Every time i floor it boggs down, almost shuts down but after i get off the gas it ruuns fine.It runs fine till i try and floor it. What would cause this?
Something is wrong within your accellerator pump cirucuit of the carb. When you open the throttle fast, the carb's normal metering cannot adjust quick enough, so the carb needs a quick shot of gas to cover up the 'hole' or bog created. If the accellerator pump or any part of it's system fails, you will have a big hole, or bog when you stab the throttle.
check dist plate and relector wheel roll pin under rotor i had one break the pin and the relector wheel move causing timing to change
Ratio411 hit it. I built a 383 Chevy for a friend one time years ago. He was dead set on a tunnel ram with 2 fours on it, so he got two 650 vac sec Holleys. It would take off fine if you eased into it, but if you ever punched it, would fall flat on it's face for a few seconds, then pick up and run like hell. Even with two accel pumps it didn't have enough volume for the long runners in the tunnel ram, creating an instant bog. I tried to get him to get the 50cc pumps, but he wouldn't listen. He finally traded the tunnel ram for a air gap with a 750 and then it did right.....
the compression of the engine would not cause a bog. its a carb or ignition problem. most likely the problem is the accelerator pump as stated before. i doubt its a simple adjustment issue. first you need to see if its working. with the motor off take off the air cleaner. put your head over the carb and look down the barrels. open the choke flap. now move the throttle. does fuel get shot down the barrels? if yes the the accelrator pump is good. if not thats the system that you need to diagnose. to help diagnose it we need to know what type of carb it is.
If the engine bogs down then you are opening the secondaries too fast or have a carb that is too large for your application. You can hide the bog by adding some low end timing ( take out some of the advance first) and by tuning the acelerator pump to shoot more fuel into the engine quicker. A larger pump cam with a shorter duration and larger shooters will accomplish this but you would be better of going to a vacuum secondary carb of the same size. I am assuming that you are running a mechanical secondary carb.
I played with the carb some and it seems to be doin better, its the summit 600 carb, and the accel pump is working i did check that, but it seems to be doin better.
What carb is on it????? Accel. pump will give you a bog but it will recover eventually and pick up speed. If yours bogs down and stays like that till you lift your foot its not the accel. pump. Could be lack of fuel, secondaries open too fast.... DOH, you guys beat me to it again. Sorry for the duplicate info.
What is a "Summit 600"? Is it a Carter AFB, like the Edelbrock carbs? If so, there are some sharp Carter guys here, I am not one of them. What you are looking for when the throttle blade open is an instant reaction by the accel pump. If the throttle is moved, even the tiniest bit, there should be fuel from the accel pump circuit. If the blades move open without that shot of fuel, there WILL be bog. So timing and adjustment of the pump shot is critical. Definately get a book that covers the type of carb you have. That is a must if you plan to keep that carb and get performance from it over the years. I thought you probably had a stock carb that had been running fine and just started doing this recently. That would indicate trash in the pump circuit or a ruptured diaphram/piston. This is why as much info as you can give is very important to getting good answers sight unseen. Make sure you get fuel instantly and at any speed of throttle movement. Make sure pump shot is constant and unbroken. A broken stream could indicate trash in the system or an air leak.
Just thought of another common problem... Did you buy the carb new? If not, then there is the possibility that the previous owner was too smart for his own good and tried to turn a vacuum secondary carb into a mechanical secondary! I have seen it many times. A guy figures that he can't see the secondaries open when he wings the throttle, so he locks in the linkage for the rear blades to open mechanically. The problem is that without an accel pump out back to cover the hole when the secondaries are forced open, you get the same big bog that you get when the primary accel pump fails. Look for a screw or tie wire in the linkage of the throttle plate that looks out of place. If the carb is designed to open the rear throttle blades via method other than mechanical linkage, it must be left that way.
Oh, okay... That is an old Holley design that is basically a 4150/60 crossed with an Autolite 4100. A nice design, but it flopped for Holley. Apparently Summit bought the rights to the design an is giving it a try. The one in the pic is vacuum secondary. You could have the wrong spring in the secondary, causing the secondaries to open too soon. That's called "crashing in" the secondaries. This carb is also subject to the "screw in the linkage" trick.
A friend just gave me a holley 6oo that he had off his Camaro that never ran right. Guess what. The secondaries have a bolt on the linkage to open mechanically. It was a fresh rebuild but no wonder it didnt work.
