Trying to find the correct clearance for solid lifter cam valve lash for my 1967 GT350 , it's been years since I have worked on it and I do mean years had valve covers off to adjust valves when my oldest son was a year old , he turned 46 . Any help would be appreciated,thanks SunnysideTom
If you have the owners' manual that goes in the glove box that spec is in the back.
Can't find my '67 owner's manual right now, but my owner's manual for my '66 GT350 shows the clearance to be 0.020 inch. Holman Moody, who makes an exact reproduction of the C3OZ-C camshaft shows the lash to be 0.018 inch. As long as you are right around those figures, I'm sure you'll be alright.
Hi
The difference between the specs are 0.020" is cold (engine temp when it has not been running)
0.018" is with the engine at normal operating temp or hot. The slight difference allows for heat expansion of engine parts. If you have the time to inspect the rocker arms--check the surface that contacts the valve stem. If the clearance was too large it can wear a groove in the rocker arm and this makes adjustment inaccurate. With the original cam and rockers set properly you will have many miles to drive before it needs to be checked/readjusted again. I find it a good time to remove the sparkplugs which allows the engine to be turned with less effort. It is really simple when you get into it. Let us know how it goes.
R.R.
Even though there might be "a number", this for a supposedly "properly" setting of the lash, you actually have a fare sum of latitude as to what will work. In defining this, what we're saying is a setting that won't lead to any sort of accelerated wear or damage but still might be a deviation from the as listed value. :-\
Typically, in this period (assumably 1967) .018" to .022" was pretty popular (performance cams generally more), but with the latitude as mentioned, this having been say, and somewhat safely, approximately .004" +/- (if not even more), this means there's a fare bit of latitude to work with. The manufactures needed this range to cover manufacturing deviations and a possibly not so accurate effort in the setting process by the human being and not to mention functional environmental conditions that created variations; so their number is just targeting somewhere in the middle of the cam-lobe "take-up-ramp" which presents a certain sum of distance. ;)
This has also proven to have been a tuning tool for the racer's; as with your car being "dialed-in" at the track, you could tighten the lash (some) to provide a minor sum of additional cam-effect or open-up the lash to reduce such, and which reaped the improvement in performance provided the owner with the simple notion of whether the camshaft was "not big enough" or "just too big" for the application. 8)
Now, I generally default for "tight"; as this if anything, it might provide an additional duration of distance and time that the lifter will spend on the take-up ramp, meaning that at this point where the lifter is transitioning from stationary (vertical motion) to being "bumped-up", there's perhaps a softer start to the action, but of course, one would have to study the lobe profile to determine this in absolute terms. :)
But whatever you choose to do, do be consistent throughout! ::)
Scott.
Also to add to what Scott had to say is that sometimes depending on the cam, you may have intake or exhaust tighter or looser than the other to vary the characteristics of the cam slightly. The cam I run is recommended to be set at. 024 for one and. 026 for the other. I forget which is which and will probably just shoot for. 025 on both the next time I set them just to make it easier ;D
Roy