Pulled out my engine today

[RichardM]

Sinking valves into a head does throw up a few issues if you want to be anal about it, unless all the seats are cut and valves stoned the same on something like a Serdi there will be variations in combustion chamber volumes, sinking a valve also means shimming the valve springs to bring them back to the correct installed height. It can run away a bit but on a low revving road smoker most of this is not that important.

Bob

I assume the cam operates a rocker arm with a foot on it and a shim for adjustment between the foot and valve head.
I was thinking more of shim thickness and if cutting the seats would bring this down to minimum, not valve spring shimming or combustion chamber volume, which I agree would be a bit anal for this engine.

 

[RaceDiagnostics]

Certainly to my amateur eyes your valve seats do not appear to be 3 angle currently.
Before buying a cutter and re-cutting, does your manual state what the stem height should be after valve seat refurb?
Would be good to know approx what material you can take off before it throws up more problems.
What shim sizes did you have in, what is the smallest you can get?

I'm not looking for perfection here or to spend a fortune, really just going for good enough. As for the manual it doesn't really cover rework, just discusses replacement of old with new, valves, seats etc.

Only a single 45deg angle is cut from the factory, the manual says, measure the width of the 45degree cut and only use a 15deg cut at the top and 60deg cut at the bottom to correct the width "if required".

My shims on the first head are;

4.75
4.75
4.75
5.01
4.75
4.75
4.75
4.75

These are the pages from the manual.

 

[RaceDiagnostics]

diesel is what ive always used , with no springs fitted , and left over night , petrol would evaporate.
No engineers blue , just three lines across the seats with a soft lead pencil , and then one full turn of the valve and inspect for results . Never ever lap with a drill , only recip movements.
But as much as its a slow old job its also very therapeutic.

Will give that a try today.

 

[RaceDiagnostics]

Just remembered that they guy who did the tig welding on the inlet manifold said he had some seat cutters, he is a retired motorbike engine rebuilder and had a lot of time for me and is only 5 minutes down the road, I could easily take the heads for him to have a look at and give an opinion.

 

[RaceDiagnostics]

I assume the cam operates a rocker arm with a foot on it and a shim for adjustment between the foot and valve head.

Yes you have a hydraulic tappet at one side of the arm which has a foot that sits in the slot in the shim/thrust washer at the other end that sits on top of the valve.

 

[minimutly]

Take a breath here. This isn't a race engine, nor is it an ultra low emmissions multivalve. Lap each valve by hand, with love and feeling. If you need to have a seat cut you will see and feel it, and then find someone to do it for you. With your chamber sizes a few thou difference in depth is neither here nor there, and unless you're going to race this neither are the seat widths or the 3 angle cuts. And don't worry about shimming valve springs neither, not for a second.
Your valves need to seal, and have the right clearances, and the engine will perform as new.

 

[Cyberprog]

Next closest is more than an hour away and illegal for me to drive to just now.

Crate it up and ship it to them.

 

[slim_boy_fat]

I have zero experience in working on engines.

Well done for tackling the job in that case, you're doing a pretty good effort so far.

My experience in pulling engines to bits was as a 'yoof', back in the days when things weren't as critical as is the case with more modern lumps.

 

[RaceDiagnostics]

Just took a 10 min break from the garage to bid on this and won!

https://www.easyliveauction.com/cat...a6646f/antique-general-interior-sale-lot-469/

 

[roofman]

Just took a 10 min break from the garage to bid on this and won!

https://www.easyliveauction.com/cat...a6646f/antique-general-interior-sale-lot-469/

Would make a great engine stand

 

[RichardM]

So back to the head The thinnest shim previously fitted is 4.75 mm and you have the option in part number 117 053 00 53 to go down to 3.7mm thickness, You should have 1mm to play with height wise for cutting the seats before getting to the territory of putting it back together and finding you don't have any clearances- i.e. plenty

 

[RaceDiagnostics]

Today, I put the springs back on the first head to try a leak test with them.

Then filled the runners with brake cleaner.

There was only just the tiniest of weeps from a couple of valves, to be honest, I am almost ready to call that good.

Here is the bounce test on the second head.

I will take the heads up the the bike engine builder tomorrow to get his opinion, nothing like getting an experienced pair of hands on the head, so I put both to one side for the rest of the day.

Next I went on to rebuilding the pistons, only lost one of the wrist pin retainers pinging across the garage.

New, bearings fitted.

Tried out the new torque gauge.

Checked the dimensions, all was good.

Then repeated for the other 8 pistons.

 

[Seadog]

only lost one of the wrist pin retainers

Gudgeon pin circlips

 

[slim_boy_fat]

Gudgeon pin circlips

"Pingfeckits", as @RaceDiagnostics discovered.

 

[Woody.v8]

There is still a big block chevy valve spring collet that made a brake for it in my workshop somewhere

 

[RaceDiagnostics]

Today I finished lapping the second head.

I then took them up to the motorbike engine builder, very local, only 5 minuets away. He tested them with petrol in the intake runners and exhaust ports, the were a couple of ports with a very tiny slow weep. He said he would not do any further work on them and would be more than happy. He was amazed that the new guides had gone in so well and maintained concentricity. He had expected that the seats would have had to be re-cut, the workshop had a full set of Nuway cutters but he advised not to do it.

He had a very interesting workshop, and was rebuilding a racing engine with titanium valves......

Next I plan to go through the 80 or so plastic bags with parts in them and remove, clean and catalogue all the nuts and bolts and decide which to replace, re-plate or reuse.

 

[RichardM]

You must get quality machined valve guides when you buy Mercedes or it could be that you heated the head and cooled the guides so that most went in with the minimum of effort.

Whichever one I'd count it as a good omen for the rebuild, well done

 

[Barking Mat]

It's taken two full days of prep to get to this stage, removing radiator and ancillaries, draining fluids, removing all hydraulic, coolant, vacuum and electrical lines. Removing the mechanical fuel injection system and all the connections to the auto box.

The first task this morning was to remove the air intake vents so that the bonnet could be lifted higher.

The car pushed out of the garage a bit to allow the engine hoist to be positioned.

The bonnet support felt secure enough like this, ready to lift.

It took nearly an hour to get the engine into this position, it kept jamming between the right exhaust manifold against the chassis rail and the bell housing on the steering box. In the end I had to remove the exhaust manifold on the right which took a at least 30 minutes due to the position of its fixing.

From then on it was straightforward to raise the engine, level it and drop the car onto its wheels then push it back out of the way.

Engine dropped onto a trolley.

Next I dragged the car lift back into place.

I then assembled the engine stand and had a tidy up.

You can see here the problem area where the bell housing fouled against the steering box. I will trim some of this off to improve clearance.

I videoed the entire extraction but will need to edit/fast forward some sections as it's 90minutes long and rather boring. I think I'll need a new PC to do it as mine is at least 12 years old and just too slow to do video editing.

Next, I'll pull off the trans and start the engine strip down and rebuild.

Sorry, latecomer to this thread.

What is that blue car lift, you've got?

How high does it go?

Really curious..

 

[minimutly]

You must get quality machined valve guides when you buy Mercedes or it could be that you heated the head and cooled the guides so that most went in with the minimum of effort.

Whichever one I'd count it as a good omen for the rebuild, well done

More likely has something to do with how they were machined - everything centred on the guide, rather than the modern way of cutting seats and guides together - some of the 16v ones I've seen are visibly off centre, but everything lines up - until you replace the guide. I've taken to indexing the guide, measuring after removal and then finding one similarly offset, indexing that and then pressing it in. Can make a big difference to the state of the finished seat.
Wish I had a Serdi...

 

[minimutly]

Today, I put the springs back on the first head to try a leak test with them.

Then filled the runners with brake cleaner.

There was only just the tiniest of weeps from a couple of valves, to be honest, I am almost ready to call that good.

Here is the bounce test on the second head.

I will take the heads up the the bike engine builder tomorrow to get his opinion, nothing like getting an experienced pair of hands on the head, so I put both to one side for the rest of the day.

Next I went on to rebuilding the pistons, only lost one of the wrist pin retainers pinging across the garage.

New, bearings fitted.

Tried out the new torque gauge.

Checked the dimensions, all was good.

Then repeated for the other 8 pistons.

The fist two in that sequence I'd be looking at again.