Can you adjust lash with solid cam while engine is running using the recommended feeler gauge?

 

No you can't.

 

Truth.com

 

You need to set the lash once at operating temp. with engine off

 

You actually can. Seen it done. Bill "Grumpy" Jenkins used to set his that way.
It was on his big block '67 or '68 Camaro. Couldn't believe it first time I watched him do it. Crane roller rockers and a stud girdle. There were no Jessel or TRD rockers then. Those guys were still kids racing their own cars then. <G> I've never seen anyone else do it. It was at the 1967 (or '68?) NHRA World Finals here in Tulsa. I had to go get a witness before he buttoned it back up, nobody would have believed me if I had just told it with no witness.

Personally, I set mine warm, then find which feeler blades check correctly cold, so I can set them correctly when I put it back together. Actually, I don't even set mine warm anymore.

 

I've never set lash on a mechanical cam any other way than with it running.

 

It's probably a pain since the feeler guage just keeps going up and down. How do you do it? I think I got an idea but would rather hear your instructions first.

 

Of course the feeler goes up and down, but that doesn't stop it from sliding in and out at the same time.

You just slide it in there (carefully, spring pinch HURTS!) like you would with it off. Takes a little messing around to get the feeler in, but it'll go. The one downside is that 2 or 3 times around the valves and you'll need a new set of feelers.

 

.....with the full valvetrain load applied.

Why would that be?

 

I imagine it would beat the hell out of them! lol

 

Full load is only applied when you come on to the cam lobe. When it's on the base circle, there is no load.

The edges of the feelers tend to get a little chewed over time from sticking them in between moving objects.

 

Must be highly accurate. Not.

 

Adjust the valves cold, subtract .03 to .04 from recommended spec.

 

One can adjust them either way but the question REALLY is What Is the Recommended Way.

Just because someone comes up with some unorthodox, generally not recommended procedure doesn't mean it's the one to use. There never seems to be a shortage of convoluted, "one-off" ways of doing things.

Engine OFF but at normal operating temperature is what you'll see most often recommended and is the procedure I used over the years.

Jake

My son, Ryan M. Cameron, graduated from West Point on 22 May 2010! He was commissioned as a 2nd Lieutenant and I pinned on his first pair of "Butter Bars" PROUDEST DAY OF MY LIFE!!

 

I'd argue that it's more accurate, as the engine is up to temp and stays there. But, that's not what the OP asked now, is it?

 

It isn't really worth fighting over. I would never attempt to adjust valve lash that way, because I feel strongly that it will reap poor results. If it works for you, that's cool with me.

As to the original question you are 100% right. You CAN do all kinds of things.

 

im trying to picture doing that.... doesnt seem to make much sense? i mean im sure one could set the pinion angle while driving down the road, but WHY is the question.

 

When you warm to operating temp and start adjusting, do you really think they are the same? The engine is cooling off the entire to you are adjusting valves.

 

Setting Jessel's on an engine that idles at 1400 RPM (as mine does) would be fun. Imagine sticking that little allen wrench in the adjuster at that speed?

Some of the sharpest racers in the country (NHRA Pro Stock) sets them with the engine off. Most set the Intake with the Exhaust rocker near full lift, the Exhaust with the Intake just starting to close. Exactly where depends on the lobe profile and lobe centers. Find the loosest spot, not hard to do. I know of no competitive engine builder/racer that sets them running anymore. With the old stud mounted roller rockers the adjuster doesn't move. That would be easier. The self centering LT1 rockers would kill the feeler blades right off. You would need narrower than normal blades. What would be the point?

Bill Jenkins was bumping the engine over to set the valves last time I saw him with one of his pro Stock engines, a couple of years ago.

 

Intake and exhaust don't change the same amount. Aluminium heads get taller, loosening the lash. However, the exhaust valves grow in length more than the intakes (they run hotter), thus the intake lash changes more than the exaust from hot to cold.