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L20b Cody's Goon


Patcon

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Gonna start this thread for Cody's motor build. We have 2 - L20b blocks. They were missing the timing covers. The one we started with was the better looking of the two. The second one looks like it has sat outside for a while. The crank snout on the worse one is really rusted.

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So I bought the 6" inch "long" rods from Nissan. I spoke to Dave Rebello about a year ago and he recommended I get the Z20 rods. I've had these for about a year. Evidently these can be hard to get in reasonably closely weighted sets. 152.45mm rods

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So the plan for right now is to build the long block and move the current head and head studs over to it. The current L16 head has been freshly redone.

Then when Cody has saved up some money we will select a head to send to Dave and have him work it, the cam and all the valve train up. Then swap it on....

We have 5-6 heads to choose from. I will need help from Dave to pick the right direction

This is the block we're working with

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2 cylinders are ugly! And 2 look pretty good. This was why we could rotate the engine. Even with a BFH.

 

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These corroded bores shouldn't be an issue because we're punching to 89mm. This block and crank measures to be uncut and untutrned

 

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Here are the rods and pistons. None of these will be reused

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Here is the crank. Complete with @Captain Obvious s specially fabricated turning tool

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When we talked to Dave last night we came up with a loose plan. We are gonna build a 2150cc motor. He didn't see a reason to try to go to the 2360cc motor.

So we will use the Z20 rods and some KA24DE pistons cut down.

Rebello will supply the pistons but I may need him to help with the machine work too.

I want to be able to run AC so that means a double row main pulley.

Dave said the 240z water pump will fit in the L20 timing cover. I will verify that this weekend. We will have to adjust the alternator to line up but it evidently doesn't take a lot to accomplish.

He also recommended running a lighter flywheel. He use to get the 12#ers from Nissan I believe. I found one at one of the vendors that is a 12# Z flywheel (Zcardepot). I believe it will fit but will verify this weekend.

We are looking to make 185-200 Hp in the finished motor. We will run the SU's we currently have to start with. Might switch to an EFI system at some point.

 

Edited by Patcon
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The engine looks like its been out in the elements for some time.

The clutch should not be an issue because you are running the 240Z flywheel and a 280ZX transmission.

Is this the motor I sent yhe intake for? If you plan to go efi, that is.

Look like a fun build.

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Flywheel is fine. A 225 mm clutch penalty is extra weight over the 200mm version.

Water pump fits front cover fine, BUT the pulley groove position is not the same as the L20 pulley. You can use a Z pulley if you also use a Z damper to get the grove in the same plane. Then you have to play with the alternator pulley position as well.

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8 hours ago, EuroDat said:

The engine looks like its been out in the elements for some time.

The clutch should not be an issue because you are running the 240Z flywheel and a 280ZX transmission.

Is this the motor I sent yhe intake for? If you plan to go efi, that is.

Look like a fun build.

Yes, I had considered using that EFI when we ditch the carbs. Provided it will flow enough air. I might have it extruded honed.

What motor was it off of again?

8 hours ago, zKars said:

Flywheel is fine. A 225 mm clutch penalty is extra weight over the 200mm version.

Water pump fits front cover fine, BUT the pulley groove position is not the same as the L20 pulley. You can use a Z pulley if you also use a Z damper to get the grove in the same plane. Then you have to play with the alternator pulley position as well.

Good point on the heavier clutch but we'll be making more power so a larger surface area seems to make sense. I plan on using a lighter flywheel so the net weight should be better. I will run a two row main pulley so we can run AC in the car. We have a factory AC setup when we get to it. Dave put us onto all of this when I told him I wanted to run AC. He mentioned we would have to move the alternator to make it all line up.

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5 hours ago, Patcon said:

Yes, I had considered using that EFI when we ditch the carbs. Provided it will flow enough air. I might have it extruded honed.

What motor was it off of again?

It came off a Datsun Silvia s110 (180SX) 1981 with the L18E engine. It may be on the smallist side.

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  • 3 months later...

I think I finally have pistons settled and on order so hopefully those don't take too long. We had to select the final head we'll use and I had to CC the combustion chambers to know what cut to make on the pistons

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  • 9 months later...

That black looks awful good!

I wound up using Pontiac blue on my 240z's block. A lighter color than Datsun Spirit but closer to the OEM spray i found on my car's motor mounts and oversprayed oil pan. There were other places i can't recall right now? 

 

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I sprayed Chrysler Corp Blue engine enamel on a couple of pieces. I’ve read that it’s supposed to be close but I’m not sure.

To me it doesn’t look like it has enough green in it, but if you google the color some do look greener.

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Sent from my iPhone using Tapatalk

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Nice block, only the freeze plug just on the right of the oilfilter is a bit outside it's hole.. normally they are just in the hole with the edge of the lid IN the hole.. On a L24-28 they have a edge were the lid sort of clicks in..?  I always use a bit of sealer. (don't know these brass ones i use steel ones with a sort of 85 degrees edge. they catch the edge in the holes..  if you know what the ... i mean haha)

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  • 1 month later...

So I have a question. I have heard that the rod bearings can lack sufficient oil because one main bearing feeds two rod bearings. There was a hack I came across to rebore the galley feeding the main larger. They suggested 1/4" but it looks pretty close to that. Thoughts??

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Considering only the math, increasing the oil passage diameter from 0.239" to 0.250" would increase the cross-section by just under 10%.  I suppose that's worthwhile, but only a Datsun engine expert would know.  It would seem to be a lot of expense for a street-use-only engine.  Have you checked Tom H's book, 'How to Modify your Nissan & Datsun OHC Engine'?

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I have the book but have not checked it. I probably should.

I thought I would call Rebello too for his thought, since I need a recommendation on a head gasket too. I'm not sure the standard L20b gasket has a big enough fire ring to cover our punched out cylinders

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So spoke to Rebello

We need to use the head gasket from  a Z24. It will need some modification to provide all the water access ports.

On another point, should we Glyptol or not? Is it worth it on a motor that is not an all out effort?

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20 hours ago, Patcon said:

 

On another point, should we Glyptol or not? Is it worth it on a motor that is not an all out effort?

Other than on a race engine it's probably just a feel good thing but nothing wrong with that. That is what these cars are all about.

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So i went to my local paint shop and had some single stage made up to match an alternator bracket that still had some factory blue on it. Cody got the block all taped up last weekend but ti was too cold. S o I sprayed it this weekend.

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It's much darker than it looks in the sunlight. Much more like the paint in the can looks. He is planning on working on the rotating assembly next weekend

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  • 2 months later...

So we had to rework the end of the oil galleys. The holes we had drilled and tapped weren't big enough for a 3/8 plug. So I found a 9/16 bit; it called for 27/64 and we drilled them again and tapped them. You have to drill them and tap them pretty deep so the plug will go in flush. You can see one of the feed holes in the threading. the plug doesn't actually go in that far. We measured for clearance.20220611_150726_resized.jpg

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