Pulling the L20b

[troyt]

Some are familiar with my L20b powered '69 SRL311. The motor is just a stock one out of a mid-70's pickup, but the old swap was done fairly well. Well it's time to pull it out, clean up the frame mods, and install a LZ23 that I've put together with a buddy. It's a Z22 short block (basically the same as a L20b block) bored to fit KA24 pistons, with a L4 head. I test fit a new header and a set of Mikuni 44s today before pulling the old motor just to make sure everything will fit. Looks good, but I was planning a 2" exhaust and the stock pipes are 1 3/4" and appear to barely fit through the x-frame holes for them.

So has anyone fit 2" midpipes through the frame? What mods were needed?
Thanks.

[Nissanman]

I'm sure Michael Spreadbury [Spriso on this Forum] has experience in this department

[fj20spl311]

2" pipe fits, sometimes its necessary to oval the pipe.
JT68 makes a nice 2" stainless steel exhaust.

exhaust link

[RCMike]

Kevin does this with the SR swaps. Depending on the size of the expected exhaust, the correct size tube is inserted.. The x retains the stability of the chassis, and once the tubing is in, welded, and the plates are back on, it is extremely strong.

Screen Shot 2019-02-27 at 9.58.29 PM.png

[FergO2k]

Properly boxed, now that is sturdy.

[troyt]

New motor is in, time to plumb and wire.

[greydog]

Mind if I ask a few questions?
If I understand correctly, you used a Z22 block, crank and rods with KA24 pistons in the short block. Then put an L head on the short block. Correct?
I believe the Z24 block is taller than the other Z engines, is that why the Z22? Did you use the L head to keep the exhaust in more/less stock position or because of availability of parts ore because you have a few in the corner or ???
Any idea what sort of hp/torque numbers you are expecting?
Will the Zseries engines accept the L transmissions from the Z cars?
Dan

[troyt]

Yes, the Z22 block is essentially the same as a L20b block, everything bolts right up. The Z24 is indeed taller. The L4 head bolts right up with a few small mods at the head/water pump interface. I have lots of L4/6 performance parts around from racing Zs, 510s, and 710s so that's what led me down this path. And the Z gearboxes (got extras of those too) bolt right up as well.
I've never built this combo before so not sure of the dyno numbers, but I'll post after I get everything done. I'm using an Isky L-475 cam, a u67 head, about 10:1 CR, shorty header, and 34 chokes in the 44s. Hoping for lots of torque...

[greydog]

Sweet! Very much a hot rod in the old sense of the word.
Please keep us posted I will be very interested to see how it turns out.

Thanks
Dan

[Gregs672000]

There used to be such a combo that I saw at Shasta back when it was the combined Datsun show and they ran the autocross on the mountain. Tons of power, 2.4liter torque.

[GeoffM]

very nice!

[Alvin]

Troy, bring it by the shop for a dyno

[troyt]

That’s my plan. The ZCG dyno has seen most of my Datsuns.

[Rutty]

I'll be interested to hear how the new engine pulls. I have an L20b in my '68 1600. Is it possible to do this mod with the L20b block and just swap out the pistons, crank, and connecting rods?

Thanks,

[2mAn]

Very exciting! Cant wait to see what it puts down!