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L20 motor dissasembly method


Curt

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They better not be L16 Pistons, at .75 over (0.030")  they'd measure 83.75mm (3.297") Dish has no part of the issue.

 

Are you sure the block is an L20B?

 

Take a picture of the FRONT of the block and post it.  I am curious as to which  block etc you actually have.

 

Doctor 510  AZ  gearhead@cox.net

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It's an l20b. It's right on the side of the block and I pulled it from a 1980 720. 

HPIM4478_zps9ad2b9cb.jpg

HPIM4480_zpsee2b3c4c.jpg

They should have noticed something was up when it didn't clean out the rust damage.

HPIM4482_zps79790fa9.jpg

The pistons also come all the way to the top of the deck.

HPIM4486_zps49bd92e4.jpg

 

I think Mike should change the title to, huge newb mistake...Always measure and verify. I think I'm going to re ring and bearing the L-18 I have that I know at least ran decent. And wait until I can buy new pistons to salvage this, whatever it turned out to be...

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Ohh good lord. They are 3.3754 not 3.31...  That number had terrible writing. So they are in fact 85.73mm wide. However. They still have way less dish than the L20b pistons. They look like more dish that the L-18 pistons in the other block though.

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Ok, good on the deck height. What about the victor reins gaskets? I read somewhere here they are wider than the felpro. The head is the semi open A87. just fully rebiult with the u20 "c" cam in it. Kinda has a wedge shape in the cylinder. not the kidney bean shape. I'd rather run one of those nismo gaskets but they are hard to find these days. Thanks for the help and the heart attack, lol But really, thanks a lot for your help.

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Ok, so the metal filter in the block under the pcv tube was rusted out to hell. It had huge holes in it and I assumed it is just to prevent splashing.

HPIM4488_zpse8b74978.jpg

Here is the deal, I ordered what I thought was the right replacement part for it but it is made of a cotton type material.

HPIM4490_zps8658b1e8.jpg

I assume this would go in the air cleaner housing from the valve cover vent. My gut feeling is this does not go in place of the metal screen that was in the bottom end. So what exactly can I use down there to replace the screen that was there? Can I leave it screen-less and just put the plate back in?

HPIM4492_zps26abbbfb.jpg

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They are supposed to have a zero deck height.  The pistons look to be L18 which is good since it will give you a bit more compression.  Don't get too hung up on the hone job, more than likely it will run just fine, all other things being OK.  Be sure to use a good FelPro head gasket.

 

Actually 0.45mm below but you can safely run up to 0.3mm above by decking the block.

 

 

 

Ok, so the metal filter in the block under the pcv tube was rusted out to hell. It had huge holes in it and I assumed it is just to prevent splashing.

HPIM4488_zpse8b74978.jpg

Here is the deal, I ordered what I thought was the right replacement part for it but it is made of a cotton type material.

HPIM4490_zps8658b1e8.jpg

I assume this would go in the air cleaner housing from the valve cover vent. My gut feeling is this does not go in place of the metal screen that was in the bottom end. So what exactly can I use down there to replace the screen that was there? Can I leave it screen-less and just put the plate back in?

HPIM4492_zps26abbbfb.jpg

 

You need part number... 11037-21001 under $10 or fold metal flyscreen in a pleated pattern and bolt in with the baffle. I would not run without it or you'll wonder where your oil mileage went.

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Got two more head gaskets. They were nos napa made in japan. Victor reinz from rock auto apparently. One was almost wide enough but still in the chamfer in a few spots. I guess my options are the nismo gasket or the datsport gasket? I remember seeing someone had a post for custom gaskets but I can't find it now. Can anyone chime in on the datsport gasket that has ran it? It's about half the cost of nismo gasket.

I'm hoping this is the correct gasket? http://www.courtesyparts.com/head-gasket-p-622284.html

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the Datsport gasket is 87mm .what Baz told me.

he has 2 types a grafite type like the stock Nissan and a composite type which is cheaper.  These are just common gaskets for the aussie market (made in Japan)for some reason they don't sell them here thru our suppliers. Had mine Fed ex or DHL shipped

Buy a couple to make it worth it and maybe a pakage deal

 

 

somebody said on here a long time ago the beckarnely one was a 87mm but cant confer this or it was a Victor Renz. I wrote it doen but lost my cheatsheet book.  since all my motors are l16s I just use the Felpro but I have one leaky already with only like 10k if that on this head change

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MPORTANT: This product is from Nissan Motorsports. That means this product may be a Genuine Nissan part from a local or overseas market, or it may be an aftermarket part and not a Genuine Nissan part at all.

 

So basically 'ya gits what ya gits'

 

Ive used NAPA L20B head gasket, worked just fine. Back from the edge is fine, at the edge will work and the head/block will draw the heat away. In the cylinder it will get very hot and erode away.

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Alright, thanks guys. It's right at the outer chamfer edge so I think it'll be fine. It was one of the napa gaskets. How do I keep it from shifting around when I put the head on. If it wiggles just a bit parts of the ring slide into the bore more.

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I've got the head on. timing kit on. At tdc the timing plate mark is slightly to the left of the notch in the cam pulley. like halfway.

HPIM4498_zps970a57dd.jpg

It's on pin position 2 and everything is lined up correctly. Is this because the block and head were decked? Should I try and find a pin location that is closer? My gut says it's fine but with the possibility of having L18 pistons in there I don't want to destroy it on startup. 

HPIM4493_zps574a57dd.jpg

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HPIM4498_zps970a57dd.jpg

 

Looks good enough. Each adjustment hole is 4 degrees or about the width of that horizontal etch mark. If you were to adjust back it would be over on the right of the notch. Perfect is the notch just barely to the right of the center of the mark. L18 pistons have nothing to do with where the notch is. At TDC compression the valves are both closed. On exhaust stroke TDC the exhaust valve is only 14 degrees away from being closed and the intake has barely been open for 16 degrees. They are, for all intents, barely off their seats.

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Looking DAMN GOOD!!!!  

Don't forget to pressurize (oil that is) the motor before you start it up.

Valve cover off, spark plugs out, timing set, fuel lines hooked up (OIL WITH SOME ZDDP IN IT IN THE OIL PAN), using a remote starter or screw driver, spin the motor until oil squirts out of the cam lobes.    

Button it up and fire away!!!!

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Sweet, I'll leave it be then. I was going to prime it with the ground down distributor drive shaft trick. I still need to have the flywheel surfaced and get that all squared away so it'll be a bit before it gets fired up. I was thinking of priming the oil sooner rather than later though. 

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  • 1 month later...

Ok, this thing is ready to go back in the truck.

The trans is still in the truck and it was a bitch getting the motor out without the trans connected to it, it would hang up really bad on the center link/oil pan. Is the best way going to be to pull the trans and put the engine and trans in mated together? Thanks for the help...

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