P1 special 10 cyl. block

N

nello

New Member
Hi,i have bought a used cyl. block for my Rover special 10,it is identical to my original one except it is 5mm shorter 《height wise).My question is could a 5mm shim be made to lift block to the desired height? and would it work.
 
Hard so say, but a 3/16" one might. Seriously though, the difference might be for a different capacity. :hmm:
 
Main issue surely is does the combination of crank stroke and rod length, piston height produce pistons that go to the top of the bore and no more?
 
What exactly do you mean by height? are you referring to the overall height of the block when sitting on ground or just the bore length or some other measurement? The P1 engines were the prewar 100 mm stroke engines, which were all the same from the factory. However there are quite a few that were worked for racing with longer strokes, often taking the 2.5 litre engines out to 3.0 litres. Of course you could also go the other way though shaving 5mm off the deck isn't going to leave much deck behind. on the other hand milling 5mm off the skirt would make little difference to the running though holding the sump on might be an issue.
 
Yes i remembered just after posting the piece above. Nearly all my books on the pre war cars are in storage so i can't check to see if there is more than one part no. etc for the 10 block. However it was a not uncommon sneak for Handicap racers to shorten the blocks and the place a plate between crankcase and block to make up the difference. By reducing the plate thickness between races the compression ratio was increased giving the car more power to overcome the the handicapping penalty from winning the last round...You may have one of those blocks...A shim of the correct height will work, just ensure any threaded holes are deep enough and the pushrod length is correct.
 
Last edited:
mikecoombs said:
Yes i remembered just after posting the piece above. Nearly all my books on the pre war cars are in storage so i can't check to see if there is more than one part no. etc for the 10 block. However it was a not uncommon sneak for Handicap racers to shorten the blocks and the place a plate between crankcase and block to make up the difference. By reducing the plate thickness between races the compression ratio was increased giving the car more power to overcome the the handicapping penalty from winning the last round...You may have one of those blocks...A shim of the correct height will work, just ensure any threaded holes are deep enough and the pushrod length is correct.
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Ok thanks
 
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