The Stovebolt Site Forums The Shop Area Engine Shop Timing/carb/fuel pump Questions

I am working trying to figuire if I have my timing right and if I am getting enough fuel. My carb has hissing sound/sucking sound coming from it and engine is sluggish when you hit the gas and am not getting full horespower out of engine and is sluggish.

Carb Question
I have a hissing sound coming from the carb and when you hit the gas you hear the hissing sound and engine does not respond to pedal immediately. Also if I goose throttle very quickly at carb it will sometimes backfire at the carb. I just rebuilt the carb last night (Rochestor B) but that did not seem to help at all. Also, what is the correct measurement for float level for this carb? I followed the instructions kit came with from napa to adjust float level and it was off a lot from its original position andjust wanted to verify that the napa instructions were correct since it was so far off but has not made my engine run better or worse.

Timing
I have gotten a timing light and have some questions about making sure I timed it right. I see the mark but the ball on the flywheel I am not sure about. I see what looks like a hole in the flywheel (like a quarter inch bolt hole) that I assume is the ball or where the ball use to be. Is there only one mark on the flywheel? Because this thing doesnt look like a ball to me like I have read but more like a bolt hole. Also once these are aligned I tightened everything down but is that all i need to do. I alos put the octane selector at the neutral or zero mark. Do I need to adjust this and I do not hear any pinging like I have read on this thread and any clarification of this pinging would be helpful.

Fuel Pump
I am not sure if this is my problem that contributes to the hissing at the carb but to me it seems like it may not be getting enough gas. I did rebuild the carb and look down carb and do see it spray when I goose throttle. How can I tell if this mechanical fuel pump good or bad easily.

Any help to resolve this hissing/sucking noise at carb and the lack of get up and go from the engine would be great. Thanks in advance.

Hy jim54521, please remember to tell us what year, engine and size of truck you're asking about. I think the hissing sound is the sound of a vacuum leak, and the engine will never run correctly with a vacuum leak. It sounds like the accelerator pump is working correctly, by giving you a squirt every time you pump the carb linkage. I think finding/repairing the vacuum leak should be your first priority. If when you have the truck running you place an unlit but turned on propane torch in the area that you hear the hissing, if there is a vacuum leak the engine will speed up when the vacuum leak draws the propane in, hope that helps.

Truck is a 53 Chevy with 235, three on tree.

I do not believe it is vaccum leak and I have done the propane test before and reinstalled intakes properly. This hissing sound is coming form inside carb. Like it is sucking the air from air intake very loudly.

Sounds like a lean condition. Try setting the float higher. The direction for the kit may have been adapted from many different carbs and combined into one. That carb is 59 years old, so I am betting the directions are not 100% accurate !

A weak fuel pump should not show up at idle unless its really bad, on its last leg so to speak. If you have a inline filter, or the steel line has been cut and repaired, add a " T " fitting and fuel pressure gauge. Most vacuum gauges will work for this. A normal fuel pump will be in the 3 to 5 psi range.

Joe

I would connect an external vacuum gauge, great tool for many items that need tweaking on any motor. With the vac gauge connected, first you can see exactly how much vac you have, 16-20 range is good, you then can fine tune your timing, rotate dist to the highest reading. Adjust the carb mixture via the vac gauge. If the needle on the gauge is bouncing all over the place you could have valves out of adjustment, etc.
Best of luck

The Ball

If your flywheel is dirty it may be hard to see the ball. I got under and pulled the cover off, cleaned the ball off and put a dab of white paint on it. Made it much easier to see.