|
By 57RancheroJim - 10 Years Ago
|
Hello guys,
I'm new here but not to Yblocks. I used the Isky E4 cam for the first time in my last 292 build. I'm happy with the way the engine performs and have about 4000 miles on it now. My question is about the valve lash clearance that was in the spec sheet that came with the cam, it calls for .015 and I have a mental block about running the valves that tight and have set them at .019 since the begging. Does anyone see a problem using either the .015 or .019 setting?
Thanks, Jim
|
|
By charliemccraney - 10 Years Ago
|
Valve lash is something that can be altered slightly for tuning purposes. .019 is probably ok and there should be no problem with .015 since that is what the cam manufacturer suggests. I would start at the manufacturers suggested lash.
|
|
By 2721955meteor - 10 Years Ago
|
|
i agree with charley,go with the makers sujestion. had simler iskey grind with 292 in the past ,it was verry noisey so tightened op from o20 sujested to.016, cut the noise with no other isues. sold the 55 bird several years ago, still runs well.
|
|
By 57RancheroJim - 10 Years Ago
|
Thanks guys. I'm just not sure why the would spec it at .015, maybe just for performance reasons but I'm more interested in longevity as this engine runs a lot of long distances at freeway speeds. My understanding is the wider the gap the longer period of time the valve has to transfer heat to the valve seat. Valve noise doesn't bother me, after all they are solid lifters and a little noise is expected. I only have slight noise on start up and once it reaches normal temp it isn't any noisier then any stock cam Y.
|
|
By charliemccraney - 10 Years Ago
|
The correct lash for a given cam is determined by much more complex things. The camshaft manufacturer knows their cam better than anyone else. There will be no problems at all using their specified lash.
|
|
By Doug T - 10 Years Ago
|
|
The things Charlie is referring to are ramps that accelerate the lifter taking up the slack (lash) in the valve train. Then when the valve train is metal to metal, the cam increases the lift rate to about the mid point of the lobe after which the rate goes down again. If you run with excessive lash then the cam encounters the lifter later and it may be at a point where the lift rate is higher than the maker intended for just taking out the slack. The cam then accelerates the lifter much faster which translates to higher forces and more wear. The length of the initial ramp is not specified by the cam grinder on the cam card and there is some range of lash that cams can accommodate. But you can't tell how much unless you carefully measure the lift from the base circle to maybe 0.025" . Follow the cam vendor's spec for lash, you will not burn the valves.
|
|
By John Mummert - 10 Years Ago
|
|
We examine cams on a Cam Doctor and look for the point where the valve side of the rocker arm reaches .002" movement per degree of crankshaft rotation. As Doug says, if this is exceeded there will be additional noise and wear. .015" is correct for the E4.
|
|
By 57RancheroJim - 10 Years Ago
|
Thanks for all the input guys. I will try the .015 setting.
|