Quote:
Originally Posted by chuckies76ta
I'm curious, Do you know what springs you are using and close and open pressures? How much lift, and what rocker ratio? I ran those Johnson short travel lifters in a 400. Made 550 hp. Sold engine years ago and still running strong with no issues. Guy just went a round trip of 2000 miles no issues. I remember the rep at Johnson telling me to set lash was very specific. Not you quarter turn or half turn after preload. I actually measured with a set of calipers.
Thanks
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I don't know what the spring rates are. I bought the heads complete from Kauffman. The cam lift is advertised at .360 lift, and the rockers are 1.65.
So, to make a short story long, I'm still chasing a problem at WOT that I've posted about before. Under load, it backfires or breaks up. I'm pretty confident that it isn't the ignition system or fuel. I'll post my tests in another reply. I ran a compression test, and watched the rocker's movement on the starter. All looked good. Since the problem is at WOT, I didn't expect to find any problems. I ran out of ideas and pulled the rockers and pushrods. The rockers are fine, and none of the rods are bent. So, I yanked the lifters. That's when I noticed the wear on the lobe. I also found a very small piece of debris in the cup of one of the lifters (hard, non-metallic). I took it apart and cleaned it. The others seem fine, but I'm going to soak them in mineral spirits for good measure.
Back to the springs. The heads arrived from Kauffman with valve cuts that weren't concentric to the seats. A local shop re-cut the valves, and all was good for a while. I don't think this is related, but I wonder if one of the springs is giving up. Since I'm this far in, I might as well have them measured. Thoughts?