Super Mini Mad
Posted 18 July 2014 - 12:48 PM
hi guys,i have a 998 auto,i have got some bolt on parts in garage gathering dust like fletcher downpipe,dtm exhaust,alloy inlet manifold,kn air filter,refurbed carb(hs4).
my question is would the hs4 carb fit straight to an auto or is there any difference in the carb.
secondly with the downpipe,filter and exhaust would i need a different needle in the carb.
if it was ok to fit these parts what sort of difference could i expect to see.
have electronic ignition already fitted too,
cheers guys
Mini Mad
Posted 18 July 2014 - 01:29 PM
As far as I'm aware, the carbs on mini's are interchangeable between autos and manuals (a quick way to check would be to get the two carbs side by side and play spot the difference).
With all those modifications you will need a new needle In your carb, however a trip to the rolling road is going to be necessary to get it running as it should, otherwise all the effort in putting the parts on will go down the drain as the car will not drive nicely at all.
With the modifications you're proposing, you might expect a slight increase in power, although if you want more performance, I would swap the dtm for either a maniflow or RC40 exhaust, in which case on a good engine you might expect up to a 20% increase in power which would make for a nice responsive engine.
Super Mini Mad
Posted 18 July 2014 - 01:38 PM
its response im after really,and to sound a bit nicer too,i did try the air filter and carb on the engine the other day,but this seemed to really upset things,it would start fine but after a few seconds would rev slightly then just cut out,even with revs on,but oddly would start again straight after but cut out again.tried adjustin jet but to no advantage.could it have needed the new needle at that point with it taking in more air.?.put the old carb and filter back on after that as ran out of time and its my daily driver.
Camshaft & Stage Two Head
Posted 18 July 2014 - 04:26 PM
you MUST use the kickdown linkage 
Up Into Fourth
Posted 18 July 2014 - 04:52 PM
I also have a 998 auto, but would be very cautious about putting on any tuning goodies which might affect low speed tickover and throttle response at low speed.
Even changing the exhaust for a larger bore system may cause issues, alloy inlet should be OK as long as the bore is not appreciably bigger than the one you have fitted.
If the tickover ends up higher or throttle pick-up is affected then it may become a right handful in traffic.
Super Mini Mad
Posted 19 July 2014 - 06:19 AM
oh dear,i was looking forward to doin it too,appreciate what you said and its been taken on board.so what to do next.convert to manual which i really didnt want to do as these are getting rarer to come by.or drop the bits i have,and go for 1275 auto,what do you think.
Camshaft & Stage Two Head
Posted 19 July 2014 - 06:24 AM
I also have a 998 auto, but would be very cautious about putting on any tuning goodies which might affect low speed tickover and throttle response at low speed.
Even changing the exhaust for a larger bore system may cause issues, alloy inlet should be OK as long as the bore is not appreciably bigger than the one you have fitted.
If the tickover ends up higher or throttle pick-up is affected then it may become a right handful in traffic.
He's right, though you can play around with the governor to help - you're looking at at least keeping the torque curve in the same place at lower rpm's (below torque converter stall speed).
Super Mini Mad
Posted 19 July 2014 - 09:11 AM
this is getting very technical now.you say the alloy inlet would be ok but how can i do this without putting a different downpipe on.will i have to keep the same air filter set up?.sorry for being a pain in the rear guys.
Super Mini Mad
Posted 19 July 2014 - 10:51 AM
i thought all 998 auto' came with an hs4 as standard. mini fitted with a stage 1 kit and a 12g295 head and it's a brilliant. I,m rebuild a pair of hs2's to go on it. I say go for it.
Super Mini Mad
Posted 19 July 2014 - 07:03 PM
maybe so,but what about the air intake,would the kn air filter be too much,might just have a crack at it tomorrow.cheers guys,il let u know ok.
Gearbox Guru
Posted 19 July 2014 - 08:38 PM
I'm sorry to disagree with most of the above...
1. Don't ******* about with the gearbox, governor or kick down linkage... You'll break it and end up having to replace the engine/transmission
2. You can fit a stage 1 kit onto a 998 auto without any modifications to the gearbox, governor, but you must get one specifically for the auto or you may struggle with the kickdown linkage...
3. Don't fit a DTM, you kill any benefit of fitting the stage 1, and probably make it worse that it is now....
4. Enjoy driving the auto for what it is, service it wel as sooner or later it fail and be an expensive fix.
Crazy About Mini's
Posted 19 July 2014 - 08:53 PM
I'm sorry to disagree with most of the above...
1. Don't ******* about with the gearbox, governor or kick down linkage... You'll break it and end up having to replace the engine/transmission
2. You can fit a stage 1 kit onto a 998 auto without any modifications to the gearbox, governor, but you must get one specifically for the auto or you may struggle with the kickdown linkage...
3. Don't fit a DTM, you kill any benefit of fitting the stage 1, and probably make it worse that it is now....
4. Enjoy driving the auto for what it is, service it wel as sooner or later it fail and be an expensive fix.
Edited by cal844, 19 July 2014 - 08:55 PM.
Camshaft & Stage Two Head
Posted 20 July 2014 - 02:10 AM
I'm sorry to disagree with most of the above...
1. Don't ******* about with the gearbox, governor or kick down linkage... You'll break it and end up having to replace the engine/transmission
2. You can fit a stage 1 kit onto a 998 auto without any modifications to the gearbox, governor, but you must get one specifically for the auto or you may struggle with the kickdown linkage...
3. Don't fit a DTM, you kill any benefit of fitting the stage 1, and probably make it worse that it is now....
4. Enjoy driving the auto for what it is, service it wel as sooner or later it fail and be an expensive fix.
Pffft . You won't break it, why will you break it? It is quite easily possible for anyone who is prepared to read the tech manual and purchase a pressure gauge to tweak the gearbox a bit. If you leave the governor rod flapping around in the breeze nothing will happen, you'll just change the gearchange points - the world won't end.
Any skilled engineer (not someone with a bent screwdriver and a rusty hammer) will be capable of rebuilding that box.
Super Mini Mad
Posted 20 July 2014 - 09:08 AM
Gearbox Guru
Posted 20 July 2014 - 10:44 AM
I'm sorry to disagree with most of the above...
1. Don't ******* about with the gearbox, governor or kick down linkage... You'll break it and end up having to replace the engine/transmission
2. You can fit a stage 1 kit onto a 998 auto without any modifications to the gearbox, governor, but you must get one specifically for the auto or you may struggle with the kickdown linkage...
3. Don't fit a DTM, you kill any benefit of fitting the stage 1, and probably make it worse that it is now....
4. Enjoy driving the auto for what it is, service it wel as sooner or later it fail and be an expensive fix.
Pffft . You won't break it, why will you break it? It is quite easily possible for anyone who is prepared to read the tech manual and purchase a pressure gauge to tweak the gearbox a bit. If you leave the governor rod flapping around in the breeze nothing will happen, you'll just change the gearchange points - the world won't end.
Any skilled engineer (not someone with a bent screwdriver and a rusty hammer) will be capable of rebuilding that box.
If you receive the number of calls I have about failed automatics, and those which have been 'reconditioned' by apparently skilled engineers then you may have a different opinion.
Yes, I agree that someone with the correct knowledge and tools will be able to adjust/rebuild the AP auto unit but it is by no means a DIY garden shed job and I would say beyond probably most mini owners.
You seem to be eager to provide advice on auto units from a knowledgeable position. What would be better for the forum community is rather than disrespect a considered opinion is provide useful explanatory guides, pictures and "how to" pieces which will allow the auto owner to gauge the level of skill required to perform certain tasks and then if they wish to continue or not.
So in summary I stand by the following statement, with an additional caveat
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