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Spark plugs/idle


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Hey guys I m new here. I got 71 240z Datsun w 1965 327 w dart heads tht I got from trade. After I set the initial timing at 4 btdc n idle at abt 950rpm . I pulled the spark plug on first cylinder n it has a oil on it .. Is there something wrong??

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There's not enough information in your first post to really say anything. Did the engine get to full temperature, was it smoking while you were setting the timing, was it oil on the plugs or oil and gas, were the plugs new or old, was there so much oil that the plug fouled, did you drive the car, etc.

 

A little wetness on the plugs of a cold engine wouldn't be super unusual.

 

Start it up and monitor vital signs like oil pressure and temperature. Get it up to normal operating temperature. Listen for unusual noises. Look for smoky, smelly exhaust. Drive it if possible and see how it runs.

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Ok I'll try my best here..

 

Well it wasn't run right it was overheated n keep shutting off so I adj timing to 4 n it stable n idle sound good sounds like radical cam. Abt 1 hg in vacuum gauge. When I drive, it seem fine but in first gear it looks like it lost a little power.

 

I have air/fuel ratio gauge and sometimes it goes to ideal n then rich. There's a smoke coming out of carb as I push throttle all the way down n u can see the smoke in there is it normal?

 

I'd suspect the spark plug s old n Mallory cap looks worned. Running electric fuel pump. Sometime it goes to 6-7 psi then lower to 3 psi. The temperature is in middle, it d go lik further sometimes. the oil pressure haven't hook up but I will soon ..

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Is it supposed to have a radical cam installed? Lumpy idle with a mild cam is not good. "Smoke" in the intake is worrisome. Overheating isn't good. Is there another digit after the "1 hg"? One inch of intake vacuum is not much.

 

Good luck with it. The guys that build up the small block chevys might have some comments. I haven't had one for many years.

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First, remove all the spark plugs. Then obtain a leak down tool with two gauges. Perform a leak down test on each cylinder. The pressure in the leak test will likely go past the rings, intake or exhaust valve. The objective is to find out how much each cylinder at top dead center with leak down test pressure applied, hold how much pressure over the tool input pressure typically 100 PSI. 80/100 or better is somewhat good. Below that rings or valves are leaking and listen to the breather for rings, Exhaust ports for exhaust valves, and carb for intake valves. Do the test one cylinder at a time and record the values. The valve guides and seals for same can be worn allowing valve cover retained oil to leak down by the valves into the cylinders. This type of testing should give an indication of the condition of the rings and valves assuming the head gasket is intact.

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Do the leak down test FIRST. Listen to the three different spots to detect where most of the pressure leakage is. If the leakage is most pronounced from the intake or exhaust, then yes if the reading is below 80 PSI do take the cylinder heads off and have them rebuilt. New guides, new valves where needed, new guide seals, reface the reusable valves, redo the valve seats and having all that done have both intake and exhaust valves leak tested with a vacuum tester by applying a vacuum to the exhaust or intake port and check the vacuum leak down. When this test is determined to be good, reassemble the heads to the remainder of the block and redo the cylinder leak test to recheck and determine the piston ring leakage. If still below 80/100 (80% good) then the lower end of the engine needs rebuilding also. Jump in and get your hands dirty and you will learn a lot. Get several books on rebuilding Small Block Chevrolet engines and read them. The best author is David Vizard.

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It seems that the initial timing is a little low at 4 degrees. I'd try to reset that up to 8 to 10 degrees and see how that works. I's also clean the spark plugs and or buy some new ones, they are cheap, and retry. Also worn cap and rotor's and spark plug wires describe your experiencing. The "big cam" idle could be just ignition miss.

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4* timing will barely give your carb enough vacuum to work with, sloppy low end. A mild cam w/ less than 220 degrees @ .050 should have at least 10-12, under 240 14-16, 260 18 - 20. A blubbery big cam sound with low timing at low idle is not going to impress anyone when you stomp the pedal. Kick the timing up to at least 10-12, set your idle mixture and idle speed. I think you'll be surprised with the difference. Make sure your total timing isn't over 36 total.

Oil on the plugs and timing have no correlation other than if you do have an oil consumption problem, the engine will be much more prone to detonation. Hopefully your wet plug is just gasoline and hasn't fired, or just a simple valve stem seal leak, not worn valve stems, or rings.

Get your entire ignition system in perfect condition, plugs, wires, cap etc. Then your fuel system, pressure, jetting and so on. Its easier than chasing a bunch of problems in random directions.

Edited by John Scott
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