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What Is The Best Set Up For 1275 A+ Engine ? What Head/cam Etc ?

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#1 chris1965mk1

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Posted 17 June 2015 - 10:34 AM

Just getting to the point where i need to plan my engine mods in my mk1 restoration and could do with some advise please !

 

I have a standard A+ 1275 engine sitting on my bench at home, head is off and has been skimmed .

 

I want to do some performance upgrades (for road use) before re-fitting and would like some advise on what head will bolt straight on and offer me the best increase in power and are things like cams/roller rockers etc worth doing ?

 

I cant afford a 1380 etc but if i can get the most out of my current engine for not too much £££ that would be the compromise .

 

My goal is to have a weekend little pocket rocket that has good acceleration (not too bothered on top end), not even thought about carbs yet ?? any ideas ??

 

Cheers  ;D



#2 sonikk4

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Posted 17 June 2015 - 11:00 AM

A decent ported and flowed head with bigger valves will be a good start. Then something like a SW5 cam or 276. Nothing much more than that or it will start to get lumpy. A good quality exhaust system 1.75" in diameter and LCB. Carb wise a HIF44 will be all you need.

 

The head will need cc'ing so you can work out the compression ratio. Standard rockers will be fine as you are not going mad here. Then once assembled and running take it to a rolling road for correct setting up. You may want to get a dizzy thats suitably curved to match the engine spec as well.



#3 carbon

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Posted 17 June 2015 - 04:35 PM

A rebuild to MG Metro spec should give you decent torque and acceleration



#4 MrBounce

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Posted 17 June 2015 - 04:50 PM

Take a look at my Midas thread. I have built a warmed over 1293 for it with not a huge spec - it's roughly MG Metro spec.


Edited by MrBounce, 17 June 2015 - 04:51 PM.


#5 Fast Ivan

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Posted 17 June 2015 - 07:15 PM

if moneys the limiting factor you might consider making sure what you have is in good shape and forego the tuning for now 

and don't neglect the gearbox and ancillaries



#6 blacktulip

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Posted 18 June 2015 - 11:11 AM

firstly check your engine over for wear unless you know that its ok. i would try and find a good big valve head that has been reconditioned already (I.e new guides, unleaded seats, fresh lapped valves and new stem seals, maybe some mild port work) if you can find one that has Rimflo valves that would be a nice bonus. Have the CR calculated and work on having it to be around 9.5:1. Then buy a new Kent MD266 cam with new followers, a vernier duplex timing chain kit (this can be bought as a kit). Match this with a fully developed stage 1 kit like the minispares one along with a rebuilt and Vizard modded HIF44 carb and you should have a very nice road engine that will pull from low down all the way up to around 6500rpm. Dont forget to have the dizzy recurved to a new advance curve, this can be sorted on a rolling road session. I would also seriously consider booking it in to have the dizzy and rolling road done by AC Dodd.



#7 chris1965mk1

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Posted 19 June 2015 - 10:13 AM

firstly check your engine over for wear unless you know that its ok. i would try and find a good big valve head that has been reconditioned already (I.e new guides, unleaded seats, fresh lapped valves and new stem seals, maybe some mild port work) if you can find one that has Rimflo valves that would be a nice bonus. Have the CR calculated and work on having it to be around 9.5:1. Then buy a new Kent MD266 cam with new followers, a vernier duplex timing chain kit (this can be bought as a kit). Match this with a fully developed stage 1 kit like the minispares one along with a rebuilt and Vizard modded HIF44 carb and you should have a very nice road engine that will pull from low down all the way up to around 6500rpm. Dont forget to have the dizzy recurved to a new advance curve, this can be sorted on a rolling road session. I would also seriously consider booking it in to have the dizzy and rolling road done by AC Dodd.

Sounds like a plan ! When you say big valve head do you mean a standard mg/metro one with the bigger valves as standard or a modified one ? I did look into getting mine done but i was told i have the smaller valve A+ type and there is little room between the valves (if bigger valves were put in it coudlnt be converted to unleaded ) Where is AC Dodd and any idea how much it would cost ? 

 

Thanks for the help 



#8 blacktulip

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Posted 19 June 2015 - 01:00 PM

 

firstly check your engine over for wear unless you know that its ok. i would try and find a good big valve head that has been reconditioned already (I.e new guides, unleaded seats, fresh lapped valves and new stem seals, maybe some mild port work) if you can find one that has Rimflo valves that would be a nice bonus. Have the CR calculated and work on having it to be around 9.5:1. Then buy a new Kent MD266 cam with new followers, a vernier duplex timing chain kit (this can be bought as a kit). Match this with a fully developed stage 1 kit like the minispares one along with a rebuilt and Vizard modded HIF44 carb and you should have a very nice road engine that will pull from low down all the way up to around 6500rpm. Dont forget to have the dizzy recurved to a new advance curve, this can be sorted on a rolling road session. I would also seriously consider booking it in to have the dizzy and rolling road done by AC Dodd.

Sounds like a plan ! When you say big valve head do you mean a standard mg/metro one with the bigger valves as standard or a modified one ? I did look into getting mine done but i was told i have the smaller valve A+ type and there is little room between the valves (if bigger valves were put in it coudlnt be converted to unleaded ) Where is AC Dodd and any idea how much it would cost ? 

 

Thanks for the help 

 

the MG metro head is a big valve head (the Vanden Plas metro was big valve too) and in my opinion is a great head but as with any head it needs to be in top condition to get the best results. i do believe the later MG heads are unleaded. AC Dodd is a member on here so you could PM him.

 

just for a comparison i have a 1275 A-series +30 which is 1301cc, Vmax2 head which is a big valve head with slight porting work, a mild if not standard cam and a stage 1 kit. it made 72bhp 78lbs/ft of torque which makes a very nice fun mini to drive.



#9 carbon

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Posted 19 June 2015 - 06:34 PM

The MG Metro engine was also reckoned to deliver 72 bhp at the flywheel



#10 Cooperman

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Posted 19 June 2015 - 06:49 PM

The 12G940 head casting with 35.6 mm inlet & 29.5 mm exhaust valves is what's needed here. Then a bit of mild 'cleaning-up' and porting of the head works very well. Vizard's book tells you how to DIY, but you don't need to do much to see an improvement. in particular, the 'steps' around the valve seat area, the short-side radius into the combustion chambers and a bit of de-masking around the edges of the inlet valves is enough.
Increase the compression ratio to around 10.2:1, clean out the casting 'flash' inside the inlet manifold and re-build it carefully.
You don't need, or even really want, a 1380 for road use. If it needs re-boring just go to the next size up and use 21253 pistons.
In terms of a camshaft, the MG Metro or Kent 266 (they are very similar) would be ideal.

#11 Spitz

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Posted 19 June 2015 - 07:42 PM

When I fitted a light weight flywheel, I was amazed at the difference it made.  Much quicker getting up to speed.  Just a thought.



#12 nicklouse

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Posted 19 June 2015 - 08:08 PM

Ok let's go back to the start.

Get your gearbox magic wand rebuilt. Get the sort motor to someone like AC Dodd (there are other engine builders out there) and get then to sort out west you want. That way it all works together and is right for cam and head and CR.

Drop gears will need to be sorted.

Don't go buying bits and hoping they work together. They have yo be made to work together and then they will.

#13 chris1965mk1

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Posted 20 June 2015 - 08:56 AM

To get me started then i found this on Ebay, anygood ? http://www.ebay.co.u...=item1c5459b00c



#14 chris1965mk1

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Posted 20 June 2015 - 09:00 AM

Also have this in my watch list however i already have Thurston Engineering getting back to me with a quote for my current block so will hold fire 

 

http://www.ebay.co.u...=STRK:MEBIDX:IT



#15 ACDodd

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Posted 20 June 2015 - 09:24 AM

I think you should start thinking about your question, best for what application?

 

AC







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