re. setting valve clearances - Service Intervals

[lotusguy]

Calvin,
As you know, two of the most 'ugly' maintenance chores on the Esprit are checking and adjusting valve clearances and changing the timing belt. Yet, there are few chores which are more important in terms of both driveability and extended engine life, aside from proper oil changes. But, these are probably the most ignored maintenance tasks.
I hate to disagree with you, but waiting until the 'C' service is the wrong thing to do, especially if you are not a robust driver.
My reasoning is this: Assume that in normal use, you average 30 MPH over the specified mileage (10k mi. for California spec, and 12.5k mi. for Federal spec. cars). Contrary to common myth, you are probably running your engine in the 3,000-3,500 RPM range., nearly the same RPM range as if you were travelling at 60 MPH in a 'taller' gear. However, it takes 1 minute to travel a mile at 60MPH, but, it takes 2 minutes to travel a mile at 30MPH. You are in fact running the engine at virtually the same RPMs, but for twice as long.
Since the service interval is determined by mileage rather than operating cycles, a less severely driven car deserves more attention than a robustly driven one. Doing the math, you will find that your valves cycle (open/close) 18,750,000 times each between service intervals at 30MPH/3,000RPM and only 9,375,000 times each between service intervals at 60MPH/3,000RPM. This means that you are expecting each valve to operate properly for almost 19 million cycles and this is if you check at the proper interval!
Like it or not, this certainly deserves proper attention. In previous posts, you very rightly espouse the importance of doing things 'by the book'. This is very sage advise and should not be compromised on such an important engine function as proper valve operation. Improper valve operation results in lower gas mileage, poor performance, excess carbon build up as well as additional physical stress being placed on engine components.
My advise is simple, if you own an Esprit, part of the package is owning the responsibility for proper maintenance as well. Just my usual $0.02...Jim '85TE


>>> Edited by lotusguy on Wednesday 13th November 15:18

>>> Edited by lotusguy on Wednesday 13th November 15:19

>>> Edited by lotusguy on Wednesday 13th November 15:29

>>> Edited by lotusguy on Wednesday 13th November 15:41

[cnh1990]

Well same thinking but different thought different process. I was talking more about 5th gear hwy drivng at 3K rpm as compared to (robust) 3rd gear 5-6K in the twisties like we do from time to time. I'm sure you would agree that the 3rd gear robust driving would be more severe. So a car driven for 10K miles at 5th gear 3K rpm as opposed to a 10k miles at a robust 3rd gear 5-6K rpm is not the same thing which was my point. Most service manuals are written with what the expected or severe usage will be (drive it like a Lotus should be). Without getting into number too much the general rule has been more rpm's or harder drive equals more wear. So if the guy drives in a consevative fashion (wimp). He could probably extend the valve check interval as he does not really take the car up on the rpm scale anyways and hence less wear. Hard to believe on would constantly drive a Lotus like that but we do see that from time to time with replies via e-mail like, you drive the car in the 5-6K range or faster than 85mph? I always think what the heck kind of question is that, when I get those.
Calvin 90 SE

[lotusguy]

Calvin,
I hear what you're saying, but with respect to valves, it's really just about operating cycles.
Assuming you're correct and the gap between 'subdued' and 'severe' driving cycles evens out, due to the time component (time of operation) between service intervals for the 'subdued' driver vs, the 'robust' one, the 'subdued' driver will still subject his valvetrain to more use than a 'robust' one would. And this does not include the variables of additional heat-up/cool-down cycles, cold starts, or operating minutes with 'old' oil a 'subdued' driver subjects his car to vs. a more 'robust' one.
I agree with you that Lotus specified the service intervals for the type of driving they expect the car to see, but again, due to the 'time of operation' component, the 'subdued' driver will still put the car through more operating cycles and more unfavorable operating conditions than the 'robust' one over the service interval...Jim '85TE

[egomes]

Does the same applied to the V8's when adjusting valve clearances at every 10K miles? (Street use only)

Thanks,

Ed-

[cnh1990]

Well Jim, that will be good subject banter. You do have several good points. But I still tend to go with engine revolutions with less physical wear of the cups,shims, and valve tops. Whatever reasoning people use check your manuals and do the right thing as peoples use habits will be different as we all are. All recommended maintenence intervals are a very good guide and not written in stone. In the absense of first hand knowledge if in doubt do what the books says to do should be the motto. Ed I'm not sure about the valve differences in V8's as opposed to 4 cyl. but you have a lot more valves in yours. It will be even more of a pain to check. Jim do you know if the valves service intervals are different in V8's? There are differences even in the 4 cyl. models.
Calvin 90 SE

[Peter J. Park]

I was told last week by the dealer that V8 valve clearances are adjusted under warranty for the first 100,000 due to an ambiguous warranty statement. Might save some pennies and/or blood, sweat and tears! Check with your local dealer.
Peter.

[lotusguy]

Calvin,
Let's be clear here. The service interval is for checking the valve clearances, not necessarily adjusting them or even finding them in need of adjustment.
Last fall, I checked my valve clearances at 12,700 miles since the last check (which had needed no adjustment). I found the valves were still within spec with the exception of one exhaust valve on the #3 cylinder, and it was just outside the spec by 0.001". Considering the work and expense involved, I 'elected' to forego the adjustment and wait until the next interval, which as you know occurred when I rebuilt my engine this past summer and did a valve job consisting of replacing all the springs and guides, three-angle grinding of all valves and lapping them back in the head. Also, I substituted a 104 intake cam for the stock 107 cam. This higher lift cam required shimming of each intake valve as the values had all changed.
So, while your valves may not need to be adjusted, Lotus recommends checking them at these intervals and I believe in following their recommendations. Lotus has never revised this interval to include a 'Severe' or 'normal' use variable via a supplemental Service Bulletin, so I presume they feel it important to perform this check. Of course, individual owners may interpret this and do anything they wish. But you have to ask yourself, who is better prepared to establish these intervals?
I'm sorry, but I do not know offhand what the service interval is for the V8 cars, nor was I aware of differing service intervals for the 907/910 engine based on model year...Jim '85TE

[lotusguy]

Peter J. Park said: I was told last week by the dealer that V8 valve clearances are adjusted under warranty for the first 100,000 due to an ambiguous warranty statement. Might save some pennies and/or blood, sweat and tears! Check with your local dealer.
Peter.

Peter,
That's wonderful news for you V8 owners, but what is the interval for checking and adjusting the valves? Surely a dealer will not perform this service at the owner's whim such as a weekly/monthly check... Jim '85TE

[cnh1990]

lotusguy said
Lotus recommends checking them at these intervals and I believe in following their recommendations. Lotus has never revised this interval to include a 'Severe' or 'normal' use variable via a supplemental Service Bulletin, so I presume they feel it important to perform this check. Of course, individual owners may interpret this and do anything they wish. But you have to ask yourself, who is better prepared to establish these intervals?

Jim,
Like I said "In the absense of first hand knowledge if in doubt do what the books says to do should be the motto". For me if I drive it harder then usual then I'll check before the recomended interval, if I drive it at 60 on the hwy if my daily driver breaks down for some reason I may go a longer interval. It's something most people don't even check anyways. Just common sense is what it is. You went 12K plus (at 30K+ total miles was it) before the last check some people go 15K. It's a judgement call. Just like an oil change. They say every 3K miles, well on the way home from FL I did go over by 450 miles. I chose to wait to change the oil at home. Did it hurt the engine? I don't think so as it was all continuous hwy miles going home much less harmful than stop and go with many cycles. So who is better prepared to establish these intervals, well now that you mention it the individual owners that are ultimately responsible for interpetation of the recomended intervals. They are very strong guidelines. If it were written in stone they would not be a recomendation it would be a requirement. As much as if they say recomended oil change interval is 3K or 3 months if the car sat there most of time like in our winter months I'm not going to run out to the the garage and change it just because it went beyond the 3 months part of the recomended interval. But then if I track the car I'll use fresh oil before and after the event. well below the milage and time interval. Just a little common sense was all I was observing. You may and will probably observe the 10K rule for your car and that's fine for you no harm in it. As for me and my particular driving habits after checking the clearances twice and finding everything okay, I'll go a bit longer the next time unless I drive it harder than than my norm for extended periods. But to everybody else that is for me and not what I'm telling you to do. We must all make our own choices based on how we use our cars and the way we drive.
Calvin 90 SE