I have a 1971 240z and unfortunately recently discovered it has little to no compression in cylinder 6. I live in a remote area of Georgia and there are not any Datsun spec nearby. So instead of rebuilding my engine I am thinking of buying a rebuilt motor. I have seen a few places on the internet and am wondering if anyone has any suggestions. I have spoke with Datsunpartsllc, Rebello and a few others. I'm sure I want to change to 2.8 liter block and maybe a performance cam. I don't want a racing engine but something with good power and reliability.My current engine is pretty stock except for headers,an electric fuel pump and smog equip removed. I would eventually like to change the SU carbs to triple Mikunis or webers

Edited June 11, 201311 yr by mark sexton

Datsun Spirit, Inc.

this is will be the last call you make.

Tell him Guy or Stephen sent you.

If compression is pretty good in the other cylinders I would just pull the head off and do a valve job. My bet is that the valves were out of adjustment (do you adjust them periodically?) and you burned the exhaust valve on #6.

After getting the valves done, slap the head back on the car and drive. While you do so, you can build an L28. IMO, it's always nice to have a running Z. The longer it's down, the higher the probability of "build fatigue" setting in...

the compression in the other 5 cylinders was good (170), the valves have not been adjusted since i bought the car 1 1/2 years ago.Been driven 3-4 k miles.Also noted smoke coming out of breather on top of valve cover, ? related

There's your problem. You bought the car, not knowing the last time the valves had been adjusted (among other things) and kept driving it. Old cars need more than just oil changes and tire rotation (as I'm sure you know).

Check your valve clearances right now, and I bet they're very tight. A fresh valve job should get you back up and running.

I agree with Leon. You have good compression on the other cylinders which would make it worth while investigating the cause before looking at a new engine. I wouldnt give up on the L24 just yet.

Check the valve clearances and see if the problem is solved. If not you can do a leak down test to determine where its leaking. If you need help doing it, just ask.

Goodluck

Chas