I have a friend with an early L24 engine with an E31 head and SUs attached. The thing has been sitting out in the elements for years but looks pretty good from the outside. Any idea what the just the E31 head and SUs would be worth? I'm thinking of making him an offer.

Couple hundred at the very most. Since it's been sitting in the weather and everything probably needs rebuilt, realistically more like $100.

Hey Enigma,

Take the air cleaner housing off and look inside the carb throats. I once bought an outdoor stored complete L24 and the carbs were ruined. Mice got into the air cleaner housing chewed through the air filter and made nests in both carbs. The urine actually pitted the floors of the carbs to the point they looked like lava rock. They even made nests on top of the pistons where they could get past open valves.

Check the thing out before you spend hard earned cash.

FWIW,

Chris

Thanks. The air cleaner is missing and I was told it was covered with an old plastic bag but it sounded like the sun at that up so basically it has been more or less completely exposed to the elements. Fortunately, it's in an area that is fairly arid so it didn't get much rain. I'll definitely tear the assy off the block and have a look-see before plunking down the $$$$.

My plan was to use the E31 as a replacement for the E88 smog head(bigger combustion chamber) on my 73'. If my research is correct, this should be a direct bolt on upping the compression from 8.76 to 9.13. I believe the E31 has round intake and square exhaust so it should be a direct bolt on?? Can anyone verify this?

I think you're right. Here is a site with good info on the different heads:

http://www.geocities.com/zgarage2001/z.html

Yes a direct bolt on. You will have to rebuild the head (due to exposure) so you might as well put larger valves (from the late E-88 or N-42) in the head.

The late E88 has a larger EXHAUST valve. There is no room on an L24 block for the larger intake valve. If you install the larger intake valve you'll have to notch the block for the intake valve to clear, and even if you do that, the valve will be so close to the cylinder wall that it is questionable whether or not that would be an improvement over the stock intake valve in an L24. If you were putting this head on an L28, then yeah, by all means put the larger intake and exhaust valves in. For the L24, you can make an argument for putting the larger exhaust in or just leaving it alone.

I was hoping to just bolt it on to the stock L24 for the improved quenching design and increased compression. I am not interested in enlarging the valves and modifying the original block.

If and when I do move to an L28, I will consider installing larger valves. In that case i would probably use my 73' E88 head, shave it, and install larger valves. I believe I have the earlier E88 with small valves and a larger combustion chamber designed for a reduction in smog emissions. All stock at this point except for the round tops. Anyway, that is not in the plans.......for now.

Thanks for all the info guys. I'm a learnin'!

I was hoping to just bolt it on to the stock L24 for the improved quenching design and increased compression. I am not interested in enlarging the valves and modifying the original block.

When I still had my L24 in my '73 I had to replace my E88 head. Don't ask why - call it a learning experience I found an E31 that had been freshened up about 10k miles ago. I had read all the good things about E31s so I was hoping for an improvement. I have to say that in the end my butt-o-meter wasn't able to tell any difference between it and the stock E88. I suspect that this improvement, like a lot of others, wont' make any major increases in horsepower unless you do things like a bigger cam to improve breathing.

I'm not trying to talk you out of this swap, just suggesting that if your current stock head is in good condition, you might want to spend your $$$ on something else, or wait until you can do a swap to an L28. Now THAT made a difference

Yeah, I think you're probably right Daniel. So, my new plans are to finish the suspension refresh I started, then start collecting parts for an L28 build up. I already have a line on a couple F54 blocks and an assortment of heads and intakes, unfortunately no P90's.

For a street car, there's no reason that a P79 head on an F54 block won't be worthwhile. The exhaust port difference isn't going to make much difference without a lot of other mods to go with.

Thanks for the suggestions Arne. I guess I need to do some more research. At the moment I'm thinking F54 flat top w/N42 although this might get the compression up too high for my street rig(9.82). Is that too high? Perhaps I could just use dished pistons to bring it down a bit(8.29) depending whether they'll work with the N42. Or may be an E88 off a 260Z(8.28). I just didn't like the look of the steel exhaust liners in the P79. Anyway, I think this thread is starting to stray from the classicz preferred topics so I'm gonna go do some research on hybridz.org.

I've got flat top pistons and an N42 head with a very mild cam. I run premium and have no pinging issues. It would be a shame to put dished pistons in an N54