Volksie heads are inherently poor performers on the intake, and most off the shelf heads flow more on the exhaust than some heads guys want, when compared to what can be achieved with the intake.
This combo with the 1.25's on the exhaust, is reducing the lift on the exhaust to effectively decrease the flow that he would have had if all the same ratio's were used. It changes the flow ratio of exhaust to Inlet.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Well, not such a 'problem', but when your chasing every ounce of performance, and who isn't, there is a flow ratio to aim for. It's the same principle that is used when deciding the valve sizes. A smaller exhaust valve is used as once the combustion has occured, the increased temperature and burnt gasses don't need as much space, and this gets optimised, same for the ports and exhaust system. It's the fine tuning of these areas that customises an engine for a specific aplication. Such as, a bigger exhaust for more power but less torque and visa versa.
And it's better than being exhausted..... and way better than constipation !!!😂
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Some talk with Col at Eastern creek and also with Craig T this weekend got me thinking; Col said put some 1:1 rockers on the exhaust valves but I though why not go bigger with the intake instead?
Would some 1.25:1 rockers on the intakes be ok with a Pobjoy 37/68 Cam?
Would anything need to be changed apart from the rocker?
Can anyone speculate as to whether this would help at all?
I have used 1.25:1 rockers on a 37/68 cam. It works well however it puts more stress on the valve springs, so if your springs are getting old you need to take this into consideration.
Oh yeah, I used em on intake and exhaust.
Probably not worth it; given the stocks clips still in use and stock valve springs...
Might look at doing it in 12 months after the motor is settled and I've had a chance to really open it up on the track
Cheers
Shaun
Good move. Get rid of the stock clips, and shim up with a bolt together shaft kit and preferebly swivel feet adjusters at the same time. If your doing up the heads now, the adjusters should go in now while the valve tips are all fresh.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
