<>70 240Z No Compression. <>Ok this is a BIG question. This is a 1970 240Z 5 speed straight 6 cylinder with no compression in #4 cylinder. I have been searching for a replacement engine (and one never knows if one is just buying another with the same problem). So at this point, I am wondering, what else is compatable and fairly easily installed? I am not really wanting to spend much more than about $2000 total (including installation). Any ideas? The rest of the car is in really great condition as our family (in prior generations) are original owners and it was gently driven.. Thanks. Kim. Doc replies:. Hi Kim,. Doc here, the best advice to give you is to rebuild the original engine. It sounds like it needs some valves, but the rest can be dealt with. To get the job done for the 2K$ you need to have some proficiency in doing the removal and installation yourself, or pay the right price for a professional installation ahd set up of the job. Case in point, the friend of mine who just went out and got a rebuilt engine took it to the local Nissan dealer before letting me know what he was up to. One thousand + $'s later and he drove it out from their shop and the new engine sounded louder than the original one. He came to me for professional help and we installed the header that he ordered, and we found out that they did not install the exhaust flange gasket, among several other problems. The commentary is that you can spend the $'s and still get a job that is not a quality, long lasting engine. Complete parts clean up and fresh painting is really not only cosmetic, but also part of the inspection internally of all the parts that make up the whole for hidden cracks, casting flaws, or previous damage, affecting the integrity of the engine. There are several things in the early engine that need to be done to give long life with the fuel that we now have, but for the most part the engine can go back to stock size without a problem. Depending on the casting number of the head, and the type of intake valve seats, it may be necessary to replace them, (brass) for the steel ones. I have seen in my more than 40 years experience, engines replaced when only the transmission modulator was bad. The Race engines replaced only to have the new one not have more power and then go back and really find the engine was good, but the old distributor had the original problem, and typically a new one does not come with the replacement engine. In this day and age the evolution of technology has been so much of a challenge that much of the older car designs or actual experience has been passed up and you must still have the experience now to solve the problems of the present, even with the older cars of the past. Datsun/Nissan made great cars and they still are great! The challenge is yours, since something was missed in the normal maintenance, possibly the service interval for the valve adjustment, it caused the burned valve in the engine. Before doing anything several tests need to be performed, and then a proper evaluation can be achieved. I hope that this helps you and that you will accept the challenge...Pass it On to your Kids! Are you a ZONC Member? JOIN ZONC! Z Owners of Northern California! Ask me How! ZDOC OUT... ^) . <>.