I started disassembly of my engine. I removed intake Timing cover Roller cam/lifters Heads When I pulled the heads, I was kinda surprised at how lean #1 and 3 were, and how black/rich #5 and 7 were. #2 4 6 8, seemed more even I had installed new NGK plugs when I put the roller in. I also re-installed my Stage 1 DP intake and Q-Jet The plugs in cyl #1 and 3 look clean, too clean #5 and 7 look poopy When I had the SP3 and AED 850, I don't remember this much of a difference in plug coloring. First pic is #1, #3 Second pic is #5 #7 Third pic is #2 #4 Fourth pic is #6 #8
It's strange, with a carb and stock intake on my old motor I always had an uneven mixture based off of spark plugs. Some were tan, others were sooty or rich. Compression test never showed any issues though. The new motor with SP3 and fuel injection, all spark plugs are showing an even tan to whitish color. I am still not totally happy with how the car runs but based off the plugs it seems at least consistent across all cylinders.
Yeah, I'm wondering if I was getting better/more even distribution with the SP3. After seeing what I saw, its going back on anyway
A good example of dual plane vs single plane is how poorly a tbi fuel injection system can run on a stock intake. Sometimes it works out fine but other times you are chasing issues with the tune that comes down to poor fuel distribution.
I'm far from an engineer, but when you look at a SP verses an DP manifold, the DP is much more convoluted. The SP seems like " Theres your mixture, suck it in" Simple analogy I know
I can't remember the full story, due to the long period of time involved here... Were those heads run with different iterations of the build? Single and DP intake, different cams? I would take a closer look at your plugs and ignore the mixture indications by coloring for now, as well as deposits in the combustion chamber. Your plugs might have signs of incorrect timing, heat range and/or detonation. I would also suggest comparing them to each piston/rod/bearing unit. Knowing the trends of the particular manifold you are using and looking at a bigger picture will help you this next time around. Good luck.
Good point! Its been a long story/journey for me, but its been a learning experience From what I recall, the plugs (NGK UR4) were all light tan upon removal before the roller install. Before the roller, I had the 413 cam with the SP3 and AED 850 After the roller I re-installed my Stage 1 intake and Q-Jet,and 8 new NGK plugs, drove it for maybe 6 miles, I heard what sounded like rods rattling when I accelerated, "whaaaaaaat" Got back home, and I heard the squeaking.
Before I do any full track runs with an unproven (to me) combo, I do some first gear runs to look at the plugs for heat range and timing indications. You can also put a couple of different types or ranges in just one bank for physical comparison. Different brands and types don't always show the same as what you'd expect from others' experiences or cross over from a chart. It's also a good idea to err to the cold side as it's much safer to deal with a low speed miss than an inaudible bearing destroyer. I think you get this better now that you are having to rebuild your engine. I also understand how frustrating it can be to have so many 'mechanics in your garage' and deal with many different views. Protecting your machine (investment) is priority.
