Guest Anonymous Posted June 13, 2002 Share Posted June 13, 2002 i just got a 71 240 z with a l28 not modified andhas a p90 head that is built and runnning 9.8:1. atleast thats what i was told. but my issue with this is no power. i had a l28 in previous z and it would haul some butt. this if i guest would be running a 18 or 19 sec quarter. the initial start has the torque you would expect but even at 2000 rpms it just doesn't do a thing. and at 4000 it cuts out. sounds like a rev limiting device but i didn't think they had those on these. any advice would be greatly appreciate. specs.... l28, p90 at 9.8:1, dual su's, five speed, stockk 240 fuel pump, msd ignition coil. and so far thats all i know. thanks. p.s. could valve lash do this. Quote Link to comment Share on other sites More sharing options...
Guest Zpeed Posted June 13, 2002 Share Posted June 13, 2002 check everything first, most commong things, plugs, leads, timing and ur fuel pump, make sure ur carbs are tuned right, could just be to lean sounds like a fuel problem, check that the fuel pump is working right, if it is, give a clean of ur SU's with some carb cleaner, and make sure all the valves and jets are working correctly.. if that turns out nothing, make sure timing is good, and vacuum is working good. is it cutting out in all gears at 4k or so.. or just one gear Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 13, 2002 Share Posted June 13, 2002 i did set the timing, at idle it was at 20 deg and i put it down to about 10. it does cut out in every gear at 4000 to 4200 rpms. does anyone know if mallory tachs have a rev limit device in the actual tac. i think i am going to change the fuel pump. should the 240 pump be expected to push this motor along. or do i need more pump. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted June 13, 2002 Share Posted June 13, 2002 Unless the fuel pump is bad, there is no reason to replace the stock pump. I have a 2.9L that runs 12's in the 1/4 and the fuel pump has never been an issue. More than likely you have an ignition component related problem. If it is cutting off at 4000 rpm in each gear then it shouldn't be fuel related. Later,norm Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted June 13, 2002 Share Posted June 13, 2002 Try turning your ignition timing up to at least 32-36 degrees at 3500 rpm. Set the timing with the vacuum advance disconnected. My car will fall flat on its face at 5000 rpm if the timing is not just right. Later,norm Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 13, 2002 Share Posted June 13, 2002 I had a friend with a 240 with a stock pump that would not keep up with his L28 motor. He was running the P79 head on a flattop engine with a cam and header, and I can't remember if it was webers or the Su's that would run out of fuel when he was on it, but it was one or the other. I agree you should check the basics and make sure you are getting good fuel flow and they filters are not clogged up. With your compression ratio, your engine should be very responsive. Also check the gap on the plugs. I know with my seadoo when I raised the compression on it, I had to tighten the gap on the plugs. If you are worried about the tach, disconnect one of the wires and take it down the road and see if you have the cutting out. If you still do, chances are it is not the tach. Just make one change at a time so you can isolate the problem, that way if it happens again, you know exactly what it is. Good luck. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 13, 2002 Share Posted June 13, 2002 I would get a Air/fuel gauge It will help you when you tune the carbs, it will tell you if you are running lean, rich, or Just right. Have you thought of putting the L28 FI parts on the car it might give it the power you are looking for! I do have an xtra FI harness if you need it Hope this Helps, Mark Quote Link to comment Share on other sites More sharing options...
DAW Posted June 14, 2002 Share Posted June 14, 2002 First I think you should run a compression test as it will tell you if there's a problem cylinder or two and you should be able to get some idea of the c.r. I'm thinking a stock L28 F54 engine cranks warm at 170lbs and that's 8.8:1. My F54 with N42 head cranks 210lbs and that's about 10.2:1, so you should be around 195-200lbs if you really have 9.8:1. Unless the head was shaved or you have pop-up pistons, you'd have 8.8:1. Look at the plugs when you run the compression test to look for mixture problems. Set the valves (unless it's a P90A head, not a P90) and check the cam timing index marks. If everything checks out mechanically, then make sure you're getting a good quality spark to the plugs, and you have adequate fuel flow. DAW Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 14, 2002 Share Posted June 14, 2002 thanks guys. i am beginning to do all of the suggested problems. one i already found was not even getting full throw of the throttle linkage. duh... but it is stiull a dog so please keep the advice coming and i will be in contact. p.s. i dont think i would want to go FI thats pretty expensive and i just got this puppy for free. and that was for a the reason of being broke. hehehe. oh any body want a 95 wrangler. thanks Quote Link to comment Share on other sites More sharing options...
boholio Posted October 9, 2002 Share Posted October 9, 2002 Just curious if you ever found out what was the problem? I just got a new Z and it is having almost the exact same issue, it falls flat on its face at 5K in every gear. ARGH!! It has the stock L24 block with E31 head, hot cam, triple webers, headers, etc... and am having no luck trying to cure it. I ended up sending it to a shop that is also having no luck. Any more bits of advice from you smart cats would be very appreciated! Quote Link to comment Share on other sites More sharing options...
Guest bigjim240z Posted October 10, 2002 Share Posted October 10, 2002 ok i would add a good fuel pump and electronic distributor..that will solve your problem if everything else is in working order...e mail me if you want specifics! Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 10, 2002 Share Posted October 10, 2002 Its a long shot, but check and make sure the balancer hasn't slipped. I had one I could not get set right, and it turns out the balancer had slipped. Once I found TDC and marked the balancer and set the timing, everything was good. Make sure the balancer bolt is tight too. Your issue is most likely timing related. Make sure your plug gaps are correct, and that the cap, rotor and plug wires are good. Also, if your SU's are bad, your engine will misbehave and not turn up. Quote Link to comment Share on other sites More sharing options...
Mike C Posted October 11, 2002 Share Posted October 11, 2002 Also check and make sure the cam was installed correctly. That can really play havoc with a motor. SOunds like my 2.4l motor that just quits at 4500 or so. It is my 3rd 240 and by far the slowest! I'm really looking forward to having the time to drop the 2.8l motor in. Quote Link to comment Share on other sites More sharing options...
boholio Posted October 11, 2002 Share Posted October 11, 2002 Thanks guys, I appreciate it. Now by installing the cam correctly, what exactly could someone do wrong? I am looking into upgrading the distrib to an electronic one and putting a good fuel pump on. I'll definintely keep everyone posted. Thanks again! Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 11, 2002 Share Posted October 11, 2002 YOu want to make sure that when the number one piston is at top dead center that the little V notch on the back of the cam sprocket lines up with the mark that looks like this - on the plate on the front of the first cam tower. Your harmonic balancer should also have the notch in it line up with the 0 on your timing scale. If the v notch on the cam is a little ahead no biggie, if it is a little or alot behind, you need to fix that, and it is a delicate proceedure if you haven't done it before. You would not want to lose tension on the timing chain and have the tensioner pop out or you will be ing Quote Link to comment Share on other sites More sharing options...
boholio Posted October 12, 2002 Share Posted October 12, 2002 Thanks for the info, I'll get to it! Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 17, 2002 Share Posted October 17, 2002 My 260z (N42, 2800cc, dished pistons, dual SUs) was falling on its face at 4500 too for a while. Well it was stuttering a bit I guess, not just an instant death. Added an electric fuel pump at the tank, in conjunction with the mechanical one on the engine, and those problems completely dissappeared. Oh yeah, check and replace your $1 fuel filter. You'd be surprised how much that can do if they are getting lots of crap in them. Quote Link to comment Share on other sites More sharing options...
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