[orionlearn]

Simon, I am late to this thread, so I may be offering some ideas that have been said already.

My first thoughts are that your 770 maybe too large. Your cubes, a guess at your VE being a max of 105% and a 5500 rpm high end would yield a need for a 683 cfm carb. The lean bogg at the lowend would indicate a big gulp of air. This combined with a a2f of 14 would create a lean bogg.

I agree with others that you want to be at 12.5:1 to help richen up the mixture. Also, 32 or 35 shooters should help, but I have noticed a similar problem when using the cast shooter vs. to holley shooters with extended brass inserts.

All said, you won't hurt the engine at 14.7:1 or below. With the price of fuel in the UK, I would live with the slight bogg!

Best Regards,

Bob