Selecting Carburetor Choke Size
Posted: November 1st, 2008, 6:59 pm
Hi Guy,
I have found quite a bit of info on selecting carb choke size based on bhp and rpm but the result seems to differ depending on the source of the information.
Would a good basis for selecting choke size for my Dellorto 45's be the peak flow of my head? When you tested it for me you found it peaked at 105CFM @10' depression and 10.4mm lift (results below)?
In your 'General Tuning Hints' section of the website you say that a 33mm diameter hole will flow 102 CFM @10' depression. For a larger hole the flow will increase by the ratio of the radius/diameter squared. Based on this, for my choke to flow 105 CFM, I would need:
105/102=1.029
(33^2) x 1.029=1120.581
Sqrt 1120.581=33.475mm choke (round up) 34mm choke
Is this a good way to look at it?
Thanks,
Ben
I have found quite a bit of info on selecting carb choke size based on bhp and rpm but the result seems to differ depending on the source of the information.
Would a good basis for selecting choke size for my Dellorto 45's be the peak flow of my head? When you tested it for me you found it peaked at 105CFM @10' depression and 10.4mm lift (results below)?
- BL peak flow.jpg (111.23 KiB) Viewed 5685 times
105/102=1.029
(33^2) x 1.029=1120.581
Sqrt 1120.581=33.475mm choke (round up) 34mm choke
Is this a good way to look at it?
Thanks,
Ben