high ratio roller rockers

[Clay Head]

Does anyone have any experience of using the 1.69:1 roller rockers as opposed to the 1.54:1 standard set?

 

I am running an A6 cam in my x-flow and with some careful work by Dave Brooks in Crewe the cam timing has been optimised to give 132lb ft torque at 5900 rpm and 169 bhp at 7200. However we feel that high ratio roller rockers may lift both torque and power while being a little easier on the valve guides. Any views and any sets for sale?

[Peter T]

Any roller rocker will alleviate wear on the valve train compared to standard components. I have not had experiance with high ratio rockers, only standard ones. One important piece of advice is to check the instalment height, as when i checked mine i found it to be out . Not sure that changing to a higher ratio will increase torque, but possibly only move it lower in the rev range. I am sure that Roger King can explain in more detail !

 

'Ready Steady'

[Anthony]

Hi, suggest great care here. Appreciate cams are different by high ratio on 264 cam will destroy engine

 

264 has 12.52/47 lift and 310 duration

 

A6 has 10.36/21 lift and 304 duration

 

Assume 169 is dyno figure or RR figure adjusted to remove assumed transmission loss. If RR at wheels wow 😬

 

Anthony

 

No engine, but 4 wheels, gearbox, diff, tank, loom, dash and now Nitrons...and a trial fitted block ( hurray !)

 

 

 

 

[Joe 90]

Roller rockers have made a fantastic improvement to my valve guide wear. It seems a bit unlikely to me that high ratio rockers will give you a better power curve with the cam you've got. It sounds like you know what your doing mechanically, but I would still advise caution, because you are in the territory where a mistake would be expensive.

 

Upgradeitis ward, awaiting open wallet surgery. 100,016 miles

[cdg]

Tim,

 

High ratio roller rockers will work very well with an A6 cam. I think you will see an improvement in both torque and power. With a similar spec. cam, high ratio rockers etc. my old 1700 made 175bhp (dynoed) on 45Webers, and 180bhp on TBs. You won't have any installation problems as the overall lift will still only be 11.5mm (similar to a 254)

 

Trust Dave...if he thinks it should work, it probably will!

 

Cheers,

Chris.

 

 

[Clay Head]

Thanks for replies

 

Chris - Great guy Dave and I definately trust him with anything mechanical. We thought it might be worth seeing what others had done win the hope of picking up some 2nd hand roller rockers. The extra lift will give the torque hopefully while the timing and duration will maintain the smooth power delivery at usable revs for road and with non-steel bottom end.

 

Thank God you put me onto him - I owe you a pint if we ever meet!