Seeking wisdom re: L20B or Z22/U67

Engine, Transmission and related drivetrain.
Post Reply
opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 30 Dec 2018 08:51

Hello,

I realize that there have been many discussions about this, but with my limited experience, I am seeking some wisdom from what many of you have already done. In my excitement of building my 710 wagon, I wanted to redo the L20B. I did just that, a while ago. But, as I get closer to putting the car back together, I have been reading about it and listening to a friend chatter about what I did with what I had.

In that excitement and some perhaps some inexperience, I put the L20B back together with a rebuilt U67 head, Shadbolt M445 cam and have a choice of induction between 38mm SUs or 42mm Webers (I want carbs). It's been all buttoned up for some time but I have since come into possession of a Z22 and this has added some things to think about for me. I have read and reread about the compression differences, detonation, how to combine the Z22 with the U67 head etc.

So, to my questions:

1. Would running what I have built with either of the carb setups I have be fine? Or what might be best?
2. Or, should I take the time (while the engines are not in the car) to match the Z22 with the U67 head?

Your thoughts, ideas and input is greatly appreciated as I explore what's possible.

Thanks in advance.

User avatar
Byron510
Moderator
Posts: 12227
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Seeking wisdom re: L20B or Z22/U67

Post by Byron510 » 30 Dec 2018 13:13

The short answer is that you will boost your compression ratio from around 9 to 10-10.5 by placing your U67 head on a Z22 block, which is good for roughly 10 HP. You’ll also increase your stroke by 200ccs, good for roughly another 20HP. The shadbolt 445 increases your usable rev range another 1500 RPM, giving you another 15-20 HP - depending on how high you twist it.

The SUs are certainly more streetable. They have a choke for cold starting, and drive well when in good shape and jetted correctly. But you can’t beat the side drafts for throttle response and tuneability - and noise, love it or hate it! Obviously the side drafts give you better breathing when you twisting the motor for everything it’s worth. So it’s your decision on how you drive the thing.

So from your stock L20B which put may be 90-100 HP to the road, with the 2.2, you end up with 140-150 on the road with the parts above. But really you will gain somewhere between 15-30 HP by installing some combination of what you have on top of a 2.2 over what your already assembled.

I have built many 2.2’s with L20B heads - I love them. I had an absolute torque monster with a 445 using a Webber 32/36 at one point. And I have an EFI one now. I’ve used twin side drafts and twin SU’s, so I’ve felt the difference in them all.

Just sharing my thoughts and experiences.

Byron
Love people and use things,
because the opposite never works.

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 30 Dec 2018 16:16

Thanks Byron! That’s the exact kind of feedback I was looking for. I’ll clean up the Z22 and make it useable...I want the torque for fun! I hope to do some autocrossing as well as cruising in the summer.

What did you decide was the best route for a head gasket? I’ve read that the easiest (therefore most expensive) is the Nismo gasket. Is this really the easiest way? Or do you donit a different way?

Thanks so much!

User avatar
Byron510
Moderator
Posts: 12227
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Seeking wisdom re: L20B or Z22/U67

Post by Byron510 » 31 Dec 2018 00:16

Honestly, I’ve gone the cheap route lately and simpy used a felpro Z22 head gasket and trimmed the front cover section off at the front cover. And I’ve tried multiple attempts at using an L head gasket front section, with silicone sealing the joints. Success rate has been about 50% with no leaks, the feast weaped which drove me nuts! I just swapped the head this summer, simply ran a bead of silicone around the front cover (over deadly clean surfaces) and it was a complete success - no oil leaks. I may continue this route.

I forgot to mention one thing, and that aligning the water jacket holes front the Z22 block up to the L series head. Using a L dearies head gasket, it’s very easy to see the 8x 8mm or 5/16 holes that need to be drilled on the plug side of the block and the trapazoidal hole at the back of the head that will properly flow the necessary water between the two for proper circulation. This has been well documented in the past, and I can confirm that failure to make this correction will result in prematurely scuffed pistons due to overly hot and expanded material at the top of the block, even in simple daily use. Ask how I know!

And of course the same matching holes need to be punched into you nice brand new Z22 head gasket. A decent hole punch and a soft plate of aluminum works well for me.

Last tie bit - are you planning on running this engine hard? If so, enlarging the #2 & 4 main gallery oil feeds to the main bearings and opening up the bearing holes is a good idea. At high RPM, the centrifugal for on the oil can actually over run the supply, rod bearing suffer...
In any case, use the 81-83 Automatic ZX Turbo or KA 86-89 oil pumps. These are high volume, with 5mm taller gears in the pumps - pressure remains the same at 60 psi max.

A few reliability tricks for your build I’ve learned along the way, should you want to gear back into it again.

Byron
Love people and use things,
because the opposite never works.

datzenmike
Supporter
Posts: 5457
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: Seeking wisdom re: L20B or Z22/U67

Post by datzenmike » 31 Dec 2018 09:08

9.84 for a stock Z22 with a 45.2cc open chamber head on a 1.2mm crushed head gasket. More if the head has been milled to flatten it.

I strongly advise putting an 86mm diameter Z22 head gasket on and marking the ring diameter on the head. Now grind away the aluminum closest to the intake and exhaust valves and up to the line, to unshroud them for much better breathing. Make a smooth curve from the valve, out and up the chamber wall.

Image

This is my U67 head I 'built' for use on a Z24 block so it's 89mm across. Yours will be 2mm narrower but you can see that there's lots of room for improvement on the L heads. The valves are very hemmed in on the sides. The point is to allow the air in and out by smoothing the transition..... somewhat like a reverse velocity stack on a side draft. An added benefit is you have lots of leeway with your compression and this will marginally reduce it.

As always put an intake/exhaust manifold gasket on the head and mark the openings and grind away any lip inside and smooth inward for an inch. Now do the same with the two manifolds. When bolted together the two match seamlessly with no lip. Some say to keep the lip but we're talking an extra 200cc of displacement the L head was never designed to flow. I say make the intake to the valve as smooth flowing as possible.


I would try to find a later '78-'80 intake (and the exhaust) that has the coolant lines cast under the runners. The U67 manifolds are co-joined and while this set up will warm the intake in cold weather (often they rust fully open and bake the intake, or they rust closed and do nothing) they certainly do nothing to cool the intake from radiated heat from the exhaust directly below it in hot weather. You can (and I have) drill two 3/8" holes in the U67 head to match the runners on the intake. The outlet, near the front of the carb, must be plumbed into the thermostat by-pass line to the lower rad inlet also. This will allow coolant from two places on the left side of the head to exit and improve circulation and remove heat from around the hot exhaust ports. The biggest benefit is the properly warming and cooling effect on the intake air in cold and hot weather respectively. The engine will remain in better tune when the intake air is kept withing a narrower temperature range.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 01 Jan 2019 09:04

Thanks Mike. Happy New Year to you!
I have the Z22 almost apart and then I will take it in to have it dunked to be cleaned. It's been sitting a long time. Thanks for the tip about unshrouding the valves. That picture explains it perfectly. (I have been following your thread on Ratsun as well). I had planned on gasket matching the ports as well, it is on my list. I've read through plenty of threads and checked part numbers, but I think I'll ask if the bearing sizes are the same in the L20B crank as on the Z22 crank? When I check part numbers they seem to match.

Thanks Byron. Happy New Year to you!
My plan is to drive the car with some spirit, some highway driving and autocrossing. I built it to drive the damn thing. (I'm glad it's not perfect so I won't have to worry about driving it). I will take all of the advice I can get. It's been a while since if gotten excited about the project again.

All the best in the New Year to all of you!

Todd

User avatar
defdes
Supporter
Posts: 5047
Joined: 12 May 2005 14:45
Location: Vermont

Re: Seeking wisdom re: L20B or Z22/U67

Post by defdes » 01 Jan 2019 09:22

I had the LZ 2.2 fin the first iteration of my 510, they don't rev high but lots of torque.
Mine sounded great too.
https://www.youtube.com/watch?v=QzqBaLhxqUc

datzenmike
Supporter
Posts: 5457
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: Seeking wisdom re: L20B or Z22/U67

Post by datzenmike » 01 Jan 2019 14:55

The rods and the mains on my Z24 project are from an L20B

L16/18/20B/Z20 Z22 Z24 and both KAs use the same rod bearings.
L20B/Z20/Z22/Z24 all use the same mains. L16/18 mains will only fit themselves. KA mains are same diameter as the L20B and up but are narrower than a rod bearing. L series mains are SO over build

L on left KA on right
Image

The old Z24 rods and mains were good but I had new Federal Mogul ones that would likely never get used and just rotated them out and new ones in without the need to remove the crank. Rods were even easier.

I also used the Z timing cover under the L series head rather than trying to come up with an L20B cover lengthened 3/4" because it's shorter. The L head actually fits and seals on a Z timing cover and all I needed was a small amount of JB weld filed down flat in one corner to widen the gasket contact patch. It would work without it but just extra insurance. The Z24 timing chain was stupid easy to lengthen 4 links. I did not use the Mercedes master links to do this. The Z22 would only need 2 links? added to fit the L cam. I chamfered and ground away casting flash at the oil entry into the oil pump. It makes a sloppy ragged 90 degree bend, thought I would smooth it some.
defdes wrote:
01 Jan 2019 09:22
I had the LZ 2.2 fin the first iteration of my 510, they don't rev high but lots of torque.
Red line on stock internals...

L20B/Z20 86mm stroke......... 7K
Z22 92mm stroke................ 6.5K
Z24/KA 96mm stroke........... 6.25K

To compare apples to apples... with an L head on the Z22/24.... I would take the lower revving Z24. That's a huge stroke increase from the L20B to the Z22 and then the Z24. A strict 6K red line is fine with me. I found a torque rating for the Z24 once for 130 ft lbs @2,800. A better breathing L head can only increase this across the board. The Z22 can't be that far this in torque and I haven't even factored in 3-6% more from the compression increase..
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 01 Jan 2019 20:03

I love torque. Makes for fun driving. Once I get the car running I’ll monkey with the hearing in the rear end as well.

Another question...with the high flow pump from a KA, is there any need for a spray bar with the M445? Or is that overkill?

Todd

datzenmike
Supporter
Posts: 5457
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: Seeking wisdom re: L20B or Z22/U67

Post by datzenmike » 01 Jan 2019 20:46

Not strictly necessary but if you want to there's no harm. I have an oil cooler on my L20B it doesn't need it but I had the 280zx parts and a Ford cooler for free. It only cost about $50 for the special hose.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 06 Jan 2019 09:51

Thanks, Mike.

So, how do you get the dipstick guide out of the L20B block? I do not want to break anything in the process? Anyone have an idea of how large the hole is for that? I’d like to make sure I have a bit ready to drill thw new hole with.

Todd

datzenmike
Supporter
Posts: 5457
Joined: 24 May 2006 12:40
Location: Van. Isle.

Re: Seeking wisdom re: L20B or Z22/U67

Post by datzenmike » 06 Jan 2019 18:44

The Z22 block has the dipstick on the left rear of the block, basically opposite of the L20B. Just live with it and check the oil when the engine is cold. :lol:
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

User avatar
Byron510
Moderator
Posts: 12227
Joined: 01 Jul 2003 23:06
Location: Maple Ridge, BC

Re: Seeking wisdom re: L20B or Z22/U67

Post by Byron510 » 07 Jan 2019 06:50

Removing the dipstick tubes without harming them is really difficult. But they are not expensive new from Nissan. In the past I have just bought new ones and drilled out the boss on the pass side of the Z22 block, then removed and plugged the dip stick tube on the drivers side of the block.

The Z22 blocks have three oil dip stick bosses, the one that matches the L20B on the pass side, and then two more on the drivers side - the fwd one used on 2WD PU’s and all pass car applications and the rear boss was used on the 4x4PU’s as they had a really strange offset oil pan to clear the front diff in that application.

Byron
Love people and use things,
because the opposite never works.

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 09 Jan 2019 19:28

Well, I called Nissan today. “No longer available” is what I got for the dipstick tube and dipstick.

I noticed all the bosses and read about some blocks having 2 dipsticks. Interesting to see all the variants that were used for different applications.

opalbeetle
Posts: 18
Joined: 14 Sep 2009 06:08
Location: near Winnipeg, Manitoba, Canada

Re: Seeking wisdom re: L20B or Z22/U67

Post by opalbeetle » 11 Apr 2019 07:01

So, I have laid out the L20B head gasket and marked the new holes to be drilled in the block. I have read as many of the posts that I could find about doing this and I will have time this weekend to tackle it. I'm cautiously nervous...

I will post pictures when I am done.

Thanks very much for the feedback and the advice here. I really appreciate it!

Post Reply