Multiple L20B’s street build

[Gp620Rat]

I looked in those “how to“ books, and it does NOT spell out what we are talking about. I will need to check the FSM.

[Stoffregen Motorsports]

Ok, I didn't read through, well really any of the replies, but I do have time for a quick reply.

 

Selling engines is going to be tricky. Engine builders take years to establish a reputation, and it comes with a sort of guarantee that they know what they are doing. So this being your first time, doesn't matter what your skill level, everything has a learning curve.

 

Down to the nitty gritty.

 

Depending on who you are selling to and what these motors will be used for...you know what, screw that. Let's stick to what I would do with these parts.

 

I would maximize the bore on each motor you build. Any L20B block can be bored to 89mm or even larger, but going to 89mm or more requires that the machinist is really good. He/she will need to measure the cylinder wall thickness. If you can get 89mm out of these blocks, then build a "2200". The books commonly refer to this as a 2150, but to be clear, these are 89mm bore with L20B cranks. Long rod motors will have the best power curve and rev potential. The best of both worlds, so I would either find some N85 rods or get some aftermarket 6" rods. Use them with cut down KA24DE pistons (with the dish) and combine them with whatever cylinder head brings the CR to around 10:1. You can go higher if you have bigger cam, but most street guys will be better off with 10:1. Race guys won't be interested unless you're going all in on the process. Nitriding, lightening, polishing, blueprinting, forged pistons, etc. So anything over 10:1 is really narrowing the resale market.

 

Most peanut heads will be too small for the 2200 and will require that the chambers be opened up. The side benefit of opening the chambers to match the bore is that you are also unshrouding the valves. The ports should get some attention, but at the very least, some grinding and smoothing in the valve bowls along with blending in the seats is easy power.

 

I can't remember exactly, but I think L28 valves are longer than L4 valves. If that's the case, it may be less expensive to install custom big valves. Hard seats, new guides, and springs to match the cam. Someone capable of setting up proper rocker geometry should make the lash pad selection. I have no idea what cams cost these days, but I just had a conversation with Dave Rebello about putting our band back together and we discussed the cost of cylinder head work and parts. This isn't apples to apples, but he said the valvetrain for our race motors would be in the $700 range. I believe he was talking about cam, valves, springs, retainers, keepers, etc. Everything involved in building a good race head. A good street head won't need all of that, but I'd expect to spend $500 or more on a properly set up valvetrain and cam.

 

The L18 blocks are being used in vintage racing these days, especially if it has not been bored and isn't cracked. I'd try to sell that block. If it has been bored, I'd build a "1900" which is an 87mm bore, L16 rods and an L18 crank. Top that off with a peanut head and a mild cam and a DGV Weber, and you're good for about 135hp. Literally the perfect engine for a fun street car. Not so much that it needs constant tinkering, but fast enough to get the occasional second gear scratch. Even if the block is cracked (which was common on L18s) it can be repaired. I know 'cause I've done it.

 

In a nutshell, you're trying to learn in a few weeks what it took Honsowetz a decade to learn. I'd rely heavily on those two books if you want to be safe. I'm happy to help where needed, but I'm not good for part numbers or actual specs (it's been over 20 years since I worked for Dave), but I can lend some building support and advice. PM me for my cell or email.

 

 

[Stoffregen Motorsports]

Oh, I forgot to mention. Re- the books. The info in there is old. I mean really old. The info on bottom ends is mostly accurate. Same for the head, valves, porting, etc, but when it comes to cams...I'd talk to someone still building these motors. Someone who has cam profiles of their own that are not listed in the books.

[banzai510(hainz)]

Lotsof L20s have cracks between the block water ports going to the head. Look at the center ones. this is on the block.  These are on running engines. I had 2 L20s go in shop cause one guy would not warentee his work with the crack when he magnafluxed the block. Was it enought to keep stock and on a running car. I will assume yes. But I scapped it. Used the other I had.

 

I myself if I would do over again

is a best stock L20 block stock pistons dish with closed chamber head. I would have the ports matchport to the Datsun Comp intake manifold that I had at the time. 1.5inch

get a mid range type cam  475 -490 lift duration 260 270 280 290 duration.  valve train of coarse

Dual Mikinis

Bolt it together and just run it

 

anything with machine shop will cost $$$$$$$$   for minor gains

 

[datzenmike]

 I bet many running L series blocks have cracks around water jacket holes and even into the head bolt holes. So what, water can't go anywhere. This tells me that any stress was relieved by the crack.... it's not like the crack will continue till the block splits in two. Besides! they are running and no problems.

 

 

[Stoffregen Motorsports]

Cracks around the head bolt hole will eventually lead to a rusted bolt and/or a stripped thread. But, I have repaired the crack by drilling and tapping two holes, one on either side of the head bolt hole, on the outside of the block. Then counterbore the outer portion of the hole and bolt it together. Essentially clamping the bolt hole shut.

 

We used to call it a frankenblock.

[Gp620Rat]

Banzai, Stoffregen- thanks for the great information. It all makes perfect sense. You are correct about trusted engine builders vs. newbies. Everyone has to start somewhere. I would not be doing anything too exotic, and I know that even that doesn’t matter; the devil is in the details and the final product. For this reason, I would like to be very careful, detailed, methodical, and enlist all of the best advice prior to doing anything at all. 

[Gp620Rat]

Banzai, Stoffregen- thanks for the great information. It all makes perfect sense. You are correct about trusted engine builders vs. newbies. Everyone has to start somewhere. I would not be doing anything too exotic, and I know that even that doesn’t matter; the devil is in the details and the final product. For this reason, I would like to be very careful, detailed, methodical, and enlist all of the best advice prior to doing anything at all. 

[Gp620Rat]

I will definitely check the blocks for the cracks that you mentioned.

 

I also have two crankshafts that are sitting in boxes. Pretty nice shape.

 

U60 is what is printed on one and U6040 on the other.

 

Average crankshaft? Anything special?

[datzenmike]

U60s were L20B and Z20 crankshafts. There is a 12201-U6080  crankshaft on the '80 720 truck. The '80' is the distinction number. '80' is for material so something changed in the metal. Still interchangeable.

[Gp620Rat]

Ok, more great info. Thanks 

[datzenmike]

I forgot that there was a change in the L20B block in or around '79-ish. Nothing drastic but most noticeable was the raised boss under the oil filter now has four tapped holes spaced around it. This block was also used for the Z20 engine but the engine ID was moved to the left center to edge and was visible between the two pairs of Z series exhaust pipes and the dip stick moved also to the left rear. It's the same block as the Z22 but cast with larger cylinders. Outwardly it's the same as the Z24 but 2cm taller at the very top deck and there is more room for the larger stroke Z24 crankshaft to fit inside.

[Gp620Rat]

YOU are a very sick man Datzenmike, but I love it! Great information, and useful! When I get home on Wednesday, I will take this information to the shop and compare it to what I have.

[Stoffregen Motorsports]

5 hours ago, datzenmike said:

I forgot that there was a change in the L20B block in or around '79-ish. Nothing drastic but most noticeable was the raised boss under the oil filter now has four tapped holes spaced around it. This block was also used for the Z20 engine but the engine ID was moved to the left center to edge and was visible between the two pairs of Z series exhaust pipes and the dip stick moved also to the left rear. It's the same block as the Z22 but cast with larger cylinders. Outwardly it's the same as the Z24 but 2cm taller at the very top deck and there is more room for the larger stroke Z24 crankshaft to fit inside.

It is almost the same as a Z22, but not quite. The cooling passages around the cylinders were different. The Z22 used steam ports between the cylinders that can be accidentally bored into when doing a major overbore.

[Stoffregen Motorsports]

My guess is that the material was downgraded on the later cranks, but that's merely speculation.

 

The only other difference I know of on the L20B blocks was cylinder wall thickness. It is my understanding that the very early L20B blocks were not as thick in the cylinders. This may or may not coincide with the M1 vs M2 casting on the blocks.

 

Not a lot of help there...

[datzenmike]

My Z24 is an M3. I pulled from an '84 but once apart the flywheel said D21 in yellow wrecking yard crayon so originally Z24i late '80s. I have no idea....

 

[Stoffregen Motorsports]

When you start digging deep, there are more questions than answers.

[Gp620Rat]

I’ll be home tomorrow, diving back into the project. You guys have given me a great amount information to consider. And I will be changing my plans, and there will most likely be parts for sale in the not too distant future.

[Slow Loris]

@datzenmike I see you have the fruiting body of a Nissan air cleaner fungus growing wild in your yard. I have that problem too. You can dig them up all you want, but they always come back.

On 4/15/2024 at 1:48 PM, datzenmike said:

My Z24 is an M3. I pulled from an '84 but once apart the flywheel said D21 in yellow wrecking yard crayon so originally Z24i late '80s. I have no idea....

 

 

[Stoffregen Motorsports]

5 hours ago, Gp620Rat said:

I’ll be home tomorrow, diving back into the project. You guys have given me a great amount information to consider. And I will be changing my plans, and there will most likely be parts for sale in the not too distant future.

If you want to sell the L18 block and crank, let me know.

[Gp620Rat]

I’ll definitely let you know. I’ve had several offers on the L18 already… still sorting through it all… i’ll be back at it tomorrow afternoon.

[iceman510]

18 hours ago, Stoffregen Motorsports said:

If you want to sell the L18 block and crank, let me know.

 

Hey, hey, hey, I asked him first.  🤣

[Gp620Rat]

…true.

[Stoffregen Motorsports]

Early bird, and all that.

[Gp620Rat]

Sorry for the long delay in getting back to this thread. I actually had to go to work and earn some money; got home and went directly to work on the 2 loose  crankshafts, and the 4 loose camshafts that I had - they’re all cleaned up now and Looking good.
 

It turns out that the A87 head that I have, is an SSS, with the peanut combustion chambers, larger valves, and large smooth intakes ports. Question: Did this originally come on an L18 or an L20B? 

I also have three 210 heads; one of which has some very large/smooth  intake ports and some nice unshrouding work on the valves; would this have been only for the L16, or has this been reworked for something else? I guess the question is: why would anybody bother with a 210 head? Or is this somehow special?

 

 

Edited April 26 by Gp620Rat
Easier readability