Fuel altered (1 Viewer)

[da snake]

I have a 426 fuel altered with a 390 rear and a 19% first gear. I have been told two different times to shift. Firstly I was told to Shift early then I was told to leave it as long as possible. I left it till just pass half track on our last run and blew the blower off just after I shifted. We are allowed a 1471 20% overdriven. Single pump with no more than 25 gpm. We have no high speed lean out. We did run 171 mph at the 1/8th but a 6.7 and 171 mph at the 1/4. Any advise would be much appreciated.
Tony.

 

[Spanky]

pm'd ya with a few ??s

 

[Ronny Robinson]

Best I can figure at that speed with that gearing you were at or above 7700 when you shifted. Depending on your percentage, most older single pump fuel combinations seldom saw much over 6500-7000. If you went over the point of keeping the load on the engine, you probably put some cylinders out which may have lifted the blower when you shifted. Alky likes to be hi-shifted, while Nitro likes to be lugged down, you'd definitely be better off to short shift. Also, stay away from using the hi-speed until you get a good handle on your baseline tune-up. The small gains you might get aren't always worth the pieces you melt in the process. JMH (no real experience with Nitro) O.

 

[da snake]

Thanks Ronnie I have since found that the throw out bearing carrier we put in was to long and was holding the fingers from locking the clutch up. So this would back up the over revving theory.
Thanks,
Tony.

 

[Ronny Robinson]

Ouch, sorry to hear that Tony, hope there was minimal damage. I'm running a Crower 3-disk for the first time this year, it's definitely a learning process. Hope the rest of your season goes better.

 

[da snake]

Thanks Ronnie your right but if it was easy everybody would be doing it. Have a look at our web site www.venomracing.co.uk our cars look very similar. Do you have a web site. We are running the 4 disc clutch but this may be a bit over the top but it was as we bought the car so have stuck with it.