Fast Eddie
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- Joined
- Oct 4, 2013
- Messages
- 21,594
Right then, you know how it is, one things leads to another, right? Yup...
So, my ‘68 Bonnie has damaged crank cases, it has obviously thrown a primary chain or two in its time. There are several weld repairs and whilst they look ok at first glance, the primary is a swine to keep oil tight. The faces will leak past a new gasket with liberally applied Wellseal. A new gaskets with very liberally applied silicone is the only way.
Run it dry I hear you say... I’d love to, as I really want to fit a Newby belt kit, but the oil seal housing has a large chunk broken away, there’s no way to fit a seal, so no way to make it oil tight.
Such damage, and such repairs, have been playing on my mind as to how true the cases may or may not be, could case misalignment be linked to my earlier gearbox failure? And how strong are they after all of this? Stress builds up over time after all.
I was planning a few upgrades anyway (no rush, just ‘as and when’) but wasn’t happy upgrading on these cases. And I’d really like to strip the bottom end anyway. But could I put it back together with suspect cases?
So, I called me ole mates Tony and Martin at TMS and bingo, probably one of the last pairs of new 650 cases were sat on their shelf waiting for me all these years.
Needless to say, those new cases are now sat on MY shelf!
Suddenly, with new cases in the game, the game plan has become clear.
So, the plan is thus:
New cases
Keep the original lightweight crank
Lightweight bushless Carrillo rods from JS
Lightweight billet 750 pistons
Morgo barrels
Hyde half race cams
Kibblewhite 6mm stemmed valves, OS inlets, comical springs
Re fit the new 5 speed box I already fitted
Newby belt drive (dry).
Apart from the rods and belt kit, everything else is already ‘in stock’ here at FESS.
Anyway, my logic is thus:
New cases will be a nice strong base, I’m not looking for a massive performance boost, but I wanna ride it like a Bonnie... a proper Bonnie!
The Carrillo rods and MAP pistons should be no heavier than stock, I think they might turn out lighter.
The current lightweight crank is a peach, it’s smooth and it’s revvy, which makes it a really enjoyable and fun ride. So, provided rod & piston weights are not very different, I don’t intend to get the crank re balanced, there are too many stories of balancers making things worse. Well, at least that’s my thinking at this stage.
Morgo barrels will make it a 750 whilst keeping the ‘long rod’ layout and without having to machine the cases.
I though a lot about keeping the current 3134 cams, I do like them, but Hyde half race cams are actually a 3134 profile but with a bit more lift. So, with it being an extra 100cc’s, I reckon the extra lift will help, but the profile will maintain the current characteristics of the engine.
The Kibblewhite valve gear should help with gas flow and springs that are both kinder on the valve train and give better valve control.
Re fitting the new 5 speed box is a bit of a no brainier!
And then, with the option of a nice dry primary case, I will fit a Newby belt drive, just because I think they’re bloody lovely!
So there you go, this IS NOT a hot rod project (it would be 900cc 8 valve job if it was) it’s more of a ‘hop up’ project aimed at keeping the Bonnie characteristics, plus some.
Don’t hold your breath waiting for updates, this will be a slow burner. But here’s some pics to start things off:
Billet MAP 750cc pistons, lovely looking things, I may round off the sharp edges around the valve pockets (ala Stan Shenton) but I think that’s all. They are slightly over size for the Morgo barrels, which is good, as I can get them finished to my requirements.
The underneath is nearly as nice as the top. Lovely:
The Hyde cams fit lovely in the new cases and turn nicely, almost like new! Morgo barrels just dropped on for the pic:
And that’s all for now sadly. Will update as and when small steps are made.
So, my ‘68 Bonnie has damaged crank cases, it has obviously thrown a primary chain or two in its time. There are several weld repairs and whilst they look ok at first glance, the primary is a swine to keep oil tight. The faces will leak past a new gasket with liberally applied Wellseal. A new gaskets with very liberally applied silicone is the only way.
Run it dry I hear you say... I’d love to, as I really want to fit a Newby belt kit, but the oil seal housing has a large chunk broken away, there’s no way to fit a seal, so no way to make it oil tight.
Such damage, and such repairs, have been playing on my mind as to how true the cases may or may not be, could case misalignment be linked to my earlier gearbox failure? And how strong are they after all of this? Stress builds up over time after all.
I was planning a few upgrades anyway (no rush, just ‘as and when’) but wasn’t happy upgrading on these cases. And I’d really like to strip the bottom end anyway. But could I put it back together with suspect cases?
So, I called me ole mates Tony and Martin at TMS and bingo, probably one of the last pairs of new 650 cases were sat on their shelf waiting for me all these years.
Needless to say, those new cases are now sat on MY shelf!
Suddenly, with new cases in the game, the game plan has become clear.
So, the plan is thus:
New cases
Keep the original lightweight crank
Lightweight bushless Carrillo rods from JS
Lightweight billet 750 pistons
Morgo barrels
Hyde half race cams
Kibblewhite 6mm stemmed valves, OS inlets, comical springs
Re fit the new 5 speed box I already fitted
Newby belt drive (dry).
Apart from the rods and belt kit, everything else is already ‘in stock’ here at FESS.
Anyway, my logic is thus:
New cases will be a nice strong base, I’m not looking for a massive performance boost, but I wanna ride it like a Bonnie... a proper Bonnie!
The Carrillo rods and MAP pistons should be no heavier than stock, I think they might turn out lighter.
The current lightweight crank is a peach, it’s smooth and it’s revvy, which makes it a really enjoyable and fun ride. So, provided rod & piston weights are not very different, I don’t intend to get the crank re balanced, there are too many stories of balancers making things worse. Well, at least that’s my thinking at this stage.
Morgo barrels will make it a 750 whilst keeping the ‘long rod’ layout and without having to machine the cases.
I though a lot about keeping the current 3134 cams, I do like them, but Hyde half race cams are actually a 3134 profile but with a bit more lift. So, with it being an extra 100cc’s, I reckon the extra lift will help, but the profile will maintain the current characteristics of the engine.
The Kibblewhite valve gear should help with gas flow and springs that are both kinder on the valve train and give better valve control.
Re fitting the new 5 speed box is a bit of a no brainier!
And then, with the option of a nice dry primary case, I will fit a Newby belt drive, just because I think they’re bloody lovely!
So there you go, this IS NOT a hot rod project (it would be 900cc 8 valve job if it was) it’s more of a ‘hop up’ project aimed at keeping the Bonnie characteristics, plus some.
Don’t hold your breath waiting for updates, this will be a slow burner. But here’s some pics to start things off:
Billet MAP 750cc pistons, lovely looking things, I may round off the sharp edges around the valve pockets (ala Stan Shenton) but I think that’s all. They are slightly over size for the Morgo barrels, which is good, as I can get them finished to my requirements.
The underneath is nearly as nice as the top. Lovely:
The Hyde cams fit lovely in the new cases and turn nicely, almost like new! Morgo barrels just dropped on for the pic:
And that’s all for now sadly. Will update as and when small steps are made.
