Camshaft retaining bolts (sprint)

[cleverusername]

Does anybody know the correct strength rating for these? I can't find the bolts for sale anywhere and since I would prefer them not to shear; I would like to buy bolts that are strong enough for the job.

[soe8m]

These two aren't up for the job anyway, even in a stronger variant. They would be 10.9 or 12.9.

You can drill two extra holes to have 4 in total but better would be using 4x 5/16 bolt.

Jeroen

[cleverusername]

These two aren't up for the job anyway, even in a stronger variant. They would be 10.9 or 12.9.

You can drill two extra holes to have 4 in total but better would be using 4x 5/16 bolt.

Jeroen

Are you sure about those strength ratings? The bolts supplies are selling for the camshafts on a Stag are only grade 5 (three lines on the bolt).

If the bolt is too hard, isn't it going to be brittle and be in danger of fracturing?

[trackerjack]

Well this has to be a first for me as on this one 12.9 would perhaps be too high a tensile strength for this application. 8.8 (grade 5) 1/4 UNF would be the correct to absorb the shock and I agree with Jeroen that 4 off bolts are better and I have a drill jig that I use to drill both the cam and the sprocket and I tap the holes 6 mm on the extra 2 holes so that the timing cannot be done wrong.

When visiting Thruxton race meeting a few years ago a dolomite sprint had wrecked its engine when the cam sprocket broke free which prompted me to add 2 more bolts. When I build an engine for someone I offer this mod.