Technical BBC Question

[Hotcrusader76]

What size bolt threads into the crankshaft snout on a BBC?
Ya know the one that secures the harmonic dampner to the crank? Is it a 1/2-20?
Please advise...

[Rexone]

yes it is , and we've got a bitchin ARP 12 point 190,000 psi bolt for it too.

[Hotcrusader76]

Rexone:
yes it is , and we've got a bitchin ARP 12 point 190,000 psi bolt for it too. Guess I need to have Jay add yet another misc part...
This freakin motor is killing me....stripped crank snout (new helicoil), three stripped head bolt threads (three new helicoils)...what gives!
If I new this was going to happen, I would have opted for another block. But no worries....I must press on.

[Rexone]

GM blocks are notorious for stripped head bolt threads. It is because they are tapped through into the water jackets and the ends of the stock head bolts rust because they stick through. Then when removed, they bring half the thread material out with them. Age old problem. And you don't find it till you go to bolt the heads back on. Studs are one fix. Crank stripping is not as common to my knowledge but very fixable with the helicoil.
That's why I like Merlins. They are blind hole in the block (and more thread). Good luck with it Ty.

[Blown 472]

Rexone:
GM blocks are notorious for stripped head bolt threads. It is because they are tapped through into the water jackets and the ends of the stock head bolts rust because they stick through. Then when removed, they bring half the thread material out with them. Age old problem. And you don't find it till you go to bolt the heads back on. Studs are one fix. Crank stripping is not as common to my knowledge but very fixable with the helicoil.
That's why I like Merlins. They are blind hole in the block (and more thread). Good luck with it Ty. Hummmm, fords dont go into the water and they are counter bored so when you deck the block you dont get into the threads, some good stuff you have there.

[Hotcrusader76]

Rexone:
And you don't find it till you go to bolt the heads back on. .
No sh*t! I had to pull the left head three times already because of the threads snapping...
I have gone to bed at night having nightmares about the head tightening sequence

[058]

GM makes engines?

[Rexone]

058:
GM makes engines? Yeah they just screwed the head bolt deal up.
Ford made the head bolts right but screwed the rest the engine up. Go figure.

[Blown 472]

Rexone:
058:
GM makes engines? Yeah they just screwed the head bolt deal up.
Ford made the head bolts right but screwed the rest the engine up. Go figure. For the sake of debate, the only thing wrong with the fords is the exhaust port, throw a set of blue thunders with the oh so great chivvy exhaust port and whaa laa chivvy killer.