470 Head Bolts - Re-torque every Spring?

[blkzoe]

All:

Rebuilt one of my 470's last winter (2013). Ran like a champ after rebuild. A thought occured to me in reference to the head bolts. They were torqued in accordance with guidance from the Mercruiser manual; and re-torqued after the initial warm-up.

THE QUESTION: Does anybody re-torque their head bolts after their initial Spring fire-up? The reason I ask is because of my European sports car experience where tightening head bolts evey 10000 miles can be standard practice. The notion of re-torquing every Spring isn't very different.

Just askin..........

BTW; am rebuilding my other 470 as of this message. New bearings, pistons, rings, total seal package, head grind, etc. It's an enjoyable sickness.

 

[stonyloam]

Re: 470 Head Bolts - Re-torque every Spring?

I never have. I do like to run a compression check every year.

 

[flipbro]

Re: 470 Head Bolts - Re-torque every Spring?

What kind of sports car do you have to torque head bolts every 10000 miles?

 

[UncleWillie]

Re: 470 Head Bolts - Re-torque every Spring?

Head bolts are usually spec'd to tighten the Bolts/Studs just to the yield point of the Bolts/Studs.
If you want to re-torque them you will need to loosen them first which will require replacing them because they have already been stretched to the yield point.

 

[matt167]

Re: 470 Head Bolts - Re-torque every Spring?

The old Rambler 6cyl, you had to retorque the head bolts every other oil change or the gasket would pop ( right from the factory service manual ), but that was an engine designed in the late 30's and moderately updated until it was replaced in 1966.. Not saying other vehicles don't need this kind of maint, but I'd have to say the 470 mercruiser does not require it.

Now, the reason that you 'might' want to do that, is the fact the block is aluminum and the head is cast iron, so different expansion/ contraction's opposite of 'normal' engines that use aluminum heads on cast iron blocks... To counteract that, you can get a set of aluminum heads. Does not need to be real special castings just make sure they have BBF exhaust flanges and not BBC.. It's an extra $1-2k for the heads/ parts but it would get more HP too. 470's are all closed cooling so even saltwater is only an issue for the heat exchanger and exhaust manifolds anyway

 

[stonyloam]

Re: 470 Head Bolts - Re-torque every Spring?

Now, the reason that you 'might' want to do that, is the fact the block is aluminum and the head is cast iron, so different expansion/ contraction's opposite of 'normal' engines that use aluminum heads on cast iron blocks...

I would guess that is why you retorque after bringing it up to operating temperature the first time you run it.

 

[matt167]

Re: 470 Head Bolts - Re-torque every Spring?

Certainly part of the recommendation agreed.

 

[blkzoe]

Re: 470 Head Bolts - Re-torque every Spring?

What kind of sports car do you have to torque head bolts every 10000 miles?

Alfa Romeo Spider '83

MGB

 

[flipbro]

Re: 470 Head Bolts - Re-torque every Spring?

Alfa Romeo Spider '83

MGB

O wow very interesting! Were these aluminum heads?

 

[blkzoe]

Re: 470 Head Bolts - Re-torque every Spring?

All:
Came across this article on head bolts; more than you ever need to know! Check out item #10; very important for 470 owners (and I didn't know that).

Perfect Engine Sealing Starts With Proper Head Bolt Use - Engine Builder Magazine

 

[blkzoe]

Re: 470 Head Bolts - Re-torque every Spring?

O wow very interesting! Were these aluminum heads?

No. regular iron.