"Unofficial" Engine Rebuild Suggestions

[Guest]

Hello All,

I have my motor down to a bare block and and now starting to get parts and clean it etc.

I am trying to rebuild the engine as economically as possible and was wondering if anyone
has an unofficial guide as to how to rebuild it, what parts absolutely have to be replaced,
what to check etc. Any help would be appreciated.

Here are a couple of shots of the block and pistons (the pistons will be replaced)

I do have the official Stag rebuild book

IMG_1331.jpgIMG_1332.jpg

This is really a helpful forum

Thanks
Joe

[Westfaling]

Joe
I think the bare minimum would be rings and crank shells and of course chains unless they're pretty new. Everything of course depends on condition. For example the oil pump can be reused if the clearances are still Okay the clearances on some of the new ones don't seem that great.
Lot's of don't dos of course like don't re grind the crank without re- heat treating it. The Haynes manual seems set up to give advice on how to check components for reuse.
Nick

[Staghound]

What is the official rebuild book? Does it just cover engines or the whole car and where can I buy one?

Andrew.

[flying farmer]

You say you are replacing the pistons. I assume you are having it rebored rather than just fitting standard size pistons in worn bores, otherwise a ring set would probably be adequate.

Since the crank is one of the weakest points on a Stag engine I reckon anything less than a perfect set of bearing surfaces is a waste of time and money. From my own experience cranks that have been reground and not hardened will wear twice as fast as the replaceable shell bearings. The worse wear normally occurs on no 2 and no 4 main bearings as these are rather too narrow for the job, however a properly reground and hardened crank should last a long time. I have a crank ground 60 thou under on the mains and after a 70,000 mile stripdown following head gasket failure there was no discerable wear on the crank or bearings and the bores still had the original honing marks.

Check the jackshaft and water pump gear teeth for wear very carefully. Worn teeth lead to the jackshaft seizing and subsequent major engine damage as the timing chains snap, happened to me 6 months after buying a Stag.
Also check the jackshaft bearing surface in the block very carefully, particularly if worn teeth are found, as the extra load tends to wear the jackshaft bore oval and since this is fed off the main oil gallery it will significantly drop oil pressure.

If the jackshaft water pump teeth are worn but the oil pump drive teeth are good, a cheaper and more reliable alternative to replacing the jackshaft and water pump is to reuse the jackshaft but fit an external water pump, either electric or a Stagdad belt driven conversion. I have both sorts fitted to different cars and both work well.

Check the cylinder head mating surfaces of the block very carefully, particularly at the rear of the block. I have come across a couple where the rear of the block has settled and the block needed skimming. The engine that suffered the jackshaft seizure came with a history file that showed three sets of head gaskets within 25,000 miles, the problem was the block needed 8 thou skimming off it to true it up, but if it needs doing make sure the timing cover is bolted in place when it is skimmed to avoid a step.

The cylinder heads need checking for straightness and corrosion eating out of the waterways if the antifreeze hasn't been replaced regularly.
Check the valves and guides for wear, and for loose valve guides which is not unheard of.

Measure the cam buckets for wear, even if they don't look too bad. They usually wear in the middle, this leads to the cam bucket rocking which can give rise to annoying tapping noises, as well as accelerating wear on the valve guides and leading to the clearance setting shims under the buckets wearing and the valve clearances increasing.

When reassembling the block check that top dead centre does actually coincide with the marks on the timing cover, I have seen them 4 degrees out which buggers any possibility of correctly timing the camshafts or ignition, and in combination with other timing mark issues can lead to the cams being set up one tooth out leading to valve to piston contact or at least an under performing engine.

Finally with the heads stripped check the cams are sitting flat on the head bearing surfaces. When heads are skimmed to remove a warp it flattens the block mating surface, but can leave the camshaft bore bent. This usually results in the cam wearing upwards into the bearing caps until it can turn freely. Engineers blue and feeler gauges will show up the problems, sometimes it is possible to rock the cam in its bearings along the length of the head with the caps removed.

With care and some fine wet and dry it is possible to true up the cam bearings, I routinely do this on every engine I rebuild.

This sounds like rather a long and daunting list of problems, but hopefully you will only encounter a small selection of them, otherwise most of the rebuild can be done by the book.

Best of luck

Neil

[mikethemechanic]

Additional info for you,look into block on outside of bores i.e. where water runs,at rear of each line of bores the lower area becomes blocked with sludge and hardened debris,use a long thin screwdriver to dislodge the debris until all water areas are clear (don,t be afraid to be heavy handed i have removed up to equivalent of bag of sugarfrom rear of block) and still do this if you are having block chemically cleaned.On heads at front is a small slot with 1/4in hole ensure this hole is clear and follow it to link holes in manifold that pass to rear of thermostat and insert suitable rod to ensure the holes are clear.All this should ensure no overheating. good luck Mike

[Guest]

What is the official rebuild book? Does it just cover engines or the whole car and where can I buy one?

Andrew.

Hello

There are PDF files of the Hayes manual

I don't have the link but I think I got it on here

Thanks

[Guest]

This is exactly what I'm looking for.....

Thanks guys