Have an issue now

[kaynnon]

well I bought my 72 in august and other than having cosmetic issues its been a good running truck. but the other day it started missing on a cylinder. I could hear a noise that sounded like a rocker arm pecking on the passenger side so I pulled the plug wire while it was running and found #8. I pulled the valve cover off and the rocker arm looked fine so I took the plug out and looked at it and it seemed ok. I put a different plug wire on it and it still had the miss. I had a brand new cap and rotor button already from a different project and changed those out and it still had the miss. I don't have a compression tester so I just put my finger in the hole and turned it over and it blew my finger out so I know its got a little atleast.

So I readjusted the valve and it still didn't help and while I was scratching my head thinking of my options staring into space under the hood the carb caught my eye, how I saw this is beyond my blind self but the little screw that holds the secondary needle hanger down is gone (oh crap!)

so now I'm thinking the screw went down and got into the valve and maybe warped it or something. Looks like I'm going to have to pull the head if for nothing else to make sure it didnt hurt the piston.

What are some of yalls thoughts, if you had a similar problem and know of something else to try.

[68gmsee]

That is one teeny tiny screw if it's the one I'm thinking of. Is it still making the clicking sound also?

There's a possibility that the screw may have gone out the exhaust, however, you could try a couple of things.

First, remove all the plugs and with a small magnet with a flexible shaft, insert into all the cylinders and see if you can pick up anything.

Borrow one or go to the nearest auto parts store and get a compression tester to see if it did any damaged to the valves.

If all that looks good I would look inside the carb secondaries to see if it's laying there.

If after all of that I still didn't find it I'd crank the engine with the plugs removed with the chance that if it's still floating inside a cylinder and may get blown out. It may also be that the screw had been missing for some time and you have another issue.

Last... check for any vacuum leaks.

[kaynnon]

it quit the pecking when I readjusted the valves, the first thing I did was check to see if the screw was laying on the secondaries with hopes. The screw may have been missing from the start like you said. wasnt able to find a vacuum leak, I thought the intake could be leaking but didnt find it. maybe the screw being so small it didnt hurt anything if it did go in there. I'll try what you said with the magnet and i really need to do a compression test on it. I was thinking of the possibility of a burnt valve on #8, i did the dollar test and held it to the tailpipe and every 3 or 4 seconds it would suck the dollar up.

[68gmsee]

I've never been one to trust the spark plug wire removal to determine a miss in a particular cylinder -especially V8's.

The sputtering or popping out the exhaust could be one of several things. It could be a valve or it could be an exhaust leak, vacuum leak in the carb, power booster, vacuum advance or timing. Could also be defective points if it still has them, cap and rotor, plug wires, or plugs themselves. Don't overlook the possibility of bad gas.

I'd start by eliminating one at a time with the easiest first like timing, carb idle air adjustment and point adjustment.

[stsalvage]

I had a issue with a cracked exhaust manifold them ram horns do not like that tight bend on the passenger side and seem to crack or brake the manifold

[1970 CST Short Wide]

Long shot but look at your rocker arm studs and make sure there not pulling out or have a groove cut in them.

[kaynnon]

just an update on this situation, after it warmed up and i was able to get out and mess with it i was checking to see if i had a spring broke, it wasnt but the exhaust spring on #8 was loose so i took the heads off and had them worked and it was a bad guide, so put em back on and it runs good now.

now i have a problem with my gas hand, for some reason it goes from half to empty way too fast