PUTNER Posted June 29, 2014 Report Posted June 29, 2014 My 691 block is in need of a freshen up just asking the question Whats the difference? Are rings etc inter-changeable? Is the freshen up worth doing? Its already been taken out to +60 is that the most that can be done ?
68supermk1 Posted June 29, 2014 Report Posted June 29, 2014 I have a 681 block with +90 pistons if that helps are 681 /691 blocks 1500cc
v8cortina Posted June 30, 2014 Report Posted June 30, 2014 I have a modified 691 (1660) in my Mk2 Cortina Duluxe. Raced the engine in the Escort for a year whilst getting the Cortina ready.
Hotspur Posted June 30, 2014 Report Posted June 30, 2014 A 691 block (1600) externally is the same as a 681. Uses the same head and pistons as a 681, small size cam followers, large main bearing caps (like a 711) and the core plugs are the same size as a 711. I believe it's an interim block between a 681, and 711. Pete
PUTNER Posted July 1, 2014 Author Report Posted July 1, 2014 Cheers for the advice .....was wondering why i couldnt find any 691 piston rings listed anywhere ....
Fiesta Steve Posted July 3, 2014 Report Posted July 3, 2014 The first two number denote the year that model was introduced.
Hotspur Posted July 3, 2014 Report Posted July 3, 2014 Ah! And one I forgot, the breather (above the fuel pump) is 711 sized, not 681 size. Pete
PUTNER Posted July 5, 2014 Author Report Posted July 5, 2014 Next question wheres the best place to get new rings from? ....already bored out to +60 now just needing a hone and new rings...
lhd1600e Posted July 5, 2014 Report Posted July 5, 2014 I have recently rebuilt a 691 for a customer and got all my parts from ian at specialized engines at grays Essex
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