Sleeved block for race engine

[Ruairidh Dunford]

Check out the cam grind on this, was fitted with Maxi valve spring and is not fitted with liners.

   

   


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[John Cornforth]

I am curious to know how dry liners are fitted and held in place, and what their outside diameter is. Are they a shrink fit using heat/cold, or is some kind of adhesive/loctite used. If the latter, would it put back some of the lost strength ?

Slightly off-topic, the first engine I rebuilt in the 1970's was for my 747cc Renault 4, with wet liners. I was told that the use of wet liners meant that the iron could be optimised for bore wear rather than for intricate block casting. It also made the open block easier to cast. All this metallurgy didn't help when a gudgeon pin circlip decided to let go (possibly due to my youthful over-revving in second gear of the three speed box) and the pin proceeded to hammer two deep grooves into the bore sides. This was eventually revealed by a distinct lack of performance on the hills of North Wales and a strange feel to the starting handle of three compressions and one "nothing". I had to drive it 250 miles from university to home in this state before repairs - good job traffic was lighter then !

[Ruairidh Dunford]

In my experience the diameters (and therefore thickness) can vary. Boring must suit what you have and the liners are then pressed in, I have always understood that an interference fit of 0.004" is correct.


Problems can obviously arise if the bore is too tight or too sloppy.

[Stuart Giles]

Check out the cam grind on this, was fitted with Maxi valve spring and is not fitted with liners.

Is that a crack in the crankcase too? Maxi valve springs or something with a similar seat pressure were pretty much a "must have" for 7000+ RPM with the cam grinds then in use when I was running a race car. Obviously this increases the load on the block joint; largely on the cam side. Never had a problem with this once the two outer studs in the tappet chest were extended past the cam through to the crankcase base. I have never used a linered block in anything other than a standard motor though. Are those Austin factory rods in your photo?

Most of the slippage/movement problems occur with dry linered Aluminium blocks, where the differential expansion between the steel liner and Ally block means that the liner will always be tighter in a cold engine that in a running hot one. For race use so-called "Top Hat" liners are often fitted so that the head gasket's fire ring sits at least partially on the narrow flange on the liners' top; a recess having been machined in the block face to ensure that the liner is still flush once it's pressed in.

[Ruairidh Dunford]

Hi Stuart - the line in the crankcase was a score, possible from a knife if I recall correctly. The engine came to me like this and was fitted with original rods - these were reused in the rebuild. The fixing adaption to the base of the crankcase you describe would have prolonged the life of this block for sure.

I have cap screws fitted in place of studs in my Ulster engine, which have held so far, but it is certainly not a racing engine.

[Steve Jones]

Stuart Giles wrote 

Never had a problem with this once the two outer studs in the tappet chest were extended past the cam through to the crankcase base.

Was this simply a case of drilling/tapping the filter gauze web in line with the two outer studs in the tappet chest and making a pair of studs that spanned between the web and the top of the crankcase emerging through the bottom of the block as normal, Stuart?

Steve

[Stuart Giles]

Stuart Giles wrote 

Never had a problem with this once the two outer studs in the tappet chest were extended past the cam through to the crankcase base.

Was this simply a case of drilling/tapping the filter gauze web in line with the two outer studs in the tappet chest and making a pair of studs that spanned between the web and the top of the crankcase emerging through the bottom of the block as normal, Stuart?

Steve

There needs to be a chunk of Ally under there for the studs to screw into.

[Steve Jones]

Thanks, Stuart that makes perfect sense.

Steve

[Bob Culver]

With the degree of chassis twist transmitted thru the crankcase, as evident by gasket problems, it is curious that failure apparently does not occur on severely used cars with rigid mounted engines and mild tune.

[Rogerfrench]

Oh but it certainly has, Bob Culver!