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Engine Rebuild Begins...


molten

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Been aquiring new parts for a few months now and  am almost ready to start engine rebuild (just need to tidy up garage first :)). Will try to post pics as I go.

Got new cam (large journal mk 3 grind)
New mains & Big end shells
New followers
New timing chain & tensioner.
New +20 pistons & rings.
Block been bored to match.

Only thing i have not bought new is push-rods (and con rods). Push rods seem ok to me, but should I have bought new ones???
Con rods still need a clean yet and will prob leave then in a bath of new oil after wire brushing clean. I have not changed the little end bush as this seems ok - just need to clean out the oil grooves.

Some pics of assy bench and block with nice beer towel  :)

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Just a quick question about core plugs. I have opted for the original 'cup' type of plug over the concave dish type, but I have read differing opinions about whether or not sealant is used on cup type plugs. Some use sealant and some dont.

So... what is the recomended option and why is this prefered?

Thanks
Scott

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2597 wrote:
Just a quick question about core plugs. I have opted for the original 'cup' type of plug over the concave dish type,


They're not supposed to be interchangeable, the block is machined differently in each case. The 'cup' and 'dish' descriptions are both usually applied to the deeper coreplugs, the early flatter type are commonly described as 'saucer', though I'm sure there are many other colloquialisms for them.
Just so we're not at cross purposes, which type are you intending to fit? And is your block machined to receive the shallow or deep type?

Cheers,
Bill.

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heraldcoupe wrote:


They're not supposed to be interchangeable, the block is machined differently in each case. The 'cup' and 'dish' descriptions are both usually applied to the deeper coreplugs, the early flatter type are commonly described as 'saucer', though I'm sure there are many other colloquialisms for them.
Just so we're not at cross purposes, which type are you intending to fit? And is your block machined to receive the shallow or deep type?

Cheers,
Bill.


Hi Bill
Hope you are keeping well.
The plugs i removed were the cup type and thats what I have purchased to replace with. Where I am a little uncertain is whether to use a sealant on the new ones when they are installed - read mixed reviews.

Cheers
Scott

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I'll be following this thread with interest Scott, as your engine spec is more or less the same as my 1500 still sitting in shiny bits on the bench. I even notice you have the same engine stand as me.

Mine should have been finished a year ago. I'm using the excuse that I've still to decide on whether to drill the centre main oil feed or not before I build it.

When you've done yours, and worked out what jetting and advance curve works best with the Mk3 cam in the 1500, I can steal all your hard won info for my engine  ;)

That's another good reason to delay doing mine.

Regarding core plug sealant; I would use Wellseal but I know others have used other types, including silicone sealant.  When this particular engine was built, about 8 years ago I think (by a well known builder), white silicone was used everywhere like it was going out of fashion.

Lastly, it's nice to see you go to all the trouble of getting "Spitfire" monogrammed workshop rags....

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Hi Sparky

You are welcome to steal anything that is useful to you mate.. ;)

When I cleaned of the cranc and mic'd, the journals, all still seem to be at the .010 spec. But I noticed on one of the big end journals that there is a very slight ridge that runs round the journal... I am trying to tell myself that as this is only a standard road engine, the ridge (although not ideal) should be ok. Am I kidding myself here? Regrind and new shells all round is just short of 180 quid. It goes against all my leadings, but as budget is now very limited - I am going to continue as planned.(might turn out to regret it).

New rod-cap boltys have been bought, but is it recomended to use new main cap bolts on rebuild as these are merely high tensile bolts unlike the 'stretch' rod bolts? Thoughts welcome..

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2597 wrote:
Hi Sparky

You are welcome to steal anything that is useful to you mate.. ;)

When I cleaned of the cranc and mic'd, the journals, all still seem to be at the .010 spec. But I noticed on one of the big end journals that there is a very slight ridge that runs round the journal... I am trying to tell myself that as this is only a standard road engine, the ridge (although not ideal) should be ok. Am I kidding myself here? Regrind and new shells all round is just short of 180 quid. It goes against all my leadings, but as budget is now very limited - I am going to continue as planned.(might turn out to regret it).

New rod-cap boltys have been bought, but is it recomended to use new main cap bolts on rebuild as these are merely high tensile bolts unlike the 'stretch' rod bolts? Thoughts welcome..


I suspect you may well regret ignoring the ridges on the journals. Are they into or out of the bearing surface?

If out you may get away with polishing it and reduce it.

Cheers

Colin

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Just taken another look at the B/E journals and mic'd. Readings as follows:

Haynes manual says spec is 1.8750 - 1.8755

Crank has previously been reground as it has .010 shells.

Rod caps torqued with .010 shells in and ID = 1.867
That crank journal mic'd at                    OD= 1.8675

What do you guys think?????????

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I've bought new big end bolts but plan to use the existing main cap bolts.

I tend to agree with Colin about the ridge on one of your big end journals but it depends upon how pronounced it is.  If it's sticking up then polishing is a good option, using 400 - 600 grit wet'n'dry lubricated with WD40 and rotated with a strap (the flat side of an old fan belt is good as you can get about a turn and a half round it) will take it down a bit, but make sure you don't go beyond the spec size. If it's a groove then it depends how deep it is. A slight groove, polished up a bit, is acceptable, but a deep gouge probably isn't.  Only you can tell really, by feeling with your finger nail. I've got a few light scores on my crank which seem to polish up okay and I'm happy with them. In a perfect world you could regrind the whole thing and be 100% happy and be £180 lighter, or just be happy that you've reduced the problem to somewhere where you feel okay with it.

Purists may shudder, but if it was too bad to polish up you could just get that one journal reground and then put .020 shells in just that one big end?

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2597 wrote:
Just taken another look at the B/E journals and mic'd. Readings as follows:

Haynes manual says spec is 1.8750 - 1.8755

Crank has previously been reground as it has .010 shells.

Rod caps torqued with .010 shells in and ID = 1.867
That crank journal mic'd at                    OD= 1.8675

What do you guys think?????????


Is that with the new .010 shells in the rod?  If so, the crank is on upper spec and the shells are half a thou too thick?  If you tighten the rod onto the crank, does it turn?  What about with an old set of shells in?

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Another thought... if you are measuring the ID of the shells when they are torqued up inside the rod, with an internal micrometer, then I'm not sure that's a valid measurement? Would the fact that the journal is not present inside the shells make them distort slightly, giving you this odd reading?

I would think the most accurate way to measure the clearance is with good old Plastigauge? You can't go wrong with that.

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I have never taken a short cut with this project yet. So I think I will not truly be happy unless the crank is reground. It will always be on my mind, me thinking when am I going to have a problem????
As much as it pains me having just spent £600 on other parts, I think another £180 is going to have to be found and maybe worth the piece of mind :'(

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molten wrote:
Anyone know what the clearance should be?

Is mains & B/E same clearance?


The manuals don't seem to give the clearances for the 1500, but the 1300 small journal crank clearances are given as 0.0005" to 0.0015" for B/E and 0.0005" to 0.0022 for the mains

Is the ridge you refer to right at the edge of the journal, may be when it was ground the radius on the grinding wheel was larger than the existing radius so leaving a step. If you place the rod with just the one shell onto the journal is the ridge to one side of the bearing surface?

Gordon

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That_Man wrote:


The manuals don't seem to give the clearances for the 1500, but the 1300 small journal crank clearances are given as 0.0005" to 0.0015" for B/E and 0.0005" to 0.0022 for the mains

Is the ridge you refer to right at the edge of the journal, may be when it was ground the radius on the grinding wheel was larger than the existing radius so leaving a step. If you place the rod with just the one shell onto the journal is the ridge to one side of the bearing surface?

Gordon


Thanks Gordon
I am now assuming that the clearances are the same on the 1500 otherwise they would have said - right?!
The ridge is actually about 2mm from the B/E oil way (!!!).

I think I will just have it checked out by machine shop (£££) :)

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Just checked the new core plugs and it seems that the large (2") plug, that is meant to go behind the cam is approx 2.5mm too small. The plug measures 51.5mm at its widest (top of the bucket) and the opening for the plug measures 53.7mm.

When I removed the old plug from this location, it was of the dished type. Sadly I threw that away so cant check but the new one in the pack is bucket type. Either way this new plug is too small. Can I get the correct size from somewhere?

Forgot to mention that this particular engine is a midget engine (not that that make any difference)

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Is the "ridge" you refer to proud of the journal surface, or is it really a score, below the journal surface? It would be unusual to have a proud ridge in that position, but quite common to have a score there, usually caused by a particle of grit entering the bearing via the oilway.

A ridge can be taken out fairly successfully, a score less so.

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2597 wrote:
Just checked the new core plugs and it seems that the large (2") plug, that is meant to go behind the cam is approx 2.5mm too small. The plug measures 51.5mm at its widest (top of the bucket) and the opening for the plug measures 53.7mm.

When I removed the old plug from this location, it was of the dished type. Sadly I threw that away so cant check but the new one in the pack is bucket type. Either way this new plug is too small. Can I get the correct size from somewhere?

Forgot to mention that this particular engine is a midget engine (not that that make any difference)


Just had a horrible thought.... Did the 1300 block differ from the 1500 block? You can probably see where i'm going with this question.
Also, the 1500 crank has longer throws. How can you tell difference between a 1500 & 1300 crank. Ie how much longer are the throws etc. Are ther any distinctive maks that are tell-tale signs of the type of crank?



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molten wrote:


Just had a horrible thought.... Did the 1300 block differ from the 1500 block? You can probably see where i'm going with this question.
Also, the 1500 crank has longer throws. How can you tell difference between a 1500 & 1300 crank. Ie how much longer are the throws etc. Are ther any distinctive maks that are tell-tale signs of the type of crank?





My parts book shows the same camshaft core plug for both 1300 and 1500 large journal engines (#148353). I've just measured the 1500 block i have in the shed and the dia of the bucket core plug is 2 1/16" . Interestingly rimmers list that as a 2" core plug :-/

Re differences in crank throws the stroke on the 1300 is 76mm and 87.5mm for the 1500, so if you measure roughly between B/E journals you should be able to figure which you have.

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