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Hi all,

I have a 1982 e21 315. I've just fully rebuild the engine. The cylinders were overbored from the stock 84mm to 87mm. The stroke was increased from 71mm to 84mm (s14 crank). It's also got the S14 144mm connecting rods. Both the head and block have been decked 4 thousands of an inch. It has custom forged pistons from IE for 10.5:1 compression ratio. It's got 2 dcoe 40 carbs running an IE intake manifold, Schrick 292 cam, TEP headers Ansa sport exhaust. When it was new it made 74 bhp and top speed was 154 kph, 96 mph. Before the rebuild with just the cam intake carbs and exhaust the power went up to ~ 112 bhp and top speed was 183 kph. Now though it makes no power, can barely get to 110 kph. I've played around with the cam timing and ignition timing to no avail. I'm currently stumped as to why it makes so little power. If anyone has any ideas it'd be welcome.

Cheers!

First thing that came up to me is whether the crankshaft was in TDC when you installed it, the cam should be installed exactly like it is supposed to be with the markings.

Have you checked compression? That would be the easiest for now. I recently rebuild an M10B18 out of an E30 and I ended up with over 11 bars of compression, where the spec should 1:10.5 be.