16 replies to this topic

[oh.go.on.then]

Hi all, can I ask peoples thoughts on a few questions I have.

 

I now have a new bottom end built, 1430, 84mm stroke and 73.5mm bore, 286 scatter. I will fit Twin 1.5" SU, MED ultralight flywheel, back plate and their crank damper, probably a Swiftune CSI distributer? and if I can find any in stock 1.4 forged rockers. 

 

Questions:

1)Head - obviously the usual work and 36mm inlet but exhaust valve size I have been advised 31mm and non hardened seat (in order to fit the valve in). I automatically in my head went 29.6mm (or whatever it is without looking) and hardened seats. Do I really need to go bigger on an engine this size?

 

2) Gearbox I have is a Cooper 998 4 syncro. I will add a 4 pin diff but can't decide if I need SCCR. I had planned to stay helical as I'm worried 1st gear may be a pig if I go SCCR. I have a gravel drive and already struggle. Diff should be 3.76 at the moment (but havent opened it up) as it is a standard Cooper 998. I also have a spare ADO16 1300GT box to see if the ratios are any better once I open the Cooper box.

 

3) Exhaust manifold - I'm looking at maniflow stage 2 LCB but I notice there is one that says it suits remote boxes for clearance. Its more expensive too. I'm sure I've fitted normal LCB's with remote box in the past though. Any advice on which ones would be suitable? I already have a 1.75" Maniflow twin box on the car which is new (although now prefer the look of the RC40 I took off).

 

4) Fuel pump - is the standard Cooper 998 electric SU pump up to the job?

 

Many thanks

 

 

[GraemeC]

From a strength perspective SC is rarely 'needed'.  Standard helical gears can take much higher power and torque levels than people thing - many of the turbo boys still run with them,. 

CR is useful for a high revving motor with a narrow power band, so the rev drop between gears remains in that power band.  A 1430 should be a torque pump able to bridge a much larger gap.

 

Look at the MiniSpares Evo helical set - stronger but still quiet and with sensible ratios.

[oh.go.on.then]

From a strength perspective SC is rarely 'needed'.  Standard helical gears can take much higher power and torque levels than people thing - many of the turbo boys still run with them,. 

CR is useful for a high revving motor with a narrow power band, so the rev drop between gears remains in that power band.  A 1430 should be a torque pump able to bridge a much larger gap.

 

Look at the MiniSpares Evo helical set - stronger but still quiet and with sensible ratios.

 

Thanks Graeme for the answer.

 

I should have said it is a road engine just for weekend blasts around the lanes so ultimate strength isn't needed. I was worried about the cam being a bit peaky but if set up ok I think you are right that the 1430 should have enough torque to to bridge the gap and the helical gears should be ok. I've read conflicting views but I think the Cooper 998 ratio's should be the same as Cooper S close ratio (depends which book I read but only opening the box up will tell me fully). If not - the 1300GT should be.

[imack]

I had a 1380 with 286 cam, 37/31 head, twin hs4's etc, it had factory S/GT ratio remote box with 3.44 fd. Those ratios were 'ok' but I think it could have done with closer ratios. As suggested above, maybe the minispares helical cr set is the way to go.
You probably want the biggest valves you can fit with a 1430.
Pretty certain the 998 cooper only had standard ratios.

[cal844]

You want hardened valve seats to give the head as much protection from recession as possible. Having big valves is OK but they're useless if the head isn't ported correctly

[oh.go.on.then]

I had a 1380 with 286 cam, 37/31 head, twin hs4's etc, it had factory S/GT ratio remote box with 3.44 fd. Those ratios were 'ok' but I think it could have done with closer ratios. As suggested above, maybe the minispares helical cr set is the way to go.
You probably want the biggest valves you can fit with a 1430.
Pretty certain the 998 cooper only had standard ratios.

 

Thanks that's helpful. I'll take a look at what the ratios look like in the Minispares helical. Its still a balance between first being too high and having close enough ratio

[oh.go.on.then]

You want hardened valve seats to give the head as much protection from recession as possible. Having big valves is OK but they're useless if the head isn't ported correctly

 

Yes agree. That said, I probably do 500 miles a year so using lead replacement would probably be ok. There's just something in me that says it doesn't make sense not to have hardened seats in this age

[imack]

I've not had any issues since leaded fuel became unavailable running Castrol valvemaster plus, or millers VSPE

[oh.go.on.then]

I've not had any issues since leaded fuel became unavailable running Castrol valvemaster plus, or millers VSPE

 

Thinking about it, I'm running a leaded 12G295 now using valvemaster so what am I worried about?

[rww]

 

 

' I should have said it is a road engine just for weekend blasts around the lanes so ultimate strength isn't needed. I was worried about the cam being a bit peaky but if set up ok I think you are right that the 1430 should have enough torque to to bridge the gap and the helical gears should be ok. I've read conflicting views but I think the Cooper 998 ratio's should be the same as Cooper S close ratio (depends which book I read but only opening the box up will tell me fully). If not - the 1300GT should be.'

 

I think your reservations regarding the 286 cam are justified as this will 'characterise' your driving experience of the engine the most. Having used the 286 in a virtually stock 1275 ( Sprint Events) but with a weber 45 , it would easily spin to just under 8k and was pretty intractable under 3.5k. You have gone for torque with the 1430 but, in my view, compromised an excellent road spec with a peaky camshaft. 

 

Having said that, when I purchased a 1275 Cooper S in the sixties I found the 2A948 cam that was fitted was difficult in traffic and I quickly reverted back to it's original AEG 510 cam which was brilliant and would pull strongly from  1k. It's all down to individual preference , but you did ask !

[rww]

 

 

' I should have said it is a road engine just for weekend blasts around the lanes so ultimate strength isn't needed. I was worried about the cam being a bit peaky but if set up ok I think you are right that the 1430 should have enough torque to to bridge the gap and the helical gears should be ok. I've read conflicting views but I think the Cooper 998 ratio's should be the same as Cooper S close ratio (depends which book I read but only opening the box up will tell me fully). If not - the 1300GT should be.'

 

I think your reservations regarding the 286 cam are justified as this will 'characterise' your driving experience of the engine the most. Having used the 286 in a virtually stock 1275 ( Sprint Events) but with a weber 45 , it would easily spin to just under 8k and was pretty intractable under 3.5k. You have gone for torque with the 1430 but, in my view, compromised an excellent road spec with a peaky camshaft. 

 

Having said that, when I purchased a 1275 Cooper S in the sixties I found the 2A948 cam that was fitted was difficult in traffic and I quickly reverted back to it's original AEG 510 cam which was brilliant and would pull strongly from  1k. It's all down to individual preference , but you did ask !

[rww]

 

 

' I should have said it is a road engine just for weekend blasts around the lanes so ultimate strength isn't needed. I was worried about the cam being a bit peaky but if set up ok I think you are right that the 1430 should have enough torque to to bridge the gap and the helical gears should be ok. I've read conflicting views but I think the Cooper 998 ratio's should be the same as Cooper S close ratio (depends which book I read but only opening the box up will tell me fully). If not - the 1300GT should be.'

 

I think your reservations regarding the 286 cam are justified as this will 'characterise' your driving experience of the engine the most. Having used the 286 in a virtually stock 1275 ( Sprint Events) but with a weber 45 , it would easily spin to just under 8k and was pretty intractable under 3.5k. You have gone for torque with the 1430 but, in my view, compromised an excellent road spec with a peaky camshaft. 

 

Having said that, when I purchased a 1275 Cooper S in the sixties I found the 2A948 cam that was fitted was difficult in traffic and I quickly reverted back to it's original AEG 510 cam which was brilliant and would pull strongly from  1k. It's all down to individual preference , but you did ask !

[rww]

Apologies for the last two ( repeat) posts. Cannot see how to delete so if moderators can hide them, then much appreciated.

[imack]

My old 1380 with 286, Longman gt15 offset valve head, 3.44 FD & S ratio box was fine on the road, it used to be my daily driver in moderate traffic. On twin hs4's it was drivable from 1800 rpm but started to come on cam at around 2500 and would rev to 8000+

My current 1380 road car runs a 649 based cam, same carbs, 37/31 offset valve head, SCCR box and 3.9 FD, its unhappy below 3000rpm and a real pain in traffic but massive fun on the right roads.

[oh.go.on.then]

 

 

 

' I should have said it is a road engine just for weekend blasts around the lanes so ultimate strength isn't needed. I was worried about the cam being a bit peaky but if set up ok I think you are right that the 1430 should have enough torque to to bridge the gap and the helical gears should be ok. I've read conflicting views but I think the Cooper 998 ratio's should be the same as Cooper S close ratio (depends which book I read but only opening the box up will tell me fully). If not - the 1300GT should be.'

 

I think your reservations regarding the 286 cam are justified as this will 'characterise' your driving experience of the engine the most. Having used the 286 in a virtually stock 1275 ( Sprint Events) but with a weber 45 , it would easily spin to just under 8k and was pretty intractable under 3.5k. You have gone for torque with the 1430 but, in my view, compromised an excellent road spec with a peaky camshaft. 

 

Having said that, when I purchased a 1275 Cooper S in the sixties I found the 2A948 cam that was fitted was difficult in traffic and I quickly reverted back to it's original AEG 510 cam which was brilliant and would pull strongly from  1k. It's all down to individual preference , but you did ask !

 

 

In hindsight I think it's a bad choice the more I read but its in there now so I'll give it a go. If I can't live with it I'll have to pull the engine and swap it out. I've never timed a cam myself so it would either have to go back to an engineering shop or I'd have to learn how to do.