I used just two straight 14mm wrenches when I adjusted my valves for the first time, this past week. I can see where the bent wrenches would work a little better, but I got along fine with my regular wrenches. Of course, I had the injector lines off, as I had removed them to get easier access to the glow plugs. With the injector lines on, it would be tougher with the normal, straight, wrenches.
Jim

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1979 Mercedes 240D (Sold to a neighbor last year,now I have room for a new one,looking for a 300D this time)
1980 Mercedes 240D(bought for a parts car, but I have fun driving it!)