barrel sleeves

Hello, ive read various articles with regard to sleeving barrels and im hoping that a push fitted sleeve, held with high stregth locktite, is going to be adequat. Seems that these days the inferance fit is used to help with the cooling process of the barrel. Are there any real pit falls that should other wise be considered? Is there a minimum/maximum thickness of liner? Any opinions/ advice would be greatly appreciated.. thanks, nigel.

Hi Nigel,

I successfully used a hand push fit for the liner on my 125 Formula Bantam. The external surface of the centrifugally spun cast iron liner was ground, and the cylinder barrel honed out to achieve this hand press fit.

You are correct in using a Loctite product to act as a heat transfer medium. Its thermal conductivity is fairly low, but a heck of a lot higher than air!

The type of Loctite does not have to be high strength, because the cylinder head retains it vertically, and a dowel prevents rotation. But, the Loctite should be a very slow setting type. This facilitates a) assembly and b) alignment before it sets.

Subsequent dismantling is easy only after the engine has been run to operational temperature. This temperature is sufficient to weaken the Loctite.

Hope this helps

Peter

Thanks for the reply and information Pete. would you know if there
is  an optimum thickness for a the sleeve? I have a 69mm external and 61mm internal sleeve ( for a 175mm barrel). I have  given myself plenty to play with in regards to the size. Can i remove all  of the original cast in  sleeve? or should i keep it as thick as possible.
again any help with this would be appreciated, thanks, nigel

A couple of questions Nigel, what piston diameter do you intend to use, at the moment your liner has a 4mm wall thickness, and do you have a flange at the top or not, lineal heat flow potential to the cylinder head is often overlooked in these big bore situations? Too thin a liner can be unstable and give problems, my water cooled barrel has a 66mm o/d for a 6mm wall and 54mm bore and was installed with a .001" interference fit and no Loctite, there are no cooling problems and seizures exceedingly rare.
In the past I have replicated Peter`s approach, with no problems, so the procedure clearly works well, but as the w/c engine produces far more heat/power than any other engine I have done, I took a different line of thinking in anticipation of problems, and it has worked ok.
Actually, this could be a good topic for an expanded discussion here on the, practically dormant, Forum?

Cheers, Trevor

Evening Trevor,hope your keeping well  Thanks for your reply.
My sleeve has, at present, a 73mm od top which is 6.53mm thick/deep, then steps down/back in to the 69mm od  i quoted ( yes a flange)... I had hoped to keep to 61.5/62mm  sized piston, ive measured up the barrel i wished to perform this on and it comes up at 68.19mm od at the base of the barrel. I had considerd having the whole of the original sleeve removed  but wasnt sure how this would effect the already bad heat transfer through what was left and weakening it may cause.  Having seen a ypvs 350 resleeved barrel i noticed that the sleeve was really thin!! maybe this was because its watercooled though.Derek has given me info also with regards to this via e-mail ( cheers derek  ) and im begining to think that its more involved than i thought, what with the porting to sort as well , one wrong move and its back to square one! Still armed with petes,dereks and your information i may have a crack.
   

Thanks, nigel.

Hi Nigel
I believe the 250cc twin built by Dr Gordan Blair at QUB had sleeves Loctited in Trevor probably knows more about this engine than I do. Also if you contact Loctite on there help line I have found them very helpful in the past [ you can find the number on the Loctite packaging ]
Bill

Thanks Bill, ill take a look.

Hello Bill,
Following your reference to the 250 QUB engine I`ve had a search and come up with the following. Of the three or four articles I have from 69/70 period only two make a reference to the liners , one shows Loctited liners , the other shrunk in, with no ref to gluing, so a little inconclusive there. Reference was also made to Loctiting the crank together, however, the more recent of the articles states that subsequent mechanical failures led to reverting to traditional press fit, which cured the problem.
There are some pretty strange dimensions shown in the various drawings published, for instance, the crank discs were a tiny 88mm in diameter, and balanced by Mallory inserts. The inlet ports , in the rotary sleeve, were a little over 15mm high and 50mm wide, the exhaust timing was 201* but only had a modest 29* of blowdown, most Bantams exceed that figure! All a little strange, but as the good prof knew more than I ever will, I am not in any position to judge, mind you I would love to have a chat with him over a pint of Ireland`s finest beverage!

Cheers, Trevor

Nigel,
The concerns I had over installing the w/c liner with a cold, hand push fit was that there would have to be clearance between liner and barrel to allow this to happen, and that the hope would be that Loctite should fill the gap. A size for size fit is better, from a contact area point of view but you won`t get the two together with a hand push, but the .001" interference guaranteed metal to metal touching and transferring heat better . You could argue for the hand push that, as a liner will run hotter than the barrel it should expand, fill the gap and make contact , or perhaps not, a bit of a gamble. With both the barrel and liner having comparable coefficients of expansion the uncertainty was worth the risk. So I stuck the barrel in the oven to warm a little to create clearance and dropped the liner in. Don`t be tempted to freeze the liner as the water produced, from the big temperature difference, will create rust which you definitely don`t want.

It might be worth pointing out that the surface area difference between a 68mm and 69mm diameter liner o/d, with both being 85mm long, is over 130sq mm, that could be worth factoring in to your calculations, with the thicker liner also providing for greater heat path flow before the liner/barrel interface is arrived at.
Assuming ign. starts at 20*before tdc and finishes at 40*after tdc you still have 300* of crank rotation to get rid of the heat before it all starts again! Oh, and your engine will survive with an extra thou piston clearance of safety, but won`t with a thou too little ?

Take care in all these floods, Trevor

Trevor, could a material such as an alloy be used for the liner material?   then nikcosil coated? would the different expansion factor help tighten up the liner to cast barrel once it gets hot, just like my pistons do, prior to siezing? I cant see any thing in the rules for the 175 set up which doesnt allow this ( i may well be wrong! ), of course, if its at all possible anyway.. thanks , nigel.

Hi Nigel,
I wouldn`t want to tackle that concept but if you could control and stabilize the heat to specific levels then it might work, but the ally would expand inwards and catch the piston, the Nikacil wouldn`t stay in place with that level of expansion and contraction and would crack .The cold piston clearance could be an interesting exercise to achieve, being needed prior to plating, afraid there is potential disaster in that idea . However, a BTW alloy job with an alloy, plated sleeve is an easy option, pricey but perfectly doable.

Hope I haven`t rained on your parade ? Cheers, Trevor

Thanks for reply Trevor, just thinking out loud. If it were possible,i guess it would have already been done..