed, but now highlight another less than optimum part. Lastly, it may be that your float levels are incorrect in your carb.. Hope this gives you a couple of things to look at. :seeya

R. Bruno

Thanks Gaffney. I will check the fuel lines first. I was thinking about the distributor also and yes, it is original. So, it sounds like I take readings of the timing at the rpm increments, and then what should I be looking for?

Hopefully, I got the float correct. I measured it carefully. I am going to go bak into the carb if all else fails.

BSeery

Fuel pump should not be a problem from idle. That is when you have the most fuel available. Fuel problems usually show up under highway speeds or when climbing hills. You will have low / no power at speed, but around the streets and idle will be fine. If your fuel pump does not have enough flow to take care of the carb after idling for a while, it wouldn't have enough for when you were on the highway.

Usually it's a float level or accelerator pump problem.

GTR1999

Rob sounds like an accelerator pump or maybe it just the engine crying out for a 4 barrel intake and carb :seeya
Gary

R. Bruno

Thanks all. Gary, I see I can still count on a wisecrack from you. :lol: I thought it was an accelerator pu,p problem at first - thus the rebuild, but I can see the fuel squirting when I tweak the throttle and I replaced the pump plunger. So, not sure where that leads me.

GTR1999

:jester
You can check a fuel pump with a vac/fuel gauge,but check the rubber hose to the pump from the steel lines. I had one kinked and collapsing on a 350. It ran fine until I floored it then it would bog and choke until the foat bowl caught up. Replaced the lines and solved the problem.
:thumbs:
Gary


[Modified by gtr1999, 4:42 PM 5/3/2004]

R. Bruno

Thanks Gary and others. I am going to replace the lines (as soon as I get time) and see if that helps (they look original and it can't hurt).