....Cylinder head gasket continuation.....pictures now..

[ppnelan]

Instead of 'Superman' holding up the head, I use ropes & pulleys hanging off a garage beam!

Matthew

[M100]

If you look in the fat Lotus Workshop Manual in the engine section they show the dowel pins. The headbolts will not do it. You're screwed if you do don't get the gasket in there perfectly centered on the bores. The compression ring of the headgasket can get hit by the piston. The gasket has two diagonally opposed headbolt clearance holes which just fit the dowel pins, all the other holes are oversized.

Hmm, not sure where you see those dowel pins, The early S1/S2 Coupe manual says nothing on the subject but in the last S4 manual (Section E page 13 & 14 plus Figure 7) it describes the modified head bolts and shows them fitted to a block.

In my experience the threads in the block are recessed down a counterbored hole that is approximately the thread clearance size and no bigger, the holes in the gasket being a snug fit on the head bolts in those locations. I recall remarking on this only a few weeks ago when looking at a friend assembling his twin cam, we both said a hollow locating dowel in the block would be a better idea rather than taking a hacksaw to what were previously perfectly good bolts at 15 quid a time!

[type26owner]

If you insert the two headbolts in the two smaller sized clearance holes in the headgasket carefully without damaging the gasket that will align it well enough most likely. The radial gap spacing of the fire rings' inner diameter of the headgasket when centered to the bores of the block drives the degree of misalignment that can be tolerated. If the metal ring is punctured, it's toast.

Since the last bit of power and efficiency to be extracted from the engine has a large affect due to the squish deck height in a hemi-spherical combustion chamber having the fire ring in the way is bad. I'm referring to the development work my dad and I did back in late sixties when we were fabricating our own pistons from forged billets he got from Kaiser Aluminum. We were blowing up engines right and left from the cast piston of the era coming apart at high rpms. Back then we were quite serious engine builders and had a part ownership of a Go-Power dyno.

[berni29]

Hi There

Here are some pictures of the skimmed head. It has these strange dots on it which you can feel with a fingernail. Also there is some damage around No4 which was hidden by the carbon.

http://www.searchsmart.co.uk/car/skim.htm

Berni

[type26owner]

Stop! That head is toast as it exists now. You might be a able to save it by having the fire ring seating surface welded and remachined again but that looks very bad. Place the headgasket on top of the head aligning it carefully to the bolt holes and take another picture please. If those pits are under the fire rings it's a serious problem because the hot combustion gas will breach the ring ring.

Suggest you have it pressure checked next because the casting looks to be defective. I think it might have a porosity problem. Unless I just can't see the fine details and that pitting was done by something bouncing around in the combustion chamber at sometime in the past. If that were the case the spherical surface would have some of the same damage likewise and it does not appear to but it's hard to see with the lighting.

You are in trouble and I'd guess there is only a 50/50 chance that head can be saved. You need the services of the best welder in the UK right about now. That Zetec swap is looking better and better now I have admit. Sorry!

That surface finish looks okay at about a <32Ra with a 62Ry from the looks of it. BTW, it's impossible to describe a surface with a single callout which is an average.

[nebogipfel]

Berni, Must agree I'm afraid. I would be very reluctant to use that head without getting it checked properly.

As Keith says it could be very porous. I suspect a good aluminium welder could restore it for you but it would then need to have the edges of the combustion chamber cleaned up and would of course need another skim.

[marcfuller]

Berni, How thick is the head now, since it was surfaced?

[JJDraper]

I have put a pic in the galleries of a new head gasket I fitted a few years back, showing cut off head bolts used for positioning. The head gasket fitted the bolts snugly (easy sliding fit) so there was no problem with movement.. special lube was used on the head bolt threads to help torque them properly.

Jeremy
PS The job can be done single handedly, as I did, but it would be a lot easier with two!

[berni29]

Hi There

Do you mean that the marks around No 4 might be holes? I have had a very good look and they are definately dents. Not sure why thay are around the edge like that. They are all just about inside the metal ring on the (standard) gasket. I will take some pics tomorrow. I was thinking that a spark plug tip or similar must have made them?

Many thanks to all of you for your input!

Berni

[type26owner]

Berni,
I had a mystery something bounce around in my #4 combustion chamber and it looked different. There were dents in the hemisphere area with raised sharp burrs. I had to knock those off and just let the carbon fill in the indentations. Yours does not look to have been peened in there. Someone did carried away doing some metal removal though because there is a radius on the perimeter edge and the other three cylinders have a sharp edge.

[rgh0]

Berni

I would not be quite so worried about the head damage. I had a similar head I bought that had had a spark plug thread insert screwed in to far. The end of the insert broke off creating very similar damage to your head. It was a stromberg head and the bit of metal from the end of the thread insert went out the inlet from no1 and then went into 2 and did a bit more similar damage.

The damage was only in the squish area of the head as the bit of metal was only trapped in that location. It just bounced around freely in the chamber and did no damage.

The head is runing happily in my race car now puttng out around 170hp after a McCoy conversion. The 85mm bore head gasket I use is well outside the damaged area which is 83mm diameter at its out edge to match the 83mm head gasket in the engine at the time it happened.

I will put a couple of before and after photos of the head in the photos Galleries

Rohan

[nebogipfel]

Berni, It's difficult to see in the photos but the damage on number 4 doesn't look like damage from a foreign body which would almost certainly be concentrated in the combustion chamber and the piston crown.

It looks like corrosion damage which may or may not have been made worse by a degree of porosity in that area of the head. The radiused edge looks likely to have been caused initially by the same process and then further radiusing caused by the combustion gases.

The critical thing is really how well and where the gasket seal will sit in that area.

I'd opt for getting the head assessed properly by a company you trust or who comes recommended.

[rgh0]

Berni

I put the photos of my head showing the similar impact damage to yours in the Yahoo Elanmods group photos section -see Stomberg Head Conversion folder. I have used all my photo space on LotusElan.net

Rohan

[berni29]

Hi There

I have applied to join your group Rohan, so look forward to seeing the pictures. In the meantime Keith asked for a picture with a gasket on the head. All the marks lie inside the gasket (just) and you can see that there has been something going on inside the combustion chamber, with some lines visible (almost like brush strokes) that is not present in the other chambers.

http://www.searchsmart.co.uk/car/marks.htm

Thanks again!

Berni

[nebogipfel]

Berni, I closeup they do look more like impacts (fairly deep and sharp edges) odd that there isnt much evidence in the chamber. The marks in the chamber look more like someone has been a bit over enthusiastic cleaning the carbon off at some stage in the life of the head. Is the piston OK?

As you say, it looks like the problems are mainly inside the critical sealing ring of the gasket.

I guess it's a case of get it repaired and resurfaced or put it back with a shiny new gasket and hope for the best