26 DB Initial valve clearance set up

[Wheelmang]

I am getting ready to grind valves in my 26 DB. Lifter/tappet nuts will be backed off all the way as I am replacing most of the valves. My car is post A193533 and the manual is calling for .004 on the inlet and .005 on exhaust with the engine hot. (BTW some of them are over .020 right now).

- What should cold clearance on initial set up be?

- How in the world, on this set up, does one set clearance on a hot engine. It looks like even if you can get to the valves with a feeler gauge and wrenches, you would need a jump suit with asbestos sleeves to keep from getting burnt on the exhaust manifold.. 

Thanks for your input 

Paul

[R.White]

Forget hot engine clearances. Do Inlet 8 and exhaust 10 on a cold engine.  Then again you guys have E10 petrol so perhaps add a couple of thou for hotter running. I would replace the springs as well. If you decide there is still too much wear with the new valves  replace the worn guides but  don't follow the advice in the workshop manual to cold chisel mark and break them off because there is too great a risk of cracking the block.  Better to pull them out.  New guides should be pressed or pulled not knocked in but you may need the camshaft out to achieve it.  Also beware the replacements may be over size.  (I had to turn them down 0.003" on my rebuild).

 

Ray.

Edited February 14, 2018 by R.White (see edit history)

[Wheelmang]

Thanks Ray: I am actually running no E fuel in this. We live close to a big lake and there is a high demand for no E fuel for the boats. 

[RichBad]

Bob B just told me this the other day - ignore the manual (that was for old fuels which burn faster).  for a rebuild set them all at 0.07” cold.  Then after it’s run for a bit and settled check them - the exhaust one is important (as gets very hot due to current slow burning fuel) and needs to have 0.007” + when hot.

 

How’s my memory Bob:)?

 

checking them hot isn’t too hard.  You need to go on a good run to get the block fully up to temp but the exhaust should cool quite quickly as it has a lot less thermal mass than the block.

[R.White]

2 hours ago, RichBad said:

Bob B just told me this the other day - ignore the manual (that was for old fuels which burn faster).  for a rebuild set them all at 0.07” cold.  Then after it’s run for a bit and settled check them - the exhaust one is important (as gets very hot due to current slow burning fuel) and needs to have 0.007” + when hot.

 

How’s my memory Bob:)?

 

checking them hot isn’t too hard.  You need to go on a good run to get the block fully up to temp but the exhaust should cool quite quickly as it has a lot less thermal mass than the block.

 

He is not running on E10 petrol.

[Ron Lawson]

The modern ULP burns slower then the old gas I can't comment on E10 as I have never used it

[R.White]

One way to achieve optimum combustion regardless of which petrol is being used is to set the timing advance relative to exhaust temperature.  It is an easy thing to fit a thermometer (or temperature sensor) to the exhaust down pipe and test drive for a couple of miles and record the temperature.  Try the same two mile test at the same speed and compare  exhaust temperature readings.  Eventually by experiment the optimum temperature can be arrived at.  Lower exhaust temperatures mean lower under hood temperatures, cooler carburettors, and less vapour lock but more importantly indicates more complete combustion before the exhaust valve opens.

 

Ray.

Edited February 15, 2018 by R.White (see edit history)

[robert b]

We put Ray,you have explained it better than me.

[R.White]

6 hours ago, robert b said:

We put Ray,you have explained it better than me.

 

I cannot claim any credit whatsoever as this idea came from an MG expert.  Believe me, some of the MG guys over here have mind boggling technical skills not found elsewhere. 

 

Ray.

[robert b]

 It is great to be able to share such information , we are always able to learn new things in this form and from some unusual places  thanks for passing it on Ray .

 

[Wheelmang]

22 hours ago, R.White said:

One way to achieve optimum combustion regardless of which petrol is being used is to set the timing advance relative to exhaust temperature.

This will be interesting to track. I just happened to take a number of temperature readings around the engine and cooling system before I took the head off. Did not know why I was doing it at the time, just seemed like it would be some good info to have. I will post new temps after I get all put back together. Might be a week or so. The honey do list is demanding some attention. 

 

[nearchoclatetown]

I hope you let the engine get to room temp before you took it apart. The head can warp if taken off while hot. The infrared is an excellent diagnostic tool. Let's you know a weak cylinder or if the radiator is flowing correctly. 

[Wheelmang]

All was cooled down. I took temp readings all over the engine and cooling system the last time it was up to operating temp. 

Forgot about the honey do list for one more day. I think it was time for valves. Every one looked like this or worse. I actually cut a finger on the edge of one when I was pulling it out.  Incredibly the seats and guides appear to be in pretty good shape. 

Edited February 16, 2018 by Wheelmang
Added text (see edit history)

[nearchoclatetown]

From here it loos like a two piece valve. You can tell better from the top after wire brushing it. The cast iron head is swedged onto the stem. If so I would change all of them.

[R.White]

One thing you might like to attend to is wear to the valve spring keepers caused by the retaining pin.  In theory, the valves should be able to rotate on their seats but when the pin wears a groove in the keeper it prevents the valve from turning.  Incidentally, this condition can also lead to a tapping sound as the pin jumps in and out of the groove under spring pressure.

[Wheelmang]

6 minutes ago, nearchoclatetown said:

From here it loos like a two piece valve. You can tell better from the top after wire brushing it. The cast iron head is swedged onto the stem. If so I would change all of them.

Thanks -  I am actually going to use valves from a couple of spare engines of the same vintage. They are in excellent shape and the budget is starting to get tight on this. I will likely do a complete and proper overhaul in the future. Two other cars got put on the back burner when this one showed up in my life.  

[Wheelmang]

7 minutes ago, R.White said:

One thing you might like to attend to is wear to the valve spring keepers caused by the retaining pin.  In theory, the valves should be able to rotate on their seats but when the pin wears a groove in the keeper it prevents the valve from turning.

Thanks Ray.

Is that groove wear? I have only pulled valves out so far. Still need to get springs and tappets out for cleaning etc. 

I am also hoping that I have enough spare keepers from the other engines that I dismantled. I noticed that some of the pins are slightly bent. Starting to think this may be the first time this engine has been opened up at 57,000 miles. Although it has a couple of over sized head studs in the block. 

[R.White]

Yes, the groove is worn by the pin under spring pressure.  If it's not too bad, the groove can be machined out.

 

Incidentally, all the pins were bent on my engine but new ones are available from Myers.  

 

Ray.

[Wheelmang]

Before I pull all the tappets and springs out of this, are they similar to the process for push rods. IE: should they be put back in the same position from which they were removed?

Thanks

[R.White]

I would keep the tappets in the same order and position because they will have a corresponding wear pattern relative to the cam lobes.  Personally I would junk the old springs; not that you are likely to get valve bounce but so you get as snappier a valve closure as possible.  Be careful how you handle the tappets.  It is an easy thing for them to drop down into the engine and that would be annoying if you have just fitted up the oil pan.! 

 

[Wheelmang]

Almost all back together with one question about the side/valve covers. I did not see any signs of these having a gasket on them when removed. They just look like a great place for oil to leak. Should they not have a gasket of some type?

 

[R.White]

There was no gasket on my engine so I  made sure the area was free of oil contamination then stuck A 1/4" strip of cork along the bottom of the valve chest. Being at the front, it holds back any oil that is swilling around on the "lands".  

 

Ray.

[MikeC5]

The gasket set I bought from Olsen’s did have a gasket for this but you could make one easily enough from a roll of cork gasket material.

Edited February 25, 2018 by MikeC5 (see edit history)

[Wheelmang]

Decided to go ahead and make a cork gasket for this. Will see how/if it works. 

BTW - engine is all back together and hope to start it up, the next sunny day, for the first time since valves. Can't run in the basement garage anymore. Smoke detectors go off and it drives the cats crazy. (Not to mention my wife) 

[R.White]

I have a length of flexible aluminium tubing which I connect up to the exhaust pipe and route to the outside so I can have the engine running in the garage. works a treat.

 

Ray.

[Mpgp1999]

I hope this helps. This is from Dyke’s automobile and gasoline engine encyclopedia 12 edition.