Talking about fails....

Technical advice Q&A

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Durango2k
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#1 Talking about fails....

Post by Durango2k » Sat Nov 21, 2015 8:13 am

...I have to add one. So, whoever may read this in xx years, you have been warned:

I wanted to fit new valve guides to my engine. Matching nos, so I had to rebuild it from scratch, as new, and as always with zero or near-zero cash.

So, I duely read the workshop manuals, and it said "cook the head for 1 hour, then fit the valve guides"

If I got the numbers right, the workshop manual says 0.01 to 0.05 mm oversize, whilst Mr. Hamill says 0.04 to 0.06 oversize, so I went for 0.04.

Took me MONTHS to find someone to turn the oversize items I got from SNG USA to that value. Everybody was feary to distort them or "getting them not right".

Then, problem. I would have preferred an oven of course, but of THAT size ? No. So, how do you cook such a turkey, then ?

First of all, SWMBO had to be out of the area for all possible reasons. Really. Make her go 200 miles away was the plan. Finally, she went together with Felix to see an old girl friend of hers in Karlsruhe. That is 500 km, enough I thought.

Then....

I found an old shell grease metal ton in my parts storage. Took out all the grease with a large spoon in the kitchen, and cleaned it very thoroughly. After that, I started to cook water on the Braun water cooker (makes 1.5 ltres each run in 2 minutes), and on the main cooker. Then, I got a water heater element you can put in the ton, so on it went.

After about an hour, I had the head in ton, filled up with water, yet half of the head was on top of it. Idea was to revert the head and doing it in 2 runs.

Now. It did not cook. For an hour it simply did not boil.

Finally, idea- I have to isolate THE BEAST.

That did the trick, after 10 or so minutes more under a cover Susanne made for my bed, it worked (also used some bathroom large towels...).

After more then an hour of boiling, I took it out, took the valve guides from the -18 fridge (manual does not say you should do that, but that was because the public would not own -18 fridges in 1961!), and started to hammer the first one in its place, sitting nicely on an 8 mm rod with a large washer and nut.

And failed.

Quickly tried no 2, and....

Failed.

They both stuck so badly at half way down, although I was really hitting them hard at full speed...

No 3 went in by 90 percent, but I decided to stop.

To cut the end short, this way it does NOT work at 0.04 oversize. No way.

Head was then brought to a competent place. They called and said the could fix it, by heating the head in their large oven to 130 or so, and using a press.

Now I ordered new valves for them to match the guides to the all-new shafts and cut the valve seats.

One of the few items I failed to fix myself .... but at least I tried. Lonely are the brave...

Carsten

P.S. - picture here:

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Last edited by Durango2k on Sat Nov 21, 2015 8:54 am, edited 1 time in total.
Jag E '66 S1 2+2, Citroen DS 23 Pallas iE, Citroen SM 3.0, Concept Centaur MK1, Citroen 11 BL '54, Sinclair C5, Velosolex

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rolando38
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#2

Post by rolando38 » Sat Nov 21, 2015 8:26 am

nice try
I wouldn't have tackled it myself so respect
At least in a few days you will know if it was a problem of size or temperture or both
2+2 1970

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PeterCrespin
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#3 Re: Talking about fails....

Post by PeterCrespin » Sat Nov 21, 2015 1:37 pm

Durango2k wrote:...I have to add one. So, whoever may read this in xx years, you have been warned...One of the few items I failed to fix myself .... but at least I tried. Lonely are the brave...
You were warned in 2013 ...

"Anyone who attempts to answer your question without having micrometer measurements is guessing. Anyone buying parts without measurements is gambling. Anyone fitting unmeasured parts to an unmeasured head is playing Russian roulette.

There are things to do with cars that are purely subjective, such as colour scheme. There are areas where lack of expertise results in no functional loss (e.g.poorly-fitted trim). Precision machining and assembly is not an area where everyone's opinion is correct or the outcome is uncertain. The outcome can be known in advance by correct measurement, calculation, machining and assembly.

There is only one correct answer if you wish to use your existing head 'as-is' and you have to work out what it is. There would be another correct answer if you chose to ream out every guide hole to a specified oversize interference fit. Opinion, luck or chance are no substitutes for measurement IMHO.

Good luck with it."

Experience is a hard teacher. Your English, your honesty, your 'can do' spirit and your creative use of hammers are to be applauded. Your foresight, perhaps less so. I hope your seat depths/valve heights were measured and the shim thicknesses worked out OK?

Pete
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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#4

Post by Durango2k » Sat Nov 21, 2015 1:51 pm

Hi Pete,

Well, "having been warned" usually does not stop me :-), plus "I sometimes forget what has been said 3 years ago"....

Now, nothing has been done yet really - they fitted new guides which is fine and does not change the game in any way.

I have ordered a set of valves and valve stem seals which should arrive in a few days.

I do have a set of new SNG springs, and I do get the valve collars and small collets from a spare big valve head. And a set of new camshaft bearing shells, bought from SNG a year ago.

So, I think I should have them measure the distance of the new valves before cutting seats to a testwise fitted cam ? To determine how much "deeper" they are allowed to cut ?


I do have a brand new loaned set of neway cutters here specific for XK engines... so I could just let them ream the guides then take the head back home and do this myself again ?

Carsten
Jag E '66 S1 2+2, Citroen DS 23 Pallas iE, Citroen SM 3.0, Concept Centaur MK1, Citroen 11 BL '54, Sinclair C5, Velosolex

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PeterCrespin
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#5

Post by PeterCrespin » Sat Nov 21, 2015 2:40 pm

Your first paragraph indicates we are brothers under the skin.

Your valve dimension question indicates the rightness of my warning.

There is a figure for valve stem height. If the valves are measured before/during cutting you can make sure everything fits if the cam and buckets are standard dimensions. Even so, I would measure everything repeatedly for every component and then keep them in sets, to make sure for example that you did not put your shortest valve with your thinnest bucket in the place where you have the smallest base circle. The biggest variable is seat cutting though, so that's the area to take great care not to overdo.

Viel Gl?ck! Wenn schon, denn schon
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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#6

Post by Durango2k » Sat Nov 21, 2015 9:12 pm

Hi Pete,

I did not find a figure for that value in Des Hammill?s book.

The workshop manual has a figure, but all I could find was in the 3.8 S1 manual (not in the 4.2 one).

It says "fit the camshaft, fit the valve, press the valve into the re-cut seat, and measure from valve stem end to camshaft BASE circle" - of course this is with oiled new camshaft bearing shells fitted.

Look for 8.13 mm clearance- this then gives "zero play", so if you want another 0.15mm (exhaust) of play it would be 8.28 you have to set it to by grinding / cutting the valve seat.

Oh and they really do NOT say what to do if the clearance is LOWER then 8.13 (too short to allow valve clearance ...).

I think I will go there and either STAY there and do it with them or take the head back home....

Carsten
Jag E '66 S1 2+2, Citroen DS 23 Pallas iE, Citroen SM 3.0, Concept Centaur MK1, Citroen 11 BL '54, Sinclair C5, Velosolex

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