What lobe separation for quad webers?

[347]

I am doing my homework on solid roller cams to put into my 11.1 comp 347.

It has 48 ida's etc. 4.1 diff, tremec 3550,Its rarely street driven see's mainly track days.

Would 106 or 108 or 110 or 112 lobes be the best choice for webers? Or doesnt it matter?

Cheers Dave

[quickjack]

According to Inglese and Cam Techniques, 110 degrees is about optimal. Overlap needs to be minimal for low rpm good behavior. This would be less of an issue on a race only motor, as low rpm manners are not so important as top end power.
I would consult a cam grinder who has experience with Webers (Cam Techniques is a good one), as every engine combination and application will vary somewhat.

[Frank Messina]

I recently spoke with with a guy I met that had Webers on a 347 in a GT40 and asked him how he got the cam figured out. He told me he got his cam grinder ( Comp Cams) to call his carb supplier ( Inglese) and they worked the numbers out. He's thrilled with the way it runs. Made sense to me.
Frank

[nanard289]

Originally Posted by 347

I am doing my homework on solid roller cams to put into my 11.1 comp 347.

It has 48 ida's etc. 4.1 diff, tremec 3550,Its rarely street driven see's mainly track days.

Would 106 or 108 or 110 or 112 lobes be the best choice for webers? Or doesnt it matter?

Cheers Dave

Hi Dave
According to your trans and engine characteristics we understand that you have a race car and your expected power will be above 400RWHP. If you want to have a high rev engine (with a top end power) you have to select a 106 or 108° cam (according to the different track characteristics). Then, it is always possible to tune your webers to adapt them to your selected came. It is obvious that many people use Weber carbs with a common 110° lobe separation but it is mainly for street use. By this way you will probably select 42 mm venturis (may be 44mm for long track) instead or 40mm that is a frequent choice for street use