luis253

I threw some rods pistons and head studs in a single cam engine, ran it 1000 miles then spun a bearing with a rod knock,
should have used engine brake in oil!
My question,
what is the tolerance for
main bearing clearance?
so far a have .001 Inches- .002 inches
that was checking it with the old and used bearings so there was alot of scarring on the bearings.

rod bearing clearance?
i have not taken a measurement yet because the whole crank is scarred up(alot with the rods), i suppose i could throw bigger bearing in there with a little bit of machine work.
would that just be micro-polishing the crank or would it be balancing it?
i was reading about grinding the crank in the manual. But if it could not be salvaged i would toss a different crank in.

engines are not hard to come by at my location but i would prefer to fix mine then replace it


Any advise, comments, suggestions all welcome!

westcoast1994

I bought a car with this same engine. Condition and mileage were unknown.

I spun a rod bearing in cylinder #3. I was optimistic that it would just need a regrind. I took the engine to my local machine shop. Before they started any work I got a phone call informing me that the crank and the one rod were not usable.

I ended up purchasing one rod and a crank from the machine shop and they sized the bearings and clearenced the entire engine. I'm not sure if I have the clearances any longer but I'll take a look.

Long story short I spun a rod bearing. Thought it could just be machined and ended up needing a crank and a rod. I posted some crappy cell phone pics of the damamge.

Pro-SeriesFab

Bearing clearance is going to be in the .0015-.002 range depending on usage and oil weight. There's little reason to run on the tight side of the clearance unless you are doing some type of pro stock/oil restriction motor and plan on running thin oil. .002-.0022 isn't going to hurt anything.

Checking inside diameter with anything other than new bearings is a waste of time. You might be able to get away with it on the bearings that use a deep babbit layer and are hardly used but there's little guarantee the bearings aren't already screwed up if you reuse old ones, even for checking.

If you want to rebuild an engine, there is absolutely no reason to not buy a dial bore gauge and learn how to use it. You can also use a 3-point inside micrometer but they are going to be 3-4x more expensive and are less versatile. Plastigauge leaves too much room for error when you need to know clearances down to .0001 or .0002. You'll need a way to check bearing inside diameter with the main caps/rod caps torqued down and an outside micrometer set to measure the bearing surface diameter on the crankshaft itself.

The only people able to answer your crank scoring question is a machine shop. It might be able to be cleaned up with one of those sandpaper belt sanders they use or if its bad enough, turned or scrapped.

luis253

Hey thanks for the pictures Westcoast1994
Pro-seriesfab i would feel more comfortable using a plastigauge then a caliper. because i dont have the chance the scar, bur, chip or scuff it with a micrometer. plastigauge can be used like toilet paper! haha
so is the three point micrometer considered a depth mic?
Also i heard somewhere the Honda cranks have a finishing on them, and after having them micro polished or grinded it takes that finishing off them so they are more likely to snap.
can anyone prove this is not the case?
along with a crank being turned, scrapped, balanced, and polished. is there away to be checked for roundness.
my main question is how can i go about repair under 700$ thats all i bought the car for so anything after that is good. haha
Questions, comments, suggestions all welcome!

westcoast1994

I would take the crank and rod to a reputable machine shop. They should be able to tell you right away if it is bad or not. They may offer a crank and rod on site or you can search the marketplace.

I can't remember exactly but had I not needed the crank and rod. My machine costs would have been around $500. And I paid about $400 for a rebuild kit.

I know how you feel about putting money into an old car. My whole deal happened 2 weeks after I bought mine. I just wanted something that would get me around. I just spent like $500 on ball joints, steering rack, and tie rod ends.

luis253

the Engine i am working with a just a spare summer motor, i got all winter to think about specs.
dude you spent way to much on those things, that was something i fixed this last year, steering rack 40$ ball joint 50$ alignment 70$

what cranks are interchangable with the a6?
such as main bearing sizes?

Pro-SeriesFab

An outside micrometer has nice ground ends on it . . . and since the bearing surface is round there is little chance of scuffing the bearing surface on the crankshaft.

The only possible issue is scuffing the bearing when checking with a dial bore gauge (talked about in a recent thread). Ideally the pressure exerted by the micrometer on the dial bore gauge is minimal but some of the cheaper gauges I've seen use a nasty looking cast piece thats chromed over on the other side of the feeler tip (the rigid/non-adjustable side) which I've seen people put lines in their bearings.

The inside micrometer I use is a browne and sharpe I got off ebay use for like $200. Its got tips to measure 2.0000-2.5000 and 2.5000-3.0000 which covers 99% of the dimensions I need to check.

Looks like this:



Depth micrometers measure in one direction only . . . inside micrometers measure radially.

Take your crank to a competent machine shop. They will be able to quote you before any work is done.

westcoast1994

Yeah I did pay a bunch. But I bought a brand new steering rack. The original looked too far gone.

I'm not exactly sure what cranks will work. But I was very interested in doing a D17 crank and rods at one point. There is a thread somewhere and it actually seems pretty easy. My friend just scrapped one with a blown head gasket. I wish I would have ripped the crank and rods out.

luis253

http://www.calibration-solutions.co....icrometers.jpg

everyone has there own name for Micrometers that very measuring style