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A little help with 1275 Build ideas please
https://www.ausmini.com/forums/viewtopic.php?f=5&t=65466		 Page 1 of 2
Author:  NAV [ Sat Sep 04, 2010 7:54 pm ]
Post subject:  A little help with 1275 Build ideas please
Hey guys, I've just sourced a 1275 (12ydtah) motor from an 1100s with 12g938 head.
I'm after a solid engine that will keep me happy for some time. So what would the best mods to go for? I'm chasing torques more than hp.
Author:  Lillee [ Sat Sep 04, 2010 8:04 pm ]
Post subject: 
What's your budget?
Author:  NAV [ Sat Sep 04, 2010 8:06 pm ]
Post subject: 
Lillee wrote:
What's your budget?

about $3k not including porting the head as thats being taken care of by a mate that owes me.
Author:  mickmini [ Sat Sep 04, 2010 10:09 pm ]
Post subject: 
If it is a late motor with the large journal crank, you cannot get more torque than by stroking it and using Cooper S rods, a good camshaft (I hear the new RE266 is very good, RE13 is also very good for torque, but if you want a RE cam give Graham a call). match up to a long manifold and a HIF44. Don't let your mate go too large on the inlet ports, better to have high gas speed from a smaller port at lower revs for torque.

All my opinion, not based on facts other than the 113ftlb of torque from my stroker.....
Author:  drmini in aust [ Sat Sep 04, 2010 10:41 pm ]
Post subject: 
On a 12G938 head (1100S) it's worth fitting Mk2 S inlet valves, then porting to suit. I followed instructions in Vizard's yellow book.
My 1412 stroker then made 112lb/ft torque with an RE13 cam, Toyota Corolla rockers and a single HS6 SU.
Max HP (at crank) was 114 @6500 rpm.
Author:  gafmo [ Sat Sep 04, 2010 11:46 pm ]
Post subject: 
Balance crank, flywheel, clutch, back, plate & rods. Straighten Rods. Crack test Crank and Head. Match the Inlet manifold ports to head.
Good Gear box & Diff
Other wise as per above
Author:  NAV [ Sun Sep 05, 2010 10:02 am ]
Post subject: 
I must note that my mate that owes me is getting the head done by a well known a series engine builder. He trusts him with all his engine work and had an 1100 that kept a healthy ron williams built cooper s honest until 100 km/h. So I trust his work.
The engine itself is 12ydtah9896 so what would that make it? going off the elevenhundred.com website it's around 67/68
So if aiming for torque would I be asking for good airspeed rather than big ports?
Cooper S inlet valves was what I was already thinking of.
What sort of carby, intake/exhaust manifolds should I run? Sizes etc as I'm open on those. I prefer a single carby for simplicity but if for a few hundred more i can get alot more torque from twins or webber/dellorto then I'll follow that road.
I'm unsure of which cam, Was already thinking RE13, but if the RE266 produces a bit more torque then thats what I would go for. It's not going to be an every car, but it does need to behave in traffic though.
Doc I was going to ask you about some toyomini rockers as they are about 1.3:1 arent they?
What sort of compression ratio should I aim for? It will only ever be run on 98 octane regardless anyway.
The gearbox is going to be fully rebuilt as well. I am getting the original gearbox with that engine as well, would it be 3 or 4 synchro? Its a remote change gearbox and I was planning on using that.
Author:  simon k [ Mon Sep 06, 2010 1:24 pm ]
Post subject: 
NAV wrote:
I am getting the original gearbox with that engine as well, would it be 3 or 4 synchro? Its a remote change gearbox and I was planning on using that.


if it's the Morris 1100 gearbox, then forget it - it's 3 syncro, and the remote mounts to the diff housing differently, you could change the diff housing, but you'd still have a snotty old 3 syndro box with a dumb diff ratio
Author:  drmini in aust [ Mon Sep 06, 2010 1:57 pm ]
Post subject: 
That engine number was an 1100S with small journal crank and S rods. Good reliable combination but you can't stroke this crank.
The engine change number to big journal crank was around 10500.

Toyota Corolla rockers are 1.46:1 not 1.3.
However it's hardly worth me making them now, by the time I find & buy from a wrecker and spent 10+ hours on em to convert, you can get 1.5 roller tips from UK cheaper.
Much the same story with my pressed steel rockers offset bushed (.044") to 1.3 conversion.

I'm running a C/R of 10.7:1 with an RE13 cam- no it doesn't ping, and it goes bloody hard from 2300-6500+.
Author:  NAV [ Mon Sep 06, 2010 5:57 pm ]
Post subject: 
simon k wrote:
NAV wrote:
if it's the Morris 1100 gearbox, then forget it - it's 3 syncro, and the remote mounts to the diff housing differently, you could change the diff housing, but you'd still have a snotty old 3 syndro box with a dumb diff ratio


Ok, back to rebuilding my spare rod change 4 syncro box then. I was planning on a gearbox build anyways.

drmini in aust wrote:
That engine number was an 1100S with small journal crank and S rods. Good reliable combination but you can't stroke this crank.
The engine change number to big journal crank was around 10500.

Toyota Corolla rockers are 1.46:1 not 1.3.
However it's hardly worth me making them now, by the time I find & buy from a wrecker and spent 10+ hours on em to convert, you can get 1.5 roller tips from UK cheaper.
Much the same story with my pressed steel rockers offset bushed (.044") to 1.3 conversion.

I'm running a C/R of 10.7:1 with an RE13 cam- no it doesn't ping, and it goes bloody hard from 2300-6500+.


Thanks doc, I wasn't thinking of stroking anyway. But it's good to know what I have now.
Would you suggest going with the RE13 over the RE266 given the option yourself?
Should I go 1.5 or 1.3 rockers with either of those cams?
Any advantage to a single hif44 v's say twins or dellorto/webber?
Author:  drmini in aust [ Mon Sep 06, 2010 7:18 pm ]
Post subject: 
NAV wrote:
simon k wrote:
NAV wrote:

drmini in aust wrote:
That engine number was an 1100S with small journal crank and S rods. Good reliable combination but you can't stroke this crank.
The engine change number to big journal crank was around 10500.

Toyota Corolla rockers are 1.46:1 not 1.3.
However it's hardly worth me making them now, by the time I find & buy from a wrecker and spent 10+ hours on em to convert, you can get 1.5 roller tips from UK cheaper.
Much the same story with my pressed steel rockers offset bushed (.044") to 1.3 conversion.

I'm running a C/R of 10.7:1 with an RE13 cam- no it doesn't ping, and it goes bloody hard from 2300-6500+.


Thanks doc, I wasn't thinking of stroking anyway. But it's good to know what I have now.
Would you suggest going with the RE13 over the RE266 given the option yourself?
Should I go 1.5 or 1.3 rockers with either of those cams?
Any advantage to a single hif44 v's say twins or dellorto/webber?

266 cam is pretty tame but good if you want low down torque.
RE13 works great in a 1275 with either 1.3 or 1.5 rockers, power band good to 7000 or more.
Graham has a new cam now, RE83?, it gives maximum grunt all the way to 6000 but then falls off. Simon K and others are running it.

re the rockers 1.3s are best for most people for road use however I like my engines to have a bit more top end so I still use 1.5s.
Single HIF44 on a good manifold works well, so do twins (preferable HS4s). Twins do need a bit more TLC. Having said that, I run a Dellorto 45 because I can jet it then forget it. But a single HS6 or HIF44 SU on a good manifold does give more midrange torque.
Author:  Lockie91 [ Thu Sep 23, 2010 7:15 pm ]
Post subject: 
NAV wrote:
simon k wrote:
NAV wrote:
if it's the Morris 1100 gearbox, then forget it - it's 3 syncro, and the remote mounts to the diff housing differently, you could change the diff housing, but you'd still have a snotty old 3 syndro box with a dumb diff ratio


Ok, back to rebuilding my spare rod change 4 syncro box then. I was planning on a gearbox build anyways.

drmini in aust wrote:
That engine number was an 1100S with small journal crank and S rods. Good reliable combination but you can't stroke this crank.
The engine change number to big journal crank was around 10500.

Toyota Corolla rockers are 1.46:1 not 1.3.
However it's hardly worth me making them now, by the time I find & buy from a wrecker and spent 10+ hours on em to convert, you can get 1.5 roller tips from UK cheaper.
Much the same story with my pressed steel rockers offset bushed (.044") to 1.3 conversion.

I'm running a C/R of 10.7:1 with an RE13 cam- no it doesn't ping, and it goes bloody hard from 2300-6500+.


Thanks doc, I wasn't thinking of stroking anyway. But it's good to know what I have now.
Would you suggest going with the RE13 over the RE266 given the option yourself?
Should I go 1.5 or 1.3 rockers with either of those cams?
Any advantage to a single hif44 v's say twins or dellorto/webber?


yep, the webber i put on little red last year, sucked through a 20litre tank in half the time, but the enhanced power range from the 1.5 SU was awesome.. even my 1100 loved the webber better, but my pocket didn't.. hate to think how much this 1380 big bore is going to suck with the big lumpy cam, enlarged manifold, head, and even bigger dellorto than that webber... :lol:
Author:  1310/71 [ Thu Sep 23, 2010 8:09 pm ]
Post subject: 
drmini in aust wrote:
I run a Dellorto 45 because I can jet it then forget it.


But you never do. You're incessantly fiddling with the jets! 8)
Author:  drmini in aust [ Fri Sep 24, 2010 10:20 pm ]
Post subject: 
1310/71 wrote:
drmini in aust wrote:
I run a Dellorto 45 because I can jet it then forget it.


But you never do. You're incessantly fiddling with the jets! 8)

Nope, I'm not Lillee, it's all sorted. 36mm chokes, 180 air correctors, 160 mains. All good...:mrgreen:
Author:  Lockie91 [ Fri Sep 24, 2010 11:08 pm ]
Post subject: 
drmini in aust wrote:
1310/71 wrote:
drmini in aust wrote:
I run a Dellorto 45 because I can jet it then forget it.


But you never do. You're incessantly fiddling with the jets! 8)

Nope, I'm not Lillee, it's all sorted. 36mm chokes, 180 air correctors, 160 mains. All good...:mrgreen:


and me 2 thanks to doc :) :wink: we almost have the same everything haha
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