Re: 4-7 swap cams?
Found this info on another site. Sounds like it could only do good?
V8 engines have paired cylinders. What this means is that you can take the firing order 1-8-4-3-6-5-7-2 and split it down the middle.
So you have 1843 & 6572. Now take the first digit of each set and they are a pair. 1 and 6 they are paired cylinders. Then take the second digit of each set, which means 8 and 5 are paired cylinders and so on.
What this means is that when 1 is at TDC (top dead center or at the top of the bore) then 6 is in the same position. The difference is that that one is ending the compression stroke while the other is ending the exhaust stroke.
Now when you by 4/7 cam it swaps the two cylinders in the firing order. The reason for this is that the engine is supposed to run smoother. Also it is easier on the main bearings and the crank because the loads of the crank are more evenly distributed. It is supposed to also assist in flattening the torque curve.
Look at the firing order. 18436572. Now look at a crankshaft. It has 4 journals, each with 2 rods on it. The 1 & 2 rods are on the same journal; likewise, 3 & 4, 5 & 6, and 7 & 8 are all "pairs" on journals. 1 fires immediately after 2; 3 immediately after 4; and 5 immediately after 6. That means, each of those 3 journals, gets 2 shots of power applied to it in rapid succession. The 4-7 swap fixes ONE of those 3 instances of successive firing on the same rod journal. There are still 2 of them. Note that the 4-7 one is right between the other 2. Eliminating that one allows the crank to return to torsional "rest", so to speak, and helps keep from breaking.
The 5,7 fuel distribution was in succession of each other and the #5 cylinder supposedly robbed fuel atomization from the #7 cylinder on open plenum/single plane intake manifolds.
69 Z/28, red/white stripe, black houndstoot with docs.