48 IDF jetting.

[Jac Mac]

Originally Posted by Caprimaniac

Hi, Jac.

Where do you find those jetting info's? My John Passini book isn't as fine- tuned as your data.

Sounds like the 41 mm off- the- shelf mains are the way to go.

No; it will not run @ 8000 continously, I'd say. But Eagle sayz 8000 is fine with the "2000" rod bolts.

I was quite sure the long rods opt'ed for longer dwell period and less rod/ cylinder wall angle which again means it will take more beating.

So, what are you refering to whan you say it can't stand the 8000 rpm beatin'? Rotating mass?

Regards
Rune

Rune,
I have a (very) old setup book from Warnefords in Australia which gives baselines for IDA's etc ( No IDF- they had not been thought of). It has been very close to the mark with most stuff I have fitted webers to & the jetting should be transferable to IDF's since they are similar in principle- at least it has been so to date on other guys stuff I have made recomendations on. Book is out of print now )

Weber jetting is configured around two main items- individual cylinder size & chosen choke( main venturi) size. Once you have chosen those with consideration to an honest assessment of how you will operate the car, then you choose your main jets-air correctors- emulsion tubes- pump jets-secondary/aux venturis. Camshaft choice is very important as well- webers dont like close lobe centers such as those used on many modern sprint/circle track motors from todays world.

While the 5.4" rod in your 347 is longer than the std 302 ( 5.09" ), your actual rod ratio in the 347 is 1.588/1 where the 302 is 1.696/1. Not saying it cannot or wont rev to 8000, just that its asking a lot with that ratio & rod angle. The rotating mass isnt a concern- piston dwell duration at TDC ( shorter ) is.