Lash pads

[Linda]

Here’s an idea if you are limited on funds. Maybe pull the whole engine and drop in a 1600 motor.You will be mobile while you decide what to do about the U20. Your tranny will work. 1600 motors are around and rather cheap. With motor in you can finish the body and be driving by summer. Paint looks good!
You mentioned being nineteen, and I thought of “Nineteen Forever“ by Joe Jackson, great tune

Linda

[Gregs672000]

Love you man! Been that 19 year old (a long time ago), only it was with a '73 620 pick up (that started my love of Datsuns!).
Please, tell us more about what you know of this engine. How has it run? Where did it make powder? What Dellorotos do you have? Tell us about the bottom end, etc. We can help you with this engine, so please ask. Also, what is your level of automotive knowledge?

[ryderfmjones21]

These pistons look weird to me..
not stock
Also each piston has a recessed area for the exhaust valve but the dont look machined to me

[ryderfmjones21]

Cylinder are kinda scored. The valve shaped indentations are no bueno.
It’s weird the motor wasn’t a noisy one when it was running.
I wonder if this is why the previous owner gave up on it.

[spyder]

Looks you have a cam timing issue. If the chain is sloppy and loose on the tensioners with a big overlap cam it can slap the pistons until the oil comes up to pressure. Yep, I have the modified "L" keepers with taller surrounds and the taller lash pads to support the Z-196 grind. If you have not changed the keepers and just re-install a new lash pad expect to see this problem reoccur.
Isky used to sell the tall lash pads for the L series engine, that's where I purchased mine. They seem to be about .264.



Solex 50mm bad boy.......

[JT68]

Looks you have a cam timing issue.

That's an understatement. Ryder said it perfectly: valve-piston contact, no-bueno: The valvetrain lost control of the valves.

[Gregs672000]

These are my Arias pistons, machined to "lower" the compression to a calculated 11.7 to 1 (stock is 9.5 to 1). That is the very ragged edge and requires very careful control of ignition timing to run them. You would NOT be able to run yours on 92 pump gas... race fuel only. Very likely your exhaust valves are bent. I'm really sorry, but this has gone from bad to worse.

Pros about your engine: You have some very expensive parts on that motor, specifically the "solex" intake manifold, carbs, forged pistons (anything else, like fancy rods or the 7 quart aluminum oil pan?). You have the 123 distributor which is very nice and would be needed if you run higher than stock compression. The rest of the car looks great, and we're hopeful that it is.

Cons: If those pistons are use able (not cracked or overly damaged) they can be machined some to reduce the compression to a more street happy ratio, but they will need machine work and we don't even know if the cylinder bores need to be bored next size up and if they would then be too small for the block. You'll likely need valves, seats, guides... a complete rebuild. This is not a low budget deal.

Roadsters are cool cars. It may be wise to consider the idea that, if you're going to get into this car, it's going to take a much longer time line and storing it and restoring it over several years is likely. Again, sorry man...

[ryderfmjones21]

I do have a 7qt oil pan and it actually came with 7.5 pound aluminum flywheel (maybe a bit to light...)that according to a ad from 1970 I found was a dealer option. I took that out though because I need to make some sort of wear plate. It’s just aluminum which the clutch will eat up fast.... and possibly a 240 clutch mod?! Also the ring gear is just pressed on so I’ll have to pin it or something. they used to put some kinda coating on it but that wore out quick. I’ll probably put that in when the clutch I have needs a replacement. I find lots of weird things on this car like a machined hood release and someone had made a aluminum alternator bracket. Kinda cool actually but I ended relocating it to the driver side.
The pistons I have don’t use snap rings which is interesting I’ve never seen the “dowel caps”? Not sure what to call them



Cylinder walls are pretty score so I’m looking at a full rebuild. Which now that I think about it I’m okay with. If the motor weren’t shot the car would be road ready!
Knowing that the motor will be built with basically all new parts is better then waiting for something that may or may not go wrong.
Heads already at a shop that has u20 experience. Plan is to do a valve job new rockers and a B cam.

For the bottom end I am going to use some forged pistons and stainless valves from Jim at Datsun restoration products.

The bearings look okay to me no scoring but I’ll have to check it out more in depth.

Crazy week...
Saturday it was just a broken lash pad and Monday it was I have the motor completely out and disassembled! Ugh.
Solvang is definitely out of the question there’s just not enough time unless I either spend some serious cash or cut ever corner in the book...
Neither I want to do ha

[ryderfmjones21]

Got a little happy with the gasket maker whoops..
I’ll take some pictures of the connecting rods and the dowels when I get home.

[ryderfmjones21]

More info on my head.
It’s never been shaved it actually measured to the exact spec.
I’m going to get it machined just because it’s off. Don’t want to have to go back.
The bore has been enlarged it measured between 3.471 to 3.4715
I believe I can use the .060 over ones or Jim’s 3.5 forged ones

[ryderfmjones21]

Please, tell us more about what you know of this engine. How has it run? Where did it make powder? What Dellorotos do you have? Tell us about the bottom end, etc. We can help you with this engine, so please ask. Also, what is your level of automotive knowledge?

It has dellortos dhla 40s it ran ok when it was running but still like poop. It would idle okay but had fuel problems when it was running I sorted that out now.
I have a decent level of knowledge but no experience with the u20. The only motors I’ve done rebuilds on were my motorcycles I have a 1600 that I did a top end on a couple years ago.
My knowledge kinda stopped once it got to the top end geometry but I think I have a decent grasp on the concepts now.

[ryderfmjones21]

Here’s an idea if you are limited on funds. Maybe pull the whole engine and drop in a 1600 motor.You will be mobile while you decide what to do about the U20. Your tranny will work. 1600 motors are around and rather cheap. With motor in you can finish the body and be driving by summer. Paint looks good!
You mentioned being nineteen, and I thought of “Nineteen Forever“ by Joe Jackson, great tune

Linda

To be honest I kinda high jacked my dads ride a few years ago...
His Datsun 1600

Cylinder 4 stopped getting spark last week... my streak of bad luck haha

I don’t mind waiting a few months to get it done. Hopefully my impatience with get my bum moving

[spyder]

Two thoughts. First. don't cut the head, it causes chain slack and retards the cam. What ever you take off can never be reversed. Second, remove the copper lines on the carbs. Prone to breakage!!

[Gregs672000]

OK! Way to jump in there! I'm super glad to hear you're able to move forward with it. You have some cool parts, and I'm excited to hear how this comes out. The 40mm Dellortos will work well. I would be curious what size main ventures (often referred to as chokes) are in it. Shine a light down the throat and look for a number stamped on the leading edge of the choke. A 34 will work but a 36-38 would be better. Nismo offered Teflon buttons instead of circlips for the rods. Don't toss the pistons, they may still have value. You're going to end up with a very nice, higher performance engine. I was lucky as a young new owner to find many of those parts too, most valuable/critical being the intake manifold.

I run 45mm DHLA-C Dellortos, 37m chokes, megajolt programmable crank fired ignition, so I'm happy to make suggestions on jetting and a timing map when you get there if desired. There are several different versions of Dellortos carbs, so looking yours up on the Internet will help you understand the differences.
HAVE FUN!

[spyder]

It won't be inexpensive but you might want to replace the valve seats and install the hardened ones in the head to use with today's gas. The Z-196 cam really starts to "come on" around 4K rpm. You also have to be careful with the cam geometry, with larger lift the wipe areas need to be as centered as possible or the cam could go off the wipe area on the follower. To use that cam you really need to change over to the "L" engine spring keepers so you can use the taller lash pads because the cam is ground down. I don't think you have enough carbs to take advantage of the flow potential the cam has. Most likely sluggish with stock diff gears. The lightweight flywheel will aggravate the low speed performance.

Yes mine is darn quick, I set it up for city driving however, it gets old turning 4k rpm @ 65 mph with 4.88 rear gears if I go on the freeway!