Quote:
Originally Posted by FredG
The solid lifters on my old C1 vette 283 had to be adjusted with the car running using a feeler gauge. I had a set of valve covers with the top cut out to keep the oil under control. I loved the sound of those solids.
Fred |
Fred is right about this technique. It was originally used on SBC's with the solid lifter Duntov cams. The technique was useful on ball stud engines like the SBC if the adjuster was either an OEM self locking adjuster or one of the early Polylock adjusters.
This is a pic of the Polylock style adjuster;
The Polylock came about because the OEM adjuster used a distorted thread style of locking mechanism that would loosen over time requiring regular maintenance. The set screw in the top of the Polylock acted as a jam nut to secure the adjuster and extend the time between lash adjustments.
The actual adjustment technique involved, starting the engine and ever so slightly loosening the lash to insert the target thickness feeler gauge for the lash you wanted to set and then progressively tightening the adjuster until the clatter from the lash disappeared and/or you could just barely move the feeler gauge around while the engine was running.
If you over tightened the adjuster, the feeler gauge would not be possible to move and certainly there would be no sound from the lifters as the clearance ramps on the cam gently brought the lifter up onto the opening ramp of the cam.
The technique, other than being messy because of how the SBC oiled the top end, was amazingly accurate. Some argued, credibly so, that it was the most accurate method of valve adjustment. With the arrival of the Polylock this type of adjustment was still possible as long as the body of the poly lock had a slight interference fit with the stud. After the lash was set for each valve the set screw (if you used a Polylock) in the top of the adjuster would be used to lock the adjuster in place.
Without ball stud rockers most other makes would not use this technique. The exception would be if your rockers had self locking adjusters. If they did then you could use the same adjustment style the SBC guys did — with the same
oil control/management issues.
Engines with adjusters that used jam nuts required one more hand than available to do this style of valve lash adjustment. As such the EOIC or other approach was used to lash the valves in an engine while not running.
If you are less than 70 you likely never heard about this stuff and definitely never saw it happen — but it did and it was / is real.
Ed