Guest kylerichardbutler Posted November 27, 2005 Share Posted November 27, 2005 Hello fellow Z lovers, This is my last resort I have tried established Z shops and recieved no answer to my problem. I have a hesitaion in my 74 260 Z, it happens when I step on the gas. It idles fine, but as soon a I lay into it it craps out. It smooths out a little bit above 2500 rpm. I have owned this car for two years and have never gotten to drive it. In the course of the two years I have tried every thing to sovle this problem. here are the things that I have checked: -crank to camshaft timming(6 times now, also performed by Zsport for $400) -ignition timming(also performed by Zsport) -carburator rebuild and adjustment(SU and webber carbs, adjustment also performed by Zsport) -loose wires -full tune up -vacume system -fuel system I have just done everything but drive this car off a CLIFF! my only theory is that it has something to do with the ignition system. maybe a resistor or condensor gone bad or possibly something to do with the transistor ignition unit. If anyone out there has any ideas I would love to here them. Quote Link to comment Share on other sites More sharing options...
GrayZee Posted November 27, 2005 Share Posted November 27, 2005 So you are saying that this problem happened with both your SU's and Webbers? cuz my first guess would be a problem with the carb's accelerator pump. Quote Link to comment Share on other sites More sharing options...
vashonz Posted November 27, 2005 Share Posted November 27, 2005 Have you tried Fairlady motors, (http://www.fairladymotors.com). Doug really knows Z cars, I think he went to japan last week, but might be back now. EDIT: BTW he's in Tacoma, so its relatively local. He is usually pretty busy with projects there. Quote Link to comment Share on other sites More sharing options...
buZy Posted November 27, 2005 Share Posted November 27, 2005 I have old stang that did the same thing. It was acc pump. Quote Link to comment Share on other sites More sharing options...
Guest kylerichardbutler Posted November 27, 2005 Share Posted November 27, 2005 Yes, the problem happens with both of the carbs. thanks for replying I am a new member and I think this site is great! edit: I went with the webber carbs because they could be rebuilt and tweeked a lot easier than the SU's. and yes they have been rebuilt including new accelerator pump. Quote Link to comment Share on other sites More sharing options...
Guest kylerichardbutler Posted November 27, 2005 Share Posted November 27, 2005 Thank you I will have to try doug for some advice. I am a new member and I really appriciate the help. Quote Link to comment Share on other sites More sharing options...
Guest kylerichardbutler Posted November 27, 2005 Share Posted November 27, 2005 It seems to me with the experience that I have the problem would lie in the mechanical workings of the engine. But like I mentioned earlier I have gone through the timing, cam timming 6 times and all the way down to the crank pulley 3 times plus had it checked by a reputible shop. It just doesn't see possible that an error in timming could be missed so many times. Does anyone have any experience with the grove and notch adjustment of the camshaft it seems pretty self explanitory. And as far as the carbs are concerned I tried both styles and the same result. I also check fuel pressure so the supply of fuel is not at question. does anyone know of any other mechanical workings of this engine that could possibly cause this. does anyone know of any electrical problems that could cause this. Quote Link to comment Share on other sites More sharing options...
v80z Posted November 28, 2005 Share Posted November 28, 2005 Have you loosened the distributor yourself and played with the dizzy timing? If you feel comfortable with that you should. Also there have been many times that I was 1 tooth off in installing my l28's distributor. It would start and idle fine but when I opened the throttle it would just bog. rotating to TDC on number one, installing the oil pump in the 11:30 position and then getting the dizzy back in there was never an exact science for me. My old vintage haynes manual detailed it as well as my "How to Hotrod L28" book. One time I was one tooth off and was playing around with the dizzy and rotated it so it lit #1 or #2 with the intake valve open and lit the weber bowls on fire. AHHH blue flames out the weber horns. Yes for me there is only one way to learn. The hardway. Grab a book and have fun !!!!!!!!!!!!!!!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted November 28, 2005 Share Posted November 28, 2005 The coil has been eliminated as a possible source? Quote Link to comment Share on other sites More sharing options...
Guest kylerichardbutler Posted November 28, 2005 Share Posted November 28, 2005 I am pretty sure that the coil is bad, according to the book the resistance is too high. I don't know wether or not this will cause thi hesitation problem that is occouring. Quote Link to comment Share on other sites More sharing options...
v80z Posted November 28, 2005 Share Posted November 28, 2005 yes it will. Also old broken down plugs wires as well. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted November 28, 2005 Share Posted November 28, 2005 Proper fuel, Good spark at the correct time and compression. Check basics, be systematic. Sounds like a power loss under load conditions. Secondary ignition problems or timing curve could be way out. Sticky advance weights, poor coil or wires definitely come up as possibilities. Of course, I'm guessing (electrical) without additional infomration. Is there a single cylinder misfire, one half of the engine or random misfiring? Can you duplicate the problem in neutral? Quote Link to comment Share on other sites More sharing options...
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