20 replies to this topic

[martin_mini]

Hi all,

 

A brief description about my engine. It is a 12A2AG01 engine I assume 12G940 is my head number? correct me if I'm wrong.

 

All parts are stock except the Twin HS2 Carbs (1.25"x 2). I have no plans on changing the cams, but I wish to install the 1.5:1 Roller Rocker soon after i overhaul my engine.

 

 

I have read other forums on stock valve springs being crushed and should opt for double valve springs when installing 1.5:1 Rocker. So,...

 

My questions are:

 

1) Minisport told me my best choice for double valve springs are Kentcams double valve springs (Part#: KENVS2 ) that suits best with minisport 1.5:1 Rocker?

2) Is this true? what double valve springs to you guys use/recommend?

3) Last but not least, I want the least amount of problems for my engine/car. Is it worth it to change the Rocker? will it ruin my engine in the future?

 

 

Looking forward for them answers guys. Thanks in advance.

 

 

[gazza82]

If you have 12G940 in the casting on the head, then you have one .. but there are different versions of 12G940 head!! You need to measure the valves and also look for any other markings (some are found under the paint!)

 

1.5 rockers will not ruin your engine but unlikely to do much for performance ..

[Dusky]

3) not worth it at all.

[martin_mini]

3) not worth it at all.

 

Thanks gazza82.

 

Dusky, thanks for the reply but could you elaborate on why you think changing the 1.5 rocker is not worth it? is it the ratio between cost and performance gain? or problems?

 

If so, other than changing the 1.5 rocker how would you recommend I increase the performance of my car? I do not wish to go hardcore on my mini, since I use it for a daily drive-able car.

Edited by martin_mini, 03 October 2016 - 03:05 PM.

[Mini Manannán]

1.5's will give you a little more top-end at the expense of bottom-end.   If you want a pleasant, tractable daily driver stick with standard specs.

[Northernpower]

You say you are going to overhaul the engine. I would change the cam and followers and not buy 1.5 rockers. There are plenty of cams out there and it would be a much bigger bang for you buck without losing any tractability.

[gazza82]

Could "overhaul" mean "service" in this case?

 

OP has already said he doesn't plan to change cams, but as we know that is the best way to get better performance. I was about to suggest the MG Metro, Kent 266 or equivalents but didn't as they said they weren't going down that route.

[racingbob]

if your going to overhaul the engine as i strip it

 

put a mg metro cam or similar in

 

i have the mg metro in mine and very happy with it

 

and leave off the 1.5 as in mine

[Northernpower]

Could "overhaul" mean "service" in this case?

 

OP has already said he doesn't plan to change cams, but as we know that is the best way to get better performance. I was about to suggest the MG Metro, Kent 266 or equivalents but didn't as they said they weren't going down that route.

I also read he said he wasn't going to change the cam but I was just offering a suggestion if the overhaul was a full one, i.e. a strip down, a cam and followers change was much better value for money than 1.5 rockers ever would be.

[Dusky]

You ll gain 1-3 bhp over 5k rpm, but you ll also lose 1-3 bhp under 5k rpm( my own dyno experience)
Not worth it on a road car that spends 95% of its Time under 5k :)

[Turbo Phil]

If the engine is totally standard but in good condition, the best thing you can do to improve performance is fit a decent stage one kit.

Phil.

[Cooperman]

As has been said many times, the basic key to improved engine power and torque is a properly gas-flowed head with increased compression ratio.

Once that is done and combined with better induction and exhaust systems, a better cam can be fitted.

The standard head is very poor in terms of ability to flow mixture, so no changing of carbs will make much difference as the limitation is the shape of the inlet ports, the shape of the combustion chamber and the diameter of the valves. 

The same applies to higher valve lift. The inlet throat and 'short-side-radius' are restrictive, so virtually no extra mixture can get into the chamber and the valves are shrouded by the chamber edge as well. Twin carbs won't help either because the restriction is in the inlet tract and combustion chamber shapes

Double valve springs are for cams which work at high revs with a peak at 6000 rpm or over, so there is no point in fitting them to an engine with a standard cam.

In the end it depends on what one is trying to achieve. if it is a competition car, then there is a lot to be done. For a road car, however, its use needs to be defined and an ideal specification arrived to give the right result. Work from the beginning forward, rather than choosing some parts, like high-lift rockers and twin carbs, then trying to decide what they might do and how to fit them.

[Turbo Phil]

I agree the head is where the key to decent power is, but simply adding a good head on an otherwise standard engine will not see anything like the gains it should if a decent inlet and exhaust system aren't fitted.
For the cost of a stage one kit you'll see the biggest improvement for the least cost. A good cylinder head and cam can then follow.

Phil.

[martin_mini]

As has been said many times, the basic key to improved engine power and torque is a properly gas-flowed head with increased compression ratio.

Once that is done and combined with better induction and exhaust systems, a better cam can be fitted.

The standard head is very poor in terms of ability to flow mixture, so no changing of carbs will make much difference as the limitation is the shape of the inlet ports, the shape of the combustion chamber and the diameter of the valves. 

The same applies to higher valve lift. The inlet throat and 'short-side-radius' are restrictive, so virtually no extra mixture can get into the chamber and the valves are shrouded by the chamber edge as well. Twin carbs won't help either because the restriction is in the inlet tract and combustion chamber shapes

Double valve springs are for cams which work at high revs with a peak at 6000 rpm or over, so there is no point in fitting them to an engine with a standard cam.

In the end it depends on what one is trying to achieve. if it is a competition car, then there is a lot to be done. For a road car, however, its use needs to be defined and an ideal specification arrived to give the right result. Work from the beginning forward, rather than choosing some parts, like high-lift rockers and twin carbs, then trying to decide what they might do and how to fit them.

 

Thanks all for the replies. What I meant overhaul as in stripped to pieces to refurbished, cleaned, lubed and so on. 

 

And yes, my car is already a stage 1. Full exhaust systems and K&N filters. 

 

Reading from your replies, most agrees that 1.5 Rocker is not worth it. Then what route do you guys suggest I go? I am now open to all suggestions. I want to achieve a more slightly powerful road car than I am having now, but I want the least amount of problems for my engine/car. In other words, I do not wish to visit the garage once every month because the engine blew up, etc. I want a faster road going car. That's all. Maybe buy the stage 2 head or O/S Inlet and exhaust valves then? 

 

 

thanks guys

[Dusky]

Mg head and a sw5/evo001/kent26 cam will get you a long way imho.