L28 or numbers matching L24

[Sky]

Hello,
So i jumped in the deep end and I bought myself a 72 240z with a l28 turbo. This came with the original l24 matching numbers engine in a box.

The existing l28 engine is working and I can drive it around but needs a good amount of work. I think some of the cylinder are worn and I’ve been told it not the most reliable.

My thoughts were to tear down the l24 as it’s not in the car (I can still drive the car while building the engine). rebuild it to make it reliable and give me some more power, stick it back in the car so I have a number matching car.
Then take the l28 rebuild it and stick it in another car. (Maybe another 240z or something else exiting but that’s for another post)

My questions are:
Is this the best idea from a financial point of view? And when I come to see it will buyer care about the matching numbers?
What is the best engine rebuild kit? And how far should I go with the rebuild?
If the cylinders are in good shape should I still re sleeve them?
So many more questions so any advice would be really appreciated!

Thank you in advance,
Sky

 

[uk66fastback]

Sounds interesting … but how original is the rest of the car? RHD or LHD?

If it’s largely original I’d keep it that way - ie rebuild the 2.4 motor and put it back - but that’s just me. There’s no real matching numbers stuff with these cars really - just the engine No. on the plate and the engine itself - save that for the Mustang owners …

 

[Mr.G]

Welcome to the fold.

Why is your L28 not reliable, and how do you know its worn. I would start with a dry and then a wet compression test and decide from there if a rebuild is needed.

Personally I would investigate in getting your L28 running right and just safely storing your L24 for posterity.

Would love to see photos and engine bay pics.

 

[Rob Gaskin]

With these cars a bit more power is usually preferred to an original engine, especially as the engines look the same. If your car has already been changed/modified I suspect it's not the type of pristine and 'original' type of car that would warrant refitting the original engine however without more info that is a guess.

It's good to have the original engine though. What else do you have with it eg carbs, exhaust manifold, intake box etc?

Another option is to modify the L24 but that may be more costly that rebuilding the L28. I took my L24 to 2.8 and L28 valves.

 

[Sky]

Welcome to the fold.

Why is your L28 not reliable, and how do you know its worn. I would start with a dry and then a wet compression test and decide from there if a rebuild is needed.

Personally I would investigate in getting your L28 running right and just safely storing your L24 for posterity.

Would love to see photos and engine bay pics.

Thanks so much for coming back to me!

I blew the head gasket last year and took it to a garage so I didn’t feel comfortable changing it myself.
They changed it for me and being quite new to this I asked them for any advice they have. They said there quite a lot of smoke coming from the top of the engine though the vent. Which is from the gasses escaping from the cylinders I think.

I’ve attached some photos and little back story is it was used in the stats for drag racing, it’s got a single carb and is turbo charged so a bit odd, it used to run so rich that it wouldn’t even ideal, I’ve since turned the carb down so it ideals and runs nicely but was warned by the garage that it was probably not the best idea to go on any long trips in it just yet.
There’s also a lot of wires all over the place which I’m trying to figure which turns out isn’t easy

 

[Sky]

Sounds interesting … but how original is the rest of the car? RHD or LHD?

If it’s largely original I’d keep it that way - ie rebuild the 2.4 motor and put it back - but that’s just me. There’s no real matching numbers stuff with these cars really - just the engine No. on the plate and the engine itself - save that for the Mustang owners …

Hey thanks for responding!
She’s a LHD, from what I can see most things are relatively original with it there new seats and a new steering wheel but I think the rest of the interior is pretty old and thinking original. It sounds like I should just work on the l28 and try get it run in more smoothly?

 

[Robotsan]

Ahh this is @julian 's old car. Still his profile pic! It's also the first Z I saw for sale and the one that made me think maybe I could actually buy one

I'm surprised it was used for drag racing! Looks too tidy for that. But I guess that could've been pre paint job.

There's also an article online about it, can't remember the magazine/website though, but it did detail the rather unorthodox engine build. They suggested it was putting out nigh on 350bhp, so it must be a handful?!

Definitely isn't the most original Z out there, so I think it wouldn't matter what engine is in it, but like Rob said, more power is probably preferable in a less original car. I do see your predicament though, as neither option is going to be cheap.

Best of luck with it.

*Edit* Found the article - https://www.carthrottle.com/post/this-300bhp-datsun-240z-is-a-strange-but-brilliant-rocketship/

 

[Farmer42]

I would stick with the L28 of the compression tests are ok. The smoke is probably valve stem oil seals which are relatively simple to replace. I would also think about replacing the carbs for triple webers or twin SUs to get it to run properly.

Keep the L24 and rebuild it over time or just store it.

 

[jonbills]

whatever you do, get rid of the suck through turbo setup. IMO, it's an inferno in waiting.

 

[Huw]

whatever you do, get rid of the suck through turbo setup. IMO, it's an inferno in waiting.

Second that.

 

[Mr.G]

Thanks for sharing pics.

If it was me I'd do some basic tests to determine health of engine. Whichnwill help determine enxt steps.

I would also find out what has been done by previous owner to lower compression, were dished pistons fitted to the 280Z engine or was lower compression obtained from fitting a ticker headgasket? When they changed the headgasket what did they replace it with? Standard gasket or did they replace it with one of equal thickness? You'd know as it's a special order.

If they've put in a standard gasket and you have standard pistons, I'd go NA. Remove the turbo bits and find some triple weber or dellortos.

If you want to remain turbo, I would suggest going fuel injected and having the car properly mapped and not using the single weber blow through system.

It won't be cheap as you ll need, injectors, ECU and proper mapping.

I can see why you are considering putting the L24 back in but the L28 NA or better still turbo will give you more smiles per hr..