Type 4 engine rebuild: take 3

[Clatter]

In all honesty,
Reading your list of goals makes me think you should go 100% stock.

Auto and smaller 1800 and all makes your build different than one than I would do.

My goal was always to make as much power for “high-speed” <—- quotation marks required running hard loaded heavy on the highway.
The exhaust works with the big valves and the big induction and the cam..

There are some downsides to this setup;
It’s a bit ‘lurchy’ at times; hard to drive gracefully at very low speeds.
This gets especially annoying in heavy traffic.
Big cams and heavy springs won’t last as long and have parasitic losses.

If it was stock carbs, 1800 and auto,
It would be worse, no doubt.


If you’re going stock induction, 1800ccs and auto trans,
I’d stay stock.
No shame in that.
Stock combo works great.
It will drive like an electric sewing machine.

Unless you plan specific modifications to your combo,
And test them,
And find this kind of thing fun,
Go with what will 100% for sure work great.


One ‘mod’ that I would always want on any motor, though, is a dynamic spin-balance job..
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Bus Motor Build

What’s That Noise?!?

[KentABQ]

[orwell84]

Thanks very much for the input. It is much appreciated. Finally started to get to work taking it all apart. One of the things I didn’t measure during my build was side clearances for the rods. The two I could get to at the moment measured about .010 and .012. I know they are toward the high end of the spec range.

The pistons look a little scuffed after only 5000 miles.

Onward...

[orwell84]

This is getting fun...#4 piston. The circlip was in the hole on the opposite side of the piston.

I know I installed these correctly. Had the rods rebushed too...I’m not sure why this would happen...

[Wildthings]

[orwell84]

[Clatter]

Good thing you opened it up!

Keep going.

Every motor you build is an opportunity to do better.
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Bus Motor Build

What’s That Noise?!?

[orwell84]

I was saying how the Chinese couldn’t even manufacture a good paperweight.

Looks like I have a bunch of good ones now...

Guess I will hitch up my depends and keep going...

It surprises me to find this kind of damage. Past engine failures have always been burned valves. I really beat on my engines years ago but never saw wiped hone marks or that kind of scoring.

This engine has always been run carefully, has never overheated. The oil pressure while on the low end has always been consistent.

I think these P & C’s are pretty much toast. Is there a decent alternative to AA for dished pistons and cylinders?

[Clatter]

Bet those P&L were tight..
FWIW I hone every set of those just to get them rounder.
Best to have them a bit on the loose side with a heavy bus.

Heads looked a bit leaky as well.
Was the case ever decked?

If you don’t have a place to get a case decked,
Might think of gluing the heads on..
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Bus Motor Build

What’s That Noise?!?

[raygreenwood]

A handful of little items.

The sealing pattern between cylinders and heads....looks poor. It looks like the cylinders may not have been sitting level.

Was the case decked? Did you remove the head gaskets snd lap the cylinders flat snd then lap them to the head openings?

Also...looking at the areas where honing marks were heavily worn.....was it worse on one side of the cylinder than the other?

Ray

[Clatter]

That circlip might have been put in ‘sharp side in’..?

Any chance you forgot to check orientation?


If the clip was in right,
Broken clips can mean crooked rods or crank..
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Bus Motor Build

What’s That Noise?!?

[SGKent]

Steve - (Clatter) do you have a honing machine like a CK-10 etc that you can use to get a straight stone on the cylinders? I have some that I am taking to be welded (broken fins) and I would like to find someone who has the ability to mount them into a CK-10 etc when done and make a couple passes to be sure they are straight. I no longer have access to one or someone who has one and is a good operator of it. It will also take a special plate made to hold the cylinder down. As to the cylinder in this thread that the snap ring failed, that gouge looks deep but one could hone it and see how deep it actually is.

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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[orwell84]

[orwell84]

[SGKent]

[orwell84]

Thank you for explaining that. It’s likely I missed it, so it’s entirely possible. On my last rebuild, I had the machinist check the rods for straightness and both ends were balanced. I checked them too by stacking them with a piston pin through all 4.

Honestly, I would just replace the (AA) pistons and cylinders. I would put my time into measuring them properly. I might also consider using better quality rings. Giving even new ones a quick hone makes sense. Thinking back it all kind of tight and unfinished feel. I chalked it up to them being new. I have only ever handled used German stuff before that. I did wash them in soapy water more than once and really kept stuff clean during assembly.

[SGKent]

if one of the clips came out most likely it was not fully seated or over stretched putting it in. I push on them with the point of a small screwdriver to be sure that they are fully seated. Put them in correctly is important to. On more than one occasion a snap ring looked seated but it popped when pushed, showing it was not - or it goes so far into the groove one can see there is not enough tension on it. Since you checked the rods that isn't it. It may be since the pins were tight that you thought there was room for the snap ring but there wasn't. If the pin pushed it out you'll see the damage on the piston where the snap ring deformed the groove.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[raygreenwood]

Most common snap rings are stamped or punched. The side of the ring that was impacted by the die....gets its edges rolled or crowned very slightly. Also,common....if you inspect a few rings on a flat surface.....they can get very slightly crowned....meaning dished.

The "dishing" can be one of the larger issues. When pressure is applied....it can act a little like the wedge shape of a piston ring....but since its reversed.....it can drive force inward...collapsing the ring and allowing the crowned edge to slip past the ledge its seated on.
This is not usually an issue if the rolled edge gets placed toward the load....and the sharp flat edge against the ledge its wedged against.

In the piston pin usage...the sharp edge goes away from the pin.

There are also snap rings made that are not punched or stamped....that have a flat surfacd on both sides. They are called "constant section" retaining rings. Ray

[busdaddy]

[orwell84]