VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Engine Surging

'51 216

Since I changed the distributor I have been able to drive the truck. I forgot to tighten the intake manifold and ended up sucking in part of that gasket.

Since replacing the gasket and the metal rings on the intake manifold I cannot get this truck to run. It starts just fine, idles high with the choke on and then begins to surge.

It will start and rev up with the choke on like a normal engine would do. And then it starts to die and then it picks back up it just goes back and forth surging the RPMs.

I have double checked the timing and I can't seem to find a vacuum leak anywhere on the manifold or the vacuum advance. What am I missing where would you guys look next?

Would there be any harm in removing the intake rings to test the seal of the manifold gaskets?

The rings align the intake maniaaold with the head. Their removal sould not afect the leakage. Go ahead and try it.

Justin
Considering the distributor is on the right side of the engine and intake is on the left I dont know why the manifold was loosened to start with.
Anyway it does sound like a vacuum leak issue, in fear of stating the obvious check for open connections including the hose at the wiper unit.
If the manifold is off check that all ports are on the same line.
Tony

The distributor and manifold were two differs problems. It is possible that the distributor was not the problem to begin with.

I got the surging to stop. Apparently the idle screw had been turned in way too far. I had the truck idling and purring like a kitten in the driveway for about 15 minutes. Then it just stopped running. It appears lean as it will fire all choked up but won't stay running.

Silly question, where does the wiper connect to the manifold?

Justin
If engine stopped I lightly seat the screw then turn it 2 full turns out, with engine running turn screw in until engine noticeably running rough then out 3/4 turn.
The wiper vacuum connection is jut forward of the rear bend of the inlet manifold.
Tony

On the later carburetors the idle mixture screw has no affect on how the engine runs at speeds above idle speed.
The timing advanced too far will cause a surge at speeds above a fast idle.

Justin,

Surging is a symptom of a lean condition. One easy fix that sometimes works is to remove the idle mixture screw and blow compressed air through that port. I had to do that occasionally on my'36 until I discovered an actual AC fuel filter that fits inside the fuel pump glass bowl. Now that problem is solved because the filter catches the debris that used to end up in the idle port.

If the throttle shaft is not loose in the carb body the idle quality is much better. If it's loose bushings intended for a Rochester Quadrajet are a perfect fit in a Carter W-1. With a snug fitting throttle shaft the carb responds very noticeably to idle air screw adjustments and it's easy to get a perfect, consistent idle.

Ray W

Thank you for the help.

I did find trouble in the fuel pump. I should have hot tanked the fuel tank....

I have cleaned out the tank and will install a fuel filter between the tank and the pump for a while to be the failure point.

Set the timing and verified the vale lash. Ready to take it for a drive and back home under it's own power.