Plan instructions for the ARF I am currently assembling calls for a firewall-to prop distance of 4.5 inches. The rear mounted carb of the OS FS-70 II Surpass and the engine mount makes this impossible. Moving the engine as far back as possible leaves the prop too far forward about 3/16 inches. Will this have any significant impact on how my model flies? The model is a WM Rambler 45.