jrusso07

Good Advice Kenny. I found a rebuilt 280ZX dizzy today for $150 with the e12-80 module. I bought it and I am making the switch! I do have a couple of single point dizzy's in my spares but think I should go for the top of line! Z car owners can't be wrong! Thanks!

I found the problem - it was with the rear carb. At first, the gas puddled at the jet nozzle with the choke on and I could see it in the nozzle with it off. It is a new nozzle and needle. Then I put the dome and piston back on and got the same crappy result. I took it off – and no gas at the nozzle. Checked the fuel delivery to the rear carb – it is fine. I took the fuel bowl cover off – dry as a bone. The needle valve was stuck closed, the edge of the tang on the float got caught up on it. I reshaped the tang so the needle contacted the arc of the tang. Put it all back together and TA-DA – she’s back! She set right up, leaned her out and she idles like a champ – pulls hard all thru the range and in all gears (big smile!). Thanks!

Thanks for the info on the ZX dizzy and carbs. My search for a ZX dizzy beigns today! How much for a new one???? I also found the colour tune tends to create a too lean condition, I always back it out a bit - no burnt valves for me! I must say, there are a lot of great old Z cars (and owners, err, not old owners but great owners...) in the great northwest! Oregon especially! Must be nice slice of Datsun heaven !! The east coast has not been kind to the japanese steel. It's a rare occurance to catch a Z on the road - but if you look hard you will find then tucked away in some nice dry garage...we have learned the hard way! I will let you know the secret of my mystery condition - this weekend (positive thinking now). Thanks again!

Mat - I was under the impression that the ZX electronic dizzy wouldn't support the tach. I guess I shouldn't belive everything I hear! I checked a bunch of things tonight - valve lash - good both hot and cold. Timing, fuel pump, banjo bolt fuel filters and the piston resistance. All "pass". The pistons both drop with a nice clunk, no wear on the needle, both pistons rise simultaneously with thottle. I swwapped out the rear piston and dome from a old (good) carb - no difference. I am really stumped... This weekend I will take it from the top and do the tune up checks and tune up procedure - step by step (inch by inch) Thanks everyone for your help!

Thanks for all the suggestions. I have tried repeatedly to balance the carbs. The air flow (unisyn) is perfectly balanced on the carbs at idle and at 3K. I used a colour tune to set the mixture. The front carb sets right up. Just dial it in and it is solid. I can't get "blue" (lean) at all on the rear carb - even with the mixture nut all the way in (lean). I does react (negatively) to an over rich setting. I checked the float level and the needle setting - both right on.... Also, I can run the the engine on the front carb all day - but only a few seconds on the rear... I am going to put an old (decent) carb on the rear after I check the fuel pump and line for obstructions. Based on your inputs I am settled that the rear carb is not set up right or it has a obstruction in it's fuel supply. Note that the rear cylinders don't contribute to any RPM change when the plugs are removed. Oh, two other observations - two things happend almost simulataneously - the temp sensor became intermittent (gauge checks out ok when lead is shorted to ground) and the oil pressure at running revs is almost at the top of the scale (where it was normally at about 70% of full scale) Thanks again for the fine advice! I am thinking electronic ignition - but I don't want to give up the tach..I think More to follow.

Hi Bryan - thanks for the reply. I checked the valve lash (hot) - 0.010 intack and 0.012 exhaust. All checked out ok. I will check them cold (.008 intake and 0.010 exhaust) tomorrow Is this what you mean by too tight - the lash is not set correctly? I also found that 4, 5 & 6 cylinders don't seam to provide any power - removing the spark plug wires does nothing. That carb (the rear one) I can't lean out. So I am guessing I have either a carb problem, or a intake manifold leak (I get a intermittent high pitch whistle but I have not been able to isolate it - it comes and goes). Worst case I have some cylinder to cylinder leakage at the head gasket - oil and water are fine...

Hi - I am new to the club and need help and advice with a 72 240Z problem. The car is stock - except that the emission controls have been removed and the auto tranny has been replaced with the period correct 4 spd. It also has AC. The car idles and runs like a champ untill I really get on it. So if I am driving along at say 60 MPH and I stomp on it, the engine misses or hesitates at about 5000 RPM. Like it is has a governor on it. I susepected ignition problems or perhaps fuel...blockage somewhere. I tried from a dead stop and in first gear it pulls hard all the way up to the yellow line. Then in second, it chokes at around 5000. It is interesting that once it chokes (stummples, has no power, gas pedal has no effect), it stays that way until the revs come back down (say run at 2000 or 3000 RPM) for a short period (about a minute or 2). It doesn't stall and after an "episode" it idles smooth as silk. I just recently installed rebuilt carbs, new plugs (NGK), new wires (NGK), new points and condesors (it is a dual point left over from the AT), new cap and rotor, a new "fireball" coil. A manifold vacuum test checks out fine. She runs smooth and strong at idle and I can rev it all day long without a problem when the engine is not under load. I check the carb floats, reset the dwell on the points, check the plug gap and wires, the connections to the dizzy have been cleaned and are secure. I put back the stock coil (thinking maybe the dizzy was arcing). The fuel filter has been replaced. I haven't checked the screens in the carb banjo bolts but they are freshly rebuilt...by a third party. Timing is set at 17 deg BTDC. This (I belive) is the non-smog setting (from a spec sheet for a 71) vs 5 deg BTDC. This is where the manifold vacuum is at it best. Also, I tried running on just the advance points in the dual point dizzy...no help here. The exhaust is new - a new Y pipe from the manifold, a ANSA center pipe (free flow) and a OEM muffler on the rear (all brand new). So I don't think the exhaust is clogged... My last guess is to check the (mechanical) fuel pump...any one know the best way to do this? Any ideas on what else to check - or a method on how to isolate the problem? An electrical connection?...something in the tranny or rear differential that is locking up or really loading down...that's a long shot! Thanks! 72 Triumph Gt6 70 Datsun SRL311 Roadster 72 Datsun 240Z (HS30)