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85 720 project


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so story is i got for a grand . on the way home the rear driver wheel came off @ 60mph duto not tightened lugz (my bad for not checking) only lost the shock mount , then my rear end breaks broke teeth or somthing havn't fixed it yet , then i pull the plugs and it very obvious the 1 &2 cylinders plugs look way different then the 3&4 so the web's need synched, so i do a compression test and the 2&3 cylenders only have 60 p.s.i and the 1&4 have 120 what the hell did i buy a freekin lemon? i'm hoping that it's just a head gasket but i have been reading that those z24s blocks crack??? what do you guys think?:lol:

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I'm liking the blue color you got on there. All i got to say is I haven't heard the blocks cracking unless you blew the head gasket and let the motor eat itself. I made the mistake of buying one that someone has blew the head and cracked the block and their fix to get it sold was put on a new head. I was sucker of that and paid the price, 3 - 5 cracks in cylinders 1 & 2, but the head when I pulled it after the blow was perfect. So I replaced it with another Z24. No problems yet but if the motor craps out again I'm getting me a KA24.


Oh and dibs on the side drafts.

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yeh i like the webers there hard to get right i still need to get a synchrometer im gonna pull the head and see whats up my number 4 cylender is getting way hotter than the others and back fires out the carbi it might be a cracked valve or somthin we'll see but right now im pullen the head off the l20 see what the nokin is then thats goin into my b210 so this one is now on hold duto the fundage and the bad compresion

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Adjacent low compression can easily be a blown gasket. This can also cause back firing through the carb. Can you get your money back? If not you are going to have to fix it and hope for the best. DO NOT run it if it's overheating! It's death to an aluminum head engine.


Have you worked on the OHC engines before? Do you know to lock the timing chain before removing the head?

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i will not run it anymore until i pull the head and no i have not worked on ohc engines before. right now i am ripping my l20 apart to see whats up with it and what im doing is jsut marking everything with tire marker so i know where it sat but i only thought you had to lock a dohc cam gears i didnt know about ohc's

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Oh yeah!


Be sure to slip a ratchet extension through the cam sprocket hole to keep it from turning while you loosen the cam sprocket bolt. (don't remove yet, just loosen it)


Now set the motor to TDC compression on #1. The #1 cam lobes on your motor should be facing down and both valves closed. Rotate the motor clockwise and line up the timing mark with the zero on the timing scale. If you slip past it turn the motor back well before the mark and try again, stopping at TDC but not going past.


Drive a wooden wedge down between the chains just under the cam sprocket. This will keep the bottom half of the chain tight and prevent the chain tensioner from falling out. If it does, the timing cover will have to come off... avoid this!!!! The wedge should be about 1" thick and taper from 1 3/4" down to 1 1/4" and about 6 1/2" long. FROM THIS POINT ON THE MOTOR MUST NOT BE TURNED OVER OR ROTATED SO TAKE OUT OF GEAR.


Now mark the sprocket and chain so they can be put back in the same relation, and remove the sprocket. The rest is pretty straight forward. If you have the EGR tube running from the exhaust side behind the head to the intake and have trouble getting it off, leave the exhaust and intake on the head and remove as one piece. Saves time and gaskets. Bit awkward. If you have the EGR tube plugged then remove the exhaust, but leave the intake to save time. Don't turn the head upside down because of the carb, just tilt up enough to clean it with a wire wheel.

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