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 Posted: 05-21-2019 07:43 am
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 575
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Crankshaft Journals & Balance

Main Journals:
63.487 - 63.513 mm (2.4995 - 2.5005 inch) Outside Dia, #1, 2, 3, 4
63.500 - 63.513 mm (2.5000 - 2.5005 inch) Outside Dia, #5 Only
0.508 mm. . . . . . . . (0.020 inch). . . . . . . . Outside Dia, Max Undersize for Regrind, Limit

0.0127-0.08128 mm (0.0005 - 0.0032 inch) Static Clearance, Mains <<<<<<<<<<<<<<<<<<<<<<<<

34.06 - 34.16 mm (1.3409 - 1.3449 inch) Width, #5 Main Journal, Standard

Rod Journals:
50.736 - 50.762 mm (1.9975 - 1.9985 inch) Outside Diameter
0.0254 - 0.08128 mm (0.0010 - 0.0032 inch) Static Clearance, Rods

V-Pulley Journal, Front,:
35.014 & 35.020 mm (1.3785 & 1.3787 in) Outside Dia, "measured" 2 cranks
41.377 & 41.605 mm (1.629 & 1.638 inch) Length, "measured" 2 cranks

Main Seal Journal, Front:
51.765 - 51.867 mm (2.0380 - 2.0420 in) Outside Dia, Lotus Engineering Spec
26.670 & 26.695 mm (1.050 - 1.051 inch) Length, "measured" 2 cranks

Main Seal Journal, Rear:
101.24 - 101.27 mm (3.98583 - 3.98701 in), Outside Dia, Lotus Engineering Spec

End Float:
0.08 - 0.20 mm (0.003 - 0.008") Spec Dimension
0.30 mm . . . . . (0.012") Service Limit

Thrust Washer "Thicknesses", All 9XX 4-Cyl:
This is UNofficial. The Standard size thrust washer's thickness was measured by me. Then all other thicknesses shown are their 'Plus' thickness added to the measured Standard thickness. (ie, 0.0925" + 0.0025" = 0.0950")

Standard = 0.0925" (2.3495 mm) A907E1000ZB, Measured
+0.0025" = 0.0950" (2.4130 mm) A907E1001ZG, 0.0925" + 0.0025" = 0.0950"
+0.0050" = 0.0975" (2.4765 mm) A907E1002ZA
+0.0075" = 0.1000" (2.5400 mm) A907E1003ZF, All Lotus Part Numbers
+0.0100" = 0.1025" (2.6035 mm) A907E1004ZL
+0.0150" = 0.1075" (2.7305 mm) Dave Bean Engineering, Special, US$12.99

"IF" you convert to a cross-drilled crank, you must also use the revised main bearing shells that go with that crank. Do NOT use the standard main bearing shells that are for "907 NON cross-drilled" cranks.

15 gr-cm (0.2 oz-in) Balance - Crank, Flywheel & Clutch

*~*~*~*~*~*~*~*~*~*~*

While I'm on a roll, most of the following specs are NOT published in any J-H or Lotus manual, so save them. I got them from Lotus Engineering.

Cylinder Block & Main Bearing Panel (907, 911, 910 & 912)

Main Bearing Bore in Block:
Standard Bore Inside Dia:
67.6961 / 67.7164 mm (2.6652 - 2.6660 inch, 2.66560" Ave) Lotus Esprit
67.7037 / 67.7164 mm (2.6655 - 2.6660 inch, 2.66575" Ave) All Others

+0.015" Oversize Bore Inside Dia:
68.0771 / 68.0974 mm (2.6802 - 2.6810 inch, 2.68060" Ave) Lotus Esprit
68.0847 / 68.0974 mm (2.6805 - 2.6810 inch, 2.68075" Ave) All Others

Lotus introduced a new, composite cylinder head gasket in Jan 1993. It's compressed thickness is 0.50mm (0.0197") greater than the original steel-asbestos-steel gasket. That effectively raises the cylinder head by that same amount, and reduces the compression ratio by approximately half a point... ie, 8.4:1 becomes 7.9:1. Either...

1) Live with it,
. . Or...
2) Deck the block by a similar dimension, and seat the liners that much deeper into the block in order to preserve the spec 'nip' (ie, the liner's exposure above the block deck).
. . Or...
3) Order new pistons with 0.5:1 more compression than you're really targeting.

*~*~*~*
IRON Liner Fit to Block:

Liner:
101.360 - 101.384 mm (3.99055 - 3.9915 inch, 3.9910" Ave) Iron Liner's Spigot OD
. 69.825 - . 69.850 mm (2.7490 - 2.7500 inch, 2.7490" Ave) Iron Liner's Depth to Flange
Datum = From top of LINER deck to the seat step

Cylinder Block:
69.723 - 69.774 mm (2.7450 - 2.7470 inch, 2.7460" Ave) Block's Liner Seat Depth
Datum = From top of BLOCK deck to the seat step.

101.397 - 101.448 mm (3.9920 - 3.9940 inch, 3.9930 Ave) Block's Liner Spigot Bore ID
0.013 - 0.088 mm (0.0005 - 0.00346 inch) Clearance, Iron Liner to Block Bore.

*~*~*~*
NIKASIL Liner Fit to Block: (really a Nikasil "coated" aluminum liner)

Liner:
102.349 - 102.400 mm (4.0295 - 4.0315 inch, 4.03051" Ave) Nikasil Liner's Spigot OD
. 69.750 - . 69.780 mm (2.7461 - 2.7472 inch, 2.74665" Ave) Nikasil Liner Depth to Flange
Datum = From top of LINER deck to the seat step.

Cylinder Block:
. 69.723 - . 69.774 mm (2.7450 - 2.7470 inch, 2.74600" Ave) Block's Liner Seat Depth
Datum = From top of BLOCK deck to the seat step

102.42 - 102.47 mm (4.0323 - 4.0343 inch, 4.0333 Ave) Block's Liner Spigot Bore ID
0.020 - 0.120 mm (0.00079 - 0.0047 inch) Clearance, Nikasil Liner to Block Bore.

Regards,
Tim Engel

Last edited on 06-03-2019 09:21 pm by Esprit2