Sir Paolo Posted August 3, 2012 Report Share Posted August 3, 2012 Gents, a quick question, please. When it comes to valve shimming, does any Lotus outlet offer a selection on a sale or return basis? If as I understand, it could take a couple of attempts to get it right, could you not order a number of combinations (based on measured requirements), then just pay for what you use. I know the shims are only a £1 or so, but it would speed up the process if you had a number of similar sizes to hand. I'd appreciate your thoughts/advise. Apologies if this is a stupid question (as you can probably tell, I've always had the luxury of someone else doing this in the past). Quote Link to comment Share on other sites More sharing options...
DrieStone Posted August 3, 2012 Report Share Posted August 3, 2012 I just went through this myself. The cam follower shims are the same size (15.5mm - 15.75mm diameter) as found on other engines. Including the Saab 99 and the Triumph TR7. A Saab mechanic might have the box of shims for the 99. It's an older engine and you can probably take it off their hands fairly inexpensively. That should give you everything you need. I was unable to source the Saab shims and ended up making 3 separate orders from JAE here in the US. I should be able to return my unused shims to them. I'll admit it was a painful process that should have taken a few days that stretched more then four weeks, especially because one of my orders I accidentally subtracted rather than added the change so I had a whole order that was completely useless to me. Quote 1997 Jeep XJ | 1983 Lotus Turbo Esprit Link to comment Share on other sites More sharing options...
andydclements Posted August 3, 2012 Report Share Posted August 3, 2012 As Jonathan suggests, look for compatible ones, that includes Imp as well. I managed to obtain a box for Hesketh Motorcycles that also fit. Andy Quote Link to comment Share on other sites More sharing options...
molemot Posted August 6, 2012 Report Share Posted August 6, 2012 I used plain washers. Careful measuring of the resulting clearances and washer thicknesses enabled the shim sizes to be calculated...then I used whatever correct shims I had to hand and ordered the others. And.....it worked!! No, I'm not suggesting you run the engine with washers as shims....but it did help to get rid of the iterative part of the procedure. Quote Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein Link to comment Share on other sites More sharing options...
DrieStone Posted August 6, 2012 Report Share Posted August 6, 2012 (edited) I used plain washers. Careful measuring of the resulting clearances and washer thicknesses enabled the shim sizes to be calculated...then I used whatever correct shims I had to hand and ordered the others. And.....it worked!! No, I'm not suggesting you run the engine with washers as shims....but it did help to get rid of the iterative part of the procedure. I did something similar because the old shims were all too tall. I ordered some thin steel and cut my own "spacers" to get me started. It worked ok, but I swear I felt like I was chasing ghosts half the time. I don't know how you'd use washers unless the center hole was very small. That said, I bet the the washer idea probably worked better than my idea. I was even trying to figure out a way I could engineer a way to grind down the original shims, but in the end I just couldn't think of a way that I could be absolutely sure that they were flat. That's one task I'm glad to be done with. I think I bolted that cam carrier down 15 times for each side. Speaking of which, I HIGHLY recommend cleaning the threads of your bolts each time before securing the carriers. I had one bolt that must have had something on it, and I wrecked the bolt hole trying to torque it down. Luckily it's not horrible to drill, tap and helicoil a fix, but what a pain. Edited August 6, 2012 by DrieStone Quote 1997 Jeep XJ | 1983 Lotus Turbo Esprit Link to comment Share on other sites More sharing options...
Sir Paolo Posted August 6, 2012 Author Report Share Posted August 6, 2012 Thanks, Gents. Looks like which ever way you cut it, it's going to be a time consuming trial and error PITA. But I do like the idea of trial fitting with washers - it might save a lot of ordering and re-ordering to get the sizes right. I did manage to pick up some NOS Hillman Imp shims. I must admit, I've been very careful about cleaning all threads, especially the captive ones in the alloy housings! I've used literally hundreds of cotton buds to clean out swarf. If I'm in for the long haul, at least the engine is on a stand - I wouldn't fancy doing it in situ! BTW - does anyone know if Sparky has a selection of shims? Quote Link to comment Share on other sites More sharing options...
Vulcan Grey Posted August 6, 2012 Report Share Posted August 6, 2012 I ordered the steel cam followers from JAE to replace my cracking cast iron original tappets. The new cam followers are thinner, so I had to get all new shims. I made cast iron ones to enable me to get accurate measurements so I could order the correct shims on the first try. My cast iron temporary shims (just used to get accurate measurements) Be careful with washers, they may be a bit cupped and give varying results... Quote Travis Vulcan Grey 89SE Link to comment Share on other sites More sharing options...
DrieStone Posted August 6, 2012 Report Share Posted August 6, 2012 You made the new shims, or you purchased them? Quote 1997 Jeep XJ | 1983 Lotus Turbo Esprit Link to comment Share on other sites More sharing options...
andydclements Posted August 6, 2012 Report Share Posted August 6, 2012 If he doesn't he certainly knows somebody who does, it depends when I'm next passing his area though. Quote Link to comment Share on other sites More sharing options...
molemot Posted August 7, 2012 Report Share Posted August 7, 2012 Washers work well...but check they are flat first, and use sizes where the holes aren't too big....also make sure that there is no edge to the holes where they are punched through...some careful work on an oilstone can take care of this. Worn proper shims get dips in the middle, too, where they impinge on the top of the valve stem...this can make fools of us all (!) so a micrometer is a better tool for measuring than a digital caliper, as the micrometer will fit down the dip and give you the true measurement. Don't you just love iterative adjustments? Thankfully zero thickness sealants have taken some of the inspired guesswork away.... Quote Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein Link to comment Share on other sites More sharing options...
Vulcan Grey Posted August 7, 2012 Report Share Posted August 7, 2012 I purchased new shims from a Lotus parts supplier in the States, after making my measurements with the cast iron shims that I made. In my experience, none of the hardened shims have worn down from their original nominal thickness at all... zero wear! That is measured with a micrometer on the centers, and compared to measuring with calipers across the whole face. And comparing that to the etched thickness specified on the shims. My engine has 80,000 miles. Quote Travis Vulcan Grey 89SE Link to comment Share on other sites More sharing options...
Mr_John111 Posted August 8, 2012 Report Share Posted August 8, 2012 Worn proper shims get dips in the middle, too, where they impinge on the top of the valve stem...this can make fools of us all (!) But also bear in mind that this dip can get you an extra 1 -2 thou either way by turning the shim over so that the dip is either eliminated or makes the actual thickness of the shim smaller than when measured with a vernier / caliper gauge. i.e. you measure the gap and its too large. The shim you have taken out has the dip (facing the top of the valve stem) you take it out and turn it over and voila the gap is correct. Or again you are re-using a shim with a dip on a different valve, with the dip facing the cam follower the gap is too small turn it over and you hit the right number. two thicknesses of shim for the price of one John Quote Link to comment Share on other sites More sharing options...
DrieStone Posted August 8, 2012 Report Share Posted August 8, 2012 In my experience, none of the hardened shims have worn down from their original nominal thickness at all... zero wear! That is measured with a micrometer on the centers, and compared to measuring with calipers across the whole face. And comparing that to the etched thickness specified on the shims. My engine has 80,000 miles. No doubt about it, a micrometer is a vital tool here. I started with calipers and didn't trust the tool enough. I picked up a used micrometer for US$40 and couldn't be happier. Always good to have an excuse to buy new tools right? My existing shims did have visible indentations in them from use. I have to imagine flipping them over would work, but I don't know if I'd trust them that way. Quote 1997 Jeep XJ | 1983 Lotus Turbo Esprit Link to comment Share on other sites More sharing options...
The Veg Posted August 11, 2012 Report Share Posted August 11, 2012 Speaking of which, I HIGHLY recommend cleaning the threads of your bolts each time before securing the carriers. I had one bolt that must have had something on it, and I wrecked the bolt hole trying to torque it down. Luckily it's not horrible to drill, tap and helicoil a fix, but what a pain. I'm pretty sure that the factory recommend using new bolts, but I don't have my manual handy to check this. In any case, JAE carry a nice set of bolts made by ARP which are great because they have a smaller head than the original bolts, making them much easier to get tools onto in close proximity to the cam-lobes. I found that they made the re-assembly job a bit easier. Quote "If you can't fix it with a hammer, it's electrical." -somebody's dad Link to comment Share on other sites More sharing options...
Mike6 Posted August 15, 2012 Report Share Posted August 15, 2012 I had endless hours playing around with shims when my head came off. Measured exactly the correct thickness purchased the shims and when they arrived measurements were not as I expected. Scratched my thinning scalp for a while and then decided to measure the thickness of the shims. They were a few thou out so even if you have done all your measurements correctly remember the shims have tolerences. Purchased more shims and with a bit of playing around got it right but remember dont rely on the number stamped on the shim. Quote Link to comment Share on other sites More sharing options...
molemot Posted August 16, 2012 Report Share Posted August 16, 2012 Mike is dead right. Just because the shim says it's a certain thickness, doesn't mean it is....always measure it before fitting. Don't forget that micrometers wear, too...especially if they've been used to measure diameters on things rotating in a lathe(!) A known standard is useful for calibration purposes. Just persevere until you have the right clearances.... Quote Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein Link to comment Share on other sites More sharing options...
andydclements Posted August 16, 2012 Report Share Posted August 16, 2012 I purchased a digital, mechanical imperial micrometer, it's flipping great for that job. I still work in thou' for that job so I just read the dial of the micrometer and that's it. No messing with a vernier scale. Quote Link to comment Share on other sites More sharing options...
Sir Paolo Posted September 13, 2012 Author Report Share Posted September 13, 2012 I was also wondering how accurate this 'gap' has to be. Especially as the manufacturers (Kent) list the clearance on my L14's as 0.008 inlet and exhaust, yet my experienced 'head builder states 0.010 inlet and 0.012 exhaust. Any advice would be appreciated - many thanks Quote Link to comment Share on other sites More sharing options...
jonwat Posted September 13, 2012 Report Share Posted September 13, 2012 Especially as the manufacturers (Kent) list the clearance on my L14's as 0.008 inlet and exhaust, The exhaust tappets should always be greater than the inlets because the exhaust valves get so much hotter than the inlets. Quote Cheers, John W http://jonwatkins.co.uk Link to comment Share on other sites More sharing options...
DrieStone Posted September 13, 2012 Report Share Posted September 13, 2012 According to the Lotus spec the tolerance is 2 thou. 910 Engine and most 907 & 912: Inlet : .005 - .007 Exhaust: .010- 0.012 Quote 1997 Jeep XJ | 1983 Lotus Turbo Esprit Link to comment Share on other sites More sharing options...
PrecisionMike Posted May 15, 2021 Report Share Posted May 15, 2021 On 07/08/2012 at 23:30, molemot said: Washers work well...but check they are flat first, and use sizes where the holes aren't too big....also make sure that there is no edge to the holes where they are punched through...some careful work on an oilstone can take care of this. Worn proper shims get dips in the middle, too, where they impinge on the top of the valve stem...this can make fools of us all (!) so a micrometer is a better tool for measuring than a digital caliper, as the micrometer will fit down the dip and give you the true measurement. Don't you just love iterative adjustments? Thankfully zero thickness sealants have taken some of the inspired guesswork away.... Hi mr molemot. What zero thickness gasket goo do you recommend Quote Link to comment Share on other sites More sharing options...
andydclements Posted May 15, 2021 Report Share Posted May 15, 2021 1 hour ago, PrecisionMike said: Hi mr molemot. What zero thickness gasket goo do you recommend Unfortunately Molemot passed away In terms of which zero thickness sealant, I believe Loctite 518 is suitable (think it may be the recommended one) but there will be other brands, just match the characteristics https://www.henkel-adhesives.com/uk/en/product/flexible-sealants/loctite_518.html Quote Link to comment Share on other sites More sharing options...
PrecisionMike Posted May 15, 2021 Report Share Posted May 15, 2021 Oh. I am sorry to hear that. I read many of his posts. He was clearly very knowledgeable and eager to share that knowledge. Thankyou for the information on the sealant. Quote Link to comment Share on other sites More sharing options...
suitably.obscure Posted July 29, 2021 Report Share Posted July 29, 2021 A very useful thread. I think I have read that removing the cam housings can be done with the engine in situ? could anyone confirm that, and anything to watch for. I last removed when the engine was out. Quote Link to comment Share on other sites More sharing options...
Gold FFM Sparky Posted July 29, 2021 Gold FFM Report Share Posted July 29, 2021 Yes, they can. Be careful not to drop any shims as you lift the towers. Magnets are useful. 1 Quote British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland. And Shitfaced Silly Sod to Sweden. Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.