First Time Engine Rebuild

[edd_barker]

Hello chaps!

Figures are back:

Head depth: 69.3mm - 2.728"

Head face to exhaust valve - 0.265" - Unleaded valve seat inserts so they will have been set to this as part of the reconditioning.

So it has been skimmed by .022 if my maths serves me correctly? And I will need pockets in the block of around .055 in order to give the correct clearance? Obviously this will be worked out with the blue-tac method. To my mind these pockets will serve to lower the CR slightly, giving me a more useable road car. Head CC is 21.5.

I await your advice! I know BMC that you are against the block pockets, Phil that you are for them. If I can use this head I can save myself about £300 as I can sell the others I have.

Thanks again gentlemen,

Edd

[philthehill]

Edd
If your engineering firm is successfully overhauling Jag V12 engines I would be more than happy using them and taking advice from them.
Your maths are correct - head skimmed 0.022".
I do not see any reason for not using the head in question.
I always use soft plasticine on top of the piston or in your case in the pockets when doing a dry assy run before final assembly.
For general information - use & fit a an old gasket - assemble the head/top end adjust the valve clearances -carefully turn over the engine (with the plugs out) 5 full revolutions (if any resistance to turning is felt stop immediately) remove the head etc and see what the thickness of the plasticine is after the engine being turned over.
Phil

[bmcecosse]

No matter how deep (and they were DEEP) I made the pockets in my 998 race engine (50 years ago now) running a full Cooper S head (so even larger exhaust valves) and a 544 camshaft - and check with plasticine - every time I lifted the head I found marks where the valves had touched the block..... Something to do with valve float I believe - well I did rev the nuts off it!
And it never broke. Even took me (when transplanted into my Elf Rally Mini) to a decent place on the Mull rally - considering I started 'hanging off the pier' second last at # 141 (no previous 'stage' experience), and we finished at 24th!

[edd_barker]

Great story BMC!

I can assure you that this engine will never be revved that hard. I tend not to go over 4000 as the gearbox whine is too annoying!

I'll instruct them to get cracking then, hopefully have it done by next week and I can finally start putting it together.

This whole project is inspired by my father's race 1275 that he built in the 70s for an MG Midget. He forgot to clean out the crank oilways, and it supposedly went like the clappers.....for about 10 miles then went straight in the bin. So there will be plenty more questions to make sure I don't make a similar error!

Thanks,

Edd

[philthehill]

The moral of the above story is clean - clean - clean and clean again.
Not only the crankshaft but those engine block oil galleries.
Get those hose oil way brushes working - available from Frosts Restorations.
Phil

[edd_barker]

Yes I have ordered some brushes, got the Gunson ones off of Fleabay.

All oil gallery plugs and core plugs were removed, the block has been dipped. I will clean it again with petrol and the brushes before knocking the new plugs back in with a smear of sealant...any particular kind recommended?

Edd

[bmcecosse]

Since it is hard seats - you won't be able to sink the valves (well - not easily) so pockets are now your only way if you want to use that head. The minimum is 300 thou clear, so you may as well go the full 40 thou sinking as is the standard suggestion. But it all depends on the use of a standard cam, and standard rockers - not 'high lift'. The rockers still need to be re-aligned over the valve tips correctly.

[philthehill]

Edd
Cleaning with paraffin is much better and the block can be hosed off if required.
As regards sealing the oil gallery plugs a small smear of LOCTITE 'Lock and Seal' is what I use with good results.
Phil

[edd_barker]

Definitely standard rockers and cam! I was planning on sticking the sintered 1275 on there as I already have a set knocking around, I may well strip the others in due course to align them.

Cleaning-wise, as the block has been dipped I'm not expecting a lot to clean, only the oil-ways to make sure. Therefore I was going to use petrol as it evaporates, and I have some! Is paraffin that much better, will it require rinsing? I have seen the block and the outside and inside look clean enough to eat off. The sump is another matter....

Any particular strength of Loctite? It seems to come in medium and permanent...

In fact whilst I'm asking, any other sealing pastes I will need? I have Hylomar blue. I'm thinking of round the sump/crank scroll seal. I have ordered some assembly oil for all moving parts.

[bmcecosse]

You want permananet Loctite. No nasty pastes or goos -and certainly not round the scroll! No special assembly pastes etc - just lashings of good clean engine oil. BMC didn't use anything like that - why would you now - it's an excuse to make you spend even more money. But do pre-load the new oil pump with oil.

[philthehill]

Edd
Smear general purpose grease on either side of the gasket being fitted. Works for me every time. As above no need for fancy sealants.
Was the block dipped before or after the machining work?
I use paraffin for cleaning as I can use my compressed air/paraffin spray gun to blast any crud out of the oil ways and off the block and parts.
Unless being used outside of the workshop petrol vapour may ignite if say a light in the workshop is switched on/off.
Petrol should not be used for cleaning in confined spaces - it can make you high.
Phil

[edd_barker]

Block dipped after all the work....APART from the pocketing which I have only just asked them to do.

So if I go to a suitable DIY superstore and buy this: http://www.diy.com/departments/bq-paraf ... 116_BQ.prd
I'll have the right stuff? I think I have some kerosene-based degreaser is that any use, or is paraffin best for general de-greasing.

Does it need rinsing off after or am I good to go with a thorough wipe down? I have a compressor and air gun so I will blow everything through with that.


Thanks,

Edd

[philthehill]

For the purposes of this exercise paraffin and kerosene are the same thing.
Clean the oil galleries after pocketing and before fitting the gallery plugs.
As you have a compressor this type of paraffin gun is a good investment - http://www.ebay.co.uk/itm/222112-Long-N ... SwxH1T12oG
Make sure that you clean out these oil galleries (in this case now fitted with screwed plugs) - picture below.
A good blow through and wipe down with a non fluffy rag will be alright.[frame][/frame]

[bmcecosse]

I always grease the head gasket - but all others dry.

[philthehill]

The reason for greasing paper gaskets is that they then remain flexible and do their job for much longer.
The problem with dry gaskets is that over time they shrink and then weep oil.
But anyway all to their own - though I shall continue to smear grease on my gaskets as I have for the last 40 years.
Phil

[edd_barker]

Comment noted about stainless, I think so far only the sill covers and the U section of trim attached to the sill have had the stainless treatment, nothing structural. You learn something every day!

Regarding gaskets, I thought that cork ones had a good soak in clean oil before fitting? Paper ones I will give a try with grease, I haven't done that previously. What about the grey composite ones, are they paper? Head I did clean last time and no problems there. I put blue Hylomar on the thermostat gasket and it got good and squished out the sides so obviously not the right method...

[edd_barker]

Comment noted about stainless, I think so far only the sill covers and the U section of trim attached to the sill have had the stainless treatment, nothing structural. You learn something every day!

Regarding gaskets, I thought that cork ones had a good soak in clean oil before fitting? Paper ones I will give a try with grease, I haven't done that previously. What about the grey composite ones, are they paper? Head I did clean last time and no problems there. I put blue Hylomar on the thermostat gasket and it got good and squished out the sides so obviously not the right method...

[bmcecosse]

The grease is obviously going to squeeze out make your painting a bit more difficult. Never known the gaskets to dry out -there is after all oil on the inner edges which soaks through to an extent. But at least it's not Red Hermiite. The only cork gaskets to be oil dipped are the half moons for the sump ends.

[edd_barker]

Grease before painting?!!?! I was planning on painting it all separately, masking off faces as necessary. No blow-over job for me thank you!!!

[edd_barker]

Hi all,

Couple of queries:

The 1275 rockers I bought a year or so ago look like this:

[/frame]

Are these scrap or can I dress them down with a file? I can just feel a ridge on one side, which makes me think that the case hardening has gone. No ridge on the shaft. Can I just buy a new shaft and use the minispares forged rocker arms and rebuild my whole rockers? Are they compatible?
http://minispares.com/product/classic/12G1221.aspx

Otherwise I'm struggling to find any sintered on ebay that look in reasonable condition so I can just stick them on till I have time to rebuild.

2. Sump looks like someone has been off-roading! The inner bracing is slightly bent, does this matter other than cosmetically? Could it be hammered out? I had a quick go, and also squeezing in the vice but no joy. I don't think the top is damaged or warped.

[frame][/frame]
[frame][/frame][frame]3. The engine came with this rocker cover (no breather pipe, vented cap) and then the bean can tappet cover breather. I was planning to re-fit this arrangement with the one breather running to the carb vacuum. Would this be best, or do I need a rocker breather to a T-piece and then the vacuum also?

[frame][/frame]

The workshop bench had an MDF top, pretty soaked with oil and grime and difficult to clean. For the purposes of the rebuild I cut some skin ply to fit, then wrapped it in white gloss vinyl (signwriters not upholsterers) which I get from work. Although it won't be particularly abrasion-resistant, it should be a doddle to keep clean and no dust. When I've finished I can flip it over for the ply side, or just keep it and screw another one in when it's worn out.

[frame][/frame]