QUESTION
I own an Elan Sprint with a Lotus twin cam engine that is built up on a Ford 120E cylinder block.
As the engine is tired and is beginning to blow smoke out of the exhaust, I am contemplating a full rebuild
How far can a Ford 120E or Lotus 701M cylinder block be re-bored over-size?
D.R. - Pennant Hills, NSW
ANSWER
This will depend on how thick the cylinder walls are.
There is a recommended minimum thickness of 2.5mm where cylinder wall flex starts to become a problem.
So its important to get ANY block ultra-sonic tested before commencing work.
These blocks are 40 years old or more and have a certain amount of internal corrosion that affects cylinder wall thickness.
However, it is still possible to find good second-hand donor cylinder blocks.
Four years ago I built a Lotus twin cam engine that used a Ford 120E cylinder block sourced from Tasmania
When this block was checked by ultra-sonic testing, the cylinder walls were in excess of 0.250" thick
This block was subsequently used to replace the original Lotus 701M cylinder block that was cracked and leaking water into the sump.
Copyright © 2014 Lotus Marques
I own an Elan Sprint with a Lotus twin cam engine that is built up on a Ford 120E cylinder block.
As the engine is tired and is beginning to blow smoke out of the exhaust, I am contemplating a full rebuild
How far can a Ford 120E or Lotus 701M cylinder block be re-bored over-size?
D.R. - Pennant Hills, NSW
ANSWER
This will depend on how thick the cylinder walls are.
There is a recommended minimum thickness of 2.5mm where cylinder wall flex starts to become a problem.
So its important to get ANY block ultra-sonic tested before commencing work.
These blocks are 40 years old or more and have a certain amount of internal corrosion that affects cylinder wall thickness.
However, it is still possible to find good second-hand donor cylinder blocks.
Four years ago I built a Lotus twin cam engine that used a Ford 120E cylinder block sourced from Tasmania
When this block was checked by ultra-sonic testing, the cylinder walls were in excess of 0.250" thick
This block was subsequently used to replace the original Lotus 701M cylinder block that was cracked and leaking water into the sump.
Copyright © 2014 Lotus Marques