Rebuilt engine wants to die when giving gas

[Macdozer]

Got a 59 AB engine that I rebuilt and started up on the floor to make sure things were good before installing it in the car.
Using a rebuilt distributor by bubbas and a stromberg 97 carb that I rebuilt.
The vacuum line was not hooked up.

The engine started right up and idled fine but if I gas it gas it would want to stall. When I gave it gas slowly it would increase rpm, but quickly giving it gas it would want to stall.
What should I look at first?

[63tango]

Accelerator pump and check valve could be your problem don't forget float level.

[27TV8]

I am having a similar problem.But when I give it gas it runs good but driving or speeding up it bucks and sometimes I hear a pop in the exhaust?
Had my two 97 carbs apart set the floats,idle screws at 1 1/2 turns,accel pump rods at winter and no change. next I will play with the ignition.
27TV8

[chap52]

27tV8- Have you unisync'nd the carbs. Search this site for how to...

[Binx]

Originally Posted by Macdozer

The vacuum line was not hooked up.

The engine started right up and idled fine but if I gas it gas it would want to stall. When I gave it gas slowly it would increase rpm, but quickly giving it gas it would want to stall.
What should I look at first?

The vacuum line must be hooked up for the distributor to work properly.

Lonnie

[flatjack9]

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Accelerator pump.

[RalphG]

I have the exact same problem with the Holley "teapot" on my 52 Merc. Idles perfect and will take off at idle with low throttle pressure (mercomatic). But step on the gas and it will die. I"ve learned to pump the gas pedal several times to be able to accelerate. I've got a new accelerator pump repair to install one of these days and I'm hoping that will cure it.
Also wondering if the "loadamatic" advance might not be working and not sure how to check it.

[flatjack9]

Best way to check the Loadamatic without removing it, is to remove the distributor cap, attach a vacuum hose to the vacuum can and see if the plate moves. If it does, your vacuum can is good and should advance the spark.

[RalphG]

Originally Posted by flatjack9

Best way to check the Loadamatic without removing it, is to remove the distributor cap, attach a vacuum hose to the vacuum can and see if the plate moves. If it does, your vacuum can is good and should advance the spark.

Vacuum pump required for this test I am guessing? I think I know where I can borrow one.

[FlatheadTed]

Like 63and Flat jack ,On a Holly or Ford carb pull the top to look and make sure you get two sprays of gas straight of when you work the throttle ,if not remove the leather plunger and oil and spread the leather ,below that there's a ball bearing valve make sure its free .Check the base of carb that there no heat riser hole venting into it ,On both carbs probe the cast iron bass holes with fine copper wire and blast out with compressed air ,fit good gaskets ,Other than that its a sticky valve or manifold leak .Ted

[Mart]

I find I can test a vacuum advance can by just sucking on it.

Mart.

[JSeery]

Originally Posted by Mart

I find I can test a vacuum advance can by just sucking on it.

Mart.

Or using one the little hand pumps, they are fairly cheap and have a gauge.

[Cheaterpete]

I have the same issue, accelerator pump are good, ignition also...I don t know what to check now...

[scooder]

In all of these cases first thing I'd do is change the condensor for a know good one, and make sure it has a good ground.

If it's a loadamatic, test the vacuum can, whip the cap off the distributor, unplug the vacuum pipe at the carb and suck on it, the points plate should move fairly easily when you suck. If it does, now suck on it again, when the points plate moves, plug the pipe with your toung and the plate should hold where you sucked it too. These test the plate moves and that the diaphragm is not holed.

Check the timing and contact point condition and gap.

Check voltage to coil, on a loadamatic, check the wire as it goes into the base of the distributor, if it's original, there will be an eye on the end of the wire, this fixes by a nut, this nut terminal should be isolated from the distributor body, by a plastic spacer and a piece of thin card like insulator inside the distributor. Some times this leaks to earth on the distributor body.

Check for good ground at the points plate on all types. The loadamatic has a wire connection to the plate, some times this is bad.

Check coil condition, replace with know good if in doubt.

Carburetor, whip the air cleaner off, with engine off, when you open the throttle there should be nice strong "jets" of gas from the ends of the accelerator pump nozzles straight away. If not your gonna be in the carb checking accelerator pump, non return ball and shuttle, make sure they both move and both seal.

Check the jets and there delivery channels for clean and good. Check the float needle for moving and sealing.

Check fuel pump delivery and condition of its sealing surfaces and diaphragm and valves, check fuel line for blockage, could also have a blockage in the fuel line pickup in the tank.

Quickest way for the last bit is usually a temporary gas supply, say a fuel line poked down the gas filler neck and clamped in position, and run this line to the fuel pump. Or from a gas can, gas can could also be used as gravity supply to take the fuel pump out of circuit.

I have an electric fuel pump for testing, so I can rig this pump up to test fuel line and tank for blockages, I also rig it up so I can test on the road with a temporary gas tank or fuel pump bypass.

Use common sence here, secure temporary stuff so you don't get gas going all over the place or stuff gets tangled.

A gas supply that's not up to spec oftentimes will idle fine all day, but put it under load ie drive it And it can't keep up with the gas required to replenish the float bowl.

Theres some test to get you started.
Report back with your findings.
Martin.