The Hillman Imp came out with the Coventry Climax inspired (not designed) 875cc all alloy motor.
Why take such a size,we do not know,it was stuck in some place where in the case of competition was concerned, was between a rock and a hard place?
The heat needs to be gradual,heat the piston slowly. Note that the steel gudgeon pin is not in the piston,its such a tight fit that it will not press home.The heat expands the alloy piston bore to such a degree,that the cold steel center pin slides in easily when offered to the hot piston.
An imps Hepolite Powermax 60 thou,piston and conrod. I have just heated the piston on an electric stove plate to enable the gudgeon pin to be inserted.Thats really fine engineering from Hepolite.
Hepolite pistons as boxed.
The racing saloons use a simple engine size,850cc 1000cc 1300cc and so on,the Imps engine was already too large for the 850cc class and at its 875cc size, too small to bore out to a 1000cc capacity. Given a set of Hepolite Powermax plus 60 thou, pistons will give us only 916cc, we never saw the competition expected.
Why take such a size,we do not know,it was stuck in some place where in the case of competition was concerned, was between a rock and a hard place?
The heat needs to be gradual,heat the piston slowly. Note that the steel gudgeon pin is not in the piston,its such a tight fit that it will not press home.The heat expands the alloy piston bore to such a degree,that the cold steel center pin slides in easily when offered to the hot piston.The pin must first be slipped into the con rod little end,its a tight fit but will press home by hand,make sure the conrod is the right way around,it will only fit the crankcase one way.
Beware of burning yourself!
An imps Hepolite Powermax 60 thou,piston and conrod. I have just heated the piston on an electric stove plate to enable the gudgeon pin to be inserted.Thats really fine engineering from Hepolite.Hepolite pistons as boxed.The racing saloons use a simple engine size,850cc 1000cc 1300cc and so on,the Imps engine was already too large for the 850cc class and at its 875cc size, too small to bore out to a 1000cc capacity. Given a set of Hepolite Powermax plus 60 thou, pistons will give us only 916cc, we never saw the competition expected.
Then came the Rootes Competitions Departments answer to the problem, this steel liner or sleeve, replaced the cast in steel sleeve in the Imps block.The new bore size gave us a magical 998cc capacity.This was perfect to enter competition in the up to 1000cc class.
The rest,as they say,is history!
We can supply this conversion ex Cape Town,we need your Mk2 block as an exchange to replace our own stock.
Roy
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