k series liner heights

[pete_h]

If I have low liner heights, is that an issue with the block? Or would new liners rectify it? How hard is it to set the liner heights if I were to rebuild?

[garybee]

The problem will be with the block, not the liners.  New liners will end up at the same height once installed. 

It is possible to shim the liners to bring them back up to the correct height,  How low are yours?

[revilla]

As well as "how low are they" you need to try to answer "why are they low". They commonly left the factory low at around 0.05mm, but the other possibility is that the block has annealed due to overheating. In this case the liners will have sunk into their seats and the problem is that whatever you do to fix them, they will sink further. If you manage to pull the liners out reasonably easily, and after a good clean they are a reasonable sliding fit back into the block that's a good sign, as sunken seats will peen over and grip the liners tightly. Also look for bright shiny seats in the block after removing the liners. Shiny silver is hard, dark grey is soft. Ultimately worth getting the block hardness tested if unsure. The problem I've found with the liner shims is that they are usually 0.1mm thick, which means that unless your liners were around zero height to start with (which probably means the block is soft anyway and so shimming is pointless) they will be too high when shimmed. The alternatives are to remove the head dowels and linish the block deck down a little with wet and dry paper wrapped around a large flat aluminium slab, or depending on how low they are you may find replacing the liners with the generally more dimensionally accurate Westwood liners will solve the problem as they are made slightly taller. If they are only a little low, you can also remove the load bearing spacer bars from the ends of the head gasket and thin it down slightly with wet and dry before replacing; this lets the head sit slightly lower to compensate for low liners.

[pete_h]

Thanks. Two of the liners were 'ok', but the worst one was almost flush, and 2 thou at its highest point. I have been struggling with overheating pretty much since I got it. I am thinking that perhaps I should go with a new block and the westwood liners, so at least I know I am starting from a good place. The head is also a bit soft (tested by DVA) and will need replacing. Unfortunately it is a VHPD one, so a new head will need some work to flow as much as the current one - or do a VVC conversion, but that won't look 'original' - though not sure how much that matters. The current head has been peened, skimmed and shimmed, and a non MLS head gasket used, to try and get to the end of the year - just trying to plan what to do next.

[revilla]

If there are big differences between the liners that's not a good sign and not good for head gasket longevity. Given that replacement good used blocks can be had cheap on eBay, if you're doing a full rebuild and the block is not in the best condition I'd say it's a no-brainer. Last thing you want is just ongoing head gasket issues on a rebuilt engine. A VVC head with the VVC delete kit is such a normal thing to see on Caterhams I wouldn't worry about it looking non-original.

[Tony Whitley]

I linished a few thou off the block of my engine, not hard to do.  I used a piece of plate glass spread with oil to check for flatness.

[oilyhands]

Uneven heights can happen not just because of an underlying problem with the block, but also because liners from different sources and manufacturers are not necessarily made to the same tolerance. There have been 4 different liner sources used by Rover and a 4 or 5 more after market. Before you scrap your block, try measuring the liner height with a singe control liner in each position, if you see a gradual decrease from one end the the other then this can be corrected by linishing the block carefully. Some blocks suffer from 'Queen Mary' syndrome where the liners slope away from the vertical like the funnels on the eponymous liner. There is no hope for those. If you have sufficient protrusion but anomalies from liner to liner this can be corrected by linishing the tops of the liners either in or out of the block. I have corrected liner heights this as a dozen or so times. 

I have corrected the liner heights by linishing the block on around 150 blockswithout issue, taking into account the caveats mentioned above.

Oily

[pete_h]

Thanks for all the info folks. I might buy a second hand engine to have a play with.

[Wrightpayne]

Or get one of these....

https://www.eliseparts.com/shop/engine-components/new-stronger-k-series-engine-block/

Or the slippery upgrade path....

https://www.eliseparts.com/shop/track-performance/performance/k-series-engine-short-block-package/

[pete_h]

I had seen those and it set me wondering. Not sure whether I would need a new crank though, and I were going to replace it, then maybe a steel one is the way to go.

[oilyhands]

There is no guarantee that the new block will be any better WRT liner height than the old unless the old block has obviously softened. Crank geometry is the same, so provided it is in good order it can be retained.

Oily

[pete_h]

Perhaps I should have started with the question... What is the proper way to measure liner heights? Currently I am using an engineers set square across the liner, and using a feeler gauge. Is there a better way using a DTI or is that accurate enough? Should the liners be clamped down when measuring?

[revilla]

This is how I do it:

 

I never found a straight edge and feeler gauge very accurate, really hard to make sure you're holding the feeler gauge properly flat, so it under-reads.

[pete_h]

Thanks - that's great. Will knock up a plate tomorrow.

[Ed White]

Is it me, or unusually nowadays, do those new blocks seem very good value? Even the short engine kit seems reasonable.