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Old 04-10-2010, 07:56 PM
eric32 eric32 is offline
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Keep going through spark plugs, need some advice.

Hello guys well I am once again putting in a new set of spark plugs in my 350 small block chevy and am trying to figure out why I keep going through them. Engine is 350, World sportsman 2 heads, 9:1 compression or a hair more. Flat top pistons, Edelbrock rpm performer, Crane hydraulic roller cam 222/230 @ 50 112 lsa with 505/515 lift. Carburetor is a holley 600 1850s with 70 primary and 76 secondary jets. Transmission is a turbo 350 with a 2200 stall.

Engine holds about 12 inches of vacuum at idle. The carb has been tuned and it runs very well with excellent throttle response and idles at 800 in park. I just recently installed a manual choke and had to go through a couple of pulls with starting and shutting it off before I could get it correct to give me a 1500 rpm idle with the choke pulled at the right spot. After doing that my plugs fouled a little but after I took it out for a good drive they cleaned up and where not fuel fouled at that point.

Am running NGK 6630 plugs gaped at .045 as recommended per there specs. Everything is new from top to bottom and the timing is set perfect at 16 initial and all in by 3500 rpm. Running brand new HEI with plug wires as well. Had issues with a brand new holley street avenger last fall and finally got a nice holley 600 brand new to put on. Had everything set good with this motor and it seemed around January things got weird after I installed a one inch spacer. I had issues with the pcv valve sucking up oil so I took it off about a month ago and installed a breather for now and is vented on both valve covers.

Installed a new set of plugs about a month ago and noticed when I start it up in a cold morning I give it a couple of shots of gas then it fires right up and it seems like it will want to spit and sputter a little bit but nothing major. After its warmed up it runs excellent and fine with no rich running conditions or anything like that.

But I keep having a miss here and there and when it is idling it will seem to drop one cylinder and then come back on. All has been checked and I drive this truck about 12 miles round trip each day to work. About 3 miles in city and 3 highway. I let it warm up for about 5 minutes till temp gauge starts to go up then take off. New coil, cap, and rotor as well. Is my engine to much for a daily driver type deal with a little performance? Wondering if I have too much of a cam but it does not seem that big. Has a lope at idle but nothing rough.

Everything has all been checked and don't know what is causing my plugs to get fouled out over time. Pulled plugs today and they did not smell like gas but where dry but over time like I have posted else where before is clean on outer part but is always oil on the lower threads. Same thing happens on my other 350 as well but thats another story. This is on all eight cylinders and the engine is a fresh build from last summer and has about 2000 miles or a little more on it. Any suggestions on what to check and do? Motor had brake in period and motor was all blueprinted and built by myself and my dad who has built hundreds over the years.

Did a compression on the on cylinder the one time and had 160 psi at idle.

Thanks and sorry for long post.
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