Funny isn't it. You think of steel as being something so solid but when you slow things down and look closely it flexes constantly. I guess the issue we have learned here is the importance of knowing how much!
Paul your diagnosis is fanbloodytastic I like the Chinese theory the rods where probably a bike in it’s former life😂 I had a similar problem when we had a new truck that was forever blowing head gaskets ,when it was made it had a liner sitting proud by a nats fart because the land in the block was machined wrong ,us old fart talk a lot looking forward to seeing it all back together and racing top lad 👍👨🏻🏭🇬🇧
Hi Paul. Just viewed your video - great job. In regard to the piston extending beyond the top of the cylinder, we deal with this on the Formula Vee race engines we build. In a standard VW Beetle air-cooled engine VW recommend that the piston should be 1.5mm below the top of the cylinder to allow for extension of the conrod and other parts at high revs. In a race engine this would be way too much so we machine the bottom of our cylinders to give a gap of about 0.15mm and this gives good compression. If we were to go level with the top of the cylinder or less than 0.05 the piston would hit the head at high revs. A VW Beetle engine doesn't have a head gasket but the cylinder fits tight to the cylinder head, so we wouldn't have the luxury of having a gasket to solve our problem. I found your video very interesting as it explores the concept of conrod stretch at high revs.
Fascinating as ever. A gasket that is more forgiving gives some piece of mind to those uncertain tolerances. Nice to see the other options and their specific application. Test for the inomalies the inaccuracies factor in fault tolerances all while ensuring heat, vibration, expansion and contraction are accounted for. Ballenced/weighted to within a hair of accuracy 🙂 #thejoysofengineering #neverstoplearning
The original head gasket break out the side makes me think it can't be entirely a crank flex issue, or it would be more consistently between cylinder pairs. However, a combination of crank flex _and_ rod stretch (both somewhat expected at high rpm) would make sense, and would explain the variation in the head gasket fails. Cheers, Paul - a perfectly logical diagnosis. But the proof is always in the pudding - I look forward to seeing how this engine behaves once the changes are done and it's put back on track. :-)
Who would want to go motor racing? Excellent as usual and love the thought process. Incredibly unlikely the crankshaft was a contributory factor as even though it’s a 3 bearing, it’s a short shaft and there didn’t appear to be a wear mark on the outer edge of the bearing. The crown and lands look perfect so the piston didn’t hit anything harder than itself suggesting there is (was) sufficient clearance to the head. I’d like to see the gasket under a 10x, it might just reveal more wear on the lower side of the fire ring and a slight flattening at the top. Also gasket looked as if it failed instantly rather than gradually as it lacks the discoloration of a slow failure. How did the driver describe it? Slightly surprised you didn’t opt for a steel gasket from the outset, especially as you were running such close tolerances. You were right to get both head and block surfaced; the block is often neglected. Years ago we use to run them against one another to check for distortion. Doubt the con rods contributed although you did question their pedigree. The gasket should confirm this. It’s possible to rim the edge of the piston but shouldn’t be necessary with the steel gasket. Pity there aren’t more track days to play. You said the valves looked perfect and I assume the plugs so ignition and fueling are good. One simple try is a double gasket to verify it’s only a clearance issue, but when you sort this you’ll have a flier. Compliments on a honest open look with nothing hidden and a thought process that is as intriguing as it is incisive. Just another great video. Keep them coming. It’s some compliment to be mentioned in the same sentence as David Vizard, but I’d be hard pressed to decide who it’s complimenting. Just brilliant!!!!!
Good video as usual, we use the cometic gaskets on our NA ardens,.it prevents the normal fire ring from eating into the heads. The only thing we have to watch out for is the copper rings that hold the parts together fouling the head.
@@HREIRLFrom your experience, I recently cometic gasket failed between 2&3 and melted the block and head. We used ARP fasteners however not 11 stud. Can excessive CR cause this, or could it be pinging? Maybe distributor is curved too aggressively? Last time we took off the head it was not damaged but the gasket was black between 2&3 both on a commetic and copper gasket. Head was skimmed so was the block.
Great the hear you are a Vizard apostle! I've watched a number of the TH-cam videos on his Mini engine development, some dating back to the 1970's. He is a true gift from the gods. Some recent videos he discusses valve spring design developments...have you looked into that for your race program?
Great content, loved this video! Just an observation, could you rule out crankshaft flex, because, thinking back to your initial head gasket failure, it failed from cylinder 4 outward, not between 4 and 3, suggesting it’s random to an extent. "Chinesium" conrod stretch, my completely uneducated guess, just from listening to you there. The stainless gasket looks the biz too!! When you build me that FIA spec engine down the line I’d like a stainless head gasket please 😂😁
Maybe the gasket overhanging the bore when torqued down squished down into the bore a bit that may be why the pistons were hitting it even though they weren’t going above the block
I’d like to know more about that gasket. Please tell me that gasket was not sourced from one of the main mini vendors out there - because they should know.
When you check the tdc stick out height add pressure to the bottom of the rod to take up any bearing clearance and recheck that height! Static and running clearances change your not compensating for the spinning, while its spinning the bearings is wanting to throw outwards, statically its slightly lower due to the clearance! If you have 0.06 clearance that would give you a minus .03 reading static but when spinning that would/ might double up adding to your stick out.
@@tobymiddleton6763 Wont be an issue now he has the correct sized head gasket, as most are designed for a plus .060" overbore. Where i used to work bought in many sets of pistons, say ten sets weigh them up and put the lightest to the side, as one piston within the engine couldn't be machined, had to retain original markings for the formula, We then measured up the pin to crown heights, we could then skim the heads of the pistons to match the height of the lightest it would then be also matched for weight balance, each rod journal would then be re-sized for length so each rod was exactly the same length not for oval journals, this gave us a consistent deck height across all pistons, we would do a dry fit up before the deck was ground.
@@HREIRL your video helped me solve the issue, why I was blowing head gaskets you were spot on with your findings, had zero deck Hight and the gasket was just as you stated, have more than 2000 miles on it now and the engine sounds and rounds very smooth, thanks for the videos and nice work. Oh if you ever need the Cad drawing for the small bore head gasket let me know 😊
Let's hope that you've sorted it. Just wondered if it could have been caused by the rods and pistons expanding at a different rate than the block and resulting in the pistons coming slightly out of the top of the block. I know from bitter experience how disappointing etc. it is to withdraw a car at the track, especially as I assume that it was advertising your business. When I was racing in the early 1960s we didn't have anything written on our cars so this didn't arise. Fingers crossed for next time, good luck.
Hi Paul, brilliant and instructive video, as always. Couldn’t you just turn a half-millimetre chamfer around the top edge of the piston? Surely the edges of the piston would be improved by this: no sharp corners to start glowing at high revs and risking detonation, and the tiny weight reduction would only be positive, albeit minuscule…? Cheers, Will
Do you know if there is a slightly higher temperature around #4 cylinder? Could you remove the material from around the edges of the top of the Pistons rather than across all the top surface. 1/8th of an inch around the edge should be enough .......width not depth :) I don't imagine you want to resort to Wills rings yet.
very interesting but doesn't the engine metal expand differently at different thicknesses of section so between cylinders it expands less or expands the same but distorts more??😊
another great content in this video,nice work mate,,i did see that janspeed would quite often fit a small length of fuse wire on the block between cylinders 2 and 3 then fit the gasket,this isnt an old wives tale its actually on one of their videos ive watched a few times,is this something you would consider doing bearing in mind this engine in question is a race engine..
The most applicable would be "Tuning BL's A-Series Engine" - but I'd also recommend "How To Modify Your Mini", which is more general, but covers a much wider range of topics including suspension, brakes, etc.
@@aussiebloke609 Thanks. Did some googling "The Tuning The A-Series Engine" you can hold off but the other one (How to Modify Your MINI) is out of print. I understand that these books are the holy grail.
@@rolflyden6324 I just found a few copies - all used, of course - on both Amazon and Ebay, for around USD $100, so they seem to be acquiring collector prices now. But still worth it, I think - that price isn't likely to go down unless there's a fresh print run at some point. I know I treasure my copy all the more now. :-)
My brother builds driveshafts and they spin them at 10-12,000 RPM’s to check any vibration, that’s why I was wondering, Do you guys race aluminum driveshafts? Or even carbon fiber ? Wonder if that’s something a mini could benefit from the weight saving
Brilliant! Love the analysis Paul. I’m interested to get your thoughts on the rods - at 6” they are a good option for me with datsun pistons in a normal deck height block. Also interested to know what sort of CR you run? Thanks
Hi Paul, is the crank cast or forged ? If it was forged would this stop any flex at high RPM ? With the stainless gasket will it flatten out to the edge of the cylinder when you torque the head down ? I just love your vids 👍👏🤤
@@HREIRL Differential thermal expansion of the rods was also my first thought - it wouldn't be that much trouble to check the actual expansion of the rods over a temperature range and compare with the same length of steel?
@@cdellis1000 Its an intresting idea Chris, and as you say wouldn't be very difficult to check on a test bench. we may well end up doing such a test in the near future as the rods are now surplus to requirements.
If the gasket overlapped the bore as much as we can see, possibly the ring deformed downward? And then the pistols can touch them. I would think those I beam rods won't stretch, no matter how bad the metal is.
Chamfering the top of the piston crowns is recommended by Keith Calver to allow for unknown expansion of components such as possible piston and rod thermal expansion, rod stretch under high rpm, head gasket manufacturing imperfections etc etc. Most of these events are not possible to measure statically or dynamically in the workshop. Only the heat of competition causes the extreme conditions. The original C-AHT 188 copper gasket is the preferred Special Tuning choice for competition use - not that Payen one you are using. I have never had a problem with the copper Special Tuning gasket now renamed GEG300 by Mini Spares. Copper compensates for surface imperfections and heat is dissipated away from the fire ring better. Chamfer the piston tops and fit the copper gasket on one of your test engines and I would be surprised if you had any more of those type of piston to fire ring problems.
Sin the late 1960s I had to face a mini which constantly overheated. The problem was, the owner a young bloke about 18 had replaced the fan...........he somehow got a fan off an Austin A??? . Turned out it blew the wrong way ----------------the lesson being that minis are blowers others suck air ............the fan was pitched the wrong way!!! The young bloke was a sucker also? Stavros , a young bloke when minis began.
taxing my memory in the mid 1990s i did my trade training and had dealings with a mini racer it was known that big overbores would destroy the factory gasket i dont remember the solution i think it may have been a oversized copper gasket that cleared the bores
Also factory gaskets only work up to 0.060 th oversize beyond 60 over you need non standard gasket eg your mls cometic type gasket or a copper gasket with oversized bore relief
I would be suspiciuos of your Chinesium, ebay sourced con rods, personally. I reckon they are stretching & allowing too much tollerance that is difficult or near impossible to allow for.
Fascinating as ever. The thought of cranks and rods flexing makes me go queasy. You are certainly a modern day Vizard!
Funny isn't it. You think of steel as being something so solid but when you slow things down and look closely it flexes constantly. I guess the issue we have learned here is the importance of knowing how much!
you and me both Paul 🤢
Great video. Fascinating diagnosis. Delightful reference to the great David Vizard. Good luck with the rebuild.
thanks John
Paul your diagnosis is fanbloodytastic I like the Chinese theory the rods where probably a bike in it’s former life😂 I had a similar problem when we had a new truck that was forever blowing head gaskets ,when it was made it had a liner sitting proud by a nats fart because the land in the block was machined wrong ,us old fart talk a lot looking forward to seeing it all back together and racing top lad 👍👨🏻🏭🇬🇧
Thanks Paul it can be the simplest things that cause the biggest problems
Hi Paul. Just viewed your video - great job. In regard to the piston extending beyond the top of the cylinder, we deal with this on the Formula Vee race engines we build. In a standard VW Beetle air-cooled engine VW recommend that the piston should be 1.5mm below the top of the cylinder to allow for extension of the conrod and other parts at high revs. In a race engine this would be way too much so we machine the bottom of our cylinders to give a gap of about 0.15mm and this gives good compression. If we were to go level with the top of the cylinder or less than 0.05 the piston would hit the head at high revs. A VW Beetle engine doesn't have a head gasket but the cylinder fits tight to the cylinder head, so we wouldn't have the luxury of having a gasket to solve our problem. I found your video very interesting as it explores the concept of conrod stretch at high revs.
Great stuff Paul, you're like an engine detective
Thanks Stewart
Fascinating as ever. A gasket that is more forgiving gives some piece of mind to those uncertain tolerances. Nice to see the other options and their specific application. Test for the inomalies the inaccuracies factor in fault tolerances all while ensuring heat, vibration, expansion and contraction are accounted for. Ballenced/weighted to within a hair of accuracy 🙂 #thejoysofengineering #neverstoplearning
Thanks dude 👍
The original head gasket break out the side makes me think it can't be entirely a crank flex issue, or it would be more consistently between cylinder pairs. However, a combination of crank flex _and_ rod stretch (both somewhat expected at high rpm) would make sense, and would explain the variation in the head gasket fails. Cheers, Paul - a perfectly logical diagnosis. But the proof is always in the pudding - I look forward to seeing how this engine behaves once the changes are done and it's put back on track. :-)
Thanks dude appricat it
Who would want to go motor racing? Excellent as usual and love the thought process. Incredibly unlikely the crankshaft was a contributory factor as even though it’s a 3 bearing, it’s a short shaft and there didn’t appear to be a wear mark on the outer edge of the bearing. The crown and lands look perfect so the piston didn’t hit anything harder than itself suggesting there is (was) sufficient clearance to the head. I’d like to see the gasket under a 10x, it might just reveal more wear on the lower side of the fire ring and a slight flattening at the top. Also gasket looked as if it failed instantly rather than gradually as it lacks the discoloration of a slow failure. How did the driver describe it? Slightly surprised you didn’t opt for a steel gasket from the outset, especially as you were running such close tolerances. You were right to get both head and block surfaced; the block is often neglected. Years ago we use to run them against one another to check for distortion. Doubt the con rods contributed although you did question their pedigree. The gasket should confirm this. It’s possible to rim the edge of the piston but shouldn’t be necessary with the steel gasket. Pity there aren’t more track days to play. You said the valves looked perfect and I assume the plugs so ignition and fueling are good. One simple try is a double gasket to verify it’s only a clearance issue, but when you sort this you’ll have a flier. Compliments on a honest open look with nothing hidden and a thought process that is as intriguing as it is incisive. Just another great video. Keep them coming. It’s some compliment to be mentioned in the same sentence as David Vizard, but I’d be hard pressed to decide who it’s complimenting. Just brilliant!!!!!
Thanks Tommy Yes defiantly think it was contact unfortunately
Great video Paul and enjoyed your analysis of the issue with the head gasket.
Thanks Conor
Good video as usual, we use the cometic gaskets on our NA ardens,.it prevents the normal fire ring from eating into the heads. The only thing we have to watch out for is the copper rings that hold the parts together fouling the head.
Ya came across that my self I think they have changed the design now to move it to a new place
@@HREIRLFrom your experience, I recently cometic gasket failed between 2&3 and melted the block and head. We used ARP fasteners however not 11 stud. Can excessive CR cause this, or could it be pinging? Maybe distributor is curved too aggressively? Last time we took off the head it was not damaged but the gasket was black between 2&3 both on a commetic and copper gasket. Head was skimmed so was the block.
Great the hear you are a Vizard apostle! I've watched a number of the TH-cam videos on his Mini engine development, some dating back to the 1970's. He is a true gift from the gods. Some recent videos he discusses valve spring design developments...have you looked into that for your race program?
I have but as yet havent found a cost effective route to market. watch this space
Great content, loved this video!
Just an observation, could you rule out crankshaft flex, because, thinking back to your initial head gasket failure, it failed from cylinder 4 outward, not between 4 and 3, suggesting it’s random to an extent.
"Chinesium" conrod stretch, my completely uneducated guess, just from listening to you there.
The stainless gasket looks the biz too!! When you build me that FIA spec engine down the line I’d like a stainless head gasket please 😂😁
very good point mick I think your sport on
Maybe the gasket overhanging the bore when torqued down squished down into the bore a bit that may be why the pistons were hitting it even though they weren’t going above the block
I’d like to know more about that gasket. Please tell me that gasket was not sourced from one of the main mini vendors out there - because they should know.
very possible Luca
When you check the tdc stick out height add pressure to the bottom of the rod to take up any bearing clearance and recheck that height! Static and running clearances change your not compensating for the spinning, while its spinning the bearings is wanting to throw outwards, statically its slightly lower due to the clearance! If you have 0.06 clearance that would give you a minus .03 reading static but when spinning that would/ might double up adding to your stick out.
Is this something you'd check on any engine or just "race/performance"? I don't think I've seen anyone do this 🤔
@@tobymiddleton6763 Wont be an issue now he has the correct sized head gasket, as most are designed for a plus .060" overbore. Where i used to work bought in many sets of pistons, say ten sets weigh them up and put the lightest to the side, as one piston within the engine couldn't be machined, had to retain original markings for the formula, We then measured up the pin to crown heights, we could then skim the heads of the pistons to match the height of the lightest it would then be also matched for weight balance, each rod journal would then be re-sized for length so each rod was exactly the same length not for oval journals, this gave us a consistent deck height across all pistons, we would do a dry fit up before the deck was ground.
Very good point chris noted 👍
Great content and interesting findings!
thanks Luis
I had the same issue with an 80 thu oversized 998, chamfered the pistons crown and used a custom compensate gasket
that is an interesting solution, how has it faired out ?
@@HREIRL your video helped me solve the issue, why I was blowing head gaskets you were spot on with your findings, had zero deck Hight and the gasket was just as you stated, have more than 2000 miles on it now and the engine sounds and rounds very smooth, thanks for the videos and nice work.
Oh if you ever need the Cad drawing for the small bore head gasket let me know 😊
Hi Paul great video. You talk about surface finish. What should that be to be correct for the stainless steel head gasket. Thanks Bernard
40RA Bernard 👍
Let's hope that you've sorted it. Just wondered if it could have been caused by the rods and pistons expanding at a different rate than the block and resulting in the pistons coming slightly out of the top of the block. I know from bitter experience how disappointing etc. it is to withdraw a car at the track, especially as I assume that it was advertising your business. When I was racing in the early 1960s we didn't have anything written on our cars so this didn't arise. Fingers crossed for next time, good luck.
thanks for the well wishes Tony. I never mind making mastakes that all part of it
Hi Paul, brilliant and instructive video, as always. Couldn’t you just turn a half-millimetre chamfer around the top edge of the piston? Surely the edges of the piston would be improved by this: no sharp corners to start glowing at high revs and risking detonation, and the tiny weight reduction would only be positive, albeit minuscule…?
Cheers, Will
good point Will and basically what we did 👍👍
Hi Paul. Is that the same type of gasket that was on the early Rover K series engine's .Realy enjoy your videos.
Do you know if there is a slightly higher temperature around #4 cylinder?
Could you remove the material from around the edges of the top of the Pistons rather than across all the top surface. 1/8th of an inch around the edge should be enough .......width not depth :)
I don't imagine you want to resort to Wills rings yet.
No I would certainly like to avoid the Wills rings for sure 😁
very interesting but doesn't the engine metal expand differently at different thicknesses of section so between cylinders it expands less or expands the same but distorts more??😊
another great content in this video,nice work mate,,i did see that janspeed would quite often fit a small length of fuse wire on the block between cylinders 2 and 3 then fit the gasket,this isnt an old wives tale its actually on one of their videos ive watched a few times,is this something you would consider doing bearing in mind this engine in question is a race engine..
something to consider all right
Another great video! Thanks.
The book you mentioned from David Vizard. Which one was that? And what other books can you recommend?
The most applicable would be "Tuning BL's A-Series Engine" - but I'd also recommend "How To Modify Your Mini", which is more general, but covers a much wider range of topics including suspension, brakes, etc.
@@aussiebloke609 Thanks. Did some googling "The Tuning The A-Series Engine" you can hold off but the other one (How to Modify Your MINI) is out of print. I understand that these books are the holy grail.
@@rolflyden6324 I just found a few copies - all used, of course - on both Amazon and Ebay, for around USD $100, so they seem to be acquiring collector prices now. But still worth it, I think - that price isn't likely to go down unless there's a fresh print run at some point. I know I treasure my copy all the more now. :-)
thats the one all right
@@HREIRL Thanks. Bought it used from the UK via eBay.👍
Wonder if a crank balancer would detect any flexing higher than what’s normal?
unfortunately not as it doesn't spin the crank fast enough
My brother builds driveshafts and they spin them at 10-12,000 RPM’s to check any vibration, that’s why I was wondering, Do you guys race aluminum driveshafts? Or even carbon fiber ? Wonder if that’s something a mini could benefit from the weight saving
Brilliant! Love the analysis Paul. I’m interested to get your thoughts on the rods - at 6” they are a good option for me with datsun pistons in a normal deck height block.
Also interested to know what sort of CR you run? Thanks
The rods are from what I have seen quite good if not a bit heavy. regarding compression ration typically aiming for 12:1 static
Hi Paul, is the crank cast or forged ? If it was forged would this stop any flex at high RPM ? With the stainless gasket will it flatten out to the edge of the cylinder when you torque the head down ? I just love your vids 👍👏🤤
Forged for sure Guy
Really enjoy this information open my head to new ideas Thank you very much.Question for you do you know Kevin Flanagan.
I sure do Tyrone a gentleman and a scolar
@@HREIRL He came over to Barbados to rally and enjoyed himself over here.Great Guy.
@@HREIRL Question can i run the water by pass through the heater back to the Radiator so i can turn to blower on to help with the cooling.
@@tyronecorbin9982 most definitely it will only help the situation 👍👍
Not knowing the actual composition of the con rods, is there a possibility of differential expansion under high temperature between con rod and block?
its passible Paul but as you say the rod is an unknown so we may never know
@@HREIRL Differential thermal expansion of the rods was also my first thought - it wouldn't be that much trouble to check the actual expansion of the rods over a temperature range and compare with the same length of steel?
@@cdellis1000 Its an intresting idea Chris, and as you say wouldn't be very difficult to check on a test bench. we may well end up doing such a test in the near future as the rods are now surplus to requirements.
Check the tram of the grinding machine other wise it will grind concave conrods can stretch o 5o at high rpm
I would have straightened the conrods then less to remove off the piston and the rings wood run true to the bore
Noted Aldo will do
If the gasket overlapped the bore as much as we can see, possibly the ring deformed downward? And then the pistols can touch them. I would think those I beam rods won't stretch, no matter how bad the metal is.
I completely agree GTE
sometimes its better to finish the race the tuner and drivers dilemma!😊😊😊
Chamfering the top of the piston crowns is recommended by Keith Calver to allow for unknown expansion of components such as possible piston and rod thermal expansion, rod stretch under high rpm, head gasket manufacturing imperfections etc etc. Most of these events are not possible to measure statically or dynamically in the workshop. Only the heat of competition causes the extreme conditions. The original C-AHT 188 copper gasket is the preferred Special Tuning choice for competition use - not that Payen one you are using. I have never had a problem with the copper Special Tuning gasket now renamed GEG300 by Mini Spares. Copper compensates for surface imperfections and heat is dissipated away from the fire ring better. Chamfer the piston tops and fit the copper gasket on one of your test engines and I would be surprised if you had any more of those type of piston to fire ring problems.
Also… over torquing the head can squash rather than compress the fire rings. 45 ft lbs maximum with no lube on the studs or nuts.
Can i used this gasket on my 1380 road car
If you can get the RA40 surface finish I dont see why not
Sin the late 1960s I had to face a mini which constantly overheated. The problem was, the owner a young bloke about 18 had replaced the fan...........he somehow got a fan off an Austin A??? . Turned out it blew the wrong way ----------------the lesson being that minis are blowers others suck air ............the fan was pitched the wrong way!!! The young bloke was a sucker also?
Stavros , a young bloke when minis began.
that has caught more than a few people over the years for sure
taxing my memory in the mid 1990s i did my trade training and had dealings with a mini racer it was known that big overbores would destroy the factory gasket i dont remember the solution i think it may have been a oversized copper gasket that cleared the bores
Also factory gaskets only work up to 0.060 th oversize beyond 60 over you need non standard gasket eg your mls cometic type gasket or a copper gasket with oversized bore relief
I would be suspiciuos of your Chinesium, ebay sourced con rods, personally. I reckon they are stretching & allowing too much tollerance that is difficult or near impossible to allow for.
Next time we pull the motor we can check this as we now have a reference
2nd, dam lol
👍