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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,267
Take a digital infrared themometer with lazer dot aiming pointer and take a temp reading of the header primary tubes just below the heads at idle and you'll find #2 and #5 run alot hotter than the rest. Like close to 100 degrees hotter sometimes.
They go on sale at harbor freight tools for $25 with a coupon sometimes and work really well.

At idle I don't think there's enough air movement through the intake manifold to make any difference in air flow to the different cylinders so it seems to me 2 and 5 run hotter because they are air cooled and in the middle of each bank with hot cylinders and heads on each side and joined together on the top surface by the cam tower that is mostly oil cooled from the inside.. a good reason to never install oil restrictors in the cam tower oil line fittings.
At higher rpms it's possible 2 and 5 do get more intake air through the intake manifold and run a little leaner than the others.

Have you removed the spark plugs after driving and seen a difference in the color or possible oil deposits? Thats better than trying to judge AFR mixtures from the insides of the header primary tubes.

Try a compression and leakdown test to see if compression is relatively even and you could move the injectors around to different cylinders.

Check individual spark plug wire resistances with an ohm meter and check to see if ignition timing from the distributor is stable while running with a timing light on different spark plug wires.

edit: What headers are those? They look like GHL with the heat exchangers removed. The collector design looks really poor and it appears the port sealing rings that go up into the exhaust ports are missing on one and two but maybe thats just black carbon soot making them hard to see.

Last edited by JFairman; 11-16-2011 at 06:14 AM..
Old 11-16-2011, 06:06 AM
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