[Tigers] Machine shop questions

[Dave Munroe]

Thanks Bob for that intelligence. Wow -  a .200" overbore....wild!

I truly am not worried considering the performance of my engine to date. But I might not be so frisky if I had  .200" bores 
in there.....

I also suspect most who overbore from max spec looking for the ultimate horsepower machine would run their engines 
much harder than I will mine. I like to give it a shot every now and then, but mostly my wife and I are just out traveling and
cruising.

Apart from the great power that comes with stroking a given block, is the shift of the power curve down the rpm range with 
a proper cam, so there's no need to rev the guts out of the engine to get some serious power to the ground. 

Long live strokers!

Dave


----- Original Message ----- 
  From: bob at hermitagewood.com 
  To: dave at munroe.ca ; tigers at autox.team.net 
  Sent: Tuesday, December 16, 2008 3:48 PM
  Subject: RE: [Tigers] Machine shop questions



  Hi Dave,
     
       I too have a 66 Mk1A Tiger and 20+ years ago I embarked on an engine rebuild.   The thick-wall-tiger-engine-block story (as told in Performance Tuning the Sunbeam Tiger) persuaded me to have the block bored .200 over.   I should say here that the machine shop thought me mad, and that they told me that there would be nothing left of the cylinders when it was done.   They also told me that it would take two passes to cut that much material, and I paid them to do those two cuts.

      While the block was off at the machine shop, I continued reading and talking to others (including people at Ford Motorsport) about my project.    I heard all the horror stories (that overbored cylinders flex, have poor ring sealing, and have a propensity to overheat) and ultimately I decided not to risk my rebuild on an extreme overbore.   It was the 1980's and nobody near me had a sonic checker with which the thrust faces of the cylinders could be checked.   Estimated cylinder thickness looking inside the water jacket might have been .125 (if memory serves), but this was between cylinders and not where the thrust load of the piston applies.

      So I didn't use my original block, and it still sits in my garage today.   Would it hold up under use?    I honestly doubt it, I would not risk using it then or now.   The significant point is, it took a .200 overbore with a good bit of material left.    My opinion is that your .060 overbore will never have an overbore-related problem.

  Best regards,
  Bob


  Bob Burruss
  Tiger #382000782