Motorsport Mickey Posted January 10, 2023 Report Share Posted January 10, 2023 Opinions vary but I always carry out a compression test with the pistons wedged up with card on edge. I think of the various times I've seen the carb pistons flapping about when the engine is turning over and try to remove this from any compression readings. As to what compreessions ? who knows ? if it makes you feel better to have a set of 180 readings against a set of 150 readings then so be it, it doesn't matter as long as all are broadly the same (within 5-10% does it for me). Mick Richards Quote Link to post Share on other sites
Hamish Posted January 10, 2023 Report Share Posted January 10, 2023 Not sure the carbs make that much difference using the starter motor. The main thing it’s the same test conditions for all pots. this is the same for wet and dry tests. Just make sure all the same conditions. as I understand it you’ve had head work so if it’s skimmed you may have elevated readings ? the important factor is that all pots are very similar as mick says i guess a range between 160 to 180 ? All pots being close. Quote Link to post Share on other sites
ianc Posted January 10, 2023 Report Share Posted January 10, 2023 My tester is like the old type of tyre pressure tester - I screw it into the plug hole and, as the engine spins, the reading increases with each stroke and when it is no longer increasing, I remove the tester and record the reading. As Mick suggests, best undertaken with throttles wide open. My car is 2238cc, has CR slightly more than 10.0, a rally camshaft, and head, manifolds etc much as can be seen in Kastner's manual. Since 1996, I have recorded consistently about 175-185 with the engine cold. Camshaft profile will likely make some difference as the engine is not spinning very rapidly, even with a modern, geared starter motor. The last time it was on a rolling road, to eliminate some pinking in the mid-range (probably caused by changes of fuel over the years), Dan & Carl at Revington recorded 90 HP at the rear wheels at 4000 rpm, and so didn't bother exploring further as they were confident that the problem was sorted. It was, as Dan & I checked on the 5 mile "test route", when the car pulled cleanly from 1800 to 5000 without any hesitation or pinking. Lovely! Incidentally, despite his years working at Revington TR, it was the first time that Dan had ridden in a Works' TR4 Rally car. Ian Cornish Quote Link to post Share on other sites
Nigel C Posted January 10, 2023 Author Report Share Posted January 10, 2023 Thanks all, It is a bit of a struggle to wedge the pistons open as there's a fitted induction/pipes etc and I thought (like Hamish) that just on the starter it wasn't to important? Anyhoo, I've always done it this way so I guess what I got and get now are all on the same benchmark. And like Ian I am using a gauge fitted to a flexi pipe and brass threaded insert to the plug hole. On this new 89mm engine large valve Ali head/fast road cam/lightened flywheel/variable timing gear/all balanced (of around 6,000 miles) and which ever incarnation of head gasket was fitted (3 to date!) I was getting readings of 240-255 across the board which, I felt was high? Quote Link to post Share on other sites
Hamish Posted January 10, 2023 Report Share Posted January 10, 2023 1 hour ago, Nigel C said: I was getting readings of 240-255 across the board which, I felt was high? I would agree with you. thus May be question the gauge? I would suggest 210/20 is high. does the engine spin over ok ? As I would think 255psi would be tough to turn over. ? Quote Link to post Share on other sites
Nigel C Posted January 10, 2023 Author Report Share Posted January 10, 2023 1 minute ago, Hamish said: I would agree with you. thus May be question the gauge? I would suggest 210/20 is high. does the engine spin over ok ? As I would think 255psi would be tough to turn over. ? fare point, I will get my next door neighbour to check his car (which is a bonkers MG Midget drag car producing 300hp) with his gauge and then mine (as mines in bits again!) funnily enough we tested torque wrenches today Quote Link to post Share on other sites
Motorsport Mickey Posted January 10, 2023 Report Share Posted January 10, 2023 22 minutes ago, Hamish said: I would agree with you. thus May be question the gauge? I would suggest 210/20 is high. does the engine spin over ok ? As I would think 255psi would be tough to turn over. ? "As I would think 255psi would be tough to turn over." No spark plugs help ! but I agree with plugs in those sort of pressures will slow the turnover down a treat. As has been said many times, the compression test gauge results are variable between gauges but useful for engine comparisons as you run it through the season, or individual cylinders against the others. Mick Richards Quote Link to post Share on other sites
Nigel C Posted January 10, 2023 Author Report Share Posted January 10, 2023 it did turn over very well; I fitted a high torque starter motor a few years (and and the previous engine) ago as the previous NOS item caught fire....and you really don't want that when dressed in GRP! Luckily I'd stopped in a one way street a mile from home to pick up a curry, when I got back to it there was a "bystander" looking at it so we had a quick chat (because I didn't want cold curry) and I jumped in a started it. He thought it sounded great...however, I didn't and so opened the bonnet to find flames under the carbs. Whilst trying to cut the power/flap the flames out/run round heedlessly/wring my hands he wanted the full history of the marque To cut him short I asked if he would like to push me home....he left My neighbour with said MG drag car came down and towed me home...and no, not with the Midget, I couldn't have stood the embarrassment! Quote Link to post Share on other sites
Nigel C Posted January 21, 2023 Author Report Share Posted January 21, 2023 so finally got back in the workshop to put the head back on and I've had a ponder...whilst taking the sump off to clean I have now got a solid copper head gasket of 1.5mm thickness. I have re-shaped it to fit the edge of the liners and also fit the as tight as possible to the squish chambers in the head. after all this work has been done I am pleased with the result as now I have 4.5mm as the smallest gasket area on the liners (where the chamber bulges out for the inlet valve) and previously I only had 2mm with the pre shaped "off the shelf "copper gaskets. And the last composite gasket was no better either. After all this fettling I had a friend anneal it for me but after fitting and running up to temp (including getting the thermostat to open on the oil cooler to flush the last remnants of oil/water from the last failure) I did three miles and turned the contents of the engine into chicken soup! I found out that he had quenched the gasket after heating it up and this made it (IMHO) to hard again. when I took the head off and inspected the gasket it barely made an impression around the liners, there was a very faint trace/shape but you couldn't feel any compression marks. This, in my minds eye means the rest of the head was 4 tho off the block and allowed all fluids to happily get together and have a party at my expense. With another friend we set up the gasket on a piece of steel mesh to support it and annealed the gasket using a larger flame propane torch and I observed all areas glowing red and we allowed it to cool naturally. I am hoping this is sufficient. My thoughts are as follows; and please shoot me down if its not a good idea! If I fit the gasket dry, torque down and then undo and very gently, raise the gasket up to see if it has compressed around the liners. If so, coat in wellseal on both sides and fit, torque down and run? if not, go away into a dark room and weep............ Basically I cant face shoveling chicken soup up hill again Quote Link to post Share on other sites
Lebro Posted January 21, 2023 Report Share Posted January 21, 2023 Copper will anneal sucessfully by either allowing it to cool slowly, or by quenching. Maybe he did not get it hot enough ? Bob Quote Link to post Share on other sites
RobH Posted January 21, 2023 Report Share Posted January 21, 2023 +1 - quenching copper after annealing does not harden it. Quote Link to post Share on other sites
Motorsport Mickey Posted January 21, 2023 Report Share Posted January 21, 2023 (edited) That's the conundrum with solid copper gaskets, some swear by them and others swear at them. You say you are running with 4 thou liner heights and the solid copper gasket will have no problem sealing there. However...the thicker copper 1.5 mm thickness is stiffer where a standard copper/asbestos/copper gasket is malleable, floppy and only 1mm thick ie .5mm or 20 thou thinner in old money. The solid copper does have a problem stretching down to the lower pressure areas around the water jacket top of the block to head, annealing will hopefully make it easier to stretch. Personally I've never used a solid copper on my engine but I would be inclined to add a "Wills ring" type seal in fine copper wire around the harder to seal waterjacket areas, shaping it around them by hand and fixing them in place with a dab of glue until it goes off. Doesn't matter what sort of glue as long as it's soft, as soon as the head is torqued down the copper wire will compress sealing the fitted side and the extra pressure through the copper gasket sealing the other side. Mick Richards Haven't got a photo myself but I've pinched a photo from JimG off the Triumph Experience site. JimG Copper wire Wills.docx Edited January 21, 2023 by Motorsport Mickey Additional info Quote Link to post Share on other sites
Ian Vincent Posted January 21, 2023 Report Share Posted January 21, 2023 Neil Revington suggests Heldtite with copper gaskets. I know Iain Paul has a solid copper gasket and has it for a while and done few miles on it. Maybe you could PM him and ask how he uses it. Rgds Ian Quote Link to post Share on other sites
Lebro Posted January 21, 2023 Report Share Posted January 21, 2023 For those without Word ! Bob Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 21, 2023 Report Share Posted January 21, 2023 There is always the Racetorations copper head gasket that is stamped to the same style as our old friend the steel shim head gasket. https://www.racetorations.co.uk/product/copper-cylinder-head-gasket-tr2-4a/ Quote Link to post Share on other sites
iain Posted January 21, 2023 Report Share Posted January 21, 2023 3 hours ago, Ian Vincent said: Neil Revington suggests Heldtite with copper gaskets. I know Iain Paul has a solid copper gasket and has it for a while and done few miles on it. Maybe you could PM him and ask how he uses it. Rgds Ian As Ian said, I use a copper head gasket. Liner heights, as MIck is right to point out,are critical. The copper does need to be properly annealed. Cherry red is the target colour……..the only way you will see this, in my experience, is in a pitch black workshop! A normal gas torch is not enough, I use a Map Gas torch, you will know when it’s annealed, they are actually very difficult to handle they get that soft. Then I use wellseal on both surfaces. So far no issues , with approx 10k miles. The beauty with the copper option is that you can tailor your compression ratio to the right sort of figure for your cam or just to bring it back down after the head has had multiple skims. Iain Quote Link to post Share on other sites
ianc Posted January 21, 2023 Report Share Posted January 21, 2023 I have been running with a pair of solid copper gaskets since June 1995 - the second one necessitated when the head warped as a result of catastrophic loss of coolant on rolling road at full chat. They were annealed for me by the School's DT manager when I was Bursar - useful to have friends! I think he used the pottery kiln. Used Wellseal as Neil hadn't discovered Heldite (not Heldtite, by the way) back then. Ian Cornish Quote Link to post Share on other sites
Nigel C Posted January 21, 2023 Author Report Share Posted January 21, 2023 thanks all for your repiies, interesting idea with the rings of wire. the Racetorations gasket is the one I started out with and, due to its one size fits all, is so close to the edge of the liner as to be non existent. no one yet as thrown out my idea of torquing, lifting and checking before re-torquing tho...... Quote Link to post Share on other sites
Motorsport Mickey Posted January 21, 2023 Report Share Posted January 21, 2023 Now I'm confused You are relying on the anneal to allow the gasket to stretch, ...not to seal around the liner... 105 big ones will do that, and yet the Racetorations 20 thou copper with built in copper compression seals around liners AND all the lower pressure water jacket sealing points... a shoo in for a good seal...is disregarded ? With your original gasket what was the compressed thickness ? the 1.5mm (60 thou) solid copper you now propose to use will reduce your compression markedly if you planned and used a 20 thou gasket originally. I use the steel competition head gaskets at 20 thou thick with 2 sealing compression rings, I cut through 1 and halfway through the other...and the headgasket still seals. The waterjacket and oil galleries and stud holes have their own sealing presses included and they seal also. The steel obviously doesn't stretch as well as annealed copper so you have to control the liner heights keenly, and every thou extra height (I have used 6 thou on occasion) increases the sealing risk on the oil and water ways. Mick Richards Quote Link to post Share on other sites
Nigel C Posted January 22, 2023 Author Report Share Posted January 22, 2023 Hopefully nothing has been disregarded, perhaps just miss led in the past. By using Racestorations pre-machined/squish-combustion chamber shaped gaskets I have found them to be lacking in the certain areas (in contact with the edges of the liners) which "may have been" the original fault Mick, don't forget this is an Ali head (ATM!) and so only 65lb (specified by Pete Cox) or to Revingtoin's recommendations 75lb loading (where do I go!). I personally think I am fighting the reduction in torque settings and thickness of gasket.....but what else can I do? Perhaps I should obtain a thinner copper gasket and start all over again? but this is what I have been advised is best to obtain the correct/best compression ratio's for modern fuels/road running?. I suspect over the years this head has had several skims/work/fettling and Revingtons (who's number is stamped on the head) say they only have the code down in their "book" as 2006 and no name/owner/spec allocated to it A thinner gasket may well "adjust" to the differences in the liner to block heights with a lower torque setting head arrangement? but will I end up with ridiculous compression ?? I'm going to bed.............................................................................................................................................. Quote Link to post Share on other sites
Motorsport Mickey Posted January 22, 2023 Report Share Posted January 22, 2023 OOpps missed the Ali head spec part, thought we were on cast What was the original gasket Copper or Composite and it's thickness ? You say; "By using Racestorations pre-machined/squish-combustion chamber shaped gaskets I have found them to be lacking in the certain areas (in contact with the edges of the liners) which "may have been" the original fault" Given that heads and blocks are identical on positioning I'd expect Darryl to have a working copper gasket turned out, he's very good at that. Do you mean the gasket edge was sticking into the chamber or sitting part way across the liner face ? If it had sealing ring on it that's the important contact surface on the liner, as said I'd expect that to be correctly positioned. Given that these copper gaskets are supposed to cover 83-92mm at 89 you are comfortably in the middle of these parameters. Mick Richards Quote Link to post Share on other sites
Nigel C Posted January 22, 2023 Author Report Share Posted January 22, 2023 there's two lines here on top of the liner. the inner one is a pencil line drawn around the squish/combustion chamber in the head the outer one is the edge of the "off the shelf/one size fits all" gasket. That, to my mines eye, is way to close for comfort (and compression!) Quote Link to post Share on other sites
Motorsport Mickey Posted January 22, 2023 Report Share Posted January 22, 2023 (edited) This is some work carried out on a TR4 Race head (cast not alloy, it subsequently ran reliably) check out the areas where it may be different from yours and list them Check out the area in between the siamesed inlet valves and the reliefs ground in there, what dimension do you think it is there, between the chamber walls ? See the gasket compression ring seal line around where the valve cut outs are ? The compression rings seals up the centre of the pressed ring, where there are 2 rings I cut out the first and half way across the second...it still seals, it has a pressed (extra material because of it) ring which does the job. If you go too far...so what ? the head gasket blows and shows you where the weakness is, you just give it a little more material there. No...I've never blown a steel headgasket cut like this, so never needed to amend the cut areas. Mick Richards Edited January 22, 2023 by Motorsport Mickey Quote Link to post Share on other sites
stuart Posted January 22, 2023 Report Share Posted January 22, 2023 I know the racers have trouble with the Ally head and arent keen on them, if this is a second hand head Im wondering why the previous owner got rid of it? I assume youve checked the amount thats been planed off it? Stuart. Quote Link to post Share on other sites
Nigel C Posted January 23, 2023 Author Report Share Posted January 23, 2023 Mick, Thanks for taking the time to post the photo etc; a thousand ships and all that. Stuart, yes I believe this had started its lift in racing and it has a Revingtons mark/code stamped on it and that is why I reverted to talking to them to see what and where it came from/went to. They did find "The Book" that holds all their info, head was sold in 2006 and unlike all the others listed they have no other data on it!! I've just been back out to the workshop and taken a few more photos so you can what I have (or don't have) I have based all the images on No2 as this was initially the problem cylinder. Image 1. the Pencil line denotes the inner edge of the liner. Where it disappears its because its right on the edge of the ali. Image 2. This shows the Revington 1.5mm thick solid copper gasket, hand worked to fit perfectly around both components on all 4 cylinders. this gasket has been the last two attempts at annealing and fitting. I decided today to fit this gasket dry, torque down to 70lb and then remove to check whether it had actually compressed around the top of the liners. It didn't so at least I'm not mopping up chicken soup again. There is a very faint outline on the gasket, no discernible "feel" to it and so I am sure it was going to fail as per the first time (looked just the same) the liquid is a drop of oil I put on to see if it spread across the head, it didn't either. I really think this gasket to thick/hard for some reason and won't compress the 4 tho needed. Revingtons specified this thickness based on the cc's/stroke/piston height from block/bore/etc to try an obtain their recommended compression ratio of around 9.5 to 10 (due to modern fuels etc?). Image 3 this shows the Revington gasket on the block Image 4 shows the Siamese area, is this acceptable? Image 5. shows the total depth of the head as of now Image 6. VERY crude depth of chamber between valves 4. 5. 6. Image 7 shows the Racetorations thin copper gasket and how close it is to the edge (orange arrow) although this did last a few thousand miles before slowly failing (sucking water into No2 and I didn't notice for sometime just kept topping it up and trying to find leaks!). Being so thin I suspect the compression ratio must have been high too. Image 8 shows a pencil line around this gasket when removed. this is a nominal 2mm whereas with the Revingtons hand worked gasket this area is now 4.5mm nominal area. 7. 8. Image 9 shows the Racetorations composite gasket, this really let go with water in No2 and oil in No's 3 & 4 after no miles at all. Again you can see how this "one size fits all" makes it very close on the edge of the liner (orange arrow) 9. So there we have it at the moment. Annealing seems to be a artform that is not easliy tapped into (for me anyway) as I have had so many conflicting answers. I have looked at heat treatment companies on line and may call one and have a talk with them. Or I could post it back to Revingtons and get them to do it? or is this to many times? or change to a thinner gasket, work to shape, anneal and try? or fit a very cheap MOSS copper composite that comes in a top end gasket set (that I have) image below. It certainly looks and feels like it would compress but there is a lot of material hanging over the siamese area and coolant holes are large and close to the edges? Or do I carry on drinking this fine single malt and tomorrow revert to fitting the upstairs bathroom out in stead.............. Quote Link to post Share on other sites
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