I have a '73 240z with the original engine and just bought a L28 long block to put in it to get more HP. Is there really that much horsepower in an L28 and is it work it to put it in and take out the original. It runs fine except that it has the crappy Hitachi carbs that need to be swapped out for SU's from Z Therapy. Am picking up the engine this weekend but wondering if it's worth it for the extra HP. I'm also planning on switching it to a 280z 5-speed. Any comments?

do it!

but save your OG engine & tranny

Depending on the year and condition, a stock 2.8 will give 20-25 more HP than a stock 2.4, and will have considerably more torque. If you are going to stay with carbs, it's pretty much bolt in job using all the L24 exterior parts. The only catch would be if the L28 you will be using is '77 or newer with round exhaust ports. If so, you'll need to get a round-port header, or use the L28 exhaust manifold, neither of which will mate up with your current exhaust.

Is it worth it? Only you can decide if 20 HP is worth the work. I personally have found that a good running L24 is quite acceptable for normal street driving, but many others will disagree.

^ i agree that an L24 is good for street driving, but my Z with the STOCK l28 in it really adds to the driving experience. i plan on bolting on a square port head w/ a header in the near future, but the TQ/HP potential of the L28s is great.

Thanks guys----L28 it is!! And I think I'll keep the L24 too. I'll make sure to check and see what year the L28 came from and check on the exhaust ports. Thanks you so much for the heads up. You guys help a lot of people and are truely appreciated! Thanks again.

I did exactly what you are about to do and have never been happier with the change . The 280 will really wake up your Z . Be sure to keep the 240 intake manifold and do get a set of round tops. You will also need the throttle linkage that connects the carbs together . The flat tops are different spacing. Also you need the thicker insulators that go between the carb and the manifold. I was just at ZTherapy this afternoon and they have the early air cleaners for the SUs hanging on a wall . My engine is a ZX with a P-79 head , it has the round ports. I am running a header . Gary

Thanks Gary----I appreciate the vote of confidence. And the heads up on the linkage and spacers.

---Tom