Rebuilding L28 - which way to go?

[240ZMan]

I'm getting ready to rebuild my L28 and need some advice from the group...

Current setup:

Block: from '80 ZX

Head: N42

Cam: mild performance grind (will probably upgrade to more agressive this summer)

Fuel delivery: Weber DGVs

Exhaust: 6:1 header + 2 1/2" pipe

Pistons: flat tops from 81-83 ZX

Option 1: Bore block to next size and replace pistons

Option 2: Use an L26 block and bore it out to stock L28 size and reuse existing pistons. This was recommended to me by a local Z specialist. I can get an L26 block from him for $100.

As I see it without having fully priced everything out yet, the differnce in cost between the 2 options is probably not more than $150 with option 2 being the cheaper route.

I'm more concerned with what is the best from a reliability and perfromance point of view vs. cost. I'd really like to find an N54 block from a later (81-83) ZX, but around here there aren't any left. Will the L26 bored out to 2.8l be as strong as the L28? That's really my biggest concern.

BTW, it's a '73 240 driven hard as weekend car with several track days per year.

[SteveK]

IMHO

To me it depends on whether you are building for power or just because you need a freshen up.

If it is the former then first off dump those DGV's they are NOT performance carbs, I know they are expensive but a set of well built SU's will perform much better.

Do that and you'll think you have a 3 litre in.

[AChev]

I am just curious where you got your prices from. Boring out the block and putting in larger pistons will cost much more than $250. I don't know if you have some really special deals, but the bore alone will cost a hefty amount, and so will new pistons. Doing a rough full price estimate should help with the decision making a little more

[ZSaint]

"Option 2: Use an L26 block and bore it out to stock L28 size and reuse existing pistons. This was recommended to me by a local Z specialist. I can get an L26 block from him for $100."

What does "reuse existing pistons" mean? You have a set of these 280 pistons so all you need to do is bore out the 260 block? Or??

I think you should keep you own block and have it bored. You can get replacement pistons cheap. Why buy another block and worry about that. Just bore your block out .060 and go for it!

[texasz]

I am just curious where you got your prices from. Boring out the block and putting in larger pistons will cost much more than $250. I don't know if you have some really special deals, but the bore alone will cost a hefty amount, and so will new pistons. Doing a rough full price estimate should help with the decision making a little more

He's having to bore either block so the price difference is in buying the 260Z block vs. buying new oversized pistons for the 280ZX block.

[240ZMan]

He's having to bore either block so the price difference is in buying the 260Z block vs. buying new oversized pistons for the 280ZX block.

Thanks Texasz, that's the biggest difference I've seen so far. It looks like the piston and ring set is about $250 vs. just rings at about $60 plus $100 for the block. Also, there's a machine shop fee of about $5 each rod/piston to press out the wrist pins if I switch pistons. So it's definitely cheaper to bore out an L26 block, probably by about $100 - $150.

I guess my big question is if that would leave the same amount of material around the cylinders as for an L28 block? The Z specialist recommending this says he's done it several times with no issues.

Also, going the L26 route let's me keep my OEM pistons. The replacements I quoted above are from Victoria British and I don't know anything about their quality. I'm pretty sure they are not OEM.

So I'm leaning towards going option 2 with the L26 but was hoping someone here might have tried this already and could share their experience.

[DatsunZsRule]

hmm. yeah, that is a tuff choice because you can't go wrong with any L Series block really (L24 L26 or L28) All are bullet proof motors IMO. No way would I ever consider replacing a good running Nissan OHC L Series engine for a V8 conversion. (No offence to all that have done it. Just my $0.02 cents) I guess if your looking to bore out any L Series block and your big into racing it then I'd say stick to your original plan on the L28 with new oversized pistons.

Your second option isn't a bad way to go either. It would for sure be one hell of a quick performer on the streets. How big of a performer you want your Z to be really depends on the thickness of your wallet

[zguitar71]

IMO bore out the L28 .040 and gowith flattops and a stage 3 cam or something close to that and get a set of Rebello bored SU's or a set of tripples. The Ztherapy SU;s would work too but for a little more you can get the bored ones and have a more top end power. There is no reason to worry about a .040 over bore on an L block. Personally I always go for more power.

[rdefabri]

I have a stock, numbers matching 1972 240Z. It has 148,000 miles, so it needs a rebuild or refresh.

The previous owner installed a Motorsport Auto 5 speed and 4.11 R180, amongst other things. Originally, I wanted to restore to original, but now I am thinking more "resto-mod". I want more power out of the stock motor, but I want to keep the numbers matching.

Rebello has a nice 2.7L that retains stock block/head, good for about 200HP, which is fine with me. Unfortunately, I suspect this will cost $3000+, which is not what I want to spend (I also have a 1966 XKE that I have to refresh).

Any thoughts as to extracting more HP out of a stock 240Z motor? I know I can mill the head and add a new cam, etc. I would bet that would yield at best 170 or HP with careful planning. I'd like something a little more, but it's been 20 years since my last Z and things have changed, so any advice?

Rich