nm9stheham
Well-Known Member
Roger.
BTW I looked a bit more (not comprehensively) but have not found solid rollers with lifts less than the smallest cam that Lunati gave.
Please Delete Thread
- Thread starter Jonnylightening
- Start date
-
BTW I looked a bit more (not comprehensively) but have not found solid rollers with lifts less than the smallest cam that Lunati gave.
Jonnylightening
Well-Known Member
Although im not too big a fan of hydraulic cam lifters im leaning towards going hyd roller. Being is it seems as if there is a bigger selection. Since itll be apart im going to try and get the most compression I can with tbe stock pistons swapped, thinest head gasket (.027) I think Cometic makes it and maybe shave the heads a few thou.? Figure out then what my compression is then go from there. Also planning on throwing a 2.02 valve in my heads along with alittle port work.
Here's a composite gasket with a .028 compressed thickness. Mr. Gasket Head Gaskets 1121G
replicaracer43
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 6,051
- Reaction score
- 7,867
Jones cams has some tight lash solid rollers you might want to look into....I would MUCH rather have a solid roller versus a hyd roller...
yellow rose
Overnight Sensation
Yep. Jones has some. Jim at Racer Brown has quite a few as well. Just did a solid roller that lashes at .016-.018 hot and I set them at .012-.014 cold.
Cam Motion has many tight lash solid lobes. I think Howard’s may have some too.
If the OP is going this route he needs to CALL (not email, or text, or Instagram or whatever...it needs to be a phone conversation) and tell the cam grinder what he wants and let the cam guy pick the lobes.
Buying an off the shelf cam is at best a massive compromise.
I adjust mine .002 looser cold. When the engine is hot the lash tightens. If your adjust them on the tight side of spec when cold they get tighter. As long as you aren't too close to zero when hot. You don't want to keep a valve open and burn it.
yellow rose
Overnight Sensation
No, everything EXPANDS with heat. Even cast iron. I’ve never ever seen a cast iron block and head combo loose lash with heat. Never. They grow. Cast iron block and aluminum heads grow more. An aluminum block and heads will grow as much as .020 depending on the how tall the block is.
So you cold lash tight. How much depends on what the block and heads are made of.
Then How come solid lifters clatter when cold and quiet down when hot? Everything expands and the lash gets tighter.
yellow rose
Overnight Sensation
What? How do the heads and block GROWING with heat close up the lash?
If you can ever get to a track again (super cross starts Sunday and hopefully the NHRA is sick of this and will get going soon) and you get the chance to see some blown alcohol stuff, get a look at them warming up.
Of course, this is an extreme example of what we are discussing, but it’s much easier to see with the naked eye.
Watch them crack one off when it’s at ambient temperature. And pay attention to the blower belt. When it lights, that belt will whip and thrash and will be so loose you’ll think it’s going to fall off. They are very loose cold.
Then keep watching close, and you’ll see the belt start getting tighter and tighter, just with warm up heat. They get much tighter on a run under load.
You’ll see that belt go from thrashing around to being pretty tight, again, with no load and warm up heat.
The exact same thing happens with pushrod length as it does with the blower drive belt. The pushrods grow, but not like the block and heads. The intake and exhaust valves grow, but not as much as the block and heads.
The more aluminum in the engine, the more it grows. The more heat in the engine (or any part for that matter) the more it grows.
So cold lash should be tighter. By how much depends on what you are running.
Cold vs. Hot Lash
Block Material
Head Material Lash Adjustment
Iron Iron Add 0.002”
Iron Aluminum Subtract 0.006”
Aluminum Aluminum
Subtract 0.012”
With an iron block and heads you would actually add 0.002-inch to the hot lash spec for a cold engine. So if the cam card tells you to set the lash hot at 0.020-inch on the exhaust side of the cam, for a more accurate cold startup, we’d set the lash at 0.022-inch.
As the engine warmed up and expanded, the lash will be very close to that spec. Of course, you still should check the lash on all the valves once the engine is warm, so these specs should only be considered as recommendations. But they will still be very close.
Rockin’ The Lash: Setting Valves Cold With Hot Lash Settings
Block Material
Head Material Lash Adjustment
Iron Iron Add 0.002”
Iron Aluminum Subtract 0.006”
Aluminum Aluminum
Subtract 0.012”
With an iron block and heads you would actually add 0.002-inch to the hot lash spec for a cold engine. So if the cam card tells you to set the lash hot at 0.020-inch on the exhaust side of the cam, for a more accurate cold startup, we’d set the lash at 0.022-inch.
As the engine warmed up and expanded, the lash will be very close to that spec. Of course, you still should check the lash on all the valves once the engine is warm, so these specs should only be considered as recommendations. But they will still be very close.
Rockin’ The Lash: Setting Valves Cold With Hot Lash Settings
"For an engine with cast-iron heads and steel valves, you can expect the lash to tighten up a couple of thousandths of an inch as it heats up-so for the cold lash you would set the valve lash a couple thousandths larger than the cam manufacturer's recommended hot lash setting."
Setting Valve Lash - How to Check and Set Your Lash the Right Way - Circle Track Magazine
Setting Valve Lash - How to Check and Set Your Lash the Right Way - Circle Track Magazine
By
Engine Builder
on
Aug 19, 2011
Engine respond to the actual movement of the valves. Since the valve cannot move until all the running clearance (valve lash) has been taken up, the amount of valve lash you use affects the engine’s performance.
The alloys of certain engine parts can be affected by thermal expansion in different ways, therefore the amount of correction factor to the lash setting depends on whether the cylinder heads and block is made out of cast iron or aluminum.
You can take the “hot” setting given to you in your cam manufacturer’s catalog or cam specification card and alter it by the following amount to get a “cold” lash setting:
• Iron Block Iron Heads – Add .002?
• Iron Block Aluminum Heads – Subtract .006?
• Aluminum Block Aluminum Heads – Subtract .012?
Compensating for a Cold Engine When Adjusting Mechanical Lifter Valve Lash
nm9stheham
Well-Known Member
Mmmmm.... oil? LOL
Seems like this is what happens:
The lash vs. temperature change is a fight between the lifter and pushrod growth versus the upper block + head + valve growth. The pushrod being made of steel with the its higher thermal expansion coefficient, and being so long relative to the cast iron upper block, head and steel valve, means that pushrod side's growth is greater than the cast iron upper block, head and valve, and closes the lash with heat. So you gotta set it looser cold
Put some aluminum in the head and/or upper block and it expands so much faster than steel that upper block, head and valve growth dominates and opens the lash with heat. So you gotta set it tighter cold.
nm9stheham
Well-Known Member
Awriiight.... I want 2 of those LOL
yellow rose
Overnight Sensation
Yep. I’ll tell you they are, all of them full of ****. You can prove me wrong. It’s easy.
Go set the lash at whatever you want cold. Then get the engine up to temp. Not just in the drive way. Then pull the cover and check one cylinder. It will be .003-.004 LOOSER than what you set them at.
Ive been lashing valves since 1980. Guys have paid me to do it because they are lazy or whatever. There has NEVER been a pushrod or an exhaust valve that will out grow a block.
Again, they are ALL wrong. It’s easy to find out for yourself.
It’s not like a magazine or Harvey Crane has been wrong before.
yellow rose
Overnight Sensation
BTW, an all aluminum combo and -.012 is not near enough. Like I said, .018-.020 is more like it. They don’t even get that right.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,861
- Reaction score
- 12,209
I can vouch for that.
I set the preload on my FTHydros to 1/4 turn cold.. After cam break-in there were a few noisy ones. I thought the cam was done. After the engine cooled, I checked the preload again, and you guessed it, not all were 1/4 turn, but no loose ones. I tightened them up to 1/2 turn and that was the end of it....... for a long time. .
1/4 turn, IMO, is just too hard to set accurately.
I think those adjusters are 28TPI so 1/4 turn would be about .009;
I wouldda thought that would be enough,but
I was wrong.
Eddy headed 367 , running at 205*F, measured at the hottest part of the stat-house.
-
