Progress on engine.

[Zak's Z]

So I broke off 3 head bolts getting the head off...but they came out with some heat and vice grips...whew. Then I cleaned all the old gasket off and looked at the piston tops. #6 is pretty badly pitted, the rest look pretty smooth. I guess I have to replace it. While I do that, I'm going to replace the rings and the main bearings. The journal/connecting rod bearings appear very new, so Im going to keep those.

Theres some bolts I didn't label that I'm going to ask for some help on later , I thought we got them all but then found a few sets on the floor and now now I can't remember where they're from.

[Nissanman]

I wouldn't bother replacing it, unless you really want to.

For new rings you will have to get the bores honed.

The machinist will determine if the bores are OK or you need to go to oversize pistons.

If the block requires a rebore then of course, you will be up for 6 new pistons:ermm:

If you intend to do the main bearing set, then do the big ends as well.

Replace the whole deal, they are not expensive and it is good insurance:paranoid:

Let the machinist see all the old parts and the crank shaft.

Unless you have the necessary expertise to inspect and repair these bits, let a competent Machine Shop do the work and provide the correct new parts for re-assembly.

The Shop may want to linish the bearing journals to make them ideal for a fresh set of bearing shells.

[Walter Moore]

I will chime in here to echo Nissanman. I have TRIED to rebuild a number of engines in my life, and the only times that I was successful were when I took the whole mess of parts to a machine shop (or two...) and had them tell me what was needed. Even if the cylinders only need honed, unless you have done that many times and know exactly how it is done, I still recommend that you let the shop do the work. Every time that I have tried to hone cylinders myself, I have failed. I am not alone in that experience either.

You may be a lot better than I am at rebuilding engines, many people are. But, in my experience the do it your self part is best left to taking the engine apart, and putting the reconditioned parts back together.

Just my opinion.

[Zak's Z]

Thanks for the advice guys. This is my first attempt at it. Im getting help from someone who has done it all before though. I had planned on taking the head in to a shop, but so far was planning to do the honing and replacing the rings and bearings ourselves.

Why is it that the honing is'nt as easy at it sounds, and what are the problems with it? I'm only asking these questions because I don't know, thanks for bearing with me.

I'd rather avoid getting 6 new pistons...why is it that you wouldnt replace the pitted one, NISSANMAN??

[Nissanman]

The trick is, if you want to call it that, with honing, is to move the machine up and down the bore at the right rate to cause the correct crosshatch pattern on the bore surface.

Also the grit used is dependant on the type of rings to be fitted.

One reference I have [HP Books, "How to Rebuild Your NISSAN/DATSUN OHC Engine" by Tom Monroe] says,

"If plain or chrome rings are used, the bore should be finish-honed with a 280-grit stone.

A 400-grit stone is good for moly rings.

A 30deg. crosshatch is suitable for all ring types."

I'm sure it is not hard to do, I just prefer, and advise others, to have a competent Shop do the job, just my input.

That piston in my opinion has seen some detonation, I reckon that is what caused the pitting.

Or maybe a little coolant leak injecting some water into #6.

Unless the ring lands are damaged, I don't see anything wrong with re-using it:ermm:

Your choice of course.

The attachment shows a piston I removed from a Nissan N14 Pulsar GTiR, son of Godzilla, with an SR20DET engine.

The result of uncontrolled boost:finger:

Now THAT is detonation damage:dead::dead:

[Zak's Z]

Thanks for the info, NISSANMAN. I took the piston into the local datsun mechanic, and he advised also to just leave it. I got a honing tool, but it has 220 grit stones. Ill have to find finer stones.

THAT is damaged, I don't feel so bad now.

[Zak's Z]

Tonight I used a ridge reamer to get rid of the slight ridges at the top of the cylinders. The first one I 'borrowed' from Canadian Tire was no good, the cutting surface was chipped, so I returned it then went to a different store and got one that was new.

I leveled the top with the cylinder top, making sure the cutting surface was under the ridge, and gave each five turns. After that I couldnt feel the ridges, and I suppose thats the what it's supposed to do. There was a very small amount of shavings I wiped off the blade after each one.

Tomorrow I'm going to hone the cylinders if I can find the finer stones first.

[Zak's Z]

Tonight we honed the cylinders with 320 grit. Any slight ridges are gone now and it feels uniform. Cylinder 1 had to be hit with 220 then 320 because there was a slight rust ring from sitting.

Then we sprayed it all out and brushed out the bottom. I'm pleased with the fact that theres nothing I can observe that went wrong. That will be left to see, of course. I didnt do it, I left this part all to someone more skilled than I am. Didnt want to risk 'learning' on it because it's my baby and I sure dont wanna have to pull the motor after a while to fix my mistakes.

Tomorrow we clean the pistons and replace the rings and bearings.

[Zak's Z]

We cleaned the pistons, installed new rings, new connecting rod bearings and started to put the short block back together.

Next is to bring the head to a shop and clean up the front pieces.