The V8 Owners Forum -

I am wanting to use socket caps everywhere! So can anyone confirm what I think are the right bolts for an interim timing cover on a RV8. I have done this by educated guessing, so probably wrong! :


5 off 5/16UNC X 3 1/4"
4 off 5/16UNC X 4 1/2"

This is calulated from the depth of the timing cover, I found that it was 2.5" in places. 3.5" in other places. The water pump has a depth of 0.6". Taken into account the washers and an estimate of the gasket depths. I think this results in about 0.6" thread into the block.

5/16 UNC Bolts

Threaded section of bolt = 5*2/16 + 1/4 = 7/8" = 875 thous, allowing at least 675 into block but measuring my old timing cover and bolt lengths I believe it is designed to have just 600 thous into the block.

thickness of washer = 58 thous
timing gasket = 20 thous (approx as uncompressed)
water pump gasket = 40 thous (approx as uncompressed)


thickness of lower part timing cover = 2505
thickness of upper part timing cover under water pump = 3472
thickness of water pump = 600
thickness of upper part timing cover not under water pump = 3208


5 X lower bolts = 2505 + 58 + 20 + 600 = 3183 = 3 1/5"
3 X upper bolts = 3472 + 600 + 58 + 20 + 40 + 600 = 4790 = 4 3/4"
1 X upper bolts = 3208 + 58 + 20 + 600 = 3886 = 3 7/8"

These strike me as odd sizes, is this right!

Just found a reference to the right bolt sizes and I was close
5 X 5/16 UNC 3 1/8"
3 X 5/16 UNC 4 3/4"
1 X 5/16 UNX 3 7/8"