John
1948 posts
Joined: 28/05/2006 16:49:46
Location: cambridge United Kingdom (Excluding channel Islands)
what lift can std 1275 springs take
what lift can std 1275 springs take before coil binding anyone know?
Posted: Feb 27, 2007 12:50 PM
what valve lift can std A+ springs take
what valve lift can std A+ springs take before coil binding occurs? any one used them on a particular aftermarket cam and had no problems?
Posted: Mar 04, 2007 02:27 PM
daniel
19 posts
Joined: 14/04/2005 02:29:38
Location: BENTONG Malaysia
1.5 high lift rockers with 310 cams, okay???
hi,
can the above work? +040 pistons, 35.7/31 intake/exos valves, pot/polished cylinder head, 310 duration Kent cams, adjustable sprocket, all new,
pls help, as i bought the MED highlift rockers and now my mechanic says i cant use it, bcos 1.5 ratio not suitable????
thanks,
Posted: May 17, 2007 02:49 AM
u do know u wont be able to drive it on the road yeah? its not going to have any power till its over 4000rpm. i think ud be far better with a milder cam even for race use. ur head isnt anything speshal either so ud need a race spec head to match if ur using a cam like that. ud be alot better going for a md286sp, wont be great on road but is usuable and should be good on the track. with the 310 cam with high lift rockers u need larger valves than that. ur standard rockers wont be up to the kinda of pressure of race springs and will break. use a 286sp cam and the 1.5:1 rockers. the valve lifts will be around 480 thousands like that. ul need the right springs too, if u use too stroung onces ul kill the power too weak and they will bounce and u wont be able to rev as high.
what is engine for?
Posted: May 17, 2007 12:50 PM
rozzer1275
70 posts
Joined: 20/08/2006 15:25:05
Location: harpenden United Kingdom (Excluding channel Islands)
high lift rockers
affraid not, have to change the pivot point of the rockers ie offset bushes or high lift rocker set.
Posted: Dec 03, 2008 01:17 PM
T. Perks
57 posts
Joined: 19/11/2006 09:21:16
Location: Wotton under Edge United Kingdom (Excluding channel Islands)
1.7:1 rockers vs 1.5:1
valve lift actually should not exceed the curtain area of the valve you are lifting but i have found when flow bench testing mini heads that you usually need to lift the valve about 5%more than that what the flow bench suggests, so at least for 5 port mini heads any way. So for a mini 1.4"inlet valve the suggested lift is 420 thou but most usually peform better when lift to around 440thou.
Posted: Feb 13, 2007 07:49 PM
Info stage 1
1.5:1 can work ok if a std cam which is low lift is kept, but its better to get a new cam and stick to std rockers or 1.3:1 rockers. with the small valves in the 998 there is no gain in having them open a long way as makes no differnce to the resistance around the valves. Even if larger valves are fitted because of the small bore dont like too much lift still as the bore shrouds them. small bore engines dont like any more valve lift than around .375 of an inch and best stick to cams under 270 duration. with the std 998 cam 230 int 240 exhaust you will get lifts at the valves with 1.5:1 of .375/.360. so the 1.5:1 rockers should work fine, but if you ever change the cam to a longer duration one the lift will be too much. also rember 1.5:1 rockers may cause coil binding of springs so best use uprated onces not too stroung tho or u will loose power around 140- 160lb would be good enouth but not factory springs as these arnt designed for high lift. also u will get increased cam wear and stress on your pushrods. So you can fit the 1.5:1 rockers and they will work ok maybe give anouther 5bhp(not alot for money spent), but a better bet is to stick to std rockers and fit a new cam of around 260-270 duration but the engine will need to come out for this.
Posted: Feb 04, 2007 12:15 PM
cam comparison
the main differnce is duration and lift swiftune is 244/244 deg duration .290" lift and phase 2 is 252/252 .305 duration. standard 1275 mini cam is 230/230 and .235 lift. both swiftune and phase 2 are short duration high lift cams, phase 2 i would expect to give cuple bhp more. the advantage of short duration high lift cams are they give good power at a normal rev range. they will pull better from low revs than standard cam if setup well and my rev slightly higher so they make a good everyday car cam. longer duration eg 270-280 duration simular lift cams will give more bhp but power at low revs say less than 2000rpm will be worse than standard. the big disadvantage of short duration high lift cams that is often missed is the stress and wear cause by the rapid lifting of the valves. the cam will wear rapidly loosing its lift and performence, valve guides get increased wear so engine will start smoking sooner, cam followers can break if not good quiality ones. bearing that in mind for most 1275's id go something bit longer duration u wont loose much bottom end just gain more bhp. eg piper bp255, kent md266, minispares evolution 1 all are between 260 and 270 duration with. i went for bp255 for my 1275 motor. if its not an everyday town car something around up to around 280 may be better suited but be prepared to rev it bit more to pull away and wont run as smooth.
have a look at my mini camshaft database can compare differnt cams on there.
http://www.edhodson.com/personal/miniresto/pages/camshaftcomparison.htm
Posted: Jan 10, 2008 12:00 AM
im planning on using a md266 kent as is everyday car and i like to keep in 4th at 30 for town to keep fuel consumthion down. il be using stage 1 kit with k&N cone filter and stubstack ported mg metro head and hif44 carb, so u think with short duration cams and faily low lift the extra lift pays off? did it idle ok still? does the rev range increase with higher lift?
Posted: Feb 13, 2007 11:13 PM
LewisCr125
136 posts
Joined: 13/04/2006 17:03:39
Location: Old Knebworth United Kingdom (Excluding channel Islands)
I'm sure the valve lift shouldn't be no larger than 25% (thereabouts) of the combustion chamber. Anymore lift and you won't get anymore gases in and the extra lift will be wasted.
Posted: Feb 13, 2007 06:41 PM
Leaded
the sw5 is quite short duration meaning good torque, fuel ecconomy and emishions, it makes most the extra power with extra lift and steeper lobe ramps. ur standard a series 998 cam is a 230/230 .235" lift the swifttune is 244/244 .281" lift at the cam.
Posted: Mar 14, 2007 09:19 PM
Roller tipped rockers
it will be as follows 230/240 duration 263/249 thousands lift at the cam with 20 deg overlap 395/374 thousands lift at the valve with 1.5:1 rockers
Posted: Apr 22, 2007 11:10 PM
Kevski style
105 posts
Joined: 12/09/2004 17:59:09
Location: Netherlands
!
Then only the nwe one from KAD wil do. You stil lift it up, but not in the old manner. You select reverse by lift up a collar onderneath the gearnob, as oposed to lifting op de entire stick. Quick shift in my opinion are great, but you have to have a good shift transmission in the first place: Quick shifts tend to amplify any point the transmission has now....
Posted: Apr 27, 2005 04:51 PM
How Heavy is an A Series Engine?
gd luck with that m8 mind ur back, rember u dont just have to lift it u have to lift it to clear the car which is about 2 foot high so ur gunna have to start out on ur knees, also if u drop it ur gunna reck ur body, iv taken mini engine out one by lifting frount of body up over the engine and subfraim, with a big bit of wood as a lever took 4 of us saves having to disconnect drive shafts ect. best try borrow a engine hoist and save ur back sorry to be a pessimist. with hoist only takes an hour, id never go back from using hoist is so much easyer. also when u lift the engine it needs to piviot at about spark pug point to get diff out, u can get bits to screw into ther spark holes to attach to it bit iv made do before by removing alternator / dynamo and puting long bolt thru fixings and putting one strap thru that, then the other thru the engine steady bracket next to block where rubber bushes go. if u dont piviot it like that u will need somone to angle it as it comes out. with rope round it or something simular.
Posted: Dec 08, 2006 06:42 PM
chrispy61
51 posts
Joined: 08/12/2005 22:27:39
Location: Torquay United Kingdom (Excluding channel Islands)
how to time in a cam
im sure its between 106-108degrees full lift on number 1 inlet valve after tdc? u need the adjustable timing gear avalible from swiftune, very sterdy bit off kit!! i would explain but its hard work. but basicly the no1 inlet valve needs to be fully open and exactly 107degrees on the timing disk which fits on the crankshaft, after top dead center, u need to find exacly where tdc is with the dial guage and where full lift occurs on no1 inlet using a pushrod and dial guage ontop. you have to work out the number of degrees of dwell aswell for tdc on the piston and full lift from the camshaft. i no not very detailed but hope it helps abit, im sure there will be an article on mini spares sum were.
Posted: Jun 27, 2006 09:25 PM
1275cc Head
Yes you can fit a 1275 head on to a 1000 as long as your valve lift does not exceed the depth of the combustion chamber and is a very good mod not only does the head flow better about 15cfm average than a 100 head but the compression ratio will be up to about 10.5 which will give more torque/power but also help with fuel economy, make sur to use the 1275 head gasket and check alinment of the water ways along the front of the block, and where the fire ring of the gasket sits. If the gasket over lyes the water hole you can fit a threaded bung to stop leakage. Remember the lift to check is the exhaust lift which will be around 318-320thous chambers are generally around 340-350thou and you have you gasket thickness on top too. Oh yes and dont use the aht 188 copper gasket as the fire ring is a little bigger use the payen Bk450, or the rover geg300.
Posted: Feb 22, 2007 08:40 PM
jag_clarke
rockers
its not worth hassle for little gain u get ur be better off just changing cam on 998 to something 260-270 duration standard is 230/240 (0.263" cam lift) on a 998 A+. these uprated cams will usually have plenty of lift for 998 and so upgrading rockers for more lift is un nessary. excessive lift ie with high lift rockers and uprated cam will loose power in a 998 vs either on there own.
if u do deside to do offset rockers u need early pressed steel ones and u have to fit offset bronze bearings not worth effort in my option as is alot of man hours for little gain. standard A+ rockers are solid steel and cant be offset they are also weaker than earlier pressed steel type so shouldnt be used at rpm above 7000rpm and should only be used with valve springs under 200lb/in. going higher than either risks random brittle failure.
Posted: Dec 03, 2008 08:21 PM
Russell Clarke
2 posts
Joined: 24/05/2010 20:15:16
Location: Belturbet Ireland (S.)
brakes
i just bought a 1990 mini checkmate, when i pres the brake pedal and lift off again it comes bak to nearly the top and then i have to lift it wit my hand,wat cud the problem be?
Posted: May 27, 2010 06:54 PM
Spi Tappet Problem
Wouldn't increasing the clearance kind of defeat the object of fitting high lift rockers? Increasing the clearance is going to give you less valve lift.
Posted: Feb 26, 2007 10:14 PM