engine break in valve lash.

[AA Performance]

I DO NOT AGREE. I would rather set the valves 004 tighter than the time cardd spec, It is safer for the camshaft to do it this way,

Yes, Yes, Yes

If the valve lash is looser then what is on the cam card, the force at which the lifter hits the cam is increased. This is not a good thing during break-in.

Seems to me that cam companys don't really know whats going on. If tightening the lash is a better deal ,is it that much trouble for them to print the correct lash adjustments on the cam card ? Includes the Cam King as you agree with the tighter lash settings.I don't no any people that purposely set lash loose unless they are trying stuff on the dyno

[CamKing]

Seems to me that cam companys don't really know whats going on. If tightening the lash is a better deal ,is it that much trouble for them to print the correct lash adjustments on the cam card ? Includes the Cam King as you agree with the tighter lash settings.I don't no any people that purposely set lash loose unless they are trying stuff on the dyno

I guess I didn't make myself clear enough for some.
I'll try not to use big words
"Tighter lash settings" are good for breaking the cam in.
That has nothing to do with what's best for making power.
When I sell a cam, the cam card will have the "Hot Valve Lash" settings on the card. That is the lash point the cam was designed to run at, and that's where it should be run. If it runs better at a different lash point, I didn't sell you the right cam. I can't tell you what the cold lash needs to be, because every engine is different. I've seen different pushrods change the lash growth from cold to hot by .002".

[AA Performance]

Tell me then why cant the clearance ramps be designed in such a way that they open & close smoothly without too much acceleration so that running a cam in, and running the engine after cam break in can use the same lash.

[CamKing]

Tell me then why cant the clearance ramps be designed in such a way that they open & close smoothly without too much acceleration so that running a cam in, and running the engine after cam break in can use the same lash.

You can with my cam designs, but that wasn't the question.

Here's what the poster said:

My question is about breaking in a brand new engine. It is a solid flat tappet lifter, and since it is cold, I am not sure what to set the initial valve lash at.

If you're 100% sure you know what your cold lash will grow to, and you're 100% sure that your valvetrain isn't going move any and increase the lash, then you can set your lash to be at the end of the clearance ramp when it's hot.
Bottom line: If you're not sure how much the lash is going to grow, it's better to be a little on the tight side.

Most of my cams use a constant velocity clearance ramp. From .001" to .018" lash, the lifter is moving the same speed. With this type of ramp, setting the lash tighter won't be easier on the valvetrain, but it'll give you a cushion in case your lash grows more then you thought it would.
There are other types of clearance ramps, like a constant acceleration ramp. These ramps are easier on the valvetrain at tighter settings.
I don't know of any style clearance ramp that is harder on the valvetrain at tighter settings.

[David Redszus]

Perhaps the very first question to be asked is whether the lash becomes tighter or looser as the engine warms up.

And to understand the reasons why.

With an OHC engine, the lash may become tighter due to seat ring settlement and valve seat run-in.

With a pushrod engine, the lash may become looser due to seating of the entire valve train.

Are we dealing with issues of seating, wear or thermal expansion?

[CamKing]

Perhaps the very first question to be asked is whether the lash becomes tighter or looser as the engine warms up.

And to understand the reasons why.

With an OHC engine, the lash may become tighter due to seat ring settlement and valve seat run-in.

With a pushrod engine, the lash may become looser due to seating of the entire valve train.

Are we dealing with issues of seating, wear or thermal expansion?

The question was and still is about setting the cold lash for break-in.
TRhe poster stated he was running a solid flat tappet cam, so we know it's not an overhead cam engine.

If you need to set your lash loose because you're pounding your seats into your head, you may want to find a new cam supplier.
On all the aluminium headed 4 valve overhead cams we supply, we normally set the cold lash at about .003" tighter then the hot lash.

[AA Performance]

Thanks for clearing that up Mike Jones . I think I was concentrating on your post more than the question at hand. While I'm at it,is there any way to tell whether a cam has a constant velocity or constant acceleration ramp. Reason I ask is that I had an issue with a BBC & we were looking for another 200RPM [ endurance boat ] & Mr Crower told us to tighten lash from 022 to .016 hot.and shim up the springs from 270 to 300+. Needless to say it showed no gain. Boats need big horsepower gains to show up anything at all.

[CamKing]

. While I'm at it,is there any way to tell whether a cam has a constant velocity or constant acceleration ramp.

If you profile the cam with a Cam Doctor, Audie Cam Pro Plus, or some other type of equipment, it's pretty easy to tell what type of ramp was used.

BTW, you should see what we do to increase top-end power on jet-boat engines.

[AA Performance]

BTW, you should see what we do to increase top-end power on jet-boat engines.

Teasing me are we! Out with it my friend ,I'm all EYES
BTW we run a "V" drive 480 BBC & just tested on the weekend with a bigger cam & were happy with the results BUT cant have enough, always looking for more.To make things worse, we tow 2 skiers @ 7000RPM for 40 to 80 miles per race.Give me this good advice MIKE JONES & educate me please.

[CamKing]

BTW, you should see what we do to increase top-end power on jet-boat engines.

Teasing me are we! Out with it my friend ,I'm all EYES
BTW we run a "V" drive 480 BBC & just tested on the weekend with a bigger cam & were happy with the results BUT cant have enough, always looking for more.To make things worse, we tow 2 skiers @ 7000RPM for 40 to 80 miles per race.Give me this good advice MIKE JONES & educate me please.

I'll PM you with a few questions on your application.
I'll have to give the v-drive some thought.

BTW, I grew up sking behind an SK runabout.

[BEDNAR1320]

As for years of experience, I have been doing several things wrong for over 50 years.

I have been doing several things wrong for 20 years, just ask my wife :lol: :lol: :lol:

MY WIFE REALLY WAS SET TIGHTER DURING BREAK-IN!

[Barry_R]

That just cost me a keyboard