5 replies to this topic

[chudley]

Has anyone fitted a mg metro head to a spi cooper before and if so what results did they get, i have just fitted one and a performance exhaust and it seems to have increased the torque and also better through the gears as 3rd and fourth dont seem to have to rev so high to gain speed i would be interested if anyone else has done the same. chud.

[Bungle]

i thought the valve sizes were the same

[chudley]

i thought the valve sizes were the same

no i believe there are two types the 33mm inlet 29mm exhaust and 35 inlet and 29 exhaust i measured them and this was what i came up with the guy at mini spares said the same and thought i was crazy.

[minimat]

Ive never tried it but have often wondered if it would make any improvement as i knew the mg heads have bigger valves than an spi (spii believe is more like a basic metro head)May have to try it one day as i have a spare in the shed,only trouble is it is only a leaded head

[Sprocket]

Standard 35mm inlet MG heads are Leaded, and the 33mm inlet MG heads are unleaded

Uprating the valve sizes to 35mm from the standard 33mm will produce a gain, as would the exhaust.

My 1400 with 35mm inlets in a standard head casting gave 87bhp 87lbft with the Kent 274 cam. From there a fully modified head still using 35mm inlets and 29mm exhausts and 1.5 ratio rockers bumped the power and torque to 100bhp 100lbft. Just to give you an idea of what does what.

[chudley]

Standard 35mm inlet MG heads are Leaded, and the 33mm inlet MG heads are unleaded

Uprating the valve sizes to 35mm from the standard 33mm will produce a gain, as would the exhaust.

My 1400 with 35mm inlets in a standard head casting gave 87bhp 87lbft with the Kent 274 cam. From there a fully modified head still using 35mm inlets and 29mm exhausts and 1.5 ratio rockers bumped the power and torque to 100bhp 100lbft. Just to give you an idea of what does what.

well thats some difference, mine is leaded but i add some leaded stufff with fuel, mine being an spi is there much more does anyone know i could do the ecu had no problem with the head and i have a new kand n filter coming and do want some 1.5 rockers if anyone has a set for sale, one small prob i have is the same as when running with the origenal head is sometimes there seems to be a bit of hesitation through mid revs could this be a sensor i have changed the lamda and coolent sensors, does anyone know o and all the vac pipes are good.