The 408

The 377 motor, while a great deal for the price I paid, had 1 little drawback. The pistons in it were L2352 TRW forged units. Nice and strong, but with a 12.5cc dish, the compession ratio was only 8.3:1 (with 76cc heads). So in Spring of '99, when I decided to replace the pistons, I figured that it would be the right time to change the crankshaft back to a 400 crank as well. My new 400 crank is a stock GM cast crank std./std. The new pistons are Keith Black hyperuetectic flat tops with 2 valve reliefs. Here's what one looks like:

I stayed with the 5.7" rods, and the compression ratio is now 9.7:1. After breaking down the 377, I had the block cleaned and new freeze plugs and cam bearings installed. The block was also bored to .040" over (from .030" over). The whole rotating assy was also balanced. Other than that, the 408 used everything else from the 377. The cam I'm running has 210/216 duration @ .050". It keeps the computer happy, and works well with the 76cc iron GM heads. The heads are 441 castings w/2.02/1.60 valves, bowl ported.

Of course, the old 200-4R tranny wasn't very happy about all this. And it finally did start making some very bad noises. Although it must be pointed out that the old 200-4R did take a lot of abuse over the last few years. I'm shocked that it even lasted this long. I'm going to go with a turbo 400 over the winter.


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