robertfrost

Hello,

on my ´69 SB I have got a water pump with eight threadholes for two different bolt patterns for the fan clutch. My old fan clutch has used the bigger pattern. Now I have got a Hayden 2747 type fan clutch with slotted holes that can use the bigger and the smaller bolt pattern. I have chosen the smaller bolt pattern now as the four bolts/washers have a better contact area to the clutch flange then. I am using the 7 blade 2 1/2" blade pitch steel fan. Any risk the original grade 8 bolts may shear off when using the smaller bolt pattern?

thanks & regards

Fred

TimAT

All of the engineering stuff (I did a quick Google search for Grade 8 shear strength) came in at about 4400 pounds for a 5/16 grade 8 bolt. IMHO, I don't think you'll have a problem.