Many , many years ago I used to strip my imp/ singer engines and replace head gaskets during the tuning process and when they failed! I wish I knew then what your excellent video has shown me today!👍❤️
Because the early PSA motors as fitted to Renault and Peugeot were mounted inclined and ran very hot they had long bolts going down to the base of the liner with a semicircular nut held captive in the outside of the block which prevented liner creep.
A great video, in fact I've just found and subscribed to your channel. We've got an Imp I bought during the mid eighties and it has the usual mods that were the norm back then - 998 with a GT head that was ported by going straight down in a drill press, fast road cam (I think it's something like 25-60-60-25 and 300 lift), combined inlet and exhaust manifold with twin 35 DHLB Dell'Ortos, front VW Golf radiator and fan, Viva front discs, front camber adjustment, etc, etc. The block is actually an 875 that was taken out to 998 using thin wall dry liners, dropped after sitting in liquid nitrogen, and using a step at the bottom of the bore to prevent the liners slipping. The top of the liners are also a few thousandths of an inch proud of the deck, which was 'bridge welded' between cylinders two and three and then stress relieved afterwards. The bridge welding just gives the gasket fire rings a little extra support. The head is clamped down with high tensile studs and nuts. It's realistically only an 8000rpm engine, but we've been running the car like this (fast road only) for about 30 years and one engine refresh, and never had a head gasket problem. We did think about going to wet liners and Wills Rings, after watching this video I'm glad we went the route we did all those years ago. I decided on the step at the bottom of the bore after hearing that Roots experimented with running pistons directly in an aluminium bore. My reasoning was they had managed to pull this off (decades before nikasil alusil etc), so a narrow band of aluminium at the bottom of the bore should be fine. It's now well and truly proven itself as an idea. Looking forward to watching more of your videos!
wow well it’s definitely stood the test of time ! interesting you sat the liner on a shoulder at the bottom of the cylinder, i have seen many a dry liner engine with the top hat fail then the liner slipped down and got munched by the crankshaft counter weights!
@@bernardwarr4187 I think it will largely depend on how they were fitted. We went out of our way to make sure they couldn't slip down the bore, being clamped between the head and a step in the bottom of the bore, and using liquid nitrogen to shrink the liners before dropping them in. Without knowing how yours were done I can't speak to their longevity. All I can say is that in our case the extra steps we took worked long term.
@@thehillmanator Unfortunately the diameter reduction on a top hat liner is going to be the perfect stress riser for multiple reasons - expansion coefficient, temperature variation, and of course reduction in material cross-section. Our reasoning was that if Hillman could successfully run a experimental engine with aluminium alloy pistons direct in a high pressure die-cast aluminium block, then we could safely leave enough aluminium at the bottom of the bore to act as a 'stop' for the steel liner. Touch wood, it's worked well thus far. I've probably got some old photos kicking around if you want to see how it looked 'in the metal'. I took some when I had the engine apart for a refresh.
Great vid When I was playing with Imps and Stilettos In the 90's my engine builder had a mod I hadn't heard of He milled the block taking the alloy layer off the cylinders Once my donk was rebored he used the boring bar to cut a recess in the tip of the liner then fitting a custom made copper oring to the top of each liner Apart from a cheats increase in compression ratio, never did the engine even consider leaking from the head gasket If I wanted to race it He had another mod of making alloy wedges to locate the liners and prevent "walking" of the liners Heard of that one??
Thanks for that - All I am going to see in the back of my my mind now when the rev counter needle goes past the high beam lamp is liners doing the Ali shuffle - is that Ali doing the liner shuffle....
Hilman Imp engines originally had a normal head gasket. I had a Ginetta G15 with 998cc version in 192. This had a gasket not wills rings, these came in about 6 months after I got mine (unfortunately). The result was a blown head gasket at high revs. Didn't do the engine any good.
Hi Andy, Excellent Job, on your last engine are the holes round the liners for water cooling / expansion/ weight saving.. Best Rgs Rodders PS Midge engine still not fitted in racer yet...
Facinating - many thanks. A question if I may. I believe early 998 blocks were dry liner but they had problems and switched to wet liner. What were the problems?
thanks glad you enjoyed it ! yes early works blocks had dry liners but after a while they used to crack under the shoulder at the top and then work there way down into the crankcase! larger radius opposed to a a square undercut removed the stress and stopped this problem.
Many , many years ago I used to strip my imp/ singer engines and replace head gaskets during the tuning process and when they failed! I wish I knew then what your excellent video has shown me today!👍❤️
Really informative and well presented. You know your stuff. Thank you for taking the time to make this.
Andy, your videos are superb. Fantastic explanations, please keep them coming and digress as much as possible.!👍
Remarkably clear, considering the complexity of the subject. Very well presented.
Andy, thank you for this wonderful video explaining this mystery to me as it is much appreciated.
nice video andy, i like the way you are very informative and make it easier to understand
Brilliant video Andy, I was actually deciding which way I wanted to go with a future build I have planned and you've made my mind up!
Many years ago, my brother worked with Andy Chesman who was putting bored out imp engines in hydroplanes
Because the early PSA motors as fitted to Renault and Peugeot were mounted inclined and ran very hot they had long bolts going down to the base of the liner with a semicircular nut held captive in the outside of the block which prevented liner creep.
A great video, in fact I've just found and subscribed to your channel. We've got an Imp I bought during the mid eighties and it has the usual mods that were the norm back then - 998 with a GT head that was ported by going straight down in a drill press, fast road cam (I think it's something like 25-60-60-25 and 300 lift), combined inlet and exhaust manifold with twin 35 DHLB Dell'Ortos, front VW Golf radiator and fan, Viva front discs, front camber adjustment, etc, etc.
The block is actually an 875 that was taken out to 998 using thin wall dry liners, dropped after sitting in liquid nitrogen, and using a step at the bottom of the bore to prevent the liners slipping. The top of the liners are also a few thousandths of an inch proud of the deck, which was 'bridge welded' between cylinders two and three and then stress relieved afterwards. The bridge welding just gives the gasket fire rings a little extra support. The head is clamped down with high tensile studs and nuts.
It's realistically only an 8000rpm engine, but we've been running the car like this (fast road only) for about 30 years and one engine refresh, and never had a head gasket problem. We did think about going to wet liners and Wills Rings, after watching this video I'm glad we went the route we did all those years ago. I decided on the step at the bottom of the bore after hearing that Roots experimented with running pistons directly in an aluminium bore. My reasoning was they had managed to pull this off (decades before nikasil alusil etc), so a narrow band of aluminium at the bottom of the bore should be fine. It's now well and truly proven itself as an idea.
Looking forward to watching more of your videos!
wow well it’s definitely stood the test of time !
interesting you sat the liner on a shoulder at the bottom of the cylinder, i have seen many a dry liner engine with the top hat fail then the liner slipped down and got munched by the crankshaft counter weights!
Interesting the hear about your project. I have fitted straight lines to me Mercedes V8, so hope it last as long as yours
@@bernardwarr4187 I think it will largely depend on how they were fitted. We went out of our way to make sure they couldn't slip down the bore, being clamped between the head and a step in the bottom of the bore, and using liquid nitrogen to shrink the liners before dropping them in. Without knowing how yours were done I can't speak to their longevity. All I can say is that in our case the extra steps we took worked long term.
@@thehillmanator Unfortunately the diameter reduction on a top hat liner is going to be the perfect stress riser for multiple reasons - expansion coefficient, temperature variation, and of course reduction in material cross-section. Our reasoning was that if Hillman could successfully run a experimental engine with aluminium alloy pistons direct in a high pressure die-cast aluminium block, then we could safely leave enough aluminium at the bottom of the bore to act as a 'stop' for the steel liner. Touch wood, it's worked well thus far. I've probably got some old photos kicking around if you want to see how it looked 'in the metal'. I took some when I had the engine apart for a refresh.
i replaced my imp head gaskets many times i never knew about the aluminium ridge on the liners, don't think it was mentioned in the manual either .
Nice! I see a plan forming for a certain orange beach buggy…
Great vid
When I was playing with Imps and Stilettos In the 90's my engine builder had a mod I hadn't heard of
He milled the block taking the alloy layer off the cylinders
Once my donk was rebored he used the boring bar to cut a recess in the tip of the liner then fitting a custom made copper oring to the top of each liner
Apart from a cheats increase in compression ratio, never did the engine even consider leaking from the head gasket
If I wanted to race it
He had another mod of making alloy wedges to locate the liners and prevent "walking" of the liners
Heard of that one??
thank you, yes have seen various different ways of sealing the pot, lots of clever engineers out there all with there own solutions!
Thanks for that - All I am going to see in the back of my my mind now when the rev counter needle goes past the high beam lamp is liners doing the Ali shuffle - is that Ali doing the liner shuffle....
😂😂😂
Hilman Imp engines originally had a normal head gasket. I had a Ginetta G15 with 998cc version in 192. This had a gasket not wills rings, these came in about 6 months after I got mine (unfortunately). The result was a blown head gasket at high revs. Didn't do the engine any good.
Really interesting video. Thanks
Wet liner is good
Hi Andy, Excellent Job, on your last engine are the holes round the liners for water cooling / expansion/ weight saving.. Best Rgs Rodders PS Midge engine still not fitted in racer yet...
Hi Rodders, hope yiur well ! Yes for the water to pass through the block
Excellent!
Many thanks!
Facinating - many thanks.
A question if I may. I believe early 998 blocks were dry liner but they had problems and switched to wet liner. What were the problems?
thanks glad you enjoyed it !
yes early works blocks had dry liners but after a while they used to crack under the shoulder at the top and then work there way down into the crankcase! larger radius opposed to a a square undercut removed the stress and stopped this problem.
@@thehillmanator Thank you once again.