I

iwallace

Active Member
hiya.
got to say this is the first time ive pulled apart a v8
started strippng my v8 today and when i got 1 of the heads off of it i could not see no signs of bore sleeves
(or have my eyes failed me big time)
i was expecting to see some sort of liner mark ontop of the block.
or do you only see that when its been re sleeved with top hat liners,
cant say what year it is from block, its got a rpi serial number, might even give them a ring tomorrow to see what they have done to it.
could it be a coscast....only heard of that name and dont know anything about it?
would there be any other id numbers on block somewhere that could give me some info on it,
will put a pic up later if i can find me phone
cheers ian
 
Oh that sounds interesting. Rpi sold coscast blocks for many years. On a normal block the liner is visible but much wider on a top hat block. The numbers are often machined off a top hat when the block is surfaced. What's the problem? Why the strip down?
 
its in a discovery and the chassis aint all that, i did have some other tuned heads and cam lined up and other bits,
i will put a pic up later, im not sure if the marks i can see are from the head gasket,
what is a coscast engine, is there any diff from the other, are they stronger?.
cheers ian
 
Coscast blocks we're cast by cosworth as a replacement when normal lr blocks stopped production. As we know on most engines a block is for life not so on rv8s. They are reckoned to be better cast but are still not top hat linered. I would be tempted to contact someone and have it top hatted. Unless your certain it's ok
 
cheers jonnyb.
i will later put a pic up when im home,
i was just expecting to see original liner, but im starting to think there is something showing,,(spec savers soon i think)
it does look like the block has been machined, but not 100%..
a mate said another way to say its coscast is the oil ways in the valley, they are all perfect and not rough cast holes. (again ive never heard of that)
i was thinking when rpi rebuilt a engine the liners would of been part of there build, not just rings and ends, if you see what i mean.
cheers ian
 
Rpi always specced coscast blocks. Until supply ran out! The blocks are complete liners etc already fitted. Just not top hats! I wouldn't trust any block pre top hat TBH. But you might get lucky! Even badly installed top hats can fail.
 
RPI spent a lot of time marketing their "superior" Coscast blocks (which they bought a pile of) as a better solution than Top Hat liners. When it was found that they did not address liner slip (or RPI ran out of Coscast- depends what you believe), RPI then had to back-pedal and start fitting Top Hat liners! They still attack other companies Top Hat products in their marketing though.
 
johnnyb70 said:
Coscast blocks we're cast by cosworth as a replacement when normal lr blocks stopped production. As we know on most engines a block is for life not so on rv8s. They are reckoned to be better cast but are still not top hat linered. I would be tempted to contact someone and have it top hatted. Unless your certain it's ok
Click to expand...
Coscast blocks were cast by Mitchell Cotts using the coscast method.
 
iwallace said:
cheers jonnyb.
i will later put a pic up when im home,
i was just expecting to see original liner, but im starting to think there is something showing,,(spec savers soon i think)
it does look like the block has been machined, but not 100%..
a mate said another way to say its coscast is the oil ways in the valley, they are all perfect and not rough cast holes. (again ive never heard of that)
i was thinking when rpi rebuilt a engine the liners would of been part of there build, not just rings and ends, if you see what i mean.
cheers ian
Click to expand...
Best way to check is to look for "coscast" written on the block ;)
Mitchell cotts used xm engine numbers. The early blocks they made weren't coscast but still had tighter tolerances between the water jacket and cylinder than late land rover production
 
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hiya.
i will look for other numbers tomorrow,
could them pistons be from a 4ltr, i got a 4ltr with heads off and pistons look the same.
am i right about in thinking.. the 4ltr pistons and crank into the 4.6 makes it up to a 5ltr, only things ive heard.
why would they use low comp pistons? could that of been for the lpg?
cheers guys
 
iwallace said:
hiya.
i will look for other numbers tomorrow,
could them pistons be from a 4ltr, i got a 4ltr with heads off and pistons look the same.
NOT SURE. THE DEEP DISH LOOKED LIKE LOW COMP, AS CONFIRMED BY JAMES, AND HE HAS BUILT LOTS
am i right about in thinking.. the 4ltr pistons and crank into the 4.6 makes it up to a 5ltr, only things ive heard.
NO, 4.6 CRANK HAS LONGER THROW, CYLINDER BORE IS IDENTICAL
why would they use low comp pistons?
NOT SURE. IS IT A 10 HEAD BOLT BLOCK OR 14. MY EYES / PHONE ARE STRUGGLING
could that of been for the lpg?
LPG BENEFITS FROM HIGHER COMP
cheers guys
Click to expand...
 
Them are non top hat liners. Check The step between liner and block( particularly the back cylinders) I thought discos we're 4 l anyway. Clean the gunk off the Pistons and check the numbers. Also look at the crank number. Normal engines are both 94mm bore.
 
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