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Max_dvdt Member
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I have a 910 conversion underway - This requires two tweaks to the front subframe: A) the passenger (US) outrigger needs relieving B) there is a contact point on the drivers engine mount structure. C) I suppose a third issue is that the drivers 907 engine mount interferes with the new girdle. The question today is how do I remove the outrigger (the thing with the yellow paint) I've undone the bolt thru the front suspension lower arm, the bolt thru the steering rack, the frame bolt and the huge lower control arm bolt but this thing seems glued on... Thank you... Attachment: Front subframe2.jpg (Downloaded 199 times) Last edited on 09-02-2019 05:22 am by Max_dvdt |
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Brett Gibson JH5 20497 Member
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My understanding is that it is not removable short of cutting it off. Brett. |
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Esprit2 Member
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Correct... the Sawzall wrench. A 910? As in Turbo? What is your plan for the turbo location and plumbing. In the Esprit, the turbo is located behind the cylinder head, where the J-H's cowl is. And the 910's exhaust manifold is shaped to put it there. A rare Brazilian car, the Emme 422T, used the 910S engine. It had a bespoke exhaust manifold that put the turbo down low and forward. When Emme went out of business, a lot of Lotus guys bought distressed inventory crate motors. The Emme exhaust manifolds were no good to them, so most were scrapped... a few went on shelves. Regards, Tim Engel |
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Max_dvdt Member
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Sorry Tim - not a Turbo... its a 910 block from Gary Kemp with a 2.4 stroker crank Gary made a slight oops and I ended up with a set of Turbo pistons which when I get to that bit will not give me the compression I want- so for about 30 minutes I entertained a supercharger.. but decided in the end to have a set of custom pistons made (path of least resistance) What I bought: the 2.4 crank some billet con rods the turbo pistons and nikasil liners easiest path I see is to just get some custom pistons. I'm guessing that between the crank and conrod billetyness and the nikasil liners a set of stock pistons wont work |
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Esprit2 Member
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The modern composite head gasket has a crushed thickness that is about 0.5 mm / 0.020" thicker than the original steel-asbestos-steel laminated gasket. That raises the head further off the block by that same amount, reducing the compression ratio by about half a point (8.0 becomes 7.5). When the Goetze composite gasket was introduced in 1993, Lotus started machining the block decks lower by that same 0.5 mm / 0.020" in order to preserve the 'spec' compression ratio. But when the gasket is used on engines built prior to 1993, they loose half a point of compression. If you're going to order custom pistons, specify a compression ratio that's half a point higher than you really want. Alternatively, you can have the block's deck cut that much lower, and then cut the liner seats lower in order to preserve the correct 'nip'... ie, the liner's stand-out above the block deck. *~*~*~*~* Replace the studs in the block that retain the head. The new gasket requires a higher torque spec that exceeds what the studs can handle... they will yield. Either install the later upgraded Lotus studs, or the ARP studs that are sold by most/ all Lotus parts vendors. For identification... The original 907 studs have flat upper ends. The upgrade 907/ 9XX studs have a depressed dimple machined into the upper ends. IF you keep the original 907 studs, then you have no choice but to use the original Lotus torque spec so as not to yield the studs. But that low torque will not take full advantage of what the composite gasket offers. Note that the torque spec given in the Jensen-Healey Workshop Manual is too high for both the original studs and the original steel-asbestos-steel gasket. Mostly the gasket... it would crush, leak again, and you'd be right back where you started. Lotus reduced that spec to: 70 lbs-ft ( 9.7 kgf-m) Front & Rear Pairs. 75 lbs-ft (10.4 kgf-m) Three Middle Pairs. Oiled threads & washers. ... but the J-H manual's torque spec was never updated. But then, the original gasket is no longer available. Regards, Tim Engel Last edited on 09-05-2019 08:09 pm by Esprit2 |
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Esprit2 Member
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Have you talked with Gary Kemp about the pistons you have and the compression they will produce? The stroker crank's longer stroke would normally drive any stock pistons too far up the bore, and they would hit the head. To prevent that, either the rods need to be shorter, or the wrist pin bores must be higher up on the pistons (Lotus did that between the 2.0 & 2.2), or a combination of both. It's possible, that the low compression Turbo pistons would have created a 'high performance' compression ratio with the appropriate length rods on the long stroke crank. If you do pursue custom pistons, then know before you order just what wrist pin height is required in order to work with the 2.4 crank and whatever the length of the new rods is. All that comes first. Then allow for the loss of compression due to the thicker composite gasket. What vintage is the 910 block you have? If before Jan 1993, then it has the old, higher deck height, so the composite head gasket will lower the compression ratio about half a point. If the block was produced after Jan 1993, then the deck height was cut 0.5mm / 0.020" lower to allow for the thicker composite gasket. All that needs to be coordinated in order to successfully build a composite engine out of a mixed bag of parts. The easiest 'out' would be for you to put the Monkey on Kemp's back to provide you with the correct pistons to work with everything else he has already sold to you. Regards, Tim Engel Max_dvdt wrote: Sorry Tim - not a Turbo... Last edited on 12-31-2019 03:50 pm by Esprit2 |
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noomg Member
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Tim, Wow, I'm continually stunned by the content of your posts. You sound more like a Lotus engineer than a Jensen-Healey hobby guy like the rest of us. It sounds like you do a lot more with Lotuses than the Jensen-Healey. Having owned a '62 Super Seven I can appreciate the addictive nature of the Lotus. |
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Esprit2 Member
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Well, I am an engineer, but I never worked for Lotus. As a car guy, I'm a Lotus fan first... I have been since I was a kid, and that was many decades ago. I like the Jensen-Healey, and it's on my bucket list. However, there is also a long list of other Lotus cars that I've not yet enjoyed, and a JH is in line behind them. At my age, it's now unlikely that I'll ever get around to a JH. I hang out on JHPS and other JH sites because of the Lotus engine. I try to help owners with it, and provide information that was never included in the original JH Workshop Manual. The 900-Series 4-cyl engines remained in production for 20 years after Jensen closed it's doors. There is a lot of information and 'common knowledge' about them in the Lotus world that seems to be ignored in the JH world. Where I live, there have been enough JH around to have been the core for a local club, but it never happened. JH owners usually joined the local Austin-Healey club just to be part of the "Healey" social family, but none of the AH guys know anything about the Jensen-Healey. So some of the JH owners have joined our Lotus club in order to get tech support for the engine. That's how I got started helping JH guys with their 907s, and my activities just expanded as JH forums popped up on the internet. Regards, Tim Engel Last edited on 12-31-2019 03:45 pm by Esprit2 |
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noomg Member
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Tim, I can see why the J-H would be at the back of the line since Chapman never made a car that wasn't cool, however you might consider moving it up just by virtue of the fact that the J-H is going to be easier and a lot cheaper to acquire than just about any Lotus. I've always had a thing for the Éclat since I saw one on a dealer's showroom. Unfortunately they're extremely hard to find and from what I've heard they have a really scary rust problem in the rear chassis. As far as the club thing goes, you might suggest to the local J-H guys instead of a club just have a monthly get together for beer and piazza and bull, that's all our club meeting really is. Usually 4 or 5 J-Hs show up along with 2 or 3 other guys who like Healeys. |
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Esprit2 Member
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The Jensen-Healey isn't at the back of my list by any means, it's just not at the absolute front. And I don't have the resources to indulge in everything I want. I have two Eclats, an Esprit S2, and a 1400 lb Europa S2. The interesting thing (at least to me) is that the 4-seat Eclat actually handles better than the Esprit S2 of the same period, and the Esprit no slouch... far from it. A 4-seater might not be as 'sexy' as a mid-engine 2-seater, but it's sure a delight to drive. The turn-in, transitional handling and steering feedback are absolutely brilliant. Chapman liked being seen in the Esprit, but he preferred driving the Elite, Eclat & Excel 4-seaters. My hands-down favorite, and my daily driver between road-salt seasons, is the Europa. The Seven might beat it for that ultimate raw sports car experience, but by comparison, the water-tight coupe Europa is a practical every day car... until the snow flies. Like now... :-( I've driven several friends' Jensen-Healeys rather briskly, and I think it's the best handling/ most comfortable example of all the tradional British roadsters. And while the 907 is one of the smallest engines of the breed, it's also one of the more powerful... or has the greatest potential for more power. Yes, by 'JH Club', I wasn't really thinking there were enough local JH owners to form a 'big' club with a mission statement and events schedule; but there's a lot to be said for having a few 'like minded' friends with whom you can share your car-passion. They had that much covered, but never pulled it all together. Regards, Tim Engel Last edited on 03-05-2020 08:10 am by Esprit2 |
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noomg Member
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Wow, that's a lot of Loti. Do they just keep following you home? The funny thing is when I owned my Super Seven back in the '70s just about everybody thought it was a VW kit car. |
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Esprit2 Member
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They not only follow me home, they move in. I've sold three, so it's not like I'm totally without restraint... but I'm weak. Tim Last edited on 01-05-2020 05:46 pm by Esprit2 |
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Max_dvdt Member
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Just to resurrect this posting - Engine Guy is almost finished the head so we are back to thinking about this problem. Our plan is to let Garry Kemp off the hook - we will assemble the engine parts we have - and then measure the dish we need on the pistons to give us close to 9.5. then get a set of custom pistons and have them nikasil'd The rods are the shorter 136mm style and we have the turbo pistons as a guide for the piston maker And yes We have the ARP stud/bolts full kit |
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Esprit2 Member
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MAX_dvdt wrote: > The rods are the shorter 136mm style The aftermarket 136mm long rods are required in order to make the longer-stroke, 2.4 Litre, aftermarket crank fit without jambing the pistons up against the head. Those short rods are NOT OEM-Lotus, and most related Lotus specs do not apply. So, if you haven't done so already, GET all the specs you can from Garry Kemp... including rod cap bolt torque. The stock-OEM rods are 139.7 +/- 0.0254 mm (5.500 inch +/- 0.001") long, center to center. Regards, Tim Engel Last edited on 03-05-2020 10:09 am by Esprit2 |
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