Technical Valve lash

The original video posted, and this discussion, is about the valve lash on solid lifter engines. Hydraulics are easy.

 

Hey Hillbilly! Good point!! Pat seems to have some good credentials but still could be hitting the crack pipe to much!!!! Pete

 

One thing to note, video was based on oh v-8 with cast iron block and aluminum head with steel lifters, pushrods and aluminum rocker arms. Flathead is all iron block with iron or steel lifters acting directly on steel or iron valves. My guess is any change change in hot an cold clearances on a flathead would be nowhere as great as a aluminum head cast iron block overhead engine.

 

And the 1900 pens and measuring devices in his pocket.

 

All my mechanical buddies I mentioned this to said, "You off your meds again?" LOL Lippy

 

i've bought a couple isky cams for my flathead over the years, and the spec sheet always shows an "warm" gap. of course that's not true!

 

Have you ever checked to see whether hot or cold water freezes first?

 

That's because it takes a real man to adjust the lifters on a Chinese Six! I like watching a vacuum gauge while adjusting 'em too.

 

No, but I've heard that and wondered about it. I don't see how hot water could freeze first, but what do I know.
As I said though, we always set the sprint motor to zero lash. If the lash tightened up, then it would have held valves open when warmed up. I know there were no valves being held open when they should have been closed. Now this is on an all aluminum pushrod engine and we always went through a thorough warm up before running it hard. I can't speak for any thing else. Only my personal experience.

 

Appels and oranges So does a longer push rod motor expand more? If the push rod is longer it follows that there is more block and head between cam and the rocker

 

i used to adjust the valves on my 1956 ford 292 PI hot. then got tired of hot oil on my hands and just set them cold, about .006" tighter. gives alittle more lift and duration, right??

 

I can’t discount the original video posted, the only solid lifter PR engines I’ve adjusted were 216’s and 235’s and did them hot while running(anyone need pre-curved feeler gauges?).
But as I mentioned before, the video doesn’t pertain to the OPs engine, he has no PRs or rocker arms. It doesn’t matter if he has Al heads, cast iron or a block of wood whittled out.
Guess I’ll find out soon enough, I did a backyard valve job on a 218, and need to fire it up in the next few weeks and recheck the clearances after it’s heat soaked. I set them looser at .012 and .014.
Should be a good comparison for the OP, only real difference is a V8 vs L6.

 

Looking forward to your results! Thanks Pete

 

Thanks Charlie!!! Pete

 

I’ve a silly idea. Head over to the FordBarn and just ask the question as it pertains to your Flathead Ford. There are many over there that have and do build them and have done more than many have seen, I’m sure with a day or two you’d have an apples to apples answer

 

Valve lash gets looser when hot. The block, head rocker stands etc. expand much more, than the push rods, valves and lifters.

How much? That depends on your engine (pushrod length, materials etc.)
But it's easy to try out. Also exhaust valves have a different shrink/expansion rate than intake valves.

On a air cooled VW you set the lash finger tight to zero cold (and than back up a quarter turn, to be on the safe side). That wouldn't work, if the lash would get tighter.

Frank

 

Dang, this thread has made me realize how long I’ve procrastinated on firing my engine up

 

REAL men adjust them while hot and running, outside, naked, in a snowstorm.

 

Boots optional or required?

 

Barefoot, you pansy!