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| Joined: | 03-12-2005 |
| Location: | Kingman, Arizona USA |
| Posts: | 532 |
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If the temp gauge is reading much less than it should, you could have fuel boiling in the carburetors. Measure your fuel pressure at the carbs when the problem occurs, it should be 2.5 psi or so. OEM fuel pumps sometimes quit once they get hot. Install a new ignition condenser, these are sometimes heat sensitive. Try a different coil and ballast resistor, these too can cause problems when hot. Check your centrifugal advance when the problem occurs, sometimes the mechanism can stick when it warms up.
Normal oil pressure once everything warms up, using 20W50 oil, is a minimum of 5 psi at 1000 rpm idle, and 30 psi at 3000 rpm. Full warmup takes about 15 minutes in very clement temperatures, and much longer if the outside air temperature is low.
You have to pull the crankshaft's fan belt pulley to slip a timing belt on or off the crankshaft gear. It is highly prudent to do this first. Next, set the crank about 45° before TDC, then mark the aligned teeth on the two timing gears with a permanent marker so you'll have a reference point in case either gear is disturbed during the belt change. This moves all four pistons well down in their bores, so as long as you don't turn the crank you can't possibly have the valves impact the pistons. During reassembly, static timing will be set after you return the crank to TDC and make sure cam timing is correct.
For the oil pump, there are three clearances: (a) the clearance between the flat face of each of the rotors and the cylindrical oil pump cavity, with the rotors in contact with the aux. housing; (b) the minimum clearance between lobes of the innter and outer rotors, and (c) the clearance between the outside of the outer rotor and the walls of the cylindrical cavity in the oil pump.
Of these, clearance (a) is the most important. Its spec is 0.000,5" min, 0.001,5" max, and the pump WILL FAIL (lose the ability to prime itself) soon after this clearance reaches 0.004" or so. In practice, this means the rotors protrude from the pump housing by the pump gasket thickness less the clearance spec. You can determine this protrusion with a feeler gauge and a straight edge across the rotors. ONLY Lotus' plastic gasket (also sold by Delta Motorsports) will work here.
It's my understanding that clearance (b) determines the pump's ability to produce oil flow. Clearance (c) seems to affect the pump's peak pressure and isn't quite as important as (b). Both of these can be 0.002" or 0.003" over spec without causing major problems. Since pump rotors are very expensive, this is a good thing.
Somewhere in there you ought to discover clues to whatever ails your car. That's usually the hard part.
Last edited on 12-18-2005 03:58 am by Mark Rosenbaum