<VV> Rocker are blowout issue resolved - I hope!
kentgoddard at msn.com
Mon Jun 22 00:40:47 EDT 2015
Many of you were following my post "? Rocker Failure - Third time?"" and providing helpful comments to address the issue I had with blowing out the bottom of a rocker arm with 500 miles on a rebuilt engine and a 2nd rocker at 600 miles. Here's the update in case it helps others.
After autcrossing the car last weekend #2 cylinder died. I pulled the rocker cover and BOTH the intake and exhaust rockers were blown out in the half-ball area, identical to the other 2. From the discoloration it was obvious they too had overheated. Running the car with the valve cover off it was obvious the oil flow was VERY LOW to all rockers even though the oil pressure was normal, pushrods were clean and installed properly, valves were properly adjusted, etc. (see previous post for all of the gory details).
So the first thing I did was install Clark's high pressure oil spring. The pressure jumped way up to 55 psig at idle and 75 psig at 3000 rpms. Great! But that provided very little additional oil flow. :-(
Next I replaced the almost-new Elgin deep dimple lifters with an old set of GM lifters that had been in a car for only 3000 miles, kindly provided by a friend. Oiling problem solved!! Robust flow to all rockers, pushrods rotate and spit oil everywhere, including into the hole that oils the half-ball area. Hopefully this resolves my issue. :-)
Others have used Elgin deep dimple lifters without problems. Are the ones I bought a bad batch? Were they just insufficient for my higher-out 140 (ISky 270 cam and milled heads) that gets driven hard? I mic'ed both lifters and they're very close dimensionally, but not identical - did this make the difference? I'll probably never know those answers, but I won't be buying Elgin deep dimples ever again.
Guess I'll take my chances and drive the car to Knoxville after all. Hope I make it! Thanks all for the assistance!
Kent GoddardSt. Louis, MO'66 Corsa 140
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