Liners or a New Block?

[AlfaLofa]

I've now completed most of the engine strip down on a spare engine I have recently acquired.

The crank/pistons are still in the block which is an LB.

The pistons are +40 and there is for/aft movement on numbers 2, 3 and 4, with substantially more movement on #3.

Number 1 piston has no movement.

The bores look good with no scoring or top lip.

The block also has a couple of sheared bolts which need rectifying. The bolts are sheared below the block surface - namely an engine mount bolt and a dynamo bracket bolt.

I don't know if there is any significance in the lateral movement of pistons 2-4, but I see no point in reassembling the engine without rectification.

In Miles Wilkins' book he states that LB blocks can be linered once they have been bored to +40 and can in theory be used indefinitely.

But I have seen conflicting advice on the board suggesting that because of wall thickness, it is risky to fit liners to LB blocks because of the extra metal that has to be removed on top of the +40.

The cost of the liners and their fitting and the rectification of the sheared bolts plus shipping the block and other costs are likely to be substantial - with apparently, no guaranteed success.

Now that new blocks are available would the best course of action be to purchase a new block and turn the LB into a coffee table?

The advantages of a new block are many - including peace of mind, plus being able to have the unit bored to a desired capacity before it is shipped.

Which course of action would you recommend - bearing in mind that any extra analysis of the existing block will simply decrease the gap between the cost of a new block and having liners fitted?

[AHM]

Which course of action would you recommend - bearing in mind that any extra analysis of the existing block will simply decrease the gap between the cost of a new block and having liners fitted?

Well it sounds like you have already convinced yourself that you need a new block.

Have you measured anything? you won't know if any of your assumptions or guesses are correct until you do.

[richardcox_lotus]

It seoends upon your budget. Yes a new block will gove you piece if mind but If memory serves, you are looking at $1300 for an unfinished new block. So you will still have full machining costs on top of that.

Regards
Richard

[rgh0]

The cost of an ultrasonic check of your existing block should be around $80 at a good engine machining shop. Based on that they should be able to recommend offset boring and potentially liners also.

Most blocks go to 83.5mm. Going beyond that either for a larger bore or for fitting liners typically depends on the individual casting and how well centred the bores are in the casting currently and the actual OD for each bore. But normally around 50% of blocks can go beyond 83.5 or can be further bored for fitting liners assuming no major corrosion present in the waters ways which is not always the case. Some people will fit liners with minimal metal behind them ( down to less than 1 mm). I tend to be conservative in this area and would not want the casting thickness to thin behind the liner in any large area especially on the thrust face of the bore. Ideally for a normal liner I would want the backing metal a minimum of 2 mm. You can buy high strength liners that don't need that much backing metal to support them but their cost is very expensive and normally cheaper now to just buy a new block than go down this route.

A new block makes the process simple quick and easy - buy a block, finish bore it and assemble. An old block needs lots of careful measurements and checks before you can be confident you will have a good outcome and will normally need some carefully thought out custom machining to get it right However the cost of a new block is high and still greatly exceeds the cost of redoing an good quality used block especially if you have it hand to work on at your leisure and are not trying to rebuild an engine quickly.

cheers
Rohan

[Quart Meg Miles]

How original do you want your car to be, Steve? Some of us still drive Elans but many seem to be happy driving bitsas. You are talking about a spare engine anyway, so what is your working engine? If you want peace of mind buy a new car and stop messing up a historic one!

My block isn't much younger than yours and in 2007 St Wilkins had it sleeved for under ?500 (before VAT) though he might have favoured me as a regular. The other bits from him came to more than that and there were some labour costs from a third party (unleaded conversion) though I did the manual assembly. I don't do competition work but don't hang about and haven't had any problems after 20,000 miles apart from the usual gasket problem at the back. Oh, and fuel vaporisation but that doesn't count!

[RichardHawkins]

Steve,

A difficult decision if you cannot do any of the measurements yourself, and I guess from your location that you don't have easy access to a non destructive test service or a nearby machine shop.

You also need to consider that the cylinders and the water jacket are also used to support the main bearings, keeping them in place with respect to the top deck of the block. Fitting liners can weaken the overall integrity of the block.

Richard Hawkins

[AlfaLofa]

Hi all,

I'm still considering my options - but I'm not sure what I'll be letting myself in for with either option.

How original do you want your car to be, Steve? Some of us still drive Elans but many seem to be happy driving bitsas. You are talking about a spare engine anyway, so what is your working engine? If you want peace of mind buy a new car and stop messing up a historic one!

I have no intention of "messing up" my car.

The assumption that I am going to fit this engine to my car is unfounded.

My car is pretty original for its age - and it is going to stay that way.

The non-original parts include:
a new windscreen (1974), plus the following during the restoration:
a new front body section (1999)
a new dash board (1999)
new seat covers (1999)
plus of course all the usual minor components

But the biggest non original component is the "bottom end" (the head was retained) after a previous owner blew up the engine back in 1971 - so nothing to do with me!

Here is the receipt for that work (which included a new LAA block):

I got hold of the spare engine because I considered a spare would be good to have (especially when I pass the car on).

Then having got the spare engine I also thought it would be good to give it the once over - without ever having the intention of sticking it in my car.

In my present condition I need something to keep me occupied and this engine seems like the ideal option.

And besides this spare engine is already an amalgamation of parts including a '66 block, a mk2 head fitted with big valves and cams of unknown spec, dellorto carbs, 6 bolt crank, AKS front cover, etc.

What I want to (as a hobby) is get the spare engine to a known spec prior to passing the whole shebang over to my nephew when the time comes.

He will then be able to do whatever he wants with the engine - but I suspect it will never be fitted to my old car.

[AlfaLofa]

Hi Richard - you are quite right.

My location does make it difficult to say the least to access the services needed to check out the block.

It would be a day trip just to drop the block off for inspection and then another day to pick it up - all so much hassle which I could really do without. Then another day to ........

[Jeff@Jae]

I agree with Rohan, get the block checked for bore shift and if it's sound just go .060" oversize. We've done quite a few +.060" piston sets over the years and no one has had to trash a cylinder block because it was +.060".

[JJDraper]

Why either? Check the block thoroughly & consider +60. My +2 was rebored to +60 by the previous owner in 1998, over 85k miles ago and is still going strong - see pics. I have redone the head gasket a couple of times and always check the condition of the bores and they seem OK (no lip), so why agonise over liners unless there is a real problem. My engine is the original 1968 block and seems to have enough meat. I too have a spare block to fiddle with against the time it really needs to be rebuilt, but mine is 85mm (!) and still seems OK. Before thinking of liners spend some cash and get the block properly appraised with regard to what metal there is.

Jeremy

[AlfaLofa]

I'm just seeking advice - but as I said above the block is a +40 LB block and Miles Wilkins says in his book:

"If for example, a block is being prepared for road use and is already bored 0.040in. oversize, on no account must it be bored any further, particularly if it is a Type LB block. In this situation sleeves are used to return the bores to the standard diameter, and in this way overbored blocks can be salvaged"

This is what I was using as my starting point.

[AHM]

This is what I was using as my starting point.

Your starting point should be measuring what you have - who says it is not ok as it is a +040? your description sounds ok.

Get your self a thin piece of steel, cut it to the bore diameter, measure clearance with a feeler gauge - simple

[rgh0]

I'm just seeking advice - but as I said above the block is a +40 LB block and Miles Wilkins says in his book:

"If for example, a block is being prepared for road use and is already bored 0.040in. oversize, on no account must it be bored any further, particularly if it is a Type LB block. In this situation sleeves are used to return the bores to the standard diameter, and in this way overbored blocks can be salvaged"

This is what I was using as my starting point.

Miles is correct here but I believe his advice comes from before the days of cheap ultrasonic measurement and offset boring. You can buy a good quality ultrasonic measurement kit now for around $1000 and it takes about 45 minutes to do a full survey of a blocks bore wall thickness. Many blocks will go to bigger bores but you need to do the checks I have described to know how to do it right. Without those checks and just boring to open up the current bores past 83.5mm you would risk a failure in about 50% of engines you would build which is why an engine builder would not do it and would say "on no account be bored beyond +40 thou".

cheers
Rohan
cheers
Rohan

[AlfaLofa]

Hi All - thank you for sharing your expertise - especially Rohan.

I've made a couple of video clips of the for and aft movement in the pots:

http://youtu.be/uW9ZsKjKSfc

http://youtu.be/qSf7dmuYoVY

The movement can heard as well as seen.

I assume this is bad news hence my earlier queries about liners/rebores/blocks etc.

Whilst hitting the internet I've found all sorts of info to put even more doubt about my course of action into my mind - including this from Lotus-Cortina.com:

"It is normally best to steer clear of blocks which have had cylinder liners fitted, unless the engine has been unused since it was done and there is proof that the work has been done by a competent firm as liners tend to move, causing head gasket problems, unless very carefully fitted".

I also saw a report saying that (given a choice) an engine builder will prefer to rebuild an old block rather than a brand new block because an old block would have "settled down" (my words) after continual heating/cooling whereas a new block is yet to undergo this process meaning a new block may exhibit deformation at some time in the future.

Any observations would be most welcome.

[rgh0]

Pistons will always rock in the bores even when new and it does not tell you much. Normally the most rock is transverse across the block and the least longitudinal along the block. However you really need to dismantle and measure the pistons and bores properly to determine what work is required.

Liners introduce a whole new range of issues but they are solvable if the block can take them and they are fitted right. They have been used successfully in many twin cams blocks and Ford even fitted them from new to recover machining problems in blocks. As long as you have a competent machine shop and enough metal left in the bores to back up the liners after they are fitted there is no real reason not to use them especially in a road engine. However with new blocks available relatively cheaply in the UK and USA now and liners versus a new block is not a clear cut decision. Unfortunately the new blocks are much more expensive by the time you get them to Australia so liners in Australia are still a clear cut economic proposition.

Luckily I have a enough spare blocks not to worry - some of my collection

Old block castings that have been aged and heat cycled are generally more dimensionally stable under stress and temperature changes which is why racing engine builders love a good old block as the base - but it must be good to begin with. I read somewhere that BMW back in the days of the 1500cc turbo formula one engines used second hand 4 cylinder 2 litre BMW blocks as the base for their formula one turbo engines for exactly that reason. For a road engine it probably does not matter.

cheers
Rohan