9 replies to this topic

[liam1288]

Hi guys, I have a 1275, hif44, full maniflow system with a Kent 266 cam... At the minute, I have some 1.5.1 roller tip rockers but they are a tad tappy and to be honest, didnt really give much more power... So I'm thinking of changing them either back to standard or maybe some 1275 gt rockers, possibly minispares 1.5 high lift forged rockers. Though would doing this just have the same affect as the roller tips on at the moment? Or would the minispares be slightly better?
Cheers

[KernowCooper]

MG Metro Type rockers are pretty good, and the 1.5s may only give a couple of BHP at the top end so I'd not spend the money for a road engine and would try the later A series MG Type, just my opinion.

[liam1288]

Thanks for the reply mate! Would those mg type be fine with coping with the 266?
What ratio are the mg type?

[KernowCooper]

I have the MG Metro Rockers on my 1330 with a 276 cam and works perfect, and as far as I know they were fitted to A+ and turbos and should be 1.3:1 standard ratio. But some say they vary as much as 1.25:1 when actually measured.

Edited by KernowCooper, 25 June 2013 - 12:42 PM.

[liam1288]

Ahh right so would the standard ones be just as fine then? It's a converted spi to carb model. The ratio would be the same right?

[Cooperman]

The later 1275/MG rockers are the ones used on the MG Metro which has a cam almost identical with the 266.

It does seem that 1.5:1 rockers don't give much advantage unless the cam is very mild. I gained 2 bhp when I went to 1.5:1 and that was only above 5700 rpm up to about 7200 rpm. Below that I gained nothing, but think I lost a bit of torque lower down below about 3000 rpm.

[liam1288]

Yeah I think I lost a bit on the bottom end... So fitting my old standard 1275 ones should be the same as the mg ones.

If I went for gt ones I heard they are about a 1.4.1 ratio but not sure plus I think they will be hard to find.
The minispares forged ones will just give the same as what I'm running now right?

[carbon]

Liam - surprised that the 1.5 ratio rockers did not make much of an improvement with your engine spec.

 

I swapped from A+ rockers to offset forged rockers on a 1293 with MD266 and RC40. Very noticeable improvement in top end, some loss in bottom end response just past tickover but by altering ignition advance curve got most of this back.

[krusher74]

I would have though higher ratio rockers would improve lower end tq as they would produce more valve lift early in the cycle, 

[ACDodd]

Erm no, when comparing high ratio rockers with standard, they increase valve overlap, meaning less low speed torque/higher idle emissions.

 

AC