Bobs600

I'm intrigued by the classified ad for e-dating caravans. Is that for a trial relationship before purchase?

Peter Davis

It took me a minute to work out what you were talking about. I had to laugh when I noticed what else was there.

BlueS6Coupe

I saw the other adverts, was wondering why that particular page ?

Peter Davis

Desperate times

Peter Davis

I thought I had a thrust washer for the chain roller guide but unfortunately somehow got lost in transit. Could you have a bo peep to see if you have a spare. I've acquired another pulley and sprocket with bearings so no need to go looking for those now. Ricky in Cairns found me them.

Peter Davis

I gave the head a bit of a clean up tonight and removed the cam followers which exposes the valve spring top. Unfortunately there is some corrosion on both the inlet manifold face and the water jacket cover face. In a couple of places on the inlet manifold it almost joins between the water jacket and the inlet. I think I'll have to get both of these surfaces refaced.
The stainless steel baffles have corroded away. I have bought new baffles from ortmanns but since stainless and aluminium are considered dissimilar metals and will speed up the corrosion process I may have a look at an alternative. I now have a template I can use.
No 2 and no 3 inlet valves have not freed up in the degreaser tub so I've tipped the head up so the inlet valves are vertical and drowned them in WD40.While this probably won't free them hopefully it'll soften the corrosion enough so that it will minimise the chances of damage during removal.

TAParker

Looks like you may have your work cut out for you.....it appears to be repairable tho.....good luck.

Bobs600

I had a discussion with a materials engineer on this very topic in reference to another post about these baffles elsewhere on this forum (BMS250FORD?). Like you, I suspected that dissimilar metals would cause a problem. My friend, a car guy whose academic specialty is corrosion and welding, said that it would not be a worry here.

When you took the cover off, did you find the old baffles had left a corroded mess inside, or had they basically disappeared?

Peter Davis

There was green clumps of corrosion inside the cover. A couple of the bolts were corroding as the water was getting past the the gasket. The baffles are pretty much gone. The bolt heads may be difficult to dislodge as the heads are very corroded. The intake side had similar clumps of green corrosion. Either no coolant was being used or there is some galvanic corrosion going on. I'd hate to think what the radiator looks like inside!! A quote of the web however says;-
"if a small area of stainless steel is placed in contact with a big area of aluminum the rate of aluminum galvanic corrosion is low due to the effect of the relative areas."

Peter Davis

Been cleaning up the head over the weekend amoungst other things. Cleaned up each of the domes with the valves in place. I'll remove the valves once I've manufactured a tool to compress the valve springs. I've found a couple of thick washers that are 29mm OD and 15mm ID which fit perfectly over the valve spring cover. I might weld in some rods to space them.
It appears there is alot of damage to the alloy, perhaps from detonation. It's the worst in no.4 which also had quite a lot of coke caked in it. The only cylinder relatively good was no.2.
Regarding the stuck valves I decided to give them a little love tap using a flat ended hex bit which freed them immediately. Now that I've cleaned up the domes I can see some pitting around the inlet valve of No.3.
I've used a block and 240 grit wet and dry paper to clean up the faces to show a little more clearly the corrosion. Upon a another inspection of the inlet face the aluminium is only around 4mm thick. I've taken a side photo to demonstrate which also shows the depth of the corrosion at that point. It may be that some weld has to be added prior to a facing due to the depth of corrosion. I'll have to get an opinion at a head reco shop.

BMS250FORD

The original choke plates were aluminium. Maybe 1.2mm. They are held in place with plated steel M6 bolts. I made my own SS plates and used new SS socket head screws. One of the cylinder heads that I disassembled had reasonably intact choke plates and the steel bolts unscrewed with a little persuasion. That is anticorrosion coolant working how it should.

Peter Davis

The bolt heads in my case are all corroded and have to be drilled out. I have to be very careful because there is a oil gallery just below and as you know a drill wants to follow the easiest path which is the aluminium. How much did you take off the face of the inlet on yours?

StreetsideStig

Dang. That corrosion doesn't look fun.

BMS250FORD

I was surprised how little was needed to clean up the inlet face. I took a trial cut at just 0.1mm to check my mounting setup and to see the low spots and found that virtually everything was cleaned up. I dialed up another 0.1mm cut just for good measure. I think you could easily take 1.0mm off this face with no issues. The biggest machining problem is the raised section that the cutter needs to be steered around. This means the job can't be done with a straight pass with a fly cutter like the cylinder face. It took me a couple of days to workout how to mount the head at the correct angle and then program a tool path to steer around the raised section. All for 10mins of action. Its all about the journey not the destination.

A cylinder head shop can probably do the whole lot in 10mins.

Peter Davis

I've been making some enquires as to where best to take the head. I did find a place called "Unlimited head jobs" in Parramatta but thought it too good to be true. I'm going to take it to "Thornliegh Cylinder head reconditioning" and have spoken to them. MT has also offered to provide me with a replacement that is in better condition. I'll still see what the shop says about the one I have in any case. My plan ultimately is to build another motor as a spare in any case (perhaps for another car)

Peter Davis

Fortunately MT has sent me a replacement head which appears to be in much better condition on first inspection. I've removed studs and some of the gaskets and put it in the degreaser tub to soak. Once the remaining gaskets have softened I'll clean it up. Fingers crossed

Peter Davis

Having spent several hours cleaning up the replacement head I decided to put it through the dishwasher much to my wifes dismay. I then liberally applied WD-40 to the valve seats to displace any moisture. I will however need to dismantle the valves to ensure no corrosion takes hold. After all of this I found something very odd/disconserting. I'm not sure if someone has modified the combustion chambers but they are for want of a better word "oval" shaped. No.1 is the most prominent example of this. What is disconserting is that the head gasket only catches a few millimeters of the edge above the port. I'll take some more photos tonight to demonstrate as my phone died last night taking these. Has anyone seen this before?
The second photo shows no.4 which has a broken off spark plug in it. While not as pronouced you can see the oval combustion chamber.
The good news is the corrosion is minimal in comparison to the original.
The choke plates are partially still there but the bolts aren't interested in budging at this point. I'll give them some time with WD-40 to try and loosen.

StreetsideStig

Haha! My housemates hate it when I wash car parts in the kitchen.

Peter Davis

I've taken some more photos to demonstrate the combustion chamber issue. No. 4 is actually the worst and is shown in the first two photos. I've lined the head gasket up to show the out of round. No.4 is actually so elongated that the head gasket overlaps a little. The third photo is of one of the other cylinders. Perhaps this was done to replace the valve seats?

FrodeyEJ1

great, determined build m8

Peter Davis

I finally received a thrust washer for the chain roller guide. I was advised that a honda motorbike part would fit. I've now installed the roller guide as per photo 3. The bottom of the roller guide can be also seen at the top of photo 4. Photo 4 shows the installed starter sprocket with chain. The starter motor is to the far right. Again very motorbike like how the starter system works. I replaced the oil seal on the front of the starter spocket prior to installation. Inside the shaft of the starter sprocket is the needle roller bearing. The starter sprocket free wheels on the cranshaft. The sprocket grabs the starter clutch (which is part of the fan pulley) when it spins via the starter motor. The starter clutch/pulley is fixed onto the splines at the front of the crankshaft. The last picture shows the whole assembly. Photo 5 shows the oil bypass which essentially is a valve which activates if the paper filter is blocked. The oil then passes through the centrifigal oil filter thats run from the cam chain.
I then came across yet another problem in that the front cover gasket I been supplied by Ortmanns didn't fit. It's a similar issue to that found by BMS250FORD with his build. I however have trimmed the holes and fitted as best it would. I've used high temp silicon to help seal. Note I'd replaced the oil seal to the front cover as well

robotnix88crx

poor engine!! good luck

Peter Davis

I took both the heads to Thornleigh head reconditioning. Not surprisingly he said that head no.2 with the out of round combustion chambers would need to be welded up so the gasket does not overlap. I walked him through the issues on both and he will evaluate and will ring me to discuss the options including approximate costs.

Kuroneko

Great stuff to see. Thanks.

StreetsideStig

I'm still loving the detail. Keep it up!