Diving into my 1st A4 rebuild!

[edwardc]

You need to get some plastigauge and measure the actual bearing clearance.

Good oil flow and pressure is the lifeblood of the engine. Worn or scarred mains will reduce the max available oil pressure and negatively impact engine lifetime.

I agree with Tenders. Seems a shame to go this far and then not fix it.

In for a penny, in for a pound. After all, its a B.O.A.T (Break Out Another Thousand)!

PS - Found this nice little "How-to" on Plastigauge: http://www.plastigaugeusa.com/how.html

[wristwister]

Thanks Tenders, that's certainly the way I'm leaning.

Regarding the crankshaft, the rod journals all look fairly pristine. The fwd main journal is as shown in my pic above. The actual bearing surfaces look good, it's the center of the journal where the bearing oil groove is that appears rough. The rear main bearing shows a similar situation, but not as much. The main bearings themselves look very good. I'm wondering whether the roughness in the oil groove area is a problem, or a normal type of wear that's no problem.

Regarding those pitted rod bearings, yes they need to be replaced. But again, the rod journals on the crank look pristine. So a question here is; provided all the clearances measure out within tolerance can I just replace the couple pitted bearings, or do rod bearings always get replaced as a full set?

I think a call to the Moyer tech line might be in order here!

All this sounds like a fine reason to call the Moyer tech line. I'll be doing that this week.

[wristwister]

OK boys and girls, journal/bearing measurements are mostly in, and most of my clearances are beyond Moyer recommended numbers, so regardless of my questions above on bearing and journal scarring it looks like I'm going to bite the bullet and go for a crankshaft grind and oversize bearings.

So that brings up a question: do I have the crankshaft grind done first, then see where the main and rod journals measure at, then order the correct oversize bearings? Or do I go with, say, .010" oversize bearings and tell the machine shop what size to grind to?

[Ram41662]

When having engine parts turned, I've always told the machinist the target spec range and we will discuss which set he thinks he will achieve. Once we are in agreement, I have the turning done before ordering the components that have to interact with the turned piece. That way if anything more is found out of whack or something goes wrong during the process I don't have a set of wrong-sized parts, i.e. 0.010" bearing when I need 0.015".

To be honest, 95% of the time I could have ordered the parts since the outcome was right on the money, but I'm a unlucky SOB, so I expect the worst.

[wristwister]

Thanks Ram, I also just had a nice chat with Ken at Moyer. The crank is now in the hands of the machinist. When I get it back, I'll call Ken again and get the appropriate bearings.

While I'm waiting for that, I've got plenty to keep me busy. I'm going to clean and strip all the castings and prime and paint them. My daughter has an interesting color scheme in mind for this engine, I'll surprise you all with that later ...

[wristwister]

So here I sit at the airport waiting for a much delayed flight, why not post an update on my A4 build!

Why am I at the airport you ask? I came down to my daughter's boat to pull all the goodies I'll need off her blown A4 to install on the A4 I'm rebuilding. Head, manifold, carb, distributor, etc. etc. etc. All together about 88 pounds of stuff. I know this because my suitcase containing all this stuff wasn't even close to the 50 lb baggage limit. So ... I transferred several of the heavy parts over to my carry on! Checked baggage now weighs 49.6 pounds, carry-on is ridiculous! Much fun trying to explain what these chunks of iron are to the TSA agent! Now my challenge will be to nonchalantly put my carry on into the overhead bin when I can barely lift the sucker off the ground!

Anyway, crank is back from the machinist, block comes back this week after being tanked, magnafluxed, honed, decked and measured. More stuff will be ordered from Moyer when I get those block measurements back. I'll clean up and paint all the goodies I'm bringing home, then hopefully next week it all goes back together.

[Hawkeye54]

Diving into A4

Wrist, great tale of what you have to do in these TSA days -- I am eagerly awaiting the chapter in this story on how you get the assembled engine BACK to your daughter's boat.
( Somehow, I can't see a Flight Attendant assisting you to load it into the overhead bin )


Rick

[lat 64]

A fully dressed A-4 needs to be gate checked. Don't you know anything?

I was at SeaTac just yesterday! I missed you I guess. I had an ameter, terminal block, winch parts kit and gobs of small parts stashed in my checked pack. I supposed it looked quite suspicious in the x-ray.

r

[wristwister]

I got in real late last night. All my bits and pieces made it home, but the wifeypoo is a bit pissed because her nice luggage reeks of grease and gas, and the frame is a bit twisted. I might owe her a new one. Chock it up to the overall rebuild cost.

[tenders]

TSA PSA: no drill bits allowed in carryon luggage.

https://www.tsa.gov/travel/security-screening/whatcanibring/items/drills-and-drill-bits

I had a few extra hours on a business trip last year before my flight took off. I had a rental car, so I doubled back to a Home Depot I’d driven past and picked up some pretty nice cobalt bits. Well, they turned out to be one checked bag more expensive than I’d expected.

Couple of weeks ago I expected a hassle over my old A4 propeller in a suitcase I checked to London. Nope. Could have carried it on too.

[Ithedan]

OK, I picked up the engine and I've started plowing into it. Here's the story; the guy I bought it from didn't know much of the history of the engine. His A4 went out, so he bought this one from someone who had supposedly started taking it apart with the intent to rebuild it. Turns out the guy I bought it from went with a diesel repower, so he sold this one.

Here's what the cylinders look like:



Now doesn't that look pretty? Heck, it even looks like fresh hone marks to me. The rest looks pretty good too. It makes me wonder whether I really want to to a complete tear down on this engine or not. What would you folks do?

Are you sure they are Hone marks? Maybe it is just the lighting but the marks look awful coarse to me. No crosshatching.

[Ram41662]

I wasn't going to say anything, especially since what I'm getting from the feed back here, it seems what is standard or acceptable for an Atomic 4 doesn't always match what I'm used to on many of my engines. For what I knew, that was a perfectly good bore and hone job.

For comparison, here is what I found when I popped the head off my A4 and gave it a quick gasket scrape and solvent wipe down. For me, it looks a little smoother and right in line with what I'd accept. YMMV.

[wristwister]

Upon the advice of Ken at Moyer, I took my block to the machine shop to have it tanked, magnafluxed, decked, honed and measured. The block is good, I'm only .002" max over the 1.562 spec on cylinders, and the honing is now professional. It's looking sweet (better be, that ain't cheap!). I just ordered all the bearings, rings, and other assorted goodies I need to put her back together. I can see the light at the end of the tunnel!

[Ram41662]

Nice, glad to hear that you had it gone over by a machinist.

FYI, after reading Don's service and overhaul manual as well as several versions of owner and service manuals, the Atomic looks like a pretty easy, straight forward engine that's easy to rebuild, service, and maintain.

Good luck with your project.

[wristwister]

So ... what do you all think?