02/11/2026
Story time
Engine building and why each build has to be approached as a one off build. Just because you're building an engine for a given application, say drag racing, dirt track, road course, off road, etc. if the combo is different from one build to the next. It needs to be approached as its own one off build, everything previous used for parameters is no longer valid unless verified with certainty to be correct. Change 1 part and you possibly change an engine system and create issues.
To explain some of those things that work on some builds but not others. I am going to use Randy Merrill 565 Big block chevy bracket engine that was recently dropped off as an example. I'm going to break this down into the 2 root causes for all of his issues pictured and previously broken parts because of those issues before he brought it to us.
Since the pistons are showing up first in the pictures, we will start with the piston to head clearance. This engine was completely assembled without verifying there wouldnt be an issue. Normal thickness head gasket wasn't enough. Now you may think, oh but how much run time. Irrelevant, the pistons were hitting directly above the wrist pin and mushroomed the chamber edges inward and indenting the piston and can see on the spark plug side where it was wearing into the piston itself. The carbon build up and fuel wash, even the clean area on the quench pad where there's no signs of detonation says the tune was safe and not a factor. Now what else did that cause? It caused the line2line coating to be completely rubbed off and the aluminum debris caused from smacking the head and binding against the cylinder wall, was embedded into the skirts and being caught with the rings causing scoring in the cylinders.
Now for the expensive stuff, yeah the new pistons are the cheap side of all this.
The lifter bushings that were installed were never drilled out beyond the supplied .040" - .060" manufacturer supplied hole to provide enough oil to the valvetrain. In some cases, if you have heads that hold oil and are slow to drain back into the pan it's beneficial to restrict the amount of oil to the top end. However, this is not the case on this build. These Dart pro 1 heads have massive drain back holes and drain rather quickly. So because of this lack of oil to the valvetrain. Randy has fought valvetrain issues for a few years now. Some of those issues including, broken valve springs due to heat from lack of oil to cool them. Broken rocker arms from gauling and binding from lack of lubrication. Mushroomed pushrod ends from lack of lubrication and possible geometry issue, I will be addressing that during assembly to verify that's not an issue. As well as the reason for the current teardown being a broken lifter tie bar and lifter that rotated in the bore causing the cam lobe to get damaged and turned into a paperweight.
So here's what will be done to resolve all of these issues. The pistons will obviously be replaced with next available size and associated machine work. The head gasket thickness will be changed to the appropriate size to eliminate contact issues. Chambers are going to get some blend work and shaping to remove burrs and shrouding. That'll open his tuning window and make it very consistent without much tuning adjustment. The lifter bushings will be drilled to allow adequate oil to be fed to the valvetrain and lifters, preventing heat and lubrication issues.
We will also be swapping out damaged parts, upgrading to a jesel valvetrain, upgrading pushrods, replacing valve springs, valve job, surface the heads, new bearings all the way thru, resetting clearances to suit this specific build, and doing full assembly.
Stay tuned for updates, this is gonna be a fun one.
