Rebuild engine

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joshuacarney
Newbee
Posts: 1
Joined: Mon Feb 13, 2023 11:39 am
My E21(s): 79 US 320i manual

Rebuild engine

Post by joshuacarney »

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.


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BertjeConti
E21 Mad
Posts: 3007
Joined: Mon Nov 04, 2013 9:49 pm
My E21(s): E12 520-6
Location: nederland , Weert

Re: Rebuild engine

Post by BertjeConti »

I'd suggest to do a compression test at first and go from there
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Megasquirted '77 E12 520-6

Aspen Silver '96 E39 523i
Wilmo
E21 Mad
Posts: 1917
Joined: Thu Jun 30, 2011 8:35 pm

Re: Rebuild engine

Post by Wilmo »

Yep, compression. Then valve clearance, then cam-timing, then ignition. Not playing around, but adjust it to the base setting.

When that all is ok, check for leaks, lost sparks etc. After that, go to base settings of the carbs and check the CO.
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