Discussion
If you anticipate regularly re-building your engine, as in, say, a race or rally application, then a vernier sprocket set is a good idea. If it's for a road engine, then just get a set of woodruff offset keys, say a 2 deg, 4 deg, 6 deg and 8 deg, so that you have a choice when doing the timing accurately.
It's a good idea to time to 2 degrees advanced from nominal to allow for initial chain stretch.
If you intend using over about 5500 rpm, then it's best not to fit a tensioner as the tensioner pad can break up at repeated high revs.
It's a good idea to time to 2 degrees advanced from nominal to allow for initial chain stretch.
If you intend using over about 5500 rpm, then it's best not to fit a tensioner as the tensioner pad can break up at repeated high revs.
thanks, just priced up a set of offset keys, they're about 7 pounds each. so a set of them aswell as standard gear is only about 20 quid cheaper than the vernier kit. do you think it is worth buying the adjustable set and save fiddling around? also if there isnt a chain tensioner how is it set and kept tensioned?
thanks in advance
thanks in advance
Nice to see real knowledge being displayed by Cooperman. Good post.
7500 is a lot of revs for an A series engine. Hope its balanced!!
Its worth remembering this engine was created in 1948 not long before I was born. Like me it has aged (probably better than me) and techniques that apply to modern twin cam crossflow hemi head engines achieve wondrous outputs which would leave the A series gasping whatever you do to it.
Still my favourite engine the 1275 being the best with the 12G940 head for everyday use and some esoteric bits and 1340cc with A40 pistons (or modern equivalents) for pure power.
Duplex chains were so much of an improvement in the 1960's that I think BMC simply did not bother with a tensioner. Remember this engine started as a low compression side valve. Tensioners on the chain were totally unnecessary.
The improvements that BMC made over 40 years included a couple of overhead cam engines based on the A series block. I rather think Harry Weslake was the brains behind this. But as in all thing at BMC it eventually came to nought.
Good luck on your rebuild.
Great to see this engine still attracts enthusiasts
7500 is a lot of revs for an A series engine. Hope its balanced!!
Its worth remembering this engine was created in 1948 not long before I was born. Like me it has aged (probably better than me) and techniques that apply to modern twin cam crossflow hemi head engines achieve wondrous outputs which would leave the A series gasping whatever you do to it.
Still my favourite engine the 1275 being the best with the 12G940 head for everyday use and some esoteric bits and 1340cc with A40 pistons (or modern equivalents) for pure power.
Duplex chains were so much of an improvement in the 1960's that I think BMC simply did not bother with a tensioner. Remember this engine started as a low compression side valve. Tensioners on the chain were totally unnecessary.
The improvements that BMC made over 40 years included a couple of overhead cam engines based on the A series block. I rather think Harry Weslake was the brains behind this. But as in all thing at BMC it eventually came to nought.
Good luck on your rebuild.
Great to see this engine still attracts enthusiasts
IMO you could theoretically change the cam without lifting the engine out, or more probably dropping the subframe and engine. But it would be bloody tight and I would not recommend this.
Given the really tight working area in a mini unless you are Harry Houdini I think engine out is a simpler better more practical proposition for the majority of serious engine mods.
It is certainly my recommendation.
Subframe out means you can prop the subframe with the engine still in, using the subframe as a working frame without needing an engine stand which garages would use. Saves costs gives a good working height for actual work on the engine.
Mini's are easily the best small car ever made, certainly the most loved.
But they are NOT easy in terms of access to most operations.
Quart in a pint pot!
Given the really tight working area in a mini unless you are Harry Houdini I think engine out is a simpler better more practical proposition for the majority of serious engine mods.
It is certainly my recommendation.
Subframe out means you can prop the subframe with the engine still in, using the subframe as a working frame without needing an engine stand which garages would use. Saves costs gives a good working height for actual work on the engine.
Mini's are easily the best small car ever made, certainly the most loved.
But they are NOT easy in terms of access to most operations.
Quart in a pint pot!
i agree ,
us teenagers need the valuable knowledge of these guys. and its much appreciated.
it has been suggested that you could bore a hole thro the inner wing to remove the cam........but i dont know how feasible that is as io only read it on here.
cooperman has most of the info you need. he's been a good help to me and my dad.
us teenagers need the valuable knowledge of these guys. and its much appreciated.
it has been suggested that you could bore a hole thro the inner wing to remove the cam........but i dont know how feasible that is as io only read it on here.
cooperman has most of the info you need. he's been a good help to me and my dad.
You can take the cam out of an 850, 997, 998, 1098 or any genuine Cooper 'S' (1071, 970 or 1275) without removing the engine as there are cam chest covers on the back of the block through which the cam followers can be taken out. The cam can then be withdrawn through a 2.5" hole which you cut in the inner LH wing.
On the non-'S' 1275, the back of the block is solid, so the cam followers can't be accessed.
Anyway, with a new cam you do need new followers, so it's an excuse to check the engine over to make sure it is OK for all that lovely power you'll be getting with the new cam, etc.
On the non-'S' 1275, the back of the block is solid, so the cam followers can't be accessed.
Anyway, with a new cam you do need new followers, so it's an excuse to check the engine over to make sure it is OK for all that lovely power you'll be getting with the new cam, etc.
Good advice from Cooperman.
These are old engines and I would check everything thoroughly and completely before using this kind of power from an A series.
The A series is a very strong engine but old technology and 7500 revs is high for an A series. I can be done one of my 1340 engines is so cammed up it revs to 8000 revs if you let it.
But not for long.
I have seen few con rods break in the A series but it does happen and usually smashes the engine block and gearbox. Very expensive.
Check it all while you can.
These are old engines and I would check everything thoroughly and completely before using this kind of power from an A series.
The A series is a very strong engine but old technology and 7500 revs is high for an A series. I can be done one of my 1340 engines is so cammed up it revs to 8000 revs if you let it.
But not for long.
I have seen few con rods break in the A series but it does happen and usually smashes the engine block and gearbox. Very expensive.
Check it all while you can.
I do rev my rally Cooper 'S' top over 7000 rpm, but it has a fully balanced, stroked 7 indexed crank made from EN40B forged steel, the rods are lightened and balanced.
However, it is always in mind that if a rod breaks of the crank snaps, all the bits will go down into the straight-cut competition gearbox and the cost will be huge, probably over £4500 to replace fully. A sobering thought!
However, it is always in mind that if a rod breaks of the crank snaps, all the bits will go down into the straight-cut competition gearbox and the cost will be huge, probably over £4500 to replace fully. A sobering thought!
Steffan said:
Subframe out means you can prop the subframe with the engine still in, using the subframe as a working frame without needing an engine stand which garages would use. Saves costs gives a good working height for actual work on the engine.
This sounds like a winter project... I didnt find any info on removing the subframe with engine one, how do you do it.... Sounds like a good idea to have the engine attached to the frame and use it as an engine stand... can use the extra money to buy some more bits for the engine instead...Gassing Station | Classic Minis | Top of Page | What's New | My Stuff