OMC

Resent purchased 69 cutlass 350 rocket 4 Barral. lifter noise when cold goes away after warm up. Runs ok at idle and normal driving. When I get on the gas hard, it seems to bog and makes kind of a low popping sound through the carb. I’ve adjusted the timing. The eng looks to be fresh but sat for a long time from my understanding. Even when I power brake it just winds up. Can anyone help me figure out what maybe the issue? Thanks.

oldcutlass

What distributor are you running and what did you set the timing to? If you have points, did you set the dwell first? Are you sure its lifter noise and not exhaust?

joe_padavano

Backfire through the intake is usually a sign the carb is lean. I'd check the accelerator pump. When was the last time the carb was rebuilt? If it sat for any length of time, the accelerator pump cup is probably dried up, and there are probably deposits from the old gas inside the carb.

shiftbyear

Your choke pulloff also controls 4 barrel opening rate. Pull the vacuum hose off while running and warmed up. If it releases fast, replace it.

olds 307 and 403

As said, a leaking choke pull off can cause the flaps to open too soon. Also check the air door tension with the motor off. Every Qjet I have owned had too loose of tension for a stock torque application, tightening did wonders. Also check the cam that lifts the secondary rods, they should lift as you press the flaps open. If it is damaged, the air door will open but the secondary rods won't lift and pull fuel.

OMC

Carb Edelbrock 600 cfm. It looks new. I did open it up and adjust the floats they were off. HEI distributer, the timing I adjusted to where it runs the best. Tried to set it with a dial timing light but when I turn the **** from zero to increase time the timing mark went negative retard, so I set it by ear and performance. Yes, it lifters after it warms up they quite down. The low popping sound I hear when I get on it reminds me of a cam going bad. Not sure. You think maybe the fuel pump may not be keeping up enough flow to the carb?

OMC

[QUOTE=shiftbyear;1326295]Your choke pulloff also controls 4 barrel opening rate. Pull the vacuum hose off while running and warmed up. If it releases fast, replace it.


Anybody good with Edelbrock carbs?

shiftbyear

It helps to elaborate on the details of your engine, maybe a picture, exact model number of carb ect. Your symptoms could be anything from a slipped timing chain to a crimped exhaust pipe. As Sherlock Holmes said, "I can't make bricks without clay!"

olds 307 and 403

Edelbrock carb, another thread😱. Is it a regular Edelbrock carb or the AVS model?

OMC

Yeah you are right! Let me get that info.

OMC

[QUOTE=olds 307 and 403;1326334]Edelbrock carb, another thread😱. Is it a regular Edelbrock carb or the

it’s regular

olds 307 and 403

You need to slow the opening of the air door, big advantage to the AVS and Qjet. Look at the secondary jets and rods, it may be lean.

OMC

Ok thanks. Headers suggestion long tube or short tube for 350 69 cutlass?

olds 307 and 403

What exhaust is currently on the car? Thornton makes a direct bolt on shorty to factory dual exhaust down pipes. Sanderson makes a very compact shorty but needs custom down pipes off their 3" collector's. The Hedman shorties are very difficult to fit under a car, they need a very tight bend due to the 3" longer straight down collector. The Hedman or Hooker Competition full length headers are probably the best match for your 350.

gs72

You might want to start with some basic fuel delivery diag. Disconnect the fuel line from the carb. Put the line into a good sized container. Crank the engine over for 15 seconds and see how much fuel you get. It should be between 8 and 16 ounces. All the carb tuning in the world won’t correct for fuel starvation

OMC

They are the long tube but they have been flattened on the bottom side. They appear to hang kinda low. It appears that the previous owner was scraping the ground. There is all new front end witch I think was installed after the flatbed tubes. I was trying to get some idea if shorties would work best for ground clearance but at the same time the difficulty of connecting the down pipes appear to be very tight.
thinks for the input. I’m thinking long tube.

olds 307 and 403

Try and look for a brand stamping or part number on the headers. Avoid Flowtech, thin and leaky flanges with pipes that usually don't fit and rust quickly.

OMC

Thanks much appreciated!

OMC

Thanks good info. I will do just that.