re. setting valve clearances - Service Intervals

[lotusguy]

SwedishSurgeon said: A question for Jim,
I read your post about valve adjustment and was curious that you mentioned removing the timing belt when you go to adjust the valves. Perhaps I read your post wrong, but you need to rotate the motor to check the others. I adjust valves all of the time and never remove the belt besides on the Esprit it's a real pain.
On the ones I do, there is a tool to compress the bucket allowing to remove the shim... will this work on a Lotus Esprit? Most shimmed valves work this way, except with the Lotus it's twice the work because there are 16 instead of 8. I haven't read into the bible yet for the procedure however you have me thinking! Could you give me the overall diameter of the shim in millimeters? I'm curious if the ones I use are the same.
Cheers,
Robert

Robert,

On the Esprit, the camshaft is fixed. It slides into the carrier and through the journals via the hole in the sprocket end once the oil seal has been removed. It is then held in place through a bolt and thrust washer on the opposite end where the end cap is. To remove it, you must use a puller on the rear of the carrier and push the cam and oil seal out the front end once the thrust washer and fixing bolt are removed. This cannot be done with the cam carrier in place due to the firewall (bulkhead) clearance.

Also, the tappets, or in 'Lotus' parlence "Cam Followers", otherwise referred to as 'Bucket Tappets'. The shim, collet, spring and valve stem 'live' underneath this tappet, so when you are measuring clearance, you are actually measuring the gap between the cam lobe and the top of the tappet, not the shim itself.

The reason you have to remove the belt for adjustment is that the camshaft will not lift off the solid journals, so you cannot lift the tappets or 'buckets' out from the top side. To expose the shims, you have to remove the entire cam carrier from the head. This is done by unscrewing the 10 torx head bolts & washers securing the cam carrier to the head(thus the E10 socket), and removing the timing belt from the sprocket. Now, you quickly rotate the cam carrier so as not to lose any of the tappets (or you can secure the tappets with bar magnets from one to another on the top side of the carrier). You will now see the shims either stuck to the underside of the tappets, or sitting in the recess in the collet on top of the valve stem. The 'bucket' essentially rides on top of the shim alone. So, your tool will not work as the shim lies underneath the bucket, not on top.

The reason I mention turning the crank 90° off TDC is to insure that all the pistons are drawn halfway down the cylinders to avoid contacting any valves as you rotate the cam to measure the clearance gaps, and to allow you to re-align the cam sprocket timing marks safely. Then rotate the crank back in the opposite direction 90° until you reach TDC before reinstalling the timing belt.

As far as the shim size, I do not have an accurate measurement of the diameter, but believe it to be 0.50". The shims are available from Lotus in thicknesses ranging from 0.060" to 0.150" in increments of 0.001". These shims are interchangable between those used in Triumph engines as well as some others. One caveat when ordering shims from an independent source, many suppliers such as JAE and Bean make their own shims from hardened Rod Stock which they cut down to the various thicknesses. The consistemcy of this Rod Stock diameter can vary to the point that the shim will bind on the collett recess and not fully seat on the valve stem. I once spent a very confusing afternoon adjusting some valves as when I measured everything out on a mic, it all measured out accurately, but when I assembled the head and re-checked clearances, they would be off. I finally discovered the problem was a shim not seating properly, so after using a bench grinder to trim the diameter of the shim so it would seat in the collett recess, everything came out fine. These shims were secured through one of the 'Indys' listed above (I won't tell you which one).

Also, in the interest of accuracy, I have created a spreadsheet program which works out the size shim you need from the variables you plug into it (measured gap, actual existing shim thickness) this eliminates the possibility of mathematical errors which could result in ordering the incorrect size shim. I will be happy to share this with anyone... just let me know.

Let me know if I have explained this coherently. If you have not actually seen the head exposed without the cam carrier, it's a little difficult to describe. Hope this helps...Jim '85TE



>> Edited by lotusguy on Friday 15th November 06:03

>> Edited by lotusguy on Friday 15th November 06:14

>> Edited by lotusguy on Friday 15th November 06:21

>> Edited by lotusguy on Friday 15th November 07:46

>> Edited by lotusguy on Friday 15th November 07:50

[SwedishSurgeon]

Hi Jim,
Thanks for the reply. After reading your reply and consulting the " Bible " you are VERY correct. These are set up the same way as the old six cylinder Jag engines as I recall. Oh boy!!! This is not an easy job on an Esprit! I feel it's a case of stupid engineering for basic tuning strikes again! As we adjust valves with " open " buckets every 30K, it's not a hard job, however when the shim is inside the bucket, the tables
of practicality are turned upside down!
FOR SALE: 1987 Turbo Esprit hci ... selling due to maintaince is a bitch! Just joking here... We love our cars and will do everything to keep them. I work on hard to deal with problems every day, so for me this is just a walk in the park on a rainy day.
Thanks again for your help Jim!

Robert

[lotusguy]

Robert,

As you say, maintenance is a b*tch. You're right as this is the exact procedure I had to use when adjusting the valves on my '63 E-Type.

The up-side, if there is one, is that with the Jag, I had to go through all this work for only 12 valves, at least now the work is 'amortized' over 16 valves...lol

Now you see why this very important item is ignored, overlooked and put off by the average Esprit owner.

But, after having performed this procedures a half dozen times on a total of 3 vehicles, the frustration factor does drop somewhat. Like many things on the Esprit, the actual work is not nearly as bad as the 2-3 hours of work needed to actually get to the work at hand.

Still, once done, and done properly, to listen to that engine purr makes it all worthwhile... I guess... Jim '85TE

[SwedishSurgeon]

Jim,
Thank you for the reply, your " Spot " on!
To whom ever reads the posts from Jim, he knows what he is talking about with Valve ajdustments.

Robert Grener
' 87 Turbo Esprit hci

[lotusguy]

SwedishSurgeon said: Jim,
Thank you for the reply, your " Spot " on!
To whom ever reads the posts from Jim, he knows what he is talking about with Valve ajdustments.

Robert Grener
' 87 Turbo Esprit hci

Robert,

Thank you for your kind words. I have owned my Esprit for almost 8 years and have done all the work myself on it save a windshield replacement.

Since this was my second Lotus (had a Europa T/C in the 70's), I was somewhat familiar with the screwy things sometimes going on in these cars.

But, I have had a collector car, in fact usually more than one, for most of my driving life. I never had the luxury of being able to pay someone else to maintain them, so I learned as I went.

I have been fortunate enough to do complete engine rebuilds on both my car as well as an '88, and have had 3 trannys apart. This and my general car knowledge gained over the years make it seem easier than it probably is.

This past summer, I did a complete rebuild on my Esprit, and am very pleased with the results. Let me describe what I did.

First, I rebuilt my carbs, replacing all gaskets, needle valve and seat, accelerator pump diaphram and spring and rejetted my idle jets from stock 52's to 62's. The latter assisting with the 3k RPM transition.

I rebuilt the bottom end with all stock components, but replaced the old, worn, cast pistons with new, lightweight, forged aluminum pistons from JE Pistons. This increased my compression ratio from 7.5:1 to 8.5:1 . I had the pistons ceramic coated on the domes reducing their operating temp. by 150°F, thereby increasing their tensile strength by 100%, and coated the skirts with a wettable dry lubricant (molybednum disulphide) to increase oil carrying capacity. I had all engine components balanced both statically and dymanically to 0.1 gr.

Then I replaced my stock 107 intake cam with a mildly higher lift 104 cam (.412" vs. stock .378"). Along with this, I rebuilt the head having a 3-angle grind done to the valves and added bronze/silicone valve guides and thin wall higher lift springs. Again, this aids with the 3k transition. The car now comes 'On Cam' at 3k, so some bottom end was sacrificed (very little) in favor of top end performance.

My turbo was rebuilt and was over-bored to accept a roller bearing rather than the stock race bearing (this adds reliability and reduces Turbo lag). I had it balanced to 0.001 gr. @ 30k RPM.
In addition, I had my wastegate adjusted to 10 lbs. of boost over the stock 8 lbs. and finally, I had my exhaust manifiold, wastegate adapter and input (hot) side of the turbo housing ceramic coated with a thermal barrier ceramic. This had the positive effects of reducing engine bay temps by 30%, increasing the exhaust gas pressure and scavenge effect, all of which also resulted in faster turbo spool-up.

Removed the airpump and all associated hardware, plugging the air injector holes in the head w/ special BSP threaded plugs. This system is only present on US spec cars and only aids emission control on cold start-up. If you warm up your car prior to driving, as I do, this is redundant, but draws 1 to 2 horseposwer.

I swapped my 110° intake cam sprocket with the 104° ignition sprocket to advance the valve M.O.P. (Maximum Opening Point) back to it's original design spec. This is a US only variant in favor of reduced emissions.

Had the distributor recurved to apply full advance (16°) @ 2,500RPM. I advanced the static timing from 1° BTDC to 13° BTDC, giving me a total advance of 29°.

I replaced all transmission seals, bearings and synchros, added a new AP Kevlar racing clutch, new, updated clutch cover and throwout bearing. Had the flywheel/clutch dynamically balanced (this is supposed to be balanced by Lotus, but was found to be off by 4.0 gr.!)
Added a new Crossgate cable (Thanks again Calvin) and crossgate shift MOD from SJSportscars making the shift tight and smooth. Rebuilt clutch master cylinder and added new slave cylinder.

Rebuilt and powder coated all brake calipers, replaced stock rubber flex brakehose w/ stainless Aeroquip hoses, added Kevlar compound brakepads, rebuilt Brake Master Cylinder.

Finally, I added all new motor/tranny mounts, replaced all coolant hoses, replaced throttle and choke cables, added new ignition wires, 'V' belts, timing belt, rebuilt semi-automatic tensioner, replaced vacuum pump, rebuilt alternator and added the superior HC model air intake hose.

Of course, I am not nearly so skilled as you as I would starve trying to make a living as a mechanic. But, I have a passion to learn all there is to know about these wonderful cars. Also, our local Lotus Club, the LOONs are a great resource of both knowledge and braun. Unlike a lot of car clubs, while we socialize we are definitely a bunch of 'wrench-turners'. Anyone trying to keep one of these cars without the aid of a local club is really doing it the hard way...Jim '85TE

[5150neo]

Hello Lotusguy,
Do you have any idea if the AP clutch you speak of will fit a 91 SE? If so, where might I purchase one?

[lotusguy]

5150neo said: Hello Lotusguy,
Do you have any idea if the AP clutch you speak of will fit a 91 SE? If so, where might I purchase one?

Hi,
The AP clutch I put in my car will definitely not work in your car (Citroen C-35 box for me, Renault box for you).

That having been said, contact Steve Roberts @ SJSportscars as I'm sure he'll have an equivalent one to fit your tranny as well. Hope this helps...Jim '85TE

[5150neo]

Oh yes, of course. For what ever reason I was thinking you had an 89 model. Thanks for the reply.
John

[cnh1990]

Also take care and inquire when changing clutch types in the SE. Although a S4s clutch and others will fit right in our cars the pressure required and the throw distances are different. In many cases the master cyl and other components must be changed to compensate for those items.
Calvin 90 SE

[5150neo]

Yes, thats why I'm trying to avoid switching to the s4s setup. The additional cost of the master cly, flywheel, throw out, disc, and clutch itself I would much rather spend on new syncros and seals while the gear box is out of the car. I trust AP products and have used them in the past but only in road racing. Hearing that AP offers a clutch for our babies of course made my eyes lite up.
John