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Bruce Sutherland
United Kingdom
1564 Posts |
 Posted - 17/05/2008 : 17:30:17
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I am rebuilding the cylinder head for my PB. I have used the search facility for valve clearance setting procedures and have read much about the importance for getting the valve timing correct by detail attention to valve stem length and/or valve seat re-cutting.
I have also read the chapters by Bob Jones in “M.G. Road Cars Vol.1.”, but I am still uncertain about precisely what I should do next.
I have fitted new bronze valve guides, and reamed them carefully to achieve the correct running clearances with the new valves’ stems, and have had the valve seats (already fitted with ‘old’ seat inserts) carefully re-cut (30 deg face angle) piloted off the new guides.
I have new valves with no collet grooves.
Please will someone advise:
a. There are differing types of valve retaining caps and collets – which are preferred?
b. What is the correct procedure and work sequence for positioning/machining the groove in the valve stem for the collets for valve cap spring retainer?
I know this is in relation to the compressed/valve open length of the springs.
The subsequent steps for setting the valve stem-to-rocker clearances with reference to the large cam valve diagram have been adequately explained, but I need some help with the above, please.
Bruce. |
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bahnisch
Australia
674 Posts |
Posted - 18/05/2008 : 11:06:39
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| Bruce, I rebuilding my F-type I used modern keepers (ie valve spring retainers) which I machined down to the original diameter and used modern single valve springs. I measured the valve seat pressure and it was 40 pounds from memory, ie equal to the original specs. There is a simple device for doing this. I did not want to overload the camshaft and drive etc as there seemed little point. I could have been even kinder to the OHC system (with softer springs) but wanted to avoid valve bounce at unacceptably low revs. The keepers and springs were the outers (?) from a relatively modern Holden Gemini (pushrod OHV) from memory, perhaps you have an equivalent Opel or somesuch. There may well be several engines in the UK that have components that you could use, although most now have some sort of OHC heads. As for installed height, I used a homemade "gauge" out of a short piece of tubing "closed" at one end and, placing it over each valve stem, marked them with a texta where the grooves had to be machined. I am unable to recall the heights above the head (upper) face and it may well vary between models. Perhaps someone else will be able to enlighten you. All of this may sound like a lot of rigmarole but it is not very time-consuming and you will probably be very pleased with the result, my car starts and runs absolutely superbly! A lot of OHC cars used to run very badly and noisily, I know from my P-type days many years ago, and I think that some still do! |
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David Allison
United Kingdom
665 Posts |
Posted - 21/05/2008 : 08:41:42
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No real short cuts - I use Blower and it take a while!
The best way is time and patience.
Regards David |
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