I'm the proud new owner of a new-to-me 1974 260z. The speedo doesn't work. The previous owner said he thought this was a chronic problem with this model. If it is, what the fix. Also, I think the carbs have been changed over to dual Weber DGV's. This is based on the fact that the SAU on my 1976 MG Miget is side draft. I know I need to do some further research, but can anyone recommend a good book for adjusting the Weber?