Barefootdan's 280z Build

[Zed Head]

On 4/7/2021 at 3:54 PM, siteunseen said:

I found something similar to what my uncle used off his rear truck hub. Cannot believe I found this. This is 70s/80s redneck engineering. His name was "Uncle Luther". Miss him too.

 

 

Watched your video.  And a day later an ad for this shows up on Yahoo.  Never ever seen this ad before.  Spooky.

https://mooxbuy.com/products/firewood-drill-bit

Edited April 9, 2021 by Zed Head

[siteunseen]

19 hours ago, Zed Head said:

 

Watched your video.  And a day later an ad for this shows up on Yahoo.  Never ever seen this ad before.  Spooky.

https://mooxbuy.com/products/firewood-drill-bit

I wonder what would happen if I watched your video? Couldn't be any worse than Facebook's Marketplace. I'm looking for a used leaf blower, search term I used was "backpack blower". It's like "best head" . 

 

[Barefootdan]

Been a bit since my last update. The head was dropped off at a local machine shop who is familiar with the L28. Head needed shaving, 3 new valves and some new bronze valve seats. Among other work such as full cleaning, shimming of the towers, and seals. I came out just under $700 for the work. More than I was planning (originally tried to stay under $500) but I am glad that they were familiar with the head and knew what to do. Well worth it in my opinion. The head should be done this week and then I will start planning on pulling the block to do the ring job. In my spare time I have pulled mostly everything from the engine bay in prep for painting. I will be getting new master cylinders for both the clutch, brake, and then a new brake booster. One thing I am curious on is the lines. Generally is it okay to reuse the hardlines? For reference the clutch line was connected while the brake lines were open while it sat. 

[grannyknot]

3 hours ago, Barefootdan said:

Generally is it okay to reuse the hardlines?

Usually it's okay, clean them with some brake cleaner and compressed air, some guys have had success with replating  them, these days I just replace them all with new copper/nickle hardlines because I can't stand the thought of the possibility of rust inside.

[Barefootdan]

Wow....I am DEFINITELY going to need to pull the bottom end now. There is no way I can put this crispy clean head on that grimy block....anyways enjoy the pictures! Check out that pitting in Cyl #6 though 😲 Would it be worth it to grind these smooth or is it more hassle than need be for a stock build? 3 new valves, shaving of 8 thousands, and a DEEP clean later:

,.;

[siteunseen]

I'd leave it alone, less is best on cylinder head repairs I say.

What the hell are we looking at here?  I've never seen valves like that but I'm no mechanic.

 

 

 

[siteunseen]

Looks good too! I forgot about the overall.

[EuroDat]

You have done a wonderfull job bringing the engine literally back from the dead.

The workmanship looks good and he shimed the towers, so he knows what needs to be done when you shave the head. I would still have a few questions for the head shop. He replaced three valves (inlets on 5 & 6 and exhaust on 6) with a completly different aftermarket vavle. The form could change your compression ratio. The originals cost $20 each through nissan. Why did he use those after market vavles?

Are you sure he used brons seats? Maybe brons guides? Brons seats don't work well with todays fuel. The L28 changed over to steal alloy seats in the N47 to run unleaded fuel. The lead "lubricated" the valve seats and helped transfer the head. The brons P/N:11098-N4200 and steal alloy P/N:11098-N4210 seats are interchangable. It could be a cost factor that made him just replace what was needed with brons (3x $22) as to replacing all seats (12x $18).

I would not grind the scratches away. Grinding them away will could alter your compression ratio and with the different valve head shape? You can use a scraper to remove the burs, I wouldn't do any more than that.

Looking forward to seeing this project progress.

 

 

[Barefootdan]

Thanks for the kind words @siteunseen & @EuroDat!!

I noticed the difference in valves too, but not until I left. I may give him a ring on monday to see why he chose those. I know it was $10 per valve so its not like I much overall. Maybe he had them in stock already.

I dont believe he used bronze seats. If I recall correctly, the old bronze seats fell out when he was doing the cleaning? I probably took that as "replacing the bronze seats with new bronze seats". But they all definitely look uniform throughout now. The receipt says "SBI SEATS" as parts and "6 INTAKE SEATS" as labor.

I'll leave the pitting as is 🙂 

[EuroDat]

SBI is  a well known valve seat supplier. I think you would have to special order brass inserts. More than likely he used steel alloy, but would be good to check.

If you have braas inserts, you should use an additive to extend the seat life.

Sorry if it sounds like I'm nitpicking, but now he knows exactly what he did. If you call him over a year, it could be a best guess response.

[Zed Head]

Check the rock arm wipe pattern before installing.  If he didn't dress the valve stem tips you might need new lash pads. 

Those three odd valves might cause an imbalance between cylinders.  Combustion chamber volume, as mentioned.  They look more massive also, and might hold heat, or not handle high RPM as well.  

Might be fine, but for $60 it might be worth swapping to stock valves.  I don't have any experience building engines, I just absorb a lot.  They look like lawnmower engine valves to me.  No offense.  Can't find anything similar on the old internet either.

[EuroDat]

Another thing to ask when you contact the head rebuilder. Ask him which model the valves are designed for. If he is a Datsun head specilist he should know the difference in valve stem lengths and probably not an issue. 

The L28 was used over a period of 8 years in the Z & ZX, but with different head combination. The N42 and N47 heads had valves with 2mm longer valve stems. These valves are often used when people shave 2mm of the later P79, P90 or P90a heads. These valves eliminate the need to shim the cam towers.

280Z 75 - 78 & 280ZX 79 to Jun 80 with NA engine had the longer correct valve stems.

280ZX Jul 80 to 83 NA and all torbo engine had shorter valve stems and will need larger lash pads.