998 Tuning - 1.5:1 Rockers
Turbo Mini Forums

My current engine spec is a

std bore 998cc with flat top pistons,
12G295 head
Kent 276 cam
Hif 44 carb

Just wondering if I added 1.5:1 ratio roller rockers would I have a problem with valve to piston clearance, or would there be sufficient clearance retaining the 276 cam?

any help would be much appreciated.

Cheers, Jon

With respect, you would be waisting your time and money.

It's well documented somewhere that past a certain lift you will not see any gains. I'm sure that the 276 cam will provide as much lift as the 12G295 head will handle.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Heed Pauls advise, I have built a couple of fast road engines using the 12g295 casting, and couldnt get any gains from anything more than the kent 266, I had gains from pocketing the block and fitting a 12g940 casting, achieved 65hp very revy lively motor.
Shane

just jumping in there, my +80 998 with flat tops, morspeed phase 3 cam and mg 12g940..

is it worth 1.5 rollers, going to be placing my order and these were an item, would i be wasting my money

gaz

did you read the posts inthis thread?

I have to say that the second engine in this thread is quite a lot different to the first.

We have run +20 998s with 12G940 and 276 cams with and without 1.5 rockers and i have to say that it is better with. However with the same engine and the 295 head it was probably better without, but not by much.

edit to say: The engines were standard bottom ends that we rev to nearly 8k, we don't get many miles to the engine. these are not the same in any way to the 998 turbo motors we build.

Edited by Ben H on 2nd Oct, 2008.

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A man without a project is like a like a woman without a shopping list.

Don't forget the valve work is a lost work.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

foot, mouth, insert.

in my defense it was late.....and im a bellend!