351 v6 noisy?

[Jim A]

I have tried to adjust valves while running on several engines where it is recommended.
I'm not sure any of those efforts gave satisfactory results.
The experiences of others here would be very interesting.

[Ed Snyder]

Originally Posted by Jim A

I have tried to adjust valves while running on several engines where it is recommended.
I'm not sure any of those efforts gave satisfactory results.
The experiences of others here would be very interesting.

I've always adjusted my valves while the engine was running, just like my Dad did on the '65 Suburban he bought new that I own now. I use a breaker bar with a socket. The hinge on the breaker bar makes it easy to hang onto the handle while the socket goes up and down.

[Troyport]

Good tip! How do you handle the feeler gauge and get the gap right? Maybe tighten until the gauge will not slide out, then loosen till it just comes out?

[Ed Snyder]

Originally Posted by Troyport

Good tip! How do you handle the feeler gauge and get the gap right? Maybe tighten until the gauge will not slide out, then loosen till it just comes out?

I use a feeler gauge set that opens up somewhat similar to a pocket knife so that the overall length when open is about 8". Use the socket to tighten or loosen until the gauge slides just easily enough that it's not stuck.

Anyone else have any comments or suggestions?

[Prowbar]

I adjust them with the engine off. I put the no. 1 cyl on powerstroke at TDC, adjust the valves, then do 6-5-4-3-2 and recheck 1. I use a 15/16" socket to turn the engine at the crank pulley. Now this is quite a chore with the big 478, haha. The intake valve closing is something I track on each cylinder.This way I always adjust valves when they are on the base circle of the camshaft.

The deluxe heater on these trucks with the V6 is a big obstruction to work around. Kind of wished mine had the simple heater to make engine work easier.

I love the self locking screws these engines have. Also it doesn't really matter if you adjust the valves hot or cold, the literature mentions the aluminum rocker arm brackets compensating for the valve lash based on the expansion difference on aluminum vs steel. I've checked it a couple of times and it is almost always spot on.

As for the .030" play in the rockers, yep that is a typical thing.

[Clarke]

Like Ed, I adjust the valves while engine is running and at Normal Operating Temperature. I have bent feeler gauges and I constantly slide the the oil lubricated feeler gauge around (while making slight valve adjustments) until I feel a slight drag.

I use a 3/8” ratchet with extension, universal joint and socket. The universal joint helps absorb some of the rocking motion, as I’m not that good of a dancer.

Switching topics slightly:

A while back I hauled a couple loads of gravel with my truck in AR (trailer and gravel weight of 8K-8.5K pounds). Then drove my truck (pulling my camper back to KS) after another warrior weekend in AR, and I noticed a faint slapping noise while pulling the truck into the garage.

The noise reminded of a loose cam chain I found on a motorcycle I was riding in college, which I was able to remedy after making adjustments to the cam chain tensioner.

Back to my truck, I’ve never heard that slapping noise again. It was really hot that day and I was towing my 4K pound camper in the KS winds. I completed another full tuneup and I didn’t find anything out of tolerance.

I often wonder if that noise was my cam chain, as I only have one gear on the cam and when I put all new gaskets on my engine (except head gaskets) about ten years ago, I noticed the cam chain had plenty of slack, but it was in tolerance. I thought about replacing the chain at the time, but had read that a new chain/gear set also has lots of slack.

I later learned that there is a double cam chain/gear set available for our engines, which I plan to incorporate one of these days.

Good luck on your continued noise research. Hopefully, it’s not anything of concern. In the meantime, great opportunity to learn a lot about these unique engines.

[Troyport]

Went at it again with the engine running and hot. I dropped the idle quite a bit, enough that the gen light was flickering. Anyway, pretty easy to do, and didn't take long to get the feel.. If the feeler went in easily, too big of a gap. If I had to force it or it wouldn't go in at all, too small of a gap. Got them all with just a little drag while moving it around. Found 2 just a little tight, but not enough to stay open... and 2 notable loose. I would guess I adjusted them before while just starting to lift. The vacuum gauge seemed steadier, and the 2 that were loose were rapping more than the rest. Now, seems more like all are just clicking. Thanks for all the help!