Double Valve Springs!
Turbo Mini Forums

Ive just stripped my cylinder head and found double valve springs! Are they standard with metro turbos or has someone bought these for my engine previously?!

I bought a phase 2 cam kit and that came with doubles, so if they dont come standard i might have already had a upgraded camshaft!

Thanks. Rich

metty turbos had double valve springs as standard mate.....

And on the 7th day........... God created turbochargers!

Rich subtract the extra lift on the phase 2 cams exhaust lift from the inlet lift on the cam and have the spring pockets machined out on the head

so the spring heights are the same as the inlets on FULL lift

this will stop rapid valve train wear!

This is just a basic mod but there is alot more to it than that

if you dont need them ill buy them of you rich :)

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

Cool cheers for the info chaps! Yeah you can have my old double valve springs i had off the head today if you want, not sure how many miles they've done though!

Benross, im not untirely sure what you mean! Do you mind explaining a bit more please? Sorry if i sound like an iditot lol

Rich

rich look on the data sheet you have for your cam

it should have the valve lift figures on there V/L

say the inlet valve lift is 8.89mm it is on the phase 2 avonbar ABRT002 SPEC

and the exhaust V/L is 9.91mm the difference between them is 1.02mm so that figure is placing more load on the valve train on the exhaust side hence some chaps on here have worn cams out and followers etc......

to help the valve train along and make the valve seat pressures the same on the inlets & exhausts you have to machine the spring pockets out on the head on the figure you have worked out.

now then this is "only a guide", most peeps just fire the cam in and hope for the best which they get many miles on it before it wears out.

but the above will make the whole valve train live longer

minispares when purchasing their valve springs have a data sheet which gives you the full correct rules regarding valve seat pressures etc ..... iam going to type this up later and up load this to the FAQ section.

mini1071s Pete has calculated that on full ramping lift the cam and the followers experience pressures in excess of 200000 psi

no wonder your race cam wears out.

like i said the above is only a guide to help things live longer.

Edited by BENROSS on 24th May, 2006.

Great!, cheers for the advice benross, ill have a look and tell you how it goes

Rich

thats 350thou and 390thou valve lift, working on std rockers with 1.2:1 ratio as a rough average, that makes 291thou lobe lift and 325thou lobe lift. Thats a lot of lift, infact thats near race cam lift, no wonder it doesnt last long.

Does that mean that you've got a low rpm engine, compared to engines with similar lift i.e race engines, but with a cam more at home in a race engine. No wonder you guys are finding shagged cams under road miles.

To put it in perspective the SW5, a road cam designed to last, runs 280thou lift.

Edit, that may not be all that usefull, i've only just realised myself what the avonbarph2 is doing. muttermumblemuttermutter

Edited by andeh on 24th May, 2006.

I've seen the future and tbh its Pie