doublekrossd
Well-Known Member
My new build is a 511 with modified little ez heads and a solid flat cam. The cam card says .016 intake and .018 exhaust for hot lash. Does anyone have any idea what it should be cold? Thanks again in advance guys!
Valve lash questions...
- Thread starter doublekrossd
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doublekrossd
Well-Known Member
I have no idea who's cam it is. The bottom end is from muscle motors but I'm having a hard time keeping contact with those guys.
doublekrossd
Well-Known Member
Nope, it's a red card muscle motors installed it in the short block.
66Satellite47
Well-Known Member
According to what I've been told, the cold is about .003 - .004 smaller with the aluminum head. Sure like to hear from the experts.
doublekrossd
Well-Known Member
Yeah, totally agree with you on the expert thing. Just wish I could make better contact with my builder...
doublekrossd
Well-Known Member
Thank you, that is what I was leaning towards
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PurpleBeeper
Well-Known Member
OK, I'll admit I'm stupid. Shouldn't the "hot lash" be tighter, not looser than the "cold lash" since the pushrod expands????????
Usually, cold measurements are about 0.002" larger. So, in your case, Intake 0.018" cold and Exhaust 0.020". You can also contact a few cam manufacturers, and see how close they agree with each other.
doublekrossd
Well-Known Member
And that is what muscle motors originally told me but I thought I had it screwed up. I haven't been able to get back in touch with them to confirm anything so I went to the web to hunt for info. Now I'm all confused! I Just want this damn thing to run right!
Yatzee
Well-Known Member
Those gaps just don't seem right to me, too large. Are you running roller, hydraulic or a combination? If the upper end is roller rockers, note the movement of the roller on the valve tip, if it's roller lifters and OE rockers up top, that's a whole different story. Do you even know the lift and duration of the cam. OE rods will expand more than rods from say Smith Bros, Trend or Manton. Even so the measurement for the rods may have been off from the beginning thus requiring strange gap to ensure the valves don't collide with the piston tops. I think you need to gather as much information on the valve train components before any gaps are set. That and measure valve to piston clearance.
doublekrossd
Well-Known Member
Why do those measurements seem so far off? Yes it has adjustable rockers up top, Harland Sharp. The cam&lifters are mechanical flat. The rollers and valves seem to be in the correct position. Yes I know the lift and duration of the cam, its all on the card. I know what all of the components are on the motor, I put them there along with my builder. Just can't get a straight answer as to where to lash them cold.
I did talk to bullet, comp, and racer brown last night. Bullet said .006 tighter, comp said .002-.003 tighter and racer brown said he'd go .004 tighter. I think .004-5 is where I'll start.
I did talk to bullet, comp, and racer brown last night. Bullet said .006 tighter, comp said .002-.003 tighter and racer brown said he'd go .004 tighter. I think .004-5 is where I'll start.
Shorthorse
Well-Known Member
There are several cam and engine builder sites online that discuss cold settings. Some recommendations are slightly different but all are very close.
http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf
http://www.cranecams.com/pdf-tech-tips/mech-lift.pdf
IQ52
Well-Known Member
I have adjusted the lash hundreds of times on aluminum heads and tested it hot and cold on Indy cylinder heads. If you have never set the hot and cold valve lash on an aluminum headed engine (or an aluminum block/aluminum head combination), its best you not try to tell doublekrossd how to set his lash. Be quiet and learn.
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66Satellite47
Well-Known Member
IQ correct me if I'm wrong, with an iron block / iron head combination lash will get tighter going from cold to hot because the valve stem grows slightly from the combustion heat but head & block change at nearly the same amount. With the iron block / aluminum head combination the aluminum head expands and the lash gets looser with the heat of combustion. My first experience with aluminum heads was my EDE Performer RPM's & they gained about .003 - .004 going from cold to hot. Sure appreciate your advice/input.
IQ52
Well-Known Member
I've read a lot of articles on the internet and called the head companies when I started using aluminum heads. I was finding such a big difference between hot and cold lashI thought my engine was falling apart. One techline, Edelbrock, told me their aluminum heads don't expand. I don't consult the techline Edelbrock very often anymore unless it is to beg them to make some improvements in their heads.
In all my tests on aluminum heads I found they expand and lift the rocker shafts away from the camshaft what I figure about .003" and I end up with .005"-.006" more valve lash. So I just run all aluminum heads about .006" tight when cold. I don't like doing hot lash, because, well, IT'S HOT. So now I try to do checks and changes after the engine cools down or in the mornings. Sometimes you just have to do it when it is hot.
Since I was a kid in the 1950's my Dad always told me to open the cold lash on our heads (iron) .002" when cold. I've found so little difference between hot and cold on iron I use the same hot and cold settings. Then I adjust the cold/hot settings to get the best performance from the camshaft.
I don't really care if I have the valve lash exactly where the cam maker says, as long as I know where it is set. I'm going to move the settings around to suit my engine anyway. I personally never open the lash over .004" more than the suggested hot setting. But I've been know to crank 'er down tighter than .004" under suggested hot.
In all my tests on aluminum heads I found they expand and lift the rocker shafts away from the camshaft what I figure about .003" and I end up with .005"-.006" more valve lash. So I just run all aluminum heads about .006" tight when cold. I don't like doing hot lash, because, well, IT'S HOT. So now I try to do checks and changes after the engine cools down or in the mornings. Sometimes you just have to do it when it is hot.
Since I was a kid in the 1950's my Dad always told me to open the cold lash on our heads (iron) .002" when cold. I've found so little difference between hot and cold on iron I use the same hot and cold settings. Then I adjust the cold/hot settings to get the best performance from the camshaft.
I don't really care if I have the valve lash exactly where the cam maker says, as long as I know where it is set. I'm going to move the settings around to suit my engine anyway. I personally never open the lash over .004" more than the suggested hot setting. But I've been know to crank 'er down tighter than .004" under suggested hot.
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68 HEMI GTS
Well-Known Member
Listen to IQ52. I also have a few Indy headed engines. It'll move around a bit on a fresh start up anyway and will need re-lashed. It's not rocket science, just needs to be in the ball park. I always set mine hot after running things in.
doublekrossd
Well-Known Member
Thank you very much for the detailed information guys! After talking with Jim at racer brown, a guy at bullet, and your opinions I went with .006 tighter when cold. I'll check again after break in and adjust accordingly from there.
Again, thanks a ton! I'm fairly new to this stuff and dont really have anyone close to me I can rely on.
Again, thanks a ton! I'm fairly new to this stuff and dont really have anyone close to me I can rely on.
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