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First of all I'm not sure this is the right forum for this, but I'll give it a try....I have been getting the DIGEST version of the daily Z chat and enjoying it a lot...I tried a few posts at the bulletine board but find that it takes forever to get a reply....

I have a 73Z with an L24, all stock except for the 72 round tops, I bought it last summer and have bills to show the engine was REBUILT about 10 years and 10000 miles ago, bills say it was OVERSIZED, doesn't specify whether this refers to bearings or cylinder bored out a few thou though. Anyway it runs like a PoS, lumpy idle and lumpy non linear response to throttle (feels like 1 or 2 aren't firing, though I know they are). I have rebuilt the carbs (with ZTHERAPY'S help), put in a new cap/rotor/points (20 thou), set the timing, new plugs/wires etc....when I set the valve lash I found all exhaust valves set to 10 thou (cold) and all intakes at 00 thou (cold(yup...no lash)), I don't know what the previous owner was thinking but...... I was wondering if this is the cause of my rough running.

Noteworthy is the fact that #3 and #4 spark plugs are oily, not fouled but definately too wayyyyy too oily. I took an old spark plug, knocked out the center and added an air nipple to check for leaks past the rings or valves, THE PROBLEM; when I pressurize the cylinder with 100 psi I find it nearly impossible to hold the cam (whole engine really) in place at/near TDC for the cylinder I'm checking as it wants to drive it downwards. ALSO with the help of a extension bar on my 1/2" socket I am able to hold against the pressure (19mm socket on cam nut at front of engine) but can HEAR AIR RUSHING OUT OF THE CYLINDER. I don't know where its going but I can hear it (a steady medium hissssssssss).......WHAT NOW....HELP PLEASE.



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I have a '73 that was doing the same thing. I gave up. I rebuilt an '81 L28, P79 head and 54 block with Z therapy round top SU carbs, Motorsport 6-1 headers, Felpro gaskets, K&N filters, etc. It has a few quirks but is for the most part wonderful. I also put in the '81 5-speed. I plan on putting in the R200 rear end later this year. Thats my 2 cents worth. Cost me about $2000 when it was all said and done.

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I know I should have done this along time ago...but I did a compression test both dry and wet...

# Dry Wet

1 102 123

2 101 118

3 120 135

4 118 132

5 113 121

6 107 116

given the results its clear the rings are gone and I need a rebuilt engine......any ideas or recently rebuilt engines for sale out there....Im in Canada just north of North Dakota..

Thanks for you patience


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You could always go for the rebulit L28 from Motorsports, but I don't know the quality or anything and it seems a little pricey. That leaves scrapyards. Look in the yellow pages under salvage yards. Finds a wrecked 78-83 Z and get it. You could leave the fuel injection on but you would need to do alot of mods. You have the carbs alreay so I suggest going this route. If you can not finds a wrecker would rebuilding the go to www. autotrader.com and do a search for cheap Z's over the US. Make a trip out of it. Finds something not good enough to salvage in itself, yet good enough to drive back to Canada and strip. You really dont even need to worry about a title if your intentions are just to take what goodies you can off it and roll the rest off a cliff. There really is no substitute for an L28 in your 240Z.

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