Built a cam bearing press. Works very well, lot gentler on the bearings vs hammering.

About to give the block the final wash before assembly and I figured I take the opportunity to do some [more] out of the box stuff beforehand.

One of the weakest points in the 7.3 block are the core parting lines that go from the bottom of the bearing cap registers down to the cam bore. The cam bore is chamfered one side only, and it has this porus line extending from it all the way up to the area where the web is thin at the cap bolt holes... Combination of stress risers, notch effects, and material thinness make conditions right in this area for fatigue cracks in the web. Indeed, most of the catastrophic crankcase cracks I've seen follow that line.





So I took a die grinder and blended the area where the castings meet at the cam bore. I also chamfered around the cam bore, and polished with a flap wheel to reduce the likelihood of fatigue cracks propagating from this area.

I only did this because the core parting lines on my block were pretty visible with mediocre alignment. I wouldn't recommend unless you're, you know, crazy like me or your block also has mediocre casting in the web.

 

Is that thing going up and down the road yet?

 

No. This thread is still called:

"Engine Build Part 2: The Assembling"


We'll know when the thing is going up the road in the next thread of this series, called:

"Engine Build Part 3: The Ascension"

 

Hopefully this is a trilogy and not a saga.

 

Had to do another round of machine shop roulette to get the head machining completed (which was recently finished).

Current issue is camshaft related:




All the cores I have contain a ton of little potmarks of material missing from the lobes... either material loss from fatigue or foreign debris. I've developed a process for putting a really fine polish on the cam but getting all these marks out requires removing a decent amount of material. Unfortunately the last cam I handed over to the local grinding outfit came back looking like this:


(Those ridges are too deep to be polished out).

This is important because with the beehive valve springs the roller to cam contact pressure will be in 6.0 territory thus any flaws in the surface or inadequate bearing contact area will increase the chances of cam failure. Alloy steel cam would be a far better option than stock case hardended cast iron, but that's over 500 dollars and means non stock timing/lift... Procrastinating clicking the buy button.

I promise I'll get to some actual assembling soon!

Another thing for future readers: if you want to use cometic MLS gaskets make sure your machinist doesn't cut the bore chamfers too wide.

 

Eh, toss an rcd stage 1 cam in

 

The machine shop hands you back the cam w/ the lobes looking like that and says its ok..?

 

It's rare, but it happens that you get chatter on a grinder. Well, from here, it looks like chatter. Anyway...it's terrible, and you are correct in not running that.

Push the "buy" button on the cam. YOLO!

 

What was/is the solution on the greedy chamfer?

 

Cometic happens to have one that just might barely have a large enough bore (probably a custom overbore design they did) but it's standard MLS embossment fire ring vs the MLX which has a progressive die roll over the steel to form the fire ring (or stopper layer as they call it). Obviously the MLX will handle increased cylinder pressure.



I need to see if decking the block a little might will get the chamfer where I want it. If it will that's what I'll do.

 

Hopefully the machine shop doesn't cause more problems doing that. You've had crap luck so far.

 

Friend who has been helping me with this build in their spare time found someone local who can cut fire rings, so I'm going to go in that direction. They sit somewhat behind the bore so the chamfer won't interfere. This way I can get the sealing characteristics I want without doing decking the block and potentially introducing more issues.

 

I admire the dedication to this build and I know it will work awesome and handle abuse once it's done. With that said, I have realized I will probably continue to pull running 7.3s and just "put in another" when the time comes.

 

If you're in an area with some good machine shops it wouldnt be near as much hassle as my threads have shown. After this is complete I've thought about building engines in the side since I now know what parts to use, what shops to work with, have the gear to do QC.

But yeah if you're just doing a stock replacement with purely bolt-on modifications a junk yard forged rod engine will take you pretty far as long as you don't remove the heads. Engines in good shape can be hard to find anymore depending on where you're at.

 

Where are you located in OR? I am outside of Boise, Idaho. From what I know we have some decent machine shops here to do engine work. I haven't dealt with them but friends have.