50 replies to this topic

[dklawson]

To the untrained eye the Mk1 servo may look like the Mk3 but they are very different to those of us with Mk1/2s. The vacuum chamber on a Mk3 servo is much bigger, the air valve is plastic, and they are typically positioned a little different. Anyone familiar with a Mk1/2 would know the Mk3 part was not correct. Mini Spares sells an aluminum bodied copy of the Mk1 servo. Painted, it can look correct and it has the correct sized vacuum chamber. However, being an aluminum casting it has a much higher quality appearance than the original cast iron servo. It's another telltale sign that the part isn't original, but it's more original than the Mk3 part.

There are early and late 12G940 castings. To look correct, you want an early 12G940 that has the top surface "smooth". Later 12G940s have material removed from the top surface of the head just behind the thermostat housing area. The AEG163 casting used on Mk1 -S cars was smooth across the top. Don't bother asking about the small valve 12G940 heads. You don't want them on an -S engine and you certainly don't want the small valves on a bored out 1275.

Which rockers you use (1.3 or 1.5) isn't completely dependant on the cam you use. Most can benefit from the higher lift of the 1.5 arms. Use the search feature here for old threads about this. There have been several discussions about the benefits of the longer arms vs. cam wear. What you do have to be particularly careful about is using the 1.5 arms with a high-lift cam. It's very easy to create the situation where your valve springs are compressed to be completely "solid" (coil-on-coil) by using long arms and high-lift. That's a bad thing.

If you have not yet located a copy of Parnell's book on the Cooper and Cooper-S, you need one for this project. It has lots of pictures detailing each Cooper and -S variant.

[dgear1984]

i have a copy of that book it is very good along with the vizards book which is also very good. i have a few others and they are ok for picture refernces only really.

I origionally wanted to make a proper replica s but that was going to cost a fortune and possible more than a proper s.

so i have kinda decided to build up my mk1 with 7.5 discs spacered drums, 4.5j vented wheels, right hand tank, boot board, 130 speedo, newton trim, oil cooler etc to make it look the part. I was thinking maybe a 1380 engine so the perfromance will be simular to a 1275 67 s. well thats my plan anyway it might take many years to build tho.

As you say the servo is differnt but i think with some paint it could look not out of place in my car. could you also paint the plastic valve to descise it? i have seen frost sell a paint that is like the old gold plating used on servos.

peoples opinion of my hopeful project.

[mk1leg]

speak to Mini Mail they might have new old stock of mk1 servo's I purchased one some years ago, if not auto jumbles such as large mini shows or the big Beaulieu auto jumble in September...........

[dklawson]

LOT977F has started mentioning budget. Don't take this wrong but if money is starting to become an issue, I would not be looking for NOS Mk1 servos, they will probably extremely expensive. Also, having an original Mk1 servo rebuilt will likely cost more than the Mini Spares reproduction. At one time I thought I was going to rebuild my Mk1 servo and it took six months just to get the rebuild kit (which was about 50 GPB at the time). When I got deep into the parts I found several severely pitted components and I gave up on the idea. Used servos at jumbles aren't likely to be better.

Regarding painting the air valve on the servo... why bother. The Mk3 servo looks so different from the Mk1/2 that painting the air valve isn't going to make a difference.

I think you'll find that a rebuilt 1275 with a good cylinder head and properly set up carbs will perform well. To keep your budget under control consider minor improvements that have to be done while the engine is out. Consider how you plan to use the car and decide on a suitable cam. If you can afford a big-valve 12G940 for the rebuild, perhaps one that's been ported, invest in that now. If you want 1.5 ratio rocker arms... put that off until later. They're expensive and can be added with the engine in the car when you're ready. If you no longer care about making this an -S clone, stick with a single carb on a good intake manifold. However, this would be the best time to invest in a decent exhaust system. Set your engine up so it can breathe well now and invest in other go-fast parts when and if you see the need and have the money.

EDIT: Picture links.
Mk1/2 Servo Clone @ Mini Spares (157 GBP with VAT): www.minispares.com/images/products/200/21A1293.jpg or http://www.7ent.com/...es2/21A1293.JPG
Mk3 Servo Clone @ Mini Spares (126 GBP with VAT): www.minispares.com/images/products/200/13H7939.jpg
Lousy angle and size on second picture. See the servo in the complete kit for more detail (142 GBP): www.minispares.com/images/products/200/SEN43.jpg or
www.7ent.com/images2/13H7939K.jpg

You can see that the Mk1/2 and Mk3 servos are VERY different looking.

EDIT #2. The darn Mini Spares links won't load. When you get the "file not found" message, strip the HTTP:// stuff off the front of the address and hit enter again. The picture should load.

Edited by dklawson, 24 October 2007 - 03:31 AM.

[dgear1984]

what decides if an engine is positive ventilation or not??

[dklawson]

what decides if an engine is positive ventilation or not??

Sorry, I don't understand the question.

[alexcrosse]

u mean earth? there all negative.

1275 s's would give out about 70bhp when actually tested, rather than the 76 they promised. With a 1380 you would be getting nearer 100bhp and 100lbft of torque.

Alot of people restoring 1275 s's seem to go for 1293 s's. I would try n keep it the same as possible, 1293 so you have a nice fresh block, try and get hold of cooper s rods and a crank. Same head, or another casting machined to the same valve sizes as the cooper s and the same cr. Twin SU's ofcourse, and thatll do you dandy. Probably get about 80-85+ out of it too (bhp) with a mild mild setup.

Hope that helped.

Alex

[dklawson]

Not all real -S cars were negative ground. As built, mine wasn't.

I was wondering if he was asking about crankcase ventilation. There were many different schemes used for this. Some had vented oil filler caps and multiple breathers plumbed into the Smiths PCV valve. Early, early cars sometimes did nothing more than run a vent tube down the back of the block.

Lot997F has already dropped several aspects of his conversion to hold down costs (see his post earlier on this page). An honest-to-God -S replica engine with an -S crank, and -S rods will be prohibitively expensive. Boring out the block to fit oversized pistons can bring the horsepower up, but without improved breathing and a different cam I wouldn't count on that 100 BHP figure.

Lot997F... what are you asking?

[dgear1984]

Not all real -S cars were negative ground. As built, mine wasn't.

I was wondering if he was asking about crankcase ventilation. There were many different schemes used for this. Some had vented oil filler caps and multiple breathers plumbed into the Smiths PCV valve. Early, early cars sometimes did nothing more than run a vent tube down the back of the block.

Lot997F has already dropped several aspects of his conversion to hold down costs (see his post earlier on this page). An honest-to-God -S replica engine with an -S crank, and -S rods will be prohibitively expensive. Boring out the block to fit oversized pistons can bring the horsepower up, but without improved breathing and a different cam I wouldn't count on that 100 BHP figure.

Lot997F... what are you asking?

I was refering to crankcase ventilation. I noticed some mention positive and thought therefore some must be negative ventilation.

My old 67 car is positive earthed. Aparently this way round help them rot and thats why we changed to negative earth.

I understand this project will cost alot in the long run but i think there is ways of saving money. looking out for bargains and a bit of hard graft can save money.

Anything engine wise with s on it means big money. thats why i thought of a A+ 1275 or 1380 etc to get simular performance but less money. after all its only a replica not a clone.

thanks

[mk1leg]

Positive crankventilation is a fairly large round ally blanked off trumpet shaped unit wich sit between twin carbs this was only a feature on export mods, only a few made it ot uk market.........will put up pic soon........

[dklawson]

I think your idea of starting with a 1275 A+ makes perfect sense from a budget standpoint. I repeat my earlier suggestion about choosing a cam now and installing it when you recondition the engine prior to installing it in the car. Other items can be added later as your budget and interest allow. Putting the cam in later will mean pulling the engine again.

Just to be clear, positive crankcase ventilation just means that you have an "active" system to deal with blow-by and oil fumes in the block. It does NOT mean that there is positive pressure inside... far from it. Both Mk1leg and I are referring to the same component, the Smiths PCV valve that would be present on an early car. There aren't many picture of it on the web but look at these two links.

http://spriteparts.c...s/PCV valve.jpg
This is a Smiths PCV valve by itself. Inside is a plunger, a rubber diaphragm, and a spring. When the manifold pressure is "right" the valve will open allowing manifold vacuum to draw in oil fumes from the crankcase. The part shown in the picture is oriented "correctly", the stem it's resting on connects to the intake manifold using a large barbed fitting. The horizontal tube on the valve is a connection point for a hose. Typically on an -S engine this hose runs between a canister breather attached to a tappet chest cover and the horizontal tube on the PCV valve. On later cars the that tappet chest breather was moved to the timing chain cover.

The link below is a DIY install of the PCV valve on a Triumph. The valve is shown correctly plumbed into the intake manifold. However, the author of this web page has improvised his connection to the crankcase. He's modified an electrical conduit box to be his breather canister and filled it with a stove hood filter and coarse screen. He's attached that to the vent nipple on the rocker cover. I've seen similar connections made on early Midgets but never on a Mini. Obviously the improvised parts don't look right. by the way, if you're cleaning and reconditioning a breather canister, they are filled with a coarse metal wool. Over here, a couple of my friends who service old British cars remove the original gauze wool and replace it with a very coarse metal scrubbing pad typically used to clean cooking grills. It works well and is stiff enough to not get sucked into the breather's port.
http://www.teglerize..._67t_filter.htm

[mk1leg]

pic as promised

Attached Files

•  mini_pcv.JPG   222.52K   10 downloads

Edited by mk1leg, 31 October 2007 - 12:50 AM.

[Guess-Works.com]

Personally, if you're looking for anything which is near the right era, the last thing you want to be doing from a looks point of view is dropping an A+ lump in there...

Find an A series 1300GT engine from an Austin (ADO16) then atleast it'll look more like a cooper block than a metro engine.. also the performance of the 1300GT is not dissimilar to the mk3 cooper S

[dklawson]

You're right, the A+ won't quite look the part. However, if you go for the 1300 engine from an AA (ADO16) it will have a funky front plate that should probably be remove/replaced. I think most had the yoke or Hardy-Spicer driveshafts also. Not insurmountable issues but more things to think about. Then there are some reliability questions. When you build this replica do you want it to be more reliable or more accurate in appearance? For example, see my pic below where you can see I've replaced my generator with an alternator.

Incidentally, in the picture link below you can see the Mini Spares Mk1 brake servo re-painted and installed in my car. I also have the round push-button solenoid. Oh... it's correct... but they have proven to be the least reliable part I've installed. The later square solenoid (which is now on my engine) is a much more reliable part.

http://home.mindspri...ompartment1.jpg

[dgear1984]

ok right abit of background. I have always like minis from as far as i can remember. I wanted a mini as my first car but dad said no they are unreliable, unsafe and rusty. I bought a bmw mini cooper a few years after my test as i liked them and it was fairly nippy. Now i have got a mk1 which i want as my "toy". I have always like motorsport and hence i like the s cars. I cannot afford and s although i would have liked one. So.. I would like my mk1 to look the part from the skin, two tone paint, vented s wheels, 7.5 dics, twin tank, boot board, newton interior etc.

Now under the skin i would like it to also be the part. As i know an s engine is rocking horse s*** i have been looking at other options. I would like the car reliable as a classic but still have the go of an old s. Im not after huge power if i was i wouldnt be doing a mini just enough to replicate a 1275 s engine. I have also got a remote clubman box (i believe) and i have just to the remote gear change from ebay (long alu one). I will be using a servo but new/ 2nd hand s are expensive so i thought a later one would do the job for example.

I didnt know much about a 1300gt? what plate are you on about.

Is 1300 gt the way to go????

Your help is always appriciated