34 replies to this topic

[postve]

Hello folks,

 

Again I am new to my 1978 classic mini with 1275 A MG Midget engine - love it - but thinking I want a bit more torque in the mid range - 1500 - 6500 - not too concerned about the top end.  Be interested in thoughts as I have heard a lot and like this forum as most of my answers have come from here.

 

So, based on what I painstaking gathered about my mini below - interested in thoughts and will reply to any further questions.  I am reading D.Vizard's mini bible and getting a lot of good solid ideas but, want to know what guys/gals have done themselves.

 

Here are the specs and welcome any and all feedback - thx so much in advance for those that have the time to deal with a newbie..

 

Engine Specs Description Specs 1275CC - MG Midget engine Carb - Type (Dual) HS2   Carb - Bowl 1.25   Carb AUC-1341/AUC-1342   Carb - Dampers AUC-1803   Carb - Float Chamber AUC - 2277   Exhaust Manifold LCB   Intake Manifold 12A309 MOWOG   Exhaust   RC-40 - single box   Cylinder Head 12G1316 - X (Smog)   CAM 731 C-AEG-800   Compression Ratio  - standard??   Gear Ratio 4.133   Slave Cylinder Pre-Verto   Distributor Petronix Electronic (New)   Ignition Coil Petronix Ignitor (New)   Alternator 70 AMP - Lucas (New)   Tyres Yokohama 165/70-10 (new)

 

 

 

 

[nicklouse]

well first i dont think it will be an inline block.

 

what is the cam? as that is what determines the power characteristics.

 

and i would bin the twins and fit a HIF44 on a good inlet manifold.

 

i would check your final drive as well. a 3.44 would be nice.

[postve]

Hey Nick

Last owner advised it is a 731 grind for the CAM and the HIF44 would that plug directly into the inlet manifold I have which I see 12A309 and forgive my ignorance if I am off the mark here. Assume 1.5 for the HIF44

As for gears ratio, well I did a basic left up one tire, pull the plugs, mark the shaft at the rad and see how many times to turn the wheel twice - got 4.133 but thinking that may not be accurate - any other suggestions

[mini13]

First thing I would do is loose the 731, if I were looking for torque I'd be looking at one of AC Dodds profiles, and a good head on std valve sizes.

[Magneto]

all the power and torque in this engine is in the head, a good head and cam combination as mentioned above will do what you're after. I built one recently that made 80 hp and 80 torques at the wheels, I've tuned it a bit since then and I'm sure it's even more now. All the power was in the mid range, right where you want it. I used one of Calver's heads, 1:14 rockers, 10.3:1 compression pistons and the SW5 cam. Worked a treat. Of course you also need a good properly sized exhaust along with the intake and carb. HIF44 is 1 3/4" carb. 

 

Of course, you could also turbocharge it.

Edited by Magneto, 05 January 2019 - 01:41 AM.

[postve]

First thing I would do is loose the 731, if I were looking for torque I'd be looking at one of AC Dodds profiles, and a good head on std valve sizes.

Interesting as I read in the mini-book that 731 is not a great option for torque and have been contemplating; the SW5-07

[postve]

all the power and torque in this engine is in the head, a good head and cam combination as mentioned above will do what you're after. I built one recently that made 80 hp and 80 torques at the wheels, I've tuned it a bit since then and I'm sure it's even more now. All the power was in the mid range, right where you want it. I used one of Calver's heads, 1:14 rockers, 10.3:1 compression pistons and the SW5 cam. Worked a treat. Of course you also need a good properly sized exhaust along with the intake and carb. HIF44 is 1 3/4" carb.

Of course, you could also turbocharge it.

Not too interested in turbo but can I ask what costs where associated with your build. Rough estimate

Thx

[Chris.Williams]

First thing I would do is loose the 731, if I were looking for torque I'd be looking at one of AC Dodds profiles, and a good head on std valve sizes.

Interesting as I read in the mini-book that 731 is not a great option for torque and have been contemplating; the SW5-07

I had an sw5-07 in a road car, very very torque oriented cam.
I also believe the ac Dodd range of cams are very nice.

[postve]

<blockquote class='ipsBlockquote'data-author="Chris.Williams" data-cid="3576327" data-time="1546662975"><p><p>Thx Chris as I have been leaning towards the SE5-07 - can I ask what size engine, carb, intake and exhaust?

[Chris.Williams]

<blockquote class='ipsBlockquote'data-author="Chris.Williams" data-cid="3576327" data-time="1546662975"><p><p>Thx Chris as I have been leaning towards the SE5-07 - can I ask what size engine, carb, intake and exhaust?

It’s was a 1098 +40, twin 1 1/4 su carbs, rc40 systemJust a wonderful road engine, had 3.444 final drive.

[postve]

<blockquote class='ipsBlockquote'data-author="Chris.Williams" data-cid="3576332" data-time="1546666184"><p><p>Ok I think that about sums it up so I think I will take my 1275 and do the following this spring;- remove731 and replace with Sw05-07- remove twins 1.25 and go with single HIFF-44- add 1.5 roller rockers- 3.44 gearsI think this should do it and welcome any more comments

[Ethel]

Engine from one of these?

 

It should go like stink in a Mini, mostly down to the final drive. A 3.44 would be a good choice, but it'd have the opposite effect to trying to up the low to mid torque.

 

The cylinder head would be the place to start, if it's standard spec and the rest of the engine isn't in need of renovation.

[Magneto]

I have no idea what it would cost to do a turbo, simply offered it as an example of an option.

[postve]

I have no idea what it would cost to do a turbo, simply offered it as an example of an option.

Thanks Magneto and everyone else for the feedback

[postve]

Engine from one of these?




It should go like stink in a Mini, mostly down to the final drive. A 3.44 would be a good choice, but it'd have the opposite effect to trying to up the low to mid torque.

The cylinder head would be the place to start, if it's standard spec and the rest of the engine isn't in need of renovation.

Thank you Ethel for the feedback