Somewhere I read that on an aluminum head / iron block engine the lash tightens up quite a bit as it heats up.
So the .012" cold lash may turn into only .006" lash hot.
It's OK as long as you never make it to zero or less.
IIRC .006" tighter when hot was what I read. (Vizard maybe? my memory is not what it used to be)

So no wonder they don't make much noise!

I actually lashed my 30-30 cam at 36 for a while. Sounded like a sewing machine. But you could also just listen to it and tell if one was "off"

 

I have always understood it that as an aluminum head heats and grows so dose the lash

 

.006 is aobut right for iron block, alum heads
One can experiment with less/more lash to see what the engine likes. The recommeded .020 cold was perfect...going to .018 the car lost power and idle quality suffered some.

Hyds are best done to mfr;s recommendations. Myth out there that "O or less than 1/4 makes it act like a solid"disagree

 

Presumably Lars the cam has an 'softer' initial take-up of clearance on the opening (and perhaps closing ramp?) - The 7/8 year old Howard hydraulic flat tappet cam in my 489 engine is a 235/242 duration @ .050" and has always a little noisy even when lash adjusted correctly. I was surprised to find the cam spec's were very similar to a Comp Cams XR288HR hydraulic roller........

 

How much lash does your FT cam use? Thats good noise man! lol

 

1/2 turn if I recall - haven't done it for a long while - in between running-up engine to temperature, pulling valve covers and getting round all the rockers I normally end-up having to go thru the procedure 2 or 3 times until I'm happy that all lashes sound the same. Being a Brit and having many beat-up old 60's 4 and 6 banger cars tappet noise is something that really irritates. Can't stand the sound of an old diesel clunker too........

 

Thanks, centuryoldracer. I was actually planning to use Howard's

 

I watched the Engine Masters show someone mentioned about running solid rollers on a hyd roller cam and found it very interesting. My question is if your heads spring pressures are set up for a solid roller could you put a hyd roller cam in and run the solid rollers without a spring change. Thought?
Thx

 

Dont understand either just pick one and set up properly.

 

I do not understand that logic at all. Of putting a solid roller on a hydraulic profile cam. Even if it was on engine masters, and even if Mustang people do it. It's a band-aid, and not even a good one. It's bad advice. Get the right cam for the right lifter.

The solid cams, both roller and flat tappet, have slow lash take-up ramps built into the lobe profile, to take up the lash/slack, so it doesn't hit/impact too hard. I heard they were only .040 high on a .030 lash cam. So that's why you can't open up the lash more than that on an old solid flat. They are so small they do not show up in the "specs".

The hydraulics do not need this lash take up ramp.
So wouldn't a hydraulic cam profile actually hit/impact the (solid) lifter harder?
Mid-lift the solids can accelerate the valve faster vs a hydraulic, but that is not where the wear occurs on a solid roller, they tend to get flattened roller bearings from the hammering from the lash take-up. Especially at idle when they do not get much oil splash. That's the whole reason for tight-lash cams, it lessens the impact. And the pressure-fed rollers. That is what helps them to live vs the old days.

My builder says it is even more important to get the "right" spring pressure on a roller than it is for a flat. It's for exactly the same reason. When you "float" the valves at high rpm the rollers hit/impact the cam hard. It doesn't hurt a flat but it can make a roller fail. You want to make sure you have enough spring pressure for your roller cam that they never float at your peak rpm. And the hydraulic roller lifters are much heavier than the solid ones, and more prone to float. And thereby to fail.

 

Well, I answered my own question about the difference in hp between a mechanical roller and hydraulic roller cam on the same engine. Super Chevy magazine did a dyno run on a small block motor with a hydraulic roller cam and then switched out the cam for a mechanical roller cam with a profile as close as possible to the hydraulic cam. They got an additional 8 hp using the mechanical cam.

 

The Engine Masters show was a follow up to this article, basically using the same cam 2 nd time around.

 

It was strictly a backyard engineering type thing dictated more by a lack of funds than anything else.....when the Explorer intake and GT40X Explorer heads came out....guys would raid the salvage yards and put them on their 5.0’s.....to make use of the X or F cam they already had (One of the most popular over the counter cams of all time...) and the extra airflow....they would buy solid lifters to stick in the block to gain some rpm.....it worked, kinda....
Why anyone would do it from scratch is beyond me....

Jebby

 

It’s the opposite actually
on the pro stock engines I lash 12 cold, and at 180 degrees water temp they are at 28

 

I personally like running things on the tighter side of the specs as there is less hammering, and things tend to last longer

 

Yep....blown Pro Mod stuff has to be lashed twice....once cold to start it and once when warm....
After a run....when cooled down, a blown Pro Mod’s valves will be open a smidge....lot of aluminum there....

Jebby

 

Yup, and you have to be really nice when warming them up (run them easy) My 10" tire car has a pro stock style engine in it, and there is a point during the intake valve event where the valve is .017 away from the piston!

 

Don't forget the very sweet sounding idle!

 

Many think theres a free lunch in doing this...doubtful.
Just because you can doesnt mean one should