14 replies to this topic

[fasteddie84]

Hi all

I have searched the site and couldn't find a definite answer so thought i would ask.

I am new to this and recently purchased a 96 1275 SPi Mayfair and I have a couple of problems with it not running right. I would like to change it to carb and before you ask, I have no issues with the emmissions check on MOT as I live in Jersey and we don't have MOT (such a bonus!).

My friend has just purchased a 92 998 Mayfair that is running on carbs so I was going to ask him if he want to lend me his car for a weekend and I could do the swap. My question is, will a 998 carb work on a 1275 engine? Also, could you see any potential problems with doing this?

[mpihornet]

it should. you will need a pressure regulator from the fuel pump as the pressure will be too high for the 998 carb. you will need to take the intake manifold as well. not sure if its got a distributor, it should still work, not sure how much ecu wiring you can take out. . it will be gutless compared to spi. it really would be a lot easier just fixing the injection

Hi all

I have searched the site and couldn't find a definite answer so thought i would ask.

I am new to this and recently purchased a 96 1275 SPi Mayfair and I have a couple of problems with it not running right. I would like to change it to carb and before you ask, I have no issues with the emmissions check on MOT as I live in Jersey and we don't have MOT (such a bonus!).

My friend has just purchased a 92 998 Mayfair that is running on carbs so I was going to ask him if he want to lend me his car for a weekend and I could do the swap. My question is, will a 998 carb work on a 1275 engine? Also, could you see any potential problems with doing this?

[fasteddie84]

Thanks mpihornet.

My plan was to remove the inlet manifold, dizzy, all wiring, fuel tank, pipes and exhaust (think that's it) and then do the same for the other car and do a straight swap.

At the moment, the car feels gutles.

I will be looking at doing so major work to the egine next year (either turbo or supercharge or 16v) and people have told me that by having carbs, it would be easier and parts will be more readily available. Is this correct? If not then I may just keep the SPI.

[minisilverbullet]

I am no expert at any stretch but i believe it is a tad more complicated than just popping a carb on. But maybe some one more knowledgeable will be along soon.

see -

http://www.minimania...4/InvDetail.cfm

http://www.theminifo...carb conversion

And there is also a wealth of knowledge on the spi mini here! I had problems with mine before, and it would seem that it will only be a handful of possibilities to eliminate to get it running sweet again!

[minisilverbullet]

I will be looking at doing so major work to the egine next year (either turbo or supercharge or 16v) and people have told me that by having carbs, it would be easier and parts will be more readily available. Is this correct? If not then I may just keep the SPI.

certainly the tuning possibilities for the spi are a little more limited. But kits, parts, upgrades do exist. With a simple stage 1 kit on my spi along with a good service, the car managed 73 bhp on the rolling road.

[fasteddie84]

Thanks for the links. After reading the first paragraph of the first link, it sort of confirms my reasoning to doing this:

"The SPi Mini might have achieved the objective of better fuel economy and emissions control, but the loss of performance and reliability still plagues the life of the SPi Mini. In addition the SPi Mini is very difficult at best to upgrade to get any significant performance enhancements. "

And also:

"This opens up the entire universe of performance enhancements and upgrades that have been developed so successfully over the years."

I have read the very helpful guide on the site about all the SPi faults and fixes but I start to think, it could be the O2 sensor but I would need to take it to the dealer to find out, which would cost around £50, then the sensor for about another £50 and then hopefully it'll be running fine for the time being.

If I spent £100 on swapping the SPi for the carb, I could be in a better position. Am I right?

Oh minisilverbullet, what arches have you got on your car?

[minisilverbullet]

Thanks for the links. After reading the first paragraph of the first link, it sort of confirms my reasoning to doing this:

"The SPi Mini might have achieved the objective of better fuel economy and emissions control, but the loss of performance and reliability still plagues the life of the SPi Mini. In addition the SPi Mini is very difficult at best to upgrade to get any significant performance enhancements. "

And also:

"This opens up the entire universe of performance enhancements and upgrades that have been developed so successfully over the years."

I have read the very helpful guide on the site about all the SPi faults and fixes but I start to think, it could be the O2 sensor but I would need to take it to the dealer to find out, which would cost around £50, then the sensor for about another £50 and then hopefully it'll be running fine for the time being.

If I spent £100 on swapping the SPi for the carb, I could be in a better position. Am I right?

Oh minisilverbullet, what arches have you got on your car?

they are called bullet arches availible at abs motorsport.

They were fitted to some german (maybe others) export models.

[fasteddie84]

Thanks for that.

Can anyone confirm that a 998 would have a 1.5" HS4 SU Carburettor and a 1275 would have a HIF44 1.75" SU carburetter.

I assuume that if I wanted to upgrade to a bigger carb in the future, I would need a new inlet manifold?

[mpihornet]

Thanks for that.

Can anyone confirm that a 998 would have a 1.5" HS4 SU Carburettor and a 1275 would have a HIF44 1.75" SU carburetter.

I assuume that if I wanted to upgrade to a bigger carb in the future, I would need a new inlet manifold?

i can confirm that unless it was messed with, your assumptions are correct. if you dont want to cut your firewall/bulkhead then make sure you get a short manifold.

also, spi is very very tunable. its a little more than with a car, but your final performance would always be better if you go with aftermarket tunable ecu. carbs are more simple (but even experts can set them up incorrectly occasionally) but either way, to get top notch performance (carb or programable ecu) you would need to take it to a rolling road

[fasteddie84]

Thanks for all of your help.

My car hasn't been messed with and my mates car was owned by new from another mates gran so I doubt she did anything to it!

My plan is to use it as a commuter until the new year and then I will strip it down and respray it and whilst I am at it, cut out a section of the bulk head for if/when I start on the engine.

My main concern with tuning the SPi is that it's more complicated than good old carbs. I prefer to have little to worry about. The only thing that would persuade me to stick with the SPi setup would be if the cost to convert is unbelievable expensive or you are better off sticking with the SPi when adding a turbo or supercharger or 16v.

[icklemini]

Can you get a 96 car through the emissions test on carbs?

Really the SPi isnt as bad as all the scaremongers would have you believe: a lot of the problems are down to lack of proper servicing.

My main concern with tuning the SPi is that it's more complicated than good old carbs

a few sensors that sort out thefueling and timing isnt that complicated...
For example:
Free flow air filter, fancy exhaust, cam swop, head mods and on carbs it'll need tuning / poss needle change.
on an SPi... no problem. bolt it on and away you go!

Dont forget good old carbs and distributors are all getting a bit 'worn out' these days... see a lot of knackered carb spindles, etc..

Granted if you plan to go down the 16v route then you'll budget accordingly as these heavy modifications arent cheap to do!

Edited by icklemini, 07 September 2010 - 03:29 PM.

[mgb1978]

I converted an SPI to Carb earlier this year. You should have everything you need as you have the donor car.
I fitted a Hif44 carb (and a points dizzy from an old 998) and the car runs fine .
The only hiccup is that the SPi doesn't have the hole for the temperature sender drilled and tapped, you could get this done or get an inline temperature sender fitted to one of the water hoses.
I managed to find a thermostat housing from an austin A35 on Ebay...this has the temperature sender fitted to it.

Also the top engine steady is different on the SPi (shorter or longer, can't remember) so try using either one to give maximum clearance for the carb.

[fasteddie84]

icklemini, like I said earlier, I live in Jersey so no problems with emissions tests as we don't have MOT (bonus). Are you saying that if you do a lot of hardware mods (like the ones you said), you won't have to get a different ECU? I am still looking at bigger mods but that'll be in the new year when I have time. I am just thinking that if my mate is willing to do a swap, and it is something that I might want to do in the future, I am better off doing it now.

mgb1978, I'm sure that I will be speaking to you a lot more since you have actually done this. Did you have a donor car? If not, I would be interested to know what parts you had to source.

Thanks everybody for your help and advise.

[icklemini]

Are you saying that if you do a lot of hardware mods (like the ones you said), you won't have to get a different ECU?

Correct: you can put a slightly hotter cam in (SW5 is a good road cam to be honest), modify the head, inlets.. exhaust... et al.
Not as radical as what you can with carbs, but it will work...
can play with injectors from different rovers too... do a search on what 'Sprocket' has done...

Edited by icklemini, 07 September 2010 - 05:58 PM.

[mgb1978]

Hi FastEddie, I have a '78 1000 and put the SPi engine into that. As far as i remember i just used the SPi engine/gearbox and exhaust/manifold as far as the Cat (stainless Fletcher single-box from there back).
Everything else was from the '78 car apart from the Hif44 and it's manifold. I used the mechanical fuel pump from the old 1000, just take the blanking plate off the SPi and bolt the pump on. I also used the older petrol tank but my fuel pipe was past it's best....the breather pipe from the SPi tank was put in instead.
Any questions, just ask here or PM me.