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| Main Bearing Clearance | Rate Topic |
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| Posted: 05-19-2019 09:09 pm |
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1st Post |
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Dakota123 Member
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Finally back to my 2.2L build after detour into Audis for a few years... Just realized that different sources have different main bearing clearance specs. My Motorbooks International Jensen Healey Shop Manual says 0.00125-0.0025 in, while several sources online give 0.0005-0.0022 in. What say those that have been there? Asking because after moving shells around I’m pretty consistently at 0.001 in. Crank does spin easily just pulling with a pinky finger, and I’m aware of the different expansion rates, but the different specs are giving me pause.
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| Posted: 05-20-2019 02:39 am |
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2nd Post |
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redracer Member
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assume you used a plastigage for these measurements and all nuts were torqued down to specs? If so, you're in the standard 907 range for normal compression,but since I have no experience with the 2.2. maybe Tim Engel can weigh in here. Hello Tim?
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| Posted: 05-21-2019 07:43 am |
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3rd Post |
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Esprit2 Member
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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 |
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| Posted: 05-21-2019 02:29 pm |
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4th Post |
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redracer Member
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Thanks once again Tim; I'll print these "updates" & put them in my shop manual. Keep rolling!, bruce
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| Posted: 05-21-2019 04:25 pm |
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5th Post |
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Dakota123 Member
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Many thanks, guys. Strictly out of curiosity, any data, anecdotal or otherwise, on what running clearances open up to once up to operating temp?
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| Posted: 05-21-2019 04:45 pm |
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6th Post |
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Esprit2 Member
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Dakota123 wrote:Many thanks, guys. Strictly out of curiosity, any data, anecdotal or otherwise, on what running clearances open up to once up to operating temp? For bearing clearances, I have no idea... sorry. For piston to cylinder bore clearances: 1) With iron liners, the clearance closes-up/ gets tighter as the engine heats up (the aluminum piston expands more than cast iron liner). That's why the assembly clearances are rather loose for the iron liner engines. 2) The later "Nikasil" liners are really Nikasil "coated" aluminum liners. Since the aluminum pistons and aluminum liners expand at about the same rate, there is little change in clearances as the engine heats up to operating temperature. Therefore the Nikasil assembly clearances (piston to bore) are much tighter to start with. See Technical Data A - Engine (TDA) for the specs. Regards, Tim Engel Last edited on 05-21-2019 09:04 pm by Esprit2 |
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| Posted: 05-21-2019 04:45 pm |
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7th Post |
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Esprit2 Member
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TDA - Technical Data, A - Engine, Naturally Aspirated 907, 912LC & 912HC From the Lotus 1980-87 Service Notes (aka Workshop Manual) https://tinyurl.com/yxfsfvrl TDA Download a copy Although the 907 was out of production by the time the 1980-87 manuals were printed, its section TDA retro-actively covered the 907 with up-dated and more complete specifications. All 907 owners should have a copy of TDA. Just to highlight a couple of additional points that are not specifically covered in TDA... *~*~*~* The J-H manual calls for torquing the cam carrier fasteners to 18-20 Lbs-ft. That's too high, and leads to stripped threads in the cylinder head. Lotus manuals specify a torque of 14-16 Lbs-ft (1.93-2.21 Kg-m or 19-21.7 N-m). Use the Lotus torque spec. *~*~*~* All J-H and Lotus torque specs for the cylinder head no longer apply to the current composite head gasket and studs. Either upgrade to Lotus' later head studs and use the later torque, or upgrade to the current ARP studs & nuts and use ARP's torque spec. The current cyl head torques are higher, and will cause all original 907 head studs to stretch... both J-H and Lotus. All old head studs should be upgraded. While it is possible to use the current composite gasket with the old, lower torque specs (out of consideration for the old, weaker studs), doing so will not take advantage of the composite's gaskets superior capabilities. Either... 1) Upgrade to the later Lotus head studs (B907E0224Z), and use the Lotus torque spec for the composite head gasket. With the Goetze Composite gasket. Note that Lotus' revised torque spec calls for the use of a Torque Angle Meter, instead of the previously specified torque wrench. Cylinder head (tighten cold, oiled threads): i) 20 Nm (light initial load using a torque wrench) ii) + 75 Degrees (using a Torque Angle Meter, TAM) iii) + 40 Degrees iv) Wait 5 minutes v) + 20 Degrees Or... 2) Upgrade to the current ARP head studs & nuts, and use ARP's required thread lube and torque spec. 110 lbs-ft (15.2 kgf-m) All Studs, ARP Ultra Torque Lube applied to threads & washers. Note that both the later Lotus and current ARP torque specs WILL cause the original 907 head studs to yield and stretch. Don't go there. In all cases, start with the center pair of studs, and work out to the ends in a criss-cross pattern, as noted in all J-H & Lotus manuals. Regards, Tim Engel Last edited on 06-03-2019 09:25 pm by Esprit2 |
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| Posted: 05-21-2019 05:07 pm |
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8th Post |
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Esprit2 Member
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redracer wrote:Thanks once again Tim; I'll print these "updates" & put them in my shop manual.You're welcome. But if you have already copied it, I suggest that you re-copy it now. Nothing has really changed, but a few things that looked good at 2:00AM looked a little strange when I read them now. So I made a few editing tweaks. Regards, Tim Engel Last edited on 05-21-2019 05:08 pm by Esprit2 |
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| Posted: 05-21-2019 05:19 pm |
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9th Post |
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Dakota123 Member
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Excellent, thanks. I do have the ARP head studs - -10.5:1 CR (final, after the thicker gasket). Stripped a couple of carrier/head threaded holes once upon a time, figured that one out! Thanks again
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| Posted: 05-21-2019 05:26 pm |
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10th Post |
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redracer Member
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Already printed out the 12 pages from your link; will do the same for the remaining items. One peculiar note I'm sure many notice in the J-H Shop Manual was the torque for two the rear cam housing plate; showed as 18-20 lbs-ft that will definitely strip the aluminum((7-8 is standard for the 6mmX1.0 pitch). On another note, for all those rebuilding the 907s, the oil pressure relief spring was set at 55psi, which is way too low for a 7000rpm engine. You can shim the spring 6mm; the small flat washers that came on the cam cover bolts are a perfect size fro the aluminum cup holding the spring.
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| Posted: 05-21-2019 05:45 pm |
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11th Post |
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Esprit2 Member
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Oops... I should give up on writing technical stuff at 2:00AM. In message #7, I originally gave a URL to Section TDB (910 specs), and it should have been TDA (naturally aspirated 907, 912LC & 912HC). I've edited msg #7 with a new URL. 907 owners should have TDA. https://tinyurl.com/yxfsfvrl I previously posted TDB, https://tinyurl.com/y6236mbn, Sorry about any confusion. Regards, Tim Engel Last edited on 05-21-2019 09:18 pm by Esprit2 |
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| Posted: 05-21-2019 06:00 pm |
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12th Post |
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Dakota123 Member
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Fantastic, thanks for the note on the relief spring!
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| Posted: 05-21-2019 06:56 pm |
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13th Post |
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Esprit2 Member
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Have you ever read about Lotus carb, cam or ignition specs, and wondered what a "Spec" number meant, like Spec 5 or Spec 9? In TDA, pages 2 & 3, there's a chart that explains how to de-code the Lotus Engine Number format. Each row is a different car model, year or market, and the far right column is the "Technical Data Section Spec Number". The numbers in that column are 1 to 10, in numerical order, from top to bottom. Those are the Spec Numbers. On page 5, there's some cam application information, on pages 12 & 13, there's carb set-up data, and on page 14 there's ignition data. On those data charts, and elsewhere, the Spec numbers refer back to the model, year and market definitions given on pages 2 & 3. Spec 5 Dellortos? They're for the 1976-80 European 2.0 907 Esprit, Elite & Eclat. Spec 9 is for the 1980-onwards European 2.2 912LC Esprit, Elite, Eclat & Excel. Specs 2, 4, 6, 7 & 8 are 2.0 907 Federal emissions Zenith-Stromberg applications... changing as emissions standards got tighter and tighter. Now you know. Regards, Tim Engel Last edited on 06-03-2019 09:33 pm by Esprit2 |
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