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18711 "Miss Jensen"  Rating:  Rating
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 Posted: 09-21-2019 06:51 pm
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subwoofer
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From Tim Engel (Esprit2):







--Joachim

Last edited on 09-22-2019 10:12 am by subwoofer

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 Posted: 09-22-2019 10:13 am
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subwoofer
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Finally worked out the kinks of the photo posting, will go back and fix all the old ones soon.

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Joachim

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 Posted: 09-23-2019 04:10 am
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Esprit2
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Joachim,
Thanks for the help with posting the photos.

One more favor? Could you delete my one blank post, #120 on the previous page. Thanks.


Everyone,
Note that Joachim posted the higher resolution versions of the JPEGs that I forwarded to him. Not the <102kb versions I posted on the previous page. If you're interested in the images, then download the higher-Res versions Joachhim uploaded... above.

Regards,
Tim Engel

Last edited on 09-23-2019 03:38 pm by Esprit2

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 Posted: 09-23-2019 09:08 pm
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Michael,

When Lotus first stroked the 907 to 2.2 Litres, it picked up a roughness that hadn't been present with the short-stroke 2.0. That's not unusual... large displacement 4-cylinders to tend to shake a bit. Lotus tried a number of things to minimize the roughness/ vibration. Then, for what remaind after all they could do in the engine, they took two more steps.

1) The 4-seat models used a flex-plate instead of a flywheel. The same basic thing that's commonly used with automatic transmissions. The thin plate has enough flex in it to absorb much of the vibration that made it to the back end of the crank. The Esprits continued with conventional flywheels.

2) Lotus found that bolting the bottom of the clutch housing to the back/ bottom of the sump 'rigidized' the combined lump, significantly reducing vibration.

If you do go forward with installing a 910-based engine, it's stock sump will have two horizontal drilled-n-tapped holes in the rear face, but no J-H clutch housing will have matching bolt holes.

However, if you also upgrade to the Toyota W58 5-spd, and use the Lotus Excel's mating clutch housing, it will have the mating bolt holes required to make it all work.

Do you need this. No. There are a bunch of Jensen-Healeys with 2.2 Litre converted 907s, and you don't generally hear the owners complaining. But, "IF" you would appreciate a smoother running engine, then one small step in that direction is to use an Excel clutch housing with your W58 5-Spd.

Then, to shim the gap to zero, Lotus has two shim washers. One is a solid 0.020" thick washer (A911E1430F), and the other is a laminated brass (A082F6358F) with which you can peal off plies as required to achieve the correct shim thickness.

If you're going to 2.2 for low end torque and civilized traffic manners, then go all the way and use the Excel's crank (it's not cross-drilled) and flex-plate.

If you're going for maximum performance, then use the Esprit's, or Excel SE's cross-drilled crank, and regular flywheel.

Then balance everything that moves on an obcessive-compulsive scale.

Regards,
Tim Engel

Attachment: 00000008e - Bell Hsg & Sump Bolted Together - 97kb.jpg (Downloaded 95 times)

Last edited on 09-23-2019 09:12 pm by Esprit2

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 Posted: 09-23-2019 09:56 pm
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mgreaves wrote:
Update that is a 910 engine not a 920.. andMax_dvdt wrote:
We are in the process of fitting a 910 block+sumpGentlemen,
If you have a 910 already, then it's a good start. The 910's compression is 'turbo' low, so you'll need new pistons, but everything else is there, including a cross-drilled crank.

If you don't have an engine yet, then consider starting with a 912, preferrably a 912HC (high compression). That way it will come with useable pistons (LC = 9.44:1, and HC = 10.9:1). If you're dumping the 'turbo' anyway, and building a naturally aspirated engine, then the rest of the 910 - 912 differences aren't great enough to worry about for a street engine.

The late 910S is the ultimate 9XX 4-cylinder. It does have larger intake ports with improved shapes, and the intake valves are 1mm larger in OD. All the other/ earlier 910s have the same valve diameters as all the lesser, naturally aspirated 9XX engines.

All Turbo exhaust valves have sodium filled stems, which are larger in diameter, and require the otherwise same basic heads to be bored larger to accept the larger valve guides for the fatter stems. But sodium filled valve stems are not an advantage for a naturally aspirated engine, since they're not needed to deal with excessive heat; and the more slender, non-sodium filled stems are less distruptive and flow better.

A 912 would have the same wide Main Bearing Panel as the 910 (the only 'wider' part of the block ass'y) and matching larger sump. Block-ass'y strength is very similar.

Depending upon what your goals are for the build, a 910 and 912LC would come with two 107 cams, while the 912HC has one 104 cam on the intake, and a 107 on the exhaust.

No matter what the rest of your build goals are, buy a new set of steel, long-skirt tappets. The original chilled cast iron tappets tend to fatigue with age (iron does that), and they're all old by now. Also, it's not a good idea to run aggressive cams on the old cast iron tappets, regardless of their age.

Aggressive cams put more side thrust loads on the tappets, and longer-skirts help keep the tappets from cockng/ binding in their bores. Garry Kemp and JAE (and probably others) have aftermarket long-skirt steel tappets that are both better, and cost less than the Lotus cast iron tappets. They also have steel tappets with different crown thicknesses in order to compensate for re-ground cams.

Regards,
Tim Engel

PS... just to be clear:
910 = 2.2 Turbo.
920 = 2.0 Turbo.

Last edited on 09-27-2019 10:23 pm by Esprit2

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 Posted: 08-18-2020 08:26 am
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subwoofer
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Small update from the land of no updates. Miss Jensen has been a hangar queen for some time, but MoT is now done. Have run a few laps around red tape after my brake upgrade caused an MoT failure last year - thanks to updated MoT guidelines.

I have had to put the old brakes back on to have her registered under SVA rules instead of as a historic vehicle. Changes to regulations a few years back opened the door for modifications to SVA class vehicles, but because of idiotic bureaucratic red tape I had to rebuild to stock, have the car approved, then reapply the mods and have her approved again. Sigh. But it's almost there now, and it will not cause issues again.

A Megasquirt 3 and a set of Jenvey Heritage throttle bodies is a likely upgrade in a year or two. https://store.jenvey.co.uk/heritage/heritage-twin-tbody-40-48mm-pair-tdp40-48

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Joachim

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 Posted: 08-18-2020 08:28 am
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subwoofer
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And driving with the stock brakes? There is no comparison to the HiSpec upgrade. Wooden is a kind description of the stock system, can't wait to have the proper brakes back on her.

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Joachim

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 Posted: 08-21-2020 03:17 am
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gmgiltd
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I am very glad that cars over 40 years old no longer require MOT tests in the UK. Statistically cars over 40 years old were more likely to lead easy low mileage lives and have more attention lavished on them and the failure rate was very low.

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 Posted: 08-21-2020 05:52 pm
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noomg
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gmgiltd,

I'm glad to hear there's a little common sense being used in the UK. Unfortunately in California they still like harassing classic car owners.

I find the topic of old cars an interesting one. What's classic and what's just an old car? This applies not just to J/Hs or only Brit cars but all cars over say 20 years old. That's about where old cars hit a fork in the road. One way leads to just a driver, the other to classic car.

A driver is just that, transportation, it has no other value to the owner. As long as it's cheap and easy to maintain it stays on the road. At some point, say around 20 years, it becomes cheaper to buy a newer driver at which point our original driver usually winds up in a junkyard.

A classic on the other hand is loved by it's owner, who may be the original owner but usually not. It requires a commitment to keep a classic on the road, a commitment a driver owner is not willing to make.

This is why there are so few old cars on the road after a number of years, unless you love it, it's just not practical to keep on the road. That's why the ones you see on the road are well maintained and safe.

So it would be nice if Big Brother would get off our butts!

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 Posted: 08-21-2020 08:26 pm
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subwoofer
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One of the perks I had to give up by reclassing as a normal vehicle (rather than "preservation worthy" as is the literal translation) is that I will have to MoT her every two years going forward, rather than every five. But mods will be easy to get approved, I think the brakes will be good for 250-300bhp since she is so light.

The system seems rigged in favour of the people selling new cars, for a more modern car it does not take much to fail an MoT and the manufacturers seem to be doing their best to make sure any repairs are uneconomical.

On a more positive note, the refurbed steering rack really transformed the feel of the car. A lot more stable and much less the feeling of a boat with waves coming in from the rear quarters. Took a long time to get it back from Robey since they didn't have any LHD racks in stock and it turned out the condition was so deteriorated that they had to sacrifice another rack for parts. Oh well...

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Joachim

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