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 Posted: 06-29-2022 11:13 pm
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S2artJH
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Joined: 06-29-2022
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Recently purchased a 1974 JH Mark II. NOW I begin to learn about the marque; lots of questions:

1) It has 225-60 R15 tires, definitely not the stock (Owner's Manual) size. What pressure should I run in them?
2) Recommended oil for Southern California weather?
3) Servicing (WHERE??) for the not-to-do-yourself type of work; I am in Anaheim, Orange County (Disneyland area)?
4) Recommended part numbers for consumables (points, plugs, rotor, cap, etc.) if available from local vendors like O'Reilly's/Auto Zone (I am aware of Delta, Martin Robey).
5) Below 2200 RPM's it "burbles" and doesn't smooth out 'til up to 2700+. Carb rebuild needed?

'nuff for now
Stuart (aka S2art, S2)
write2stuart@hotmail.com

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 Posted: 06-30-2022 04:08 pm
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noomg
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Stuart,

Congrats on your new (to you) car, they are wonderful unappreciated cars, hope you like it. In answer to your questions:

1) Factory psi (24/24) should be fine while the tires are bigger they're still supporting the same weight.
2) What else the classic sportscar oil Castrol GTX 20/50.
3) Most guys do their own work since it's not easy to find a Jensen-Healey dealership. The closest place I know of is an all makes British service shop in San Pedro.
4) About the only things you'll find for a J/H at a local A/P store are spark plugs, an oil filter and maybe a fan belt.
5) Going to need a little more info on this one; what kind of carbs, when were they last serviced or rebuilt (if ever)?

Don't expect much help from your local A/P store, the average clerk has not only never seen a J/H, they've never even heard of one!

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 Posted: 07-05-2022 07:47 pm
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Esprit2
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1) The tires are clearly not the factory size. Do you intend to stick with them, or drop back to something closer to stock? A bit off topic, but I used to autocross two Lotus (4-seat Eclat and 2-seat Esprit S2) and a couple of Toyota MR2 Mk 1. I ran 225/50x14s all the way around on each of them.

My humble opinion, but...
At low pressures, like 22-24psi, the wide tires started to feel like marshmallows, and the car's handling felt like it was connected to the road via rubber bands. Turn the steering wheel and wait for something to happen. Wait for it... it's coming. The ride was good, but the handling was not 'sporty'.

For autocross, I used a tire pyrometer to monitor tire temperatures, and checked all four tires immediately after each run. Optimum pressures would vary with the weather/ temperatures, and the type of course; but typically ran around 41-42 psi.

Those auto-X pressures were too high for the street, producing an uncomfortably harsh ride.. So I'd compromise between marshmallow and auto-X, and usually set the street pressures at 28-30 psi for normal driving. If I was planning to go for a drive on the twisty roads, I'd bump the pressures up a little, to 30-34... 'depending'.

There's no one correct pressure, and what's right for you will be a combination of your car's set-up, and your driving style. Where are you between 'spirited' and 'milquetoast'? 225mm wide tires on a J-H doesn't imply milquetoast.

2) The recommended viscosity oil is __W50, with __W60 being a nice option if you can find it. The number to the left of the 'W' is more negotiable. Lotus & Jensen recommended 20W50, and that's a great choice. But some modern oils offer options like 15W50, 10W50, 0W50, and 10W60. All would be acceptable viscosity options, as long as you choose a quality, HIGH ZDDP oil. And keep the number to the right of the 'W' at 50 or above.

The 907's design process started in the late 1960s. 'Old' technology. It uses ordinary metals (aluminum, iron, steel, some brass), with no modern anti-wear treatments or coatings. Like most engines of the time, it relies heavily upon a high level of Phosphorus in the oil to provide anti-wear protection. Modern low-Phosphorus oils are NOT APPROPRIATE, do NOT use them!!

You want a bare minimum of 1200 ppm (parts per million) of Phosphorus in the oil. Most oils use ZDDP to add phosphorus... Phosphorus is the 'P' in 'ZDDP'. Since phosphorus is only one part of ZDDP, it takes more than 1200ppm ZDDP to deliver the required level of phosphorus... typically 1300ppm ZDDP to deliver 1200ppm phosphorus... depending on a lot of variables. And 1200ppm of phosphorus should be your target minimum.

1200 ppm - Mobil One 15W-50.
1300 ppm - Valvoline VR1 20W-50 Racing Oil
1300 ppm - Mobil One 10W-60 'Extended Life' (not sold in USA).
1400 ppm - Brad-Penn 20W-50 'Penn Grade' (hard to find).
1600 ppm - Mobil One 20W-50 V-Twin Motorcycle oil.
1750 ppm - Mobil One 0W-30 & 0W-50 Racing oils.
All the above oils, even the Boutique "racing" oils, contain full street additive packages, so they're safe to use for normal long change intervals.

Back in the day, when the 907 was in production, Mobil 1 had a 20W50 full synthetic motor oil that contained 1600ppm phosphorus. When modern oil standards (like the API standards) reduced the allowable levels of phosphorus, Mobil 1 210W50 could no longer be certified as an 'automotive' oil. So Mobil simply re-labeled it as a 'motorcycle' oil. It's the same great stuff, still has 1600ppm phosphorus, you just need to shop in the motorcycle aisle.

Many modern 'Racing Oils' are not really "racing" oils. I call them boutique racing oils. They still contain a full compliment of the required 'Street' additives that are required for long oil change intervals, so they're appropriate for street use. They are a more sporty oil company's way of putting high-phosphorus oils into the hands of serious car guys. Sports cars, street rods, autocrossers... etc. The Valvoline and Mobil One racing oils mentioned above contain full additive packages, and are appropriate for street use.

4) Recommended part numbers for consumables (points, plugs, rotor, cap, etc.) if available from local vendors like O'Reilly's/Auto Zone (I am aware of Delta, Martin Robey).

Did the car come with the J-H Workshop and Parts manuals? If not, youi should get copies.

Delta Motorsports has you covered. JAE is a Lotus specialist near you, and they also take care of J-H as far as the engine is concerned.

In general, the Lucas distributor is similar to those used in most Britcars of the day. Each application had specific advance curves, etc required by a given engine, so a distributor for 'that engine' would have a unique 'Despatch Number' (ie, part number). But for general service & repair parts, like points, rotor, cap, they would be the same as used on many Britcars. Ask for the MGB part... it will fit.

The Lotus 907, 910, 911 & 912 engines (the 9XX family) are the only engines that mounted the Lucas distributor horizontally. In order to prevent oil leaks 'thru' the distributor, Lucas added an internal lip seal to the distributor. If you try to order a replacement, NO MG, Triumph, Britcar parts supplier will know what you're talking about. Delta and the Lotus parts vendors will know, and they stock the seal.

Oil Filters for ALL Lotus 907 engines.
Lotus . . . . . . . . . . . C907E6000F All Esprits
Coopers . . . . . . . . . Z29A
Coopers/Fiaam. . . . . FT4883
Baldwin. . . . . . . . . . B163
K&N . . . . . . . . . . . . HP-2004 (big, it's a tight fit)
Lucas . . . . . . . . . . . F5534
Mann. . . . . . . . . . . . W712/38
Mobil-1 . . . . . . . . . . M1-204 Full (standard) Size
Mobil-1 . . . . . . . . . . M1-102 Small Size
NAPA Gold. . . . . . . . 1307 Full Size
Purolator Pure-One. . PL20081
Wix. . . . . . . . . . . . . 51307 Full Size
Car/ Engine Application Cross-Refs
Chrysler. . . . . . . . . . 2.2 4-Cylinder
Ford V8 . . . . . . . . . . 289/ 302/ 351 Windsor
Ford V6 . . . . . . . . . . 2.8 Liter (USA models, Mustang II etc)
Ford L4 . . . . . . . . . . 1.6 / 2.0 / 2.3 (USA applications)
Ford / FoMoCo . . . . . DIRY-6731A
MG . . . . . . . . . . . . . MGB / MGB-GT
Range Rover, 1994 . . Classic
SAAB. . . . . . . . . . . . 99 / 900 / 9000
Volvo. . . . . . . . . . . . All Volvo gas engines (except 850)
All have the req'd Pressure Relief Valve & Anti-Drain Back Valve.

5) Below 2200 RPM's it "burbles" and doesn't smooth out 'til up to 2700+. Carb rebuild needed?

Which carbs are installed?

225 tires are pretty sporty, and not stock. So, what else about the car is not stock/ high performance? Are the cams 'hot', hotrod replacements, or stock? Which carbs are installed, and how are they set-up/ jetted??

IF the engine is bone stock, the engine should have a smooth idle. Start by checking the cam timing and ignition timing. If all is normal/ correct, then turn to the carbs.

Modern gas/ petrol containing ethanol will 'go bad' and produce jet-plugging varnish deposits in as little as 2.5 months. If the car has sat idle a lot, and the gas has been allowed to 'go bad' in the system, then the carbs may need a general cleaning. At a minimum, clean the jets.

If the carbs are clean, then I'd start by checking the 'balance'. An engine with perfectly jetted carbs will run like crap if the carbs are out of balance. Now you're back to 'where do you find a shop' that understands carburettors. I can't help you there. But I'd start by calling JAE (they're not far from you), and ask them if they know of any shops in the area that know the Lotus engines/ carburethors, etc.

This forum is a great resource for J-H owners. However, you need to take some basic steps toward preparing yourself to take care of the car. I'd say that step one will be to buy the manuals, and get familiar with them. The early J--H manuals were pretty short on details, and contained some incorrect specs. Plus, things have changed in the last ~50 years, but the J-H manuals have never been updated. Therefore, you would also be wise to pick-up copies of the later Lotus manuals. I'd recommend the 'Engine - Section EA' and the 'Tech Data Section A (TDA) from the 1983-87 Esprit S3 & Turbo Esprit Service Notes (aka, workshop manual). TDA will also include updated torque specs.

The original head gasket was deleted/ replaced in 1993. The new, composite head gasket is torqued to a new, higher torque. Higher than the original head studs can tolerate... they will yield. If the head ever has to come off, upgrade the head studs to the later Lotus parts ('B' prefix part number), or to the popular ARP aftermarket studs. Both of which require higher torque specs. Different... one torque for the later Lotus studs, and a different, higher torque for the ARP studs. One thing that is guaranteed... the original J-H head studs and torque won't work... UNLESS you find an original early head gasket sitting on a shelf somewhere... NOS.

Regards,
Tim Engel

Last edited on 07-11-2022 06:48 am by Esprit2

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