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1275 Mongrel Build Advice


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#1 Superdeluxe

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Posted 26 March 2020 - 07:50 PM

Hello all,

I've most likely gone about this the wrong way but instead of buying a complete engine I seem to have accumulated a pile of engine parts to build up a 1275. I do like making things difficult for myself.

My mini currently has its pre A plus 998 fitted. When I remove it I'll split it and use the gearbox and ancillaries for the new build.

I have accumulated the following:

1275 GT 11 stud block (getting bored +040)
12G940 head (getting 36/31 valves etc)
New old stock CAM6232 crank
A+ rods
Getting a minispares EVO001 cam.

I'm looking for around 10.5:1 compression ratio.

Any recommendations or advice on pistons, bearings etc would be greatly appreciated as I'm not 100% sure which parts are interchangeable between pre A plus and pre A plus.

I'm trying to keep costs down obviously but trying to build the best all round engine I can. 90+ bhp would be fantastic.

I've already fitted the minispares 7.5 inch disc brake conversion and uprated the suspension with genuine hi lo's and gas adjust dampers. (New standard cones going in soon). So the car just needs more power now.

Cheers in advance

Rich

#2 Cooperman

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Posted 26 March 2020 - 10:24 PM

That all sounds OK.

For pistons the P21253 - 40 will be fine. They have an 8.3 cc dish, so base your CR calculations on that. Gasket volume is usually regarded as 4 cc.

Evo001 cam is great. It's not bhp you need it is good mid-range torque and for that the Evo001 is ideal.

Make sure you do a 'dummy build' before assembling finally. Have the block decked to bring the piston tops to deck level at TDC.

One of the most important things is to gas-flow the head. That is the key to better performance with the A-Series engine. There is no point in having a great cam and bigger valves if the head is still restricting gas flow.



#3 Superdeluxe

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Posted 26 March 2020 - 11:01 PM

Thanks for the info cooperman. I am going to send the head to Turbo Phil for its work when I'm building the block up. Thanks for the advice regarding decking the block and piston choice.

#4 ACDodd

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Posted 26 March 2020 - 11:14 PM

Drop that Cr, aim for 9.75:1 max.

Ac

#5 Superdeluxe

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Posted 27 March 2020 - 12:15 AM

Cheers AC. Does my spec require a lower compression ratio as it's not high power I'm after?

#6 Superdeluxe

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Posted 27 March 2020 - 12:29 AM

Initially I was after building some sort of fire breathing monster but after reading peoples advice and realizing how much fun the car is even with 40bhp just over double the power would definitely be enough. I was inspired by Keith Calvers sports tourer engine build article and was hoping for similar results but using the evo001 cam.




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