crankshaft - grind or replace?
 

If you spun a bearing... would you recommend regrinding the crank? or replacing it?

What are the pros and cons to performance, reliability, originality between either option?

I just went through this. Short story it depends on how much it was damaged. I sent mine to CCR. Armundo is the guy. Well respected crank restoration and repair. There are others that will chime in. He can tell you if the journals have been damaged to what degree and let you know if you what your options are. Good luck.

They certainly can be repaired. To do it correctly will probably cost much more than a good used one.

Or grind for oversized bearings

That may not be the case anymore. Good used cranks have become scarce, and prices are typically in the $1200-2000 range. Good repairs are around $900. At least this was the case when I was looking for a 74.4 Carrera crank last year.

Was just looking at your engine rebuild question thread and saw this. I recently had my engine rebuilt and had the crankshaft center drilled and the journals ground down. I believe from 215mm to 200mm. Than added longer connecting rods. Wasn't for power but for durability. I understand the centerdrilling sends oil to the center cylinders which are regularly the last to get oil. The longer rods adds to the life of the engine.

You guys in california have all the options...

In the Midwest... not so much...

Shipping a crank to California and back sounds expensive and high risk for damage...

Armando is in TX.

First question I have... what year did you have this done on? (read that there were more issues with older crank that were in magnesium cases)
Second... what conclusion brought you to needing to have the crank work done?
Finally... have you had the engine back up and running since? If so... how is she doing?

I hear ya there. Seems the best shops are either east coast or out west.

If there are any good shops in the Midwest... either they aren't making enough of an impact in the air cooled world, or they just don't like to market themselves.

I'm going to end up sending all my engine parts to Ollie's in Arizona. Why??
Because they are the ONLY shop that actually talked to me when I called them. Pretty sad that nowadays, I'm just thankful to find a place of business that actually WANTS to do business with a new client.

When you grind the crank for all journals, you're either going to need oversize bearings (VERY expensive) or you need new rods with a different big end bore. When you're into new rods, that opens the opportunity for a custom length. But the length of stock rods is not some sort of huge shortcoming. That said, there is a benefit to adjusting the rod length-to-stroke ratio.

Anyhow, repairing one journal is not a big deal. Sure Armando at CCR can do it. Just be aware that sometimes his turnaround time is a crap shoot. You could instead send it to Ollies in AZ or Marine Crankshaft in CA. Those are two well known shops that know exactly what you need done and how to do it.

Here's Ollies price list for reference- see page 3

http://www.olliesmachine.com/uploads/Ollies_Price_List.pdf

You're looking at $275 to start, just to grind and weld one journal. Then it needs to be polished. After that you'll want to remove the plugs and clean it. MUST clean the crank by removing the plugs any time it's been treated to abrasive work.

Also a good idea to cross drill the crank to feed the center rod journals (#2 and #5) from the #4 main journal. There's no downside to this, other than you need to enlarge the feed hole in the case bearing saddle for #4 main in the case. Which means you also need to enlarge the feed hole in the #4 main bearing a little bit.

The reason it's done on #4 main is because the crank, in it's original configuration, is fed oil from the ends. The engine case of course delivers oil to all of the main bearings. But only #1 and #8 mains actually put oil inside the crank to deliver oil to the rod journals. That means #2 and #5 rod journals get oil last because they're in the middle. The drilling done on the crank creates new internal passages from the #4 main journal to send the oil directly to #2 and #5 rods. The reason the #4 main journal (or the bearing) is grooved is to ensure an ample amount of oil is captured by the groove and sent into the crank to feed the rod journals. This grooving is just like what the #1 main journal looks like. The reason the hole in #4 main journal is enlarged is to ensure the oil seeks out this location- a path of lesser resistance is a larger hole.

Here's a good discussion on the cross drill http://forums.pelicanparts.com/911-engine-rebuilding-forum/230656-cross-drilling-crank.html And in post #38 I shared a link to a previous discussion that has a diagram showing where the oil goes. I created a modified diagram in post #13

http://forums.pelicanparts.com/911-engine-rebuilding-forum/582197-another-crank-cross-drill-question.html#post7778315

Pictures of crank journals would be helpful . . .

We rebuilt a 3.6L race engine in 2012 - the crank had some pits in it and #5 rod bearing was
really bad- machine shop polished crank and balanced engine (crank, rods, pistons, etc) and
the engine has run great for several seasons now (we did a minor refresh this past winter -
rings, bearings)

http://forums.pelicanparts.com/911-engine-rebuilding-forum/688754-964-crankshaft-pits.html

You may just need to get the crank polished . . .

If you don't have a good engine machine shop near you - then cgarr is close to send parts . . .
there may be others of course . . . we once found a 70 year old man grinding cranks in a small
town - he had been doing stock car race cranks for a long time . . . we use "Chuck's Speed
Shop" here in Phoenix - but they have to go get a retired machinist to do Porsche heads . . .

Regards,

PS: for your engine stand HF is fine with the Pelican engine yoke - we use a HF engine lift/hoist
also to get the engine in the truck sometimes . . .

I spun two rod bearings in my 3.3L turbo engine (#2 and #5). I brought my crankcase, crank, rods, etc to JB Racing in Fl. They gave me a few different solutions to fix the problem. Since fixing the stock rods included resizing and ARP rod bolts, my thought process was just to go with the Carillo rods, and get the crank offset ground, thereby stroking the motor. We also did the center main bearing oiling mod, and used the Nascar Clevlight bearings. My engine is now a 3.6L and we are looking for 950HP or so on E85 at 26Lbs of boost.
Armundo at CCR did the crankshaft work, and did an excellent job! I have also heard the horror stories about the long turn around time, but JB Racing handled all of that for me and the turn around tim, including shipping, was about 6 weeks or so.

The engine is an 84 3.2. On my rebuild I was looking to make the engine more reliable and as stated by others here it seems the center cylinders 2,5 get less oil than the others. My mech suggested this he also suggested while I'm having the crank drilled to shave the journals and get longer connecting rods. This also would make the engine stronger. Yes the engine runs great though it's burning oil. Mech.belives the heads were machined wrong and will be taking it apart again this winter to fix that problem.

http://forums.pelicanparts.com/uploa...1506604149.JPG
http://forums.pelicanparts.com/uploa...1506604149.JPG
This is the crank after drilling.