K-queries: loadsa new engine build quandaries

[Mankee]

How do! Do you like what I did in the title? No. I'll get me coat then...

 

Anyhoo, I've recently bought a cheap high-mileage 2001 MG ZR 160 VVC engine to tinker with over the next year or two to replace the standard 1.8K I currently have. My end aim is probably 200+bhp after reading advice from oily in this 'ere thread. I have an absolute truckload of K-series-related questions, which I thought I'd note this thread for others to use instead of emailing DVA every half an hour, as I know he's a busy man!

 

First up, I've checked the engine number 18K4KN30, which confirms that it is indeed a 1.8 16v K-series with VVC from a 2002 model year MG ZR 160 with A/C and manual transmission, so I'm hoping that it's got the stronger 160 pistons in it. More on that later.

 

I pulled the head off earlier today and here's what the combustion chambers look like: clicky clicky. Reading one of Rob Bell's Ultimage MG pages, it seems that I do have a 160 head because of the valve shrouding, correct? Yippee!

 

The engine had done relatively inter-stellar milage, just over 127k! There's no way that the original head gasket would have survived I thought, and there was a 5-layer MLS gasket plus another shim fitted, along with metal dowels. Thing is that the shim was fitted between the block and the head gasket, so it went from top to bottom: head, head gasket, shim, block. Is that normal? I was under the impression that a head-saver shim was used under the head to try and rescue them after annealing? Maybe it's a decompression shim to reduce the compression ratio if the head has been significantly planed? Any thoughts welcome!

 

I've not measured the liner protrusions yet, but was planning on removing the liners to reseal them with Hylomar Blue and decking the block with a flat surface and emery paper to get rid of all the old gunk. Also not measured the head surface for "banana-ness" yet or properly checked for gasket indentations.

 

Finally in today's stream of thoughts; pistons. I'm wondering if I do actually have the stronger 160 pistons or standard jelly ones that will melt when I track the car. Does anyone have a picture of these 160 pistons and the location of the stamping?

 

My pistons are CAKED in crud and are half-way down the bores so I can't get anything down there to clean them yet, without risk of marking the liners. They are coming out along with the rods anyway, so will do a proper inspection then. Meanwhile, some pictures of them here, from the front timing belt end to the rear flywheel end: piston 1, piston 2, piston 3, piston 4.

 

Do the cutouts look standard fare or have my pistons had valve contact at some point in their well-used lives? I'll need to check them over once they are out, but if they aren't 160 pistons or are knackered, then I'll have to add a set of forged pistons and some early single-tang rods to my shopping list. Doh! At least I'll be able to rev the hell out of it then and not have to worry as much.

 

Thanks for reading. Good night!

[oilyhands]

They are 160 pistons.., the cut-outs look normal (for 160s..)

 

If you have a shim, then I would check the heads hardness and it's thickness..

 

 

Oily

[Mankee]

Thanks Dave! I'll get the pistons out and have a look to see if they are suitable for reuse or knackered. And also get the head tested for hardness using a bouncy ball thing.

 

When I come to put the whole lot back together, is it best to stick with the Payen BW750 gasket seeing as I'm resetting the liner heights or automatically go for the Land Rover MLS job? I won't be racking up any miles on the road and will probably do a max. of 1,000 track miles a year. If the elastomer lasts for a few years then I don't mind a regular head gasket refresh. Also, is there any need to change the lower oil rail for the uprated part in a Caterham application, or mainly for Discos with mega transmission/resonance stresses?

 

Thanks as always.

[oilyhands]

The main advantage of the MLS is the shim that protects against surface porosity, this can be virutally eliminated by peening the surface of the head where the fire ring sits before skimming. The elastomer gasket is more tolerant of uneven/incorrect liner heights than the MLS one, so I would use it in preference, especially if the liners are not perfect. You may have CR issues if your head has been overskimmed, in which case you may need to use the MLS gasket and shim.

 

I dont use the LR rail unless I am asked to, the stock rail hasnt given any problems that I can see on the engines I have built.

 

Oily

[Mankee]

I've found a bit more time to do some more dismantling of my engine to see what I've got on my hands. Haven't had the chance to have the head hardness tested but have had a look at the gasket matching face and measured the head height.

 

There's no indentation as such from the usual areas when a head has gone soft, but there are marks from the metal immediately around the fire rings (I think that's the right term?) and the area where the the different layers of gasket are joined together. Pictures here and here.

 

I've measured the head height at various points and I think it's right on the limit, with figures ranging from 118.72mm to 118.77mm. I did have a figure of 118.91mm at one point, but this is probabaly best ignored as an anomaly. I found a little bit of warpage when using a straight edge on the gasket surface of the head, but this might have been because of the carbon buildup around the combustion chambers that I've not removed.

 

So, the question is, is the head knackered or is there a chance that it is serviceable and worth reusing the casting and the valves for my new engine build?

 

Onto the bottom end now. I didn't measure liner protrusions because, in all honesty, they didn't actually protrude above the deck enough for me to use my feeler gauges! The thinnest feeler I had was 0.15mm, which is almost 6 thou. I'm hoping that once I've pulled all the liners out, cleaned up the block deck and resealed the liners that the correct protrusion will be restored.

 

It looks like I've got the original oil rail still fitted, which I will retain, rather than going to the Land Rover oil rail. The big end bearings (bearing for no. 2 was still stuck to the crank when I took this picture; schoolboy error!) were well due for a renewal though, with no. 1 looking pretty battered. Picture of the bearing caps. Question; is it worth using uprated rod bolts?

 

The main bearings (here and here) were also showing a bit of wear, which isn't surprising for the mileage the engine has done. Crank doesn't seem too bad, with the exception of the bit of wear on the no. 1 journal. I was planning on having the crank, bottom pulleys, flywheel and clutch balanced as part of the build, but how far gone does the crank need to be before it is considered as scrap? Can you get oversize main bearings in the event of a crank regrind?

 

Lastly, onto the pistons. It's the first time I've taken a bottom end of an engine apart before, so I was a bit shocked at how loose the top two compression rings were! I thought that they were completely knackered, but I guess this is normal? The oil control ring seemed to be a fairly tight fit.

 

Something slightly disheartening was 135 stamped on the crown, as well as the brand AE stamped on the other side. I was under the impression that 160 pistons should have 160 stamped on them? I can't find any information on the rods either. There doesn't seem to be much wear on the pistons though thankfully, so there is a possibility of them being reused if they are suitable.

 

Thanks in advance!

[oilyhands]

..

 

Edited by - oilyhands on 5 Sep 2010 20:15:02

[oilyhands]

Give the crowns a bit of a cleanup and post the photos, also a very close pic. of one of the combustion chambers. The engine looks pretty varnished up so it has seen a hard life.

 

Oily