Lotus Elan

Engine Woes Advice Required......

PostPost by: mark030358 » Thu May 05, 2005 11:14 pm

Started my engine tonight after after a rebuild and I think I have a serious problem.

After first drowing all the valve gear in oil, putting a little oil in the bores, priming the oil pump, filling the filter with oil etc etc stared to crank the engine (with no plugs installed) to get some oil pressure. After cranking a while the gauge stared to register, perhaps 20 psi. By which time the fuel pump glass was full.

Then fitted the plugs, leads and cranked again. Engine started second crank, sounds really quiet BUT I have only 40 psi of oil pressure maximum on a cold engine (standard oil pump fitted). Other twin cams I have had with rebuilt engines registered far more than this. Anyway, ran the engine for about 10 minutes and the pressure started to fall, to about 35 psi. The engine fan did not cut in and the temp gauge showed no where near hot. The engine bottom and top end were built by probably "the most reputable twincam builder in the UK" (at vast expense) and the head was fitted by myself.

Does this seem reasonable given that a hot oil pressure should read between 35 to 40 psi. Any suggestions most appreciated.

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PostPost by: rgh0 » Fri May 06, 2005 9:23 am

40 psi cold is exactly right. The relief vavle is set on the standard pump to this pressure so it should not run higher when cold and should be between 30 and 40 psi at around 3000 to 4000 rpm when hot. Engines with a higher reading will have a pump fitted a high pressure relief valve spring but this is not needed in a road engine.

The racing high volume / high pressure pumps have their relief valve set at 60 psi.

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