Datsun Roadster Forum-311s.org

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.

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

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

exhaust link

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.

Properly boxed, now that is sturdy.

New motor is in, time to plumb and wire.

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

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...

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

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.

very nice!

Troy, bring it by the shop for a dyno

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

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,

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