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Build the dream 1275
https://ausmini.com/forums/viewtopic.php?f=5&t=1228		 Page 1 of 6
Author:  WhoDat [ Wed Jul 21, 2004 8:02 pm ]
Post subject:  Build the dream 1275
My scrounger/engine builder has accepted the challenge, now I have to give him the "List" of parts/numbers I require him to find to build the dream 1275.

So tell me, assuming a stock 1275 as the base unit, [yet to be aquired], what do I need to add to build up a solid, well performing engine/gearbox/drive train combination? I will be upgrading all 'innards and accessories required to build a well balanced power unit. So matching carbs to exhaust, brakes to power output, etc etc etc will need to be considered.

Engineering facilities and expertise for porting, rebores, etc etc etc is all organised [not me obviously]. This build will be put together over time and replace the 1100 when completed.

Budget needs to remain within reason so the 16v DOHC head beauty from the USA is out. Let's stick with tried and proven A series componentry, but even within that arena there is so much choice...

End result criteria: Fast Road
1 Power output target - round the 100 horses mark [120 would be nice but not at the expence of strength]
2 Top speed - irrelivant, [will not be asked to go over 120 Kph on the highway anyway all the fun is going to be in the twisty bits]
3 Highest priority - accelleration off the line [torque, torque and more torque] I intend dabbling in hill-climbing and motorkhana type events in future. It also helps when I give the ricers the bird. High revving not critical as long as ample power gets to the wheels quickly.
4 Must be strong - all replacement upgrades need to be race proven specs for strength. Not too much racing load is expected, I just want it to be strong enough when asked not to break bits off.
5 Must be nimble, take off like a rabbit, turn on a sixpence [the're smaller than a dime LOL] and be strong as an ox.
6 I have a high preference to retain the 10's for their agillity, turning circle, road holding and power to the ground capabilities.
7 Oh yes, the plan is to supercharge this beast to get some serious grunt happening later.

So give me your shopping list.
Which Head, Cam, Rockers and other squiggly bits in the engine do I need?
Which box, ratios, diff, etc in the gearing department?
Which carbie setup and gas removal system?
Extras I haven't thought of?

All advice gratefully accepted.
Cheers Dat
Author:  dewey [ Wed Jul 21, 2004 11:10 pm ]
Post subject: 
Well I'm very interested to see what comes of this project because I too would like to do up a 1275 myself.... pretty much exactly the same objectives as yourself.

Based on what I've heard when it comes to supercharging, you're better off selecting your pistons and head chamber capacity (is that the correct terminology?) so that your compression is right for the amount of boost. The more boost you wanna push through it the lower the compression should to be (I think).

dewey
Author:  dr trim [ Wed Jul 21, 2004 11:30 pm ]
Post subject: 
dewey wrote:
The more boost you wanna push through it the lower the compression should to be (I think).


u got it in one my black brother :wink:
Author:  WhoDat [ Wed Jul 21, 2004 11:45 pm ]
Post subject: 
Thanks for that fellas

Boost will come down the track a bit. Re-working the head and swapping piston shapes to get the CR down to suit will not be a problem when we reach that stage.

My primary objective right now is to get together what is needed to to put the this power plant together. I have a pretty good idea of what I think I need, but I trust my engineering expertise about as much as my ability to fly using 2 feathers while flapping my arms about.

I've been noting all the great advice coming from ausmini members over the last few months and am building my shopping list but the big question marks I still have are...

What cam would suit this setup?
What carbie setup would best suit?
What gearing should I use?
Author:  drmini in aust [ Thu Jul 22, 2004 7:24 am ]
Post subject: 
If not turbocharging/supercharging it yet I would fit a Graham Russell RE-13 cam and 1.5 rockers, MK2 S inlet valves, unleaded exhaust seats, C-AEA526 valve spring set, Weber 45DCOE or Dellorto 45DHLA, and a Maniflow med bore LCB.
Port the head out and machine it to give 10.0-10.5:1 C/R, and run 98 octane unleaded fuel.

And go get a Pulsar electronic dizzy, or put a Pertronix ignitor into a Lucas one. 8)

<edit> for all round off-freeway performance I'd go with a 3.44 diff. Don't forget to put a comp diff pin in when you build the box... :wink:

<edit 2> If you want a cam that will suit supercharging later, Russell Eng can grind it with a wider LCA (ie less overlap). That is basically what kazjim is using in the 998 turbo.
Author:  WhoDat [ Thu Jul 22, 2004 4:33 pm ]
Post subject: 
Thanks Doc. All added to the list

RE-13 cam - what is the duration and lift on this one?

The Mk2 S inlet valves, would that equate to what I currently have on the list?...
rimflow highflow competition valves 37mm inlet 29mm outlet
[from the specs on a stage 3 1275 from the MiniSport catalogue]

Also single Weber/Dellorto? would you not get better overall gas flow through twins [with smaller dia]

Definately going LCB & EI and 4Pin comp diff.
Author:  drmini in aust [ Thu Jul 22, 2004 4:51 pm ]
Post subject: 
A 45 Weber or Dellorto is a 2 barrel carb, one barrel goes to each port, equivalent to 2x SUs.
But they would want to be bigger than 1-1/2s to flow as well.

Russell Eng RE-13 cam is about 277* duration intake, 286* exhaust, at .020" clearance with 1.5 rockers. Measured on mine when I built it.
Power band is wider than a Kent 286.
And they have a bigger nose radius so they don't wear out quick like my VP3 did... :cry:

I think 37mm intakes are too big for a street motor. Too close to the exhausts... no metal between them. Can't fit unleaded seats....

MK2 S ones are 35.6mm. You can get them in rimflow too. :wink:

I'll have to get back to you on the lift, I think it's around .390" with stock rockers.
Author:  WhoDat [ Thu Jul 22, 2004 5:14 pm ]
Post subject: 
Cheers - your a legend

I hear today that my scrounger has already primed his engineering works contact about this "special" build project coming up. They don't normally do A series, but they do do race builds for a living so your details are just what the Doc ordered [pun intended]

Thanks mate.
Author:  gafmo [ Thu Jul 22, 2004 6:04 pm ]
Post subject: 
As Dewey Mentioned I'm watching this post closley as the ideas are very similar.

Also as a couple may know I'm geeting a Jap 1275 A+ will there much differance.
Author:  Gareth_1330 [ Fri Jul 23, 2004 10:51 pm ]
Post subject: 
Add to the list.... Mini K or cooper S gearbox, remote boxes act as another engine steady, and rod changes have shitty shifts. Mine has a rod change box, because its what i had... I soon found my 1275, being over 100hp, banged against the firewall, snapped exhaust mounts (all of them), i bought a bottom engine steady... waste of money, so i fitted a custom top engine steady, My car being a round nose didn't have a top steady like the clubmans, but mines tougher than that, anyway, the custom steady, and nolathanes on every steady seems to have solved the prolem.... Im sure they put those top steadys on the clubmans to compensate for the lack of support provided by the rod change, they even fitted it to the tourqueless 998, what chance does over 100hp have? ..... :twisted:

Yeah, make sure Graham does your cam, My VP3 had its lobes chopped of too, and Grahams cams are Gold!....

Muflers havn't been mentioned yet either, RC40 is always good, ive got a Genie Turbo on mine, it was Grahams recomendation, need i say more...

And a central oil pick up pipe... dont want to be sucking air when cornering hard do we?
Author:  gafmo [ Fri Jul 23, 2004 11:18 pm ]
Post subject: 
Im guessing the Genie Turbo is not a Turbo Tuf as I have in Garage as I have.

I'm Glad Graham is around the corner from my place. I have also been told his LCB are good also and cheaper than most
Author:  WhoDat [ Sat Jul 24, 2004 12:54 am ]
Post subject: 
Thanks Gareth,

Mini K or Cooper S gearbox added. I take it that these are remote boxes from what you are saying. Any other types of remote boxes that I should be avoiding? and assuming there are other flavoured less desirable remotes out there, how does my scrounger ID the Mini K or Cooper S gearbox amoungst the others? casing numbers perhaps?

Muflers - RC40 - righto.
[I was thinking leaving the pea shooter tailpipe insitu but disconnected, then fiiting a set of side exhausts [just cut back a bit out of sight :lol:] Not sure if that would work under an Van though? would be a kool sleeper strategy if it did but.

Do I get any brownie points for having the central oil pick up pipe on the list already? But thanks for pointing it out. It's a bit like christmas.

'He's checking his list,
then checking it twice..."

Back to business. I have my "project initiation resource scoping meeting" [read - piss up BBQ] with my scrounger tomorrow evening. So if you can think of anything we have left out.....

Thanks to all contributors
Author:  min13k [ Sat Jul 24, 2004 1:09 am ]
Post subject: 
chevy drop pipes :twisted:
makka
Author:  drmini in aust [ Sat Jul 24, 2004 7:21 am ]
Post subject: 
22G1128 is the Mini-K or Cooper S Mk2 gearbox case #. Was also used in early Clubbies.

There's not much difference in the ratios between Mk2 S and the others- on an S the 1st, 2nd, 3rd gears are 1/18th higher geared (ie less gap to 4th).

S diff is 3.44, Mini-K is either 3.765 or 3.647 (both were listed in parts book).

S box used Hardy Spicer inner U/Js, the others had rubber. If you have the latter I'd change it and the driveshaft setup to pot joints these days. :wink:
Author:  WhoDat [ Sat Jul 24, 2004 10:33 am ]
Post subject: 
It's sounding like a Mk2 S engine/gearbox unit is the go for the base unit to look for.

With the workover planned, I suspect that it doesn't need to be in pristine condition when we find it. Anyone got a completely shagged unit in their parts bin you want to get rid of? Oops, that's my scrounger's job. LOL

What do you think is a fair price for a very worn Mk2 S power unit that still has a standard bore?
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