potential setup

[timsz]

I have a 71 240Z. I was going to put a f54 block, e31 head, close ratio 5 speed, lightened flywheel, aluminum driveshaft, 200sxt diff. with 4.11 gears. SU carbs. It's just for street. Would 3.90 or 3.70 gears be better? Or a different head? Any info or help? thank you very much.

[Walter Moore]

The gears in the late S130 5 speed are pretty tall. If you intend to swap the differental anyway I wouldn't go lower than a 3.90 ratio. The 4.11 should be great, so long as you can stay with an R180. If you had a 72 or later the R200 is the way to go, but the rumor is that it doesn't work in the 70-71.

The F54 block is a 2.8L right? That block, with flat top pistons and an E31 head is reputed to have something like a 10.5-1 compression ratio. Unless you are going to go fuel injection with a pretty sophisticated ignition control module that isn't going to work well with pump gas. I have trouble with my stock L24 with the ZX distributor and the vacuum advance hooked up. (the L24 with an E31 is 9.5-1 or something like that.) I get all kinds of pinging when running gas with an octane rating below 92. I found a station locally that sells 94 octane fuel and it LOVES that. If I disconnected the vacuum advance I might get by with a lower octane, but...

Anyway, back to your question... didn't the late L28 come with dished pistons? That might lower the compression down to street usable. The E31 has small valves, so if you put it on an L28 you need to have larger valves installed. (But you probably already knew that.) I recommend that you search the forums for more details, since I am just pulling what I can remember from the top of my head.

These subjects have been discussed many times in the past.

[timsz]

thank you very much. I'll do more checking.

[LeonV]

The gears in the late S130 5 speed are pretty tall. If you intend to swap the differental anyway I wouldn't go lower than a 3.90 ratio. The 4.11 should be great, so long as you can stay with an R180. If you had a 72 or later the R200 is the way to go, but the rumor is that it doesn't work in the 70-71.

Not sure what rumor you're talking about. You can put an R200 in any Z, given that you have the correct mounting equipment, i.e. mustache bar and curved rear transverse link bar. This is covered extensively.

The F54 block is a 2.8L right? That block, with flat top pistons and an E31 head is reputed to have something like a 10.5-1 compression ratio. Unless you are going to go fuel injection with a pretty sophisticated ignition control module that isn't going to work well with pump gas. I have trouble with my stock L24 with the ZX distributor and the vacuum advance hooked up. (the L24 with an E31 is 9.5-1 or something like that.) I get all kinds of pinging when running gas with an octane rating below 92. I found a station locally that sells 94 octane fuel and it LOVES that. If I disconnected the vacuum advance I might get by with a lower octane, but...

A stock flat-top L28 block with a stock E31 will have compression in the low 10's and will definitely require high octane fuel. Shave the head and bore the block, and that number goes up.

FWIW, the reason that you have trouble with the vac advance of the ZX distributor is because it's designed for an engine with EGR. An engine with EGR needs more advance. Too much advance isn't a good thing and you'll be better off either disconnecting it or running a different vac advance module.

Anyway, back to your question... didn't the late L28 come with dished pistons? That might lower the compression down to street usable. The E31 has small valves, so if you put it on an L28 you need to have larger valves installed. (But you probably already knew that.) I recommend that you search the forums for more details, since I am just pulling what I can remember from the top of my head.

These subjects have been discussed many times in the past.

The late L28 (F54) came with flat-top pistons, it was the early L28 (N42) that came with dished pistons. One caveat is that turbo blocks (F54) came with dished pistons.

You absolutely do not "need" to put in larger valves into an E31 that's going on top of an L28. It gets "recommended" a lot but is not a necessity. This is not a race engine build.

Keep in mind that bigger valves, especially on a head with a small combustion chamber, will be more shrouded than smaller ones. This has potential for negative effects unless dealt with.

thank you very much. I'll do more checking.

A good build goes much further than a parts list. The only specification you mentioned is "it's just for street". In that case, I'd recommend a stock L24/26/28 with triples, open exhaust, 3.9 (or numerically higher) R200 and late ZX 5-speed. The diff and trans wake up the car way more than a mild engine build.

Pertinent information is plentiful and oft discussed, spend at least a few months on reading and planning to make sure you know what you really want. For example, DatsunZgarage.com can get you started with the basics, but don't take everything you read as gospel.

[Zed Head]

I have a 71 240Z. I was going to put a f54 block, e31 head, close ratio 5 speed, lightened flywheel, aluminum driveshaft, 200sxt diff. with 4.11 gears. SU carbs. It's just for street. Would 3.90 or 3.70 gears be better? Or a different head? Any info or help? thank you very much.

Is this a list of parts that you're planning to get or do you have some already? A wish-list? Some of these things will cost a lot of money, for small benefit, like trying to install a short-nose diff in the Z body to get the 4.11 ratio, when you could have 3.9 in a long-nose R200 for much less money. Same with the head, if you have to have a high CR, an N42 or N47 will get you there much cheaper and easier (simple bolt-on with that block) than an E31.

[d240zx2]

Back when 721 was alive, I installed a ZX 5-speed and R200 3.90 diff. As the trans is a close-ratio unit, I really enjoyed it and the combination really woke up the car, although it wasn't really asleep. That truly is a delightful combination for any S30 out there.

[timsz]

I knew nothing about car engines, etc. a year ago. I'm trying to do this restoration myself, except for info I get from people like you. I couldn't do it without your help and you don't know how much I appreciate it. I get on this site and other sites almost every night, trying to learn. I learn so much I get confused sometimes, and ask for your help. thank you very much, TimsZ

[timsz]

I forgot to mention I have these parts and more.

[LeonV]

Is this a list of parts that you're planning to get or do you have some already? A wish-list? Some of these things will cost a lot of money, for small benefit, like trying to install a short-nose diff in the Z body to get the 4.11 ratio, when you could have 3.9 in a long-nose R200 for much less money.

The S12 (Nissan 200SX) Turbo had a 4.11 long-nose R200, which is a bolt in just like any other R200.

Same with the head, if you have to have a high CR, an N42 or N47 will get you there much cheaper and easier (simple bolt-on with that block) than an E31.

Any L24/26/28 head is a bolt on on any L24/26/28 block.

[Zed Head]

Didn't know that about the S13 diff (or had known it but forgot it). Walter made the best point about the diff ratio though. It depends on the transmission used.

I think you missed my point on the head, even though you actually kind of made the point in Post #4. "Will it bolt on?" wasn't the question. The E31 head on the L28 block (assuming it has flat-top pistons) will be more problematic and costly to get to run right for a street car. Since he doesn't know much about engines, a close to stock setup might be the easiest, quickest way to get the car on the road. If it's a flat-top piston F54 block, get a P79 or P90 head. No worries about CR or head gaskets or valve size (air flow). It will be a 1982 280ZX engine.

Nice that he's got a pile of parts to work with. It really comes down to the budget available. It's not a "restoration" though, it's just a 240Z with a set of later model parts in it.

[LeonV]

Didn't know that about the S13 diff (or had known it but forgot it). Walter made the best point about the diff ratio though. It depends on the transmission used.

I think you missed my point on the head, even though you actually kind of made the point in Post #4. "Will it bolt on?" wasn't the question. The E31 head on the L28 block (assuming it has flat-top pistons) will be more problematic and costly to get to run right for a street car. Since he doesn't know much about engines, a close to stock setup might be the easiest, quickest way to get the car on the road. If it's a flat-top piston F54 block, get a P79 or P90 head. No worries about CR or head gaskets or valve size (air flow). It will be a 1982 280ZX engine.

Nice that he's got a pile of parts to work with. It really comes down to the budget available. It's not a "restoration" though, it's just a 240Z with a set of later model parts in it.

To avoid further confusion, the diff in question is an S12 diff, not S13. The S13 diff is a short nose.

Post #4 says that you don't have to do anything to an E31 to bolt it onto an L28, and it backs up what I'm attempting to convey. People mention that you have to put in larger valves to make it work, but that is far from the truth. An E31 won't be any more problematic and costly to use than an N42 or N47, as you proposed. If you already have an E31 and N42 in hand, the differences in using the two are negligible. Altered heads and blocks muddy it up further.

I side with your point about just using a stock engine and that is what I'm preaching here, referring to the end of post #4.