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Hi all,

So I park the can one day and all is well then then next day I go to take it for a cruise and it's spitting up through the carburetor. At first I thought it was an exhaust leak then I went to take off from a dead stop and it hesitated really bad and you can just hear it popping though the carb.

I thought perhaps it was time for a tune up - I changed the plugs, points, synchronized the points, checked the timing - right at 6 degrees - and it's still spitting through the carb. I've never adjusted the valves in the 3 years the car's been running. Maybe that's the problem.

I was just curious if I can pick your brains and see if anyone has had a similar experience and what you all might recommend.

Thank you in advance,
Crin

As time goes by and cars require less and less maintenance, we tend to forget just what a good comprehensive tune-up consisted of. You started a tune-up, my suggestion is to complete it; check manifold vacuum, compression, fuel pump pressure and volume, valve adjustment, check timing chain slack, check intake manifold gaskets for leaks, function of the heat riser valve, and all the other little things associated with a good comprehensive tune-up. You may get a quick clue from the compression and manifold vacuum readings.

While you're at it, remove the air filter, hold the choke open if necessary, and with the engine running above an idle, is gasoline leaving both main jets at more or less equal streams? While it doesn't match your symptom, as long as you're there check the accelerator pump action.

Somewhere in the course of the above you'll find your problem and as an added plus of doing a full tune-up, you should now have thousands of miles of worry-free driving ahead of you.

Hi,

As an update, I ran a compression check and here are the results:

Cyl #1: 130 psi - holds steady
Cyl #2: 130 psi - holds steady
Cyl #3: 130 psi - holds steady
Cyl #4: 130 psi - holds steady
Cyl #5: 50 psi - holds steady

Cyl #6: 30 psi - pressure drops and I can hear it 'puffing' through the carburetor.

Cyl #7: 30 psi - pressure drops and I can hear some 'puffing' through the carburetor.

Cyl #8: 130 psi - holds steady.

So now I know something but I literally have less than 500 miles on this engine since it was rebuilt about 6 years ago.

Where do I go from here? Check the valve adjustment? That is my next inclination.

Thank you,
Crin

Sure, check the valve clearances. Hot clearance specs are 0.004" intake and 0.006" exhaust. With any hot clearance at all, valve seats integrity may be suspect.

Not that it necessarily applies to your problem, but was the cylinder head was retorqued several times after the rebuild until it no longer needed tightening?

Sticking valves

Hi Crin,
I went through this with my 6 cylinder and it turned out to be the head gasket. I am not a mechanic, but the way you describe the 2 cylinders with bad compression and say you can hear 'puffing' through the carburetor makes me wonder if that is your problem. I did not have oil in my antifreeze or vice versa, but compression was leaking from one cylinder on the compression stroke, through to the cylinder with open valves beside it and back out the intake. When you say there are very few miles on the engine, I would sure think that would be a good place to start. Initially, I thought the head just needed retorqued once, after one heat cycle, but as Dave (Owen_Dyneto) stipulates, the head nuts must be chased until they no longer need torquing. I'm willing to bet there are lots of Packard heads out there that are not at 'max-torque'! Chris

Thank you all for your input. As I'm piecing this all together it has dawned on me that I have been seeing this odd looking 'foam' of sorts in the radiator. I'm willing to bet it all on the head gasket. And now the more I think of it I only torqued the head down once after I got it back from the machine shop. I'm also thinking that maybe I should add another washer on the bottom of those acorn nuts - maybe they're bottoming out on the stud making the torque reading not really mean what it should.

Well now the next question - should I go with Olson's gaskets for a head gasket or do you all recommend another vendor? Is there another vendor for that matter?

Thanks again for the help. I'll take a head gasket over a stuck valve - I think...

-Crin

Hi,

One more question for you all. I saw this in one of the online manuals regarding cylinder head tightening (please see the attached picture). It mentions using a specific torque wrench and apply 150-160 as indicated on that wrench. My little engineering brain is telling me those numbers are in-lbs. I just want to verify that with you all.

I would imagine 150 ft-lbs would torque the stud clear off the block.

Thanks,
Crin

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Those are arbitrary units, neither ft-lbs nor inch-lbs. 60 ft-lbs would correspond to 720 inch-lbs.

Hmmm... So if I have a modern day torque wrench, what would I need to torque the head nuts to?

Thanks
Crin