Suspect engine noise from the NADA 109

[GreatWhiteNorth]

I started work on the '67 NADA 109 today. Only two mechanical orders of business...replace a leaky wheel cylinder and bleed the brakes, and then attend to a valvetrain noise that the PO told me was a bent pushrod.

Got the top valve cover off, and was able to get the rocker shaft assembly lifted up on the studs high enough to remove all the pushrods. One pushrod was warped a little, not even sure I would say it was "bent". Two others were very slightly out of round. I had an entire replacement set, so I replaced those three, and set the valve lash according to the shop manual. Buttoned it back up and fired it up, and the noise is still there...

It sounds like a loose rocker arm, but I know it's not that...at least not on the top side. It's a pretty bad rattling sound that speeds up with the engine rpms. I plan on pulling the side cover off tomorrow and checking the exhaust side, but I'm not overly optimistic that will be the problem...it really sounds like it's coming from the top of the engine.

Anyone have any other suggestions or opinions on things I should start to check for? I have a complete spare engine that I was told was running when pulled, but I really did not have the intentions of getting that far into this vehicle before I put it up for sale. I do have a lot of replacement parts available, though, including another complete head and valvetrain. Anyways, any suggestions right about now would be great.

Thanks.

[kevkon]

Did you check all of the springs and keepers, none broken? How about the lifters? The valves all move freely? Oil supply to the valve train?

[LaneRover]

Any chance that your valves are out of adjustment?

[GreatWhiteNorth]

I checked all the springs and components on the top side, and adjusted the valve lash there. Everything looks like it's oiling just fine. I haven't pulled the side cover to look at the exhaust side, but will today. Still hoping the exhaust valves may be out of adjustment, but it really sounds like it's coming from up top. I guess the sound could transfer from the exhaust side easy enough though. If nothing stands out on the exhaust side, I'll pull the top cover again and start the engine with it off and see if I can find something that way.

[Linus Tremaine]

what about

These engines often make noise due to wear on the distributor drive shaft. The only way to inspect it is to pull the shaft out. The side cover needs to come off and there is a bolt that holds the distributor mount thingy in the head. Then, you have to twist/lift the shaft out and inspect the gear.

The noise usually isnt that bad but if the gear is really worn its possible. Also, the gear is down in the side cover area, so the sound would be more down there. I suppose if the top bushing is worn you could get rattle from the top of the shaft.

[kevkon]

If it were me, I'd start with the engine running with the valve cover off. That will tell you pretty quickly were the noise is coming from, especially if it's in the valve train.

[GreatWhiteNorth]

Pulled the side cover, and the farthest back exhaust valve was way loose...like .050 clearance. Couple of other exhaust were mildly loose, so I reset all of them. I went ahead and pulled the top cover again, and double checked the clearances on all the intake valves as well. Fired her up, and it's night and day. There is still a slight tap on one rocker...probably one I mal-adjusted, but it idles perfectly. I think that will be all for my endeavor...if the new owner wants to delve further, then I have a complete motor plus and additional head and valvetrain that they can use to swap parts if they wish.