Lotus Elan

Valve Clearance Question: .009 to .011 for exhaust only?

PostPost by: thehackmechanic » Wed Mar 04, 2020 1:25 pm

(Europa TCS guy who posts twin-cam questions here)

Forgive me for beating the dead horse, but I'm a noob who wants to be really sure he's not screwing this up.

I see that, in the manual, it lists the valve clearance spec as 0.005 to 0.007 for the intake valves, and for exhaust the clearance is 0.006 to 0.008 up to engine number 9951, and 0.009 to 0.011 for later engines. I see that there is a recommendation that 0.009 to 0.011 be used for all engines. I just want to be certain: That .009 to .011 is still for the exhaust valve clearance only, right? The recommended intake clearance spec is still 0.005 to 0.007, correct?

Thanks.

--Rob Siegel
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PostPost by: 2cams70 » Wed Mar 04, 2020 1:36 pm

Rob we'll give you advice if on your BMW website you stop comparing BMW engineering with Lotus engineering and telling everyone how crappy Lotus engineering is in comparison. Stick to BMW's if that is what you prefer.
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PostPost by: William2 » Wed Mar 04, 2020 1:41 pm

BMW engineering isn't all it's cracked up to be either!! For instance, on one of their popular 6 cylinder engines that have been around for many years, the timing chains have a habit of failing and the engine has to come out to repair it. The timing chain is at the rear of the engine - what a strange design.
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PostPost by: thehackmechanic » Wed Mar 04, 2020 1:52 pm

Whoa. Tough crowd. While I did express frustration with all the fettling required to get the Dave Bean cartridge-style water pump kit and its custom inner and outer timing covers properly fit and sealed, you might have missed the multiple articles I've written for Hagerty where I talk about how much I adore my Europa, how the people who dish on it being a "bread van" have never seen it in the flesh I mean fiberglass, how it's like nothing else I've ever owned or driven, how it's absolutely addicting to get behind the wheel, and how, after 40 years in storage, every single electrical system came up running perfectly, so take THAT all you purveyors of tired Lucas jokes.

https://www.hagerty.com/articles-videos ... n-the-wild

So we're good, right? :^)

But seriously... that 0.009 to 0.011 spec is ONLY for exhaust valves, and the recommended intake valve clearance is still 0.005 to 0.007, right?

--Rob
'74 Europa TCS, 20k miles, stored since '79, resurrected in 2019
'73 BMW 3.0CSi
'72 BMW 2002tii, '73 BMW 2002
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PostPost by: nmauduit » Wed Mar 04, 2020 2:52 pm

thehackmechanic wrote:I just want to be certain: That .009 to .011 is still for the exhaust valve clearance only, right? The recommended intake clearance spec is still 0.005 to 0.007, correct?


these ranges should work for most engines, esp. street (fwiw I use a tad more clearance on the intake with a 8thou initial clearance target rather than 7, from fast road tune and up, to be on the safe side, depending on what is rebuilt and likely to break in into a narrower clearance down the road - I keep 10 thou as exhaust initial clearance target - clearances to be measured on fully torqued in head). If you want to fine tune your clearance target you may want to look into the thermal expansion coefficient of the valve material.
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PostPost by: JonB » Wed Mar 04, 2020 3:43 pm

From the Lotus Service Manual (Elan Plus 2):-

Inlet: .005 - .007 inch
Exhaust:
- to engine LP.9951 .006 - .008 inch
- from engine LP.9952 - .009 - .011 inch

Measured when the engine is cold. So basically, yes, you're right (depending on the engine number). I think the later numbered engines are Big Valve engines (but I am prepared to be corrected on that point).

PS, sorry about the "tough crowd" response to your post. I liked your reply. Truth is, every car has its problems and detractors, just as each has its fans. None are perfect - just like people.
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PostPost by: ericbushby » Wed Mar 04, 2020 4:26 pm

Hi Rob,
The simple answer to your simple question is- Yes!
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PostPost by: 1owner69Elan » Wed Mar 04, 2020 7:11 pm

Engine builder on my high spec twincam set mine at 0.008" and 0.010"
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PostPost by: The Veg » Thu Mar 05, 2020 3:09 am

JonB wrote:I think the later numbered engines are Big Valve engines (but I am prepared to be corrected on that point).


I'm no authority but I think you're right. Mine is in the latter group of numbers but was not originally a Big Valve.
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PostPost by: The Veg » Thu Mar 05, 2020 3:22 am

William2 wrote:BMW engineering isn't all it's cracked up to be either!!


A friend of mine was a BMW-certified wrench but quit working on them after seeing too many horror-stories.

Their motorcycles are a whole different animal though, as the two divisions are rather independent of each other. Not perfect, but much fewer of the crazy stories like with the cars.
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PostPost by: 2cams70 » Thu Mar 05, 2020 5:09 am

William2 wrote:BMW engineering isn't all it's cracked up to be either!!


BMW back in the late 60's when they first started developing proper cars obviously benchmarked what Ford UK had done very closely. Like Ford they had a McPherson strut front suspension system of very similar design. Like Ford they used common platforms and parts shared across as wide a range of models as possible in order to produce good products at very low development and production costs. Like Ford they had common engines and transmission components shared across a wide a variety of models over a long period of time. In fact I believe they even poached a lot of Ford staff back then.

The early BMW 6 cylinder models were almost guaranteed to crack a cylinder head in any sort of warm weather and the M30 engine had many changes to it's head design during it's very long life.

With regards to modern BMW's what can I say! A good drive but yes long term durability is an issue. Here in a wealthy suburb of Melbourne I recently spotted an unregistered 2006 model BMW 740i V8 (one of the Chris Bangle design models) with a council collection sticker on it by the side of the road. It was unlocked with the keys in the door pocket so naturally I tried to fire it up but didn't have any luck doing so. I found the owner through some old paperwork in the car and managed to contact him to see if I could purchase it for a nominal sum or just take it off his hands for free.

When asked what was wrong with it his words were that the transmission was "rooted" and that he had already arranged for a charity organisation to come and collect it so unfortunately (or perhaps fortunately!) he could not give it to me. Wow - $200,000 vehicle back in 2006, $0 vehicle in 2020!

The postscript on this is that afterward I did a google search on the model and all it's issues and all I can say is that I was very lucky not to have ended up with yet another garden ornament!
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PostPost by: William2 » Thu Mar 05, 2020 9:51 am

I believe the vast majority of engines use the wider valve clearance. I have always been advised to try and set them to the wider tolerance of 0.007/0.011 particularly for the exhaust valves.
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PostPost by: alan.barker » Thu Mar 05, 2020 9:53 am

I thought with valve clearances you follow the workshop manuel with standard cams.
If you fit special cams e.g. Piper or QED etc you follow what the supplier says so the clearance suits the ramps of the Cams.
Maybe Rohan can give us some info.
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PostPost by: vincereynard » Thu Mar 05, 2020 2:05 pm

I'm told by a Merc technician that all the German panzer cars are no big deal reliability and quality wise.

The reason in PCP Finance. All the car has to do is survive for the 3 years contract then the manufacturers make loads more doss selling horrendously expensive spares to 2nd and subsequent owners.

Nice trick!
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PostPost by: draenog » Thu Mar 05, 2020 2:21 pm

2cams70 wrote:
William2 wrote:When asked what was wrong with it his words were that the transmission was "rooted" and that he had already arranged for a charity organisation to come and collect it so unfortunately (or perhaps fortunately!) he could not give it to me. Wow - $200,000 vehicle back in 2006, $0 vehicle in 2020!

I guess you're using "rooted" in the Australian sense, i.e. "f***ed" :)
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