scout 80 unsteady vacuum and hard start

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outlaw47

New member
I have a '63 Scout 80 152 with about 250 miles on a fresh rebuild the problem I am having is more often than not it takes about 10- 15 seconds of solid cranking to start and then when it does it sounds like it is only firing on a couple cylinders but other times I look at the key and it fires up and runs great, once it is running it is great runs perfect I set the idle air screw using my ear and idle speed and that helped a little bit then I hooked up a vacuum gage and at idle with the vacuum side of the fuel pump disconnected it bounces between 16 and 20 in hg so am I doing this correctly does this indicate something is wrong?? Also my timing is around 15 degrees it seems to be happy there if I try to bring it to factory settings it gets very upset
 
I have not done a compression test yet I will see if I have time to do one tomorrow but any idea why I could have a sticky valve I just rebuilt the head 250 miles ago?? Could my oil be to heavy (15w-40 rotella)??
 
outlaw47 said:
But any idea why I could have a sticky valve I just rebuilt the head 250 miles ago????
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You bet! Bad fuel or new fuel put in a tank with old fuel residue.

Been there done that! :icon_redface:

if you are against a good tank cleaning, add about 8 oz of atf to a full tank and take her out for a long road speed drive. You May see a bit of smoke now and then but the oil will lube the guides long enough to rid the tank of the old crud.

Your oil choice from a weight perspective is fine. Not much zinc but that's another story
 
Ok I will give it a shot but I drained the tanks and replaced all the lines when I rebuilt the motor I have however been putting off cleaning and sealing them.:icon_cry: I thought the oil I was using is high in zinc, what oil would be a better choice?
 
One thing about a sticky valve, you'll almost certainly hear a tapping or ticking from exessive clearance.
While it is running rough, could you pull plug wirers and pinpoint the offending cylinder?
Oil wise the swepco product ihon sells is good. There are plenty of others that fit the levels. Most are special application oils like racing versions.
 
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Ok a quick update I put some lucas top end lubricant and fuel system cleaner and have been running that through the tank I adjusted my air/fuel screw and timing a little bit and is starts much easier/consistently but still have very unsteady vacuum at idle once it hits 800-1000 rpm the vacuum is smooth. Using a stethoscope the valve train all the way across is nice and quiet I am still trying to find my compression tester (lost in the move) is there anything else that could cause the vacuum issue or is this even an issue? Also when I check the engine vacuum should I have the vacuum pump side of the fuel pump disconnected?
 
You have the vac gauge hooked up to the intake tree/port in the center on the drivers side... Right? The same place the vac pump hooks up but no pump on that line?

We can't guess any further till you get a compression test done. Basically one hole is not pulling the same vac as the others. Not much that cen cause what you are seeing
pull the wires one by one and see which has the smallest decrease in rpm. That will the the offending cylinder.
 
the vacuum side of the fuel pump disconnected it
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I have the same question as Robert. If you have vacuum wipers, the "vacuum" in goes to the wipers. The out goes to the manifold. For a good test, disconnect the vac pump at the manifold and take a vacuum reading at the manifold fitting.
 
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