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  #21  
Old 09-10-2019, 10:04 AM
Zeb Zeb is offline
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Originally Posted by gwunter View Post
If you really don't want them to fail again go with the harlandsharp or Warren diesel setup. But be sure your sitting down when you price them out.

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Youíre thinking rockers. There is absolutely no need for Harland Sharp (which have fitment issues) or WDIís setup on a motor like the OP is building.
  #22  
Old 10-18-2019, 09:28 PM
alwaysdiesel alwaysdiesel is online now
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Everything is coming along good, got almost all my parts ordered and block/heads are finished now. Pretty well stuck to my original plan, WDI 205/30s, Gear*ead tunes, Kc stage 2, BD mani's, Colt stage 2 cam, RCD valve springs, Oringed heads, pushrods...etc etc

Machine shop just finished up with everything so I'll be picking it up on Monday, but I had some questions about pistons. A few cylinders had 0.005-0.007" wear and a deeper gouge made them bore 0.020" over. Mahle .020" pistons run about $900 a set, so I was thinking of spending a little more and going coated, possibly 0.050" flycut since I am running a bigger cam, I know it isn't necessary but they don't cost much more. I know the coating helps dissipate the heat. Can anyone shed some light, what is the limit for stock pistons?
  #23  
Old 10-19-2019, 08:40 AM
Zeb Zeb is offline
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Originally Posted by alwaysdiesel View Post
Everything is coming along good, got almost all my parts ordered and block/heads are finished now. Pretty well stuck to my original plan, WDI 205/30s, Gear*ead tunes, Kc stage 2, BD mani's, Colt stage 2 cam, RCD valve springs, Oringed heads, pushrods...etc etc

Machine shop just finished up with everything so I'll be picking it up on Monday, but I had some questions about pistons. A few cylinders had 0.005-0.007" wear and a deeper gouge made them bore 0.020" over. Mahle .020" pistons run about $900 a set, so I was thinking of spending a little more and going coated, possibly 0.050" flycut since I am running a bigger cam, I know it isn't necessary but they don't cost much more. I know the coating helps dissipate the heat. Can anyone shed some light, what is the limit for stock pistons?
The money you spend on coating on the pistons is an absolute waste, imo. If you were to have the motor apart in a couple thousand miles, you absolutely couldn’t tell they were coated.
As far as fly cuts, I prefer to avoid them on a small cam. On a larger cam, (Stage 3 or 4 it’s almost impossible to avoid it). I prefer to keep the top of the piston flat. I usually take 0.015”-0.20” off the top of the piston (depending on deck height, etc) and roll the bowl lip back, but don’t totally eliminate it.
Stock pistons are plenty strong enough for 700-800 hp. Nitrous, a lot of rpm, or something else stupid is what’ll kill them.

Last edited by Zeb; 10-19-2019 at 08:43 AM.
  #24  
Old Yesterday, 11:54 PM
alwaysdiesel alwaysdiesel is online now
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So I've working out of town since November and the engine progress has been slow. I got my bottom end all together and mocked up a cyl head but have ran into some issues. I am running test springs on #4 cyl and clearances are tight. Originally I had tack welded a couple old lifters to avoid having my plungers collapse and give me false readings, but my exhaust valves ended up contacting the piston towards the end of the exhaust stroke.

So I've swapped back to hydraulic lifters and rechecked my clearances. At TDC compression stroke, there is only 0.054" intake clearance and 0.052" exhaust clearance, Confirmed valves are fully closed. During valve overlap, clearances don't get any tighter than 0.051" on exhaust or intake.

My setup is Colt Stg 2 cam, Motorcraft lifters, RCD pushrods (0.007" shorter) factory rocker assemblies, 120# RCD springs, Motorcraft head gasket, Mahle 0.020" Over pistons
The block got machined, and I am sitting close to MAX piston protrusion (rough 0.030-0.032") Heads got fully rebuilt, and they say everything was done to "spec" although I've read that most machine shops air on the side of caution and set the valves deeper (0.020" average) They did say they topped the valve stems to account for valve depth but did not give me specific numbers. I will try contacting again this week.

I also checked lifter preload, at TDC compression, It took 0.098" to bottom the lifters. I checked max plunger travel and got 0.200", so that would give me 0.102" preload. From what I've read this is fairly normal?
Thoughts?
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