New at engine rebuild L16

[Richie]

Hey, I took the head off my L16 and notice cylinder 3 got some scratches in it. I’m wondering what is the max bore I can go?

[datzenmike]

 

 

There might be some faint cross hatch from when the cylinder was honed. This is normal. Vertical lines are not. Does your fingernail catch on the scratch marks?

 

Does it run alright? If it runs well and doesn't burn oil, leave it alone.

 

 

Your L16 is 83mm so you can usually get 0.5mm or 1mm over size pistons and ring set. If you can find stock size L18 pistons you could go all the way out to 85mm. I wouldn't go more than out to 85mm. You could go higher but not worth anything.

[Stoffregen Motorsports]

Yes, the fingernail test. If you can feel them with your fingernail, it's bad. But you may be able to power hone the scratches out (just a couple thousandths). Yes, this increases your piston to wall clearance, but new rings with the gaps adjusted to the new bore size will help.

[DanielC]

It may be difficult to find L-16 pistons, but it is easier to find L-24 pistons.   Same bore size, piston pin height, but with possibly different dishes in them, but a set of six, giving you two unused pistons.

[datzenmike]

The L24 240z pistons are flattop (no dish) so compression would go up (about 9.75) and again you would want in 0.5mm or 1.0mm over size. This assumes that the bore is too scratched to fix.

[Richie]

20 hours ago, datzenmike said:

 

 

There might be some faint cross hatch from when the cylinder was honed. This is normal. Vertical lines are not. Does your fingernail catch on the scratch marks?

 

Does it run alright? If it runs well and doesn't burn oil, leave it alone.

 

 

Your L16 is 83mm so you can usually get 0.5mm or 1mm over size pistons and ring set. If you can find stock size L18 pistons you could go all the way out to 85mm. I wouldn't go more than out to 85mm. You could go higher but not worth anything.

Yea my finger nail catches and it’s vertical lines. From what I know from the guy I bought it from it never leaked oil and the old head gasket I took off showed no leaks. 

[Richie]

https://imgur.com/a/36ku1Ip
 

i didn’t take a photo of cylinder 3 and the vertical scratches but for sure my nail catches. What would you guys do to the block. I’m already having the head rebuilt. 

[datzenmike]

Linky not workie. Always check after posting.

[Richie]

https://imgur.com/a/36ku1Ip
 

this one worked for me 

3 minutes ago, datzenmike said:

Linky not workie. Always check after posting.

 

[datzenmike]

 

I managed to locate this but can't really see much.

 

Did you run the engine? did it run alright?

 

Here's another

 

 

[Richie]

 

3 minutes ago, datzenmike said:

 

I managed to locate this but can't really see much.

 

Did you run the engine? did it run alright?

 

 

yea two years ago I got it running fine no weird noises or leaks at all. It sat in a garage for almost 5 years with no leaks. After I got it started that one time two years ago it didn’t fire up anymore but I found that problem from a faulty wire harness. 

12 minutes ago, datzenmike said:

 

[Richie]

Hey, 

so my L16 cylinder 3 has vertical scratches and my nail catches. I was told on here to bore it out to L18 piston sizes. I found a kit on California Datsun with L18 rebuild kit. What size piston, style and bearing sizes would I get. The shop I’m taking it to said they will bore to the size of the new pistons for me and deck it.  Thanks for the help. Like I said I’m new at engine rebuild and any recommendations would help.
 

https://www.californiadatsun.com/engine-overhaul/510-620-521-l16-l18-l20b-2-0-engine-overhaul-rebuild-master-kit.html

 

[datzenmike]

I don't care much for CD.

 

Do NOT have the block decked. The L16 pistons are already above the deck at TDC.

 

Most of the rebuild kit you don't need. I would keep it to  L18 pistons (I thought were no longer available or hard to get) Used would be ok if in good condition. L18 or L20B rings will also work in them. Rod and main bearings and a gasket kit.

[Richie]

13 minutes ago, datzenmike said:

I don't care much for CD.

 

Do NOT have the block decked. The L16 pistons are already above the deck at TDC.

 

Most of the rebuild kit you don't need. I would keep it to  L18 pistons (I thought were no longer available or hard to get) Used would be ok if in good condition. L18 or L20B rings will also work in them. Rod and main bearings and a gasket kit.

 

 

yea California Datsun screwed me over on a 32/36, but I eventually got it. So tomorrow when it’s done raining I’ll post a pic of the cylinders. The engine ran fine before. But if by the picture you recommend boring to L18 piston size then I’ll go with that. Also why shouldn’t I get it decked? Just out of curiosity not trying to question your method just trying to learn. 

[datzenmike]

Vertical scratches suggest a broken ring and/or ring land.

 

If you have a Weber they are easy to rebuild.

 

Seldom does the deck ever need to be trued up, unlike the aluminum head which can get a little warped. The head and the block are only separated by the crushed gasket thickness between them. The L16 piston rises slightly above the deck and while there is room, unnecessary lowering of the deck should be avoided.... first for the closing of the piston to head clearance and also the added cost of machining.  

[Crashtd420]

37 minutes ago, Richie said:

 

 

yea California Datsun screwed me over on a 32/36, but I eventually got it. So tomorrow when it’s done raining I’ll post a pic of the cylinders. The engine ran fine before. But if by the picture you recommend boring to L18 piston size then I’ll go with that. Also why shouldn’t I get it decked? Just out of curiosity not trying to question your method just trying to learn. 

One thing if you go with L18 pistons that maybe the only rebuild for the motor.... 

I'm not sure the limits of over boring is but there is a limit... you can get pistons at .5mm steps ... I see L16 pistons on ebay... basically stock bore is 83mm... the L18 is 85.. 

Also be aware of how the pistons are kept in place... the stock rod has the pin pressed into it and the piston floats....

Some aftermarket pistons float the piston pin in the rod... and yes you can hone the stock rod to float the pin if necessary....

[datzenmike]

2mm increase is pretty safe, that's 1mm off all the way round the cylinder. I've done a 87mm Z22 block to 89mm. New pistons cost about the same so you could just go 0.5mm and run 0.5mm over size L16 pistons.... but if you can find L18 pistons why not bore it to 85mm. It may take more that one pass to increase 1mm and the machinist may want more for this.

[Richie]

https://www.ebay.com/itm/Piston-Set-w-Rings-STD-L18-L20B-Eng-fits-Datsun-510-620-610-710-720/172530538386?fits=Model%3A510|Make%3ADatsun&hash=item282b9f1792:g:NKEAAOSwhilZYCT-

 

so I found these on eBay. Seem

legit?

[Crashtd420]

24 minutes ago, datzenmike said:

2mm increase is pretty safe, that's 1mm off all the way round the cylinder. I've done a 87mm Z22 block to 89mm. New pistons cost about the same so you could just go 0.5mm and run 0.5mm over size L16 pistons.... but if you can find L18 pistons why not bore it to 85mm. It may take more that one pass to increase 1mm and the machinist may want more for this.

I think 2mm is safe too but I also think it's the max for the L16 block.....

I always wondered why you couldn't bore an L16 out like an L20b to say 87mm,  if they can fit the same head? Bores are technically in the same location..... is it a wall thickness thing?

[datzenmike]

The bore spacing is the same all the way up to the KA engines. An L16 head will bolt to a KA block though not advised.

 

 

To me these look like L20B pistons

 

Don't forget that both the L18 and L20B have the same bore but different dish size. The L18 dish is only 4.36cc while the L20B dish is almost 4 times this amount at 11.36cc. 

 

If these are the exact ones being sold and are L20B pistons they will fit but will drop the compression from 8.43 down to 7.99. I would call that a no no. The smaller  dish for an L18 piston would produce a 8.9 compression.

[Richie]

1 minute ago, datzenmike said:

The bore spacing is the same all the way up to the KA engines. An L16 head will bolt to a KA block though not advised.

 

 

To me these look like L20B pistons

 

Don't forget that both the L18 and L20B have the same bore but different dish size. The L18 dish is only 4.36cc while the L20B dish is almost 4 times this amount at 11.36cc. 

 

If these are the exact ones being sold and are L20B pistons they will fit but will drop the compression from 8.43 down to 7.99. I would call that a no no. The smaller  dish for an L18 piston would produce a 8.9 compression.

Right I remember you said that dish and flat effect compression. When you guys say L16 oversized pistons what size does that mean? I found .75mm piston heads for L16 and it says oversized. 
 

https://www.ebay.com/i/132423426828?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=132423426828&targetid=1068323860310&device=m&mktype=pla&googleloc=9031090&poi=&campaignid=11758056140&mkgroupid=112020220737&rlsatarget=pla-1068323860310&abcId=9300462&merchantid=101677530&gclid=Cj0KCQiAoab_BRCxARIsANMx4S6YZ-MgKPp-qxo4r1dNVhYu4oy48vtuuLtc0JdVu8CSnzPJzccd3akaAgjvEALw_wcB

[Crashtd420]

Basically L16 is 83mm bore

Over size would be usually 

83.5

84

84.5

85mm L18 ....

 

Every .25mm is = approx .010 inch....

So the .75 is as they say .030 over....

 

Those pistons are 83.75mm....

[Crashtd420]

19 minutes ago, Richie said:

Right I remember you said that dish and flat effect compression. When you guys say L16 oversized pistons what size does that mean? I found .75mm piston heads for L16 and it says oversized. 
 

https://www.ebay.com/i/132423426828?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=132423426828&targetid=1068323860310&device=m&mktype=pla&googleloc=9031090&poi=&campaignid=11758056140&mkgroupid=112020220737&rlsatarget=pla-1068323860310&abcId=9300462&merchantid=101677530&gclid=Cj0KCQiAoab_BRCxARIsANMx4S6YZ-MgKPp-qxo4r1dNVhYu4oy48vtuuLtc0JdVu8CSnzPJzccd3akaAgjvEALw_wcB

Those would work....

[Richie]

So they wouldn’t work because in order to remove the scratches I’d have to bore 85mm

11 minutes ago, Crashtd420 said:

Basically L16 is 83mm bore

Over size would be usually 

83.5

84

84.5

85mm L18 ....

 

Every .25mm is = approx .010 inch....

So the .75 is as they say .030 over....

 

Those pistons are 83.75mm....

Or because it just clicked in my head what you mean. So 83mm original bore size. If I get .75mm oversized heads, I bored out .75mm so then the bore size would be 83.75mm

Edited December 29, 2020 by Richie
Correction

[Crashtd420]

Just now, Richie said:

So they wouldn’t work because in order to remove the scratches I’d have to bore 85mm

 

Are you sure? That would be some really deep scratches.... 

If the scratches are that deep you might be better off having a machine shop prebore the block to confirm how far they would have to bore it to clean up the cylinders.... what if they are deeper and the block is useless ...