Engine tin screws, Just need 4 Options

[bbrock]

I'd been thinking for a long time about trying some stainless "cap head" screws (rounded head / allen socket), rather than the more squared off shoulder of the original cheese heads .. (if I can find them in M6x12). Just think they'd look better - but is there any reason those would be a bad idea?

Well, the original steel fasteners are pretty bad. Hard to imagine it getting much worse. I'm a bit of a stickler for originality but refuse to put those back in. But out of curiosity, I googled galvanic corrosion of stainless and aluminum. It seems an SS fastener in an aluminum block will be no problem, but an aluminum fastener in an SS block would be a big problem.

[bdstone914]

Well, the original steel fasteners are pretty bad. Hard to imagine it getting much worse. I'm a bit of a stickler for originality but refuse to put those back in. But out of curiosity, I googled galvanic corrosion of stainless and aluminum. It seems an SS fastener in an aluminum block will be no problem, but an aluminum fastener in an SS block would be a big problem.


@Brent

You can get SS cheese head screws. I still find them PITA to remove and install in tight places.
I am going to add blue Loctite to the ones I install in my engine. Wonder if anti seize will stop galvanic action or affect negatively the torque holding ability.
Bruce

Can you post that information about corrosion? Very interesting. Maybe the aluminum fastener is weaker?
Thinking about the SS screws at the bottom of the bad pad that go through an aluminum sleeve. They corrode badly.
Bruce

[barefoot]

Death to the cheesheads !!! I replaced every one of them with SS socket head screws.
MUCH easier to deal with.
Barefoot

[bbrock]

Can you post that information about corrosion? Very interesting. Maybe the aluminum fastener is weaker?
Thinking about the SS screws at the bottom of the bad pad that go through an aluminum sleeve. They corrode badly.
Bruce

Here's one of the sources and I found a couple others that said basically the same thing. https://www.bssa.org.uk/topics.php?article=89
It appears what is important is the ratio of cathode to anode. Since aluminum is the sacrificial anode in this pairing, a small aluminum fastener in a sea of receiving cathode will quickly corrode away to the point of failure. But in the reverse, the small amount of cathode in an SS fastener can't receive enough of the surrounding aluminum anode material to significantly damage it. I thought that was fastenating... see what I did there? (IMG:style_emoticons/default/lol-2.gif)

Interesting idea on the SS cheese heads. Might be a good option for the most visible and accessible screws. I wondered the same about locktite or anti seize.

[jd74914]

Can you post that information about corrosion? Very interesting. Maybe the aluminum fastener is weaker?
Thinking about the SS screws at the bottom of the bad pad that go through an aluminum sleeve. They corrode badly.
Bruce

Here's one of the sources and I found a couple others that said basically the same thing. https://www.bssa.org.uk/topics.php?article=89
It appears what is important is the ratio of cathode to anode. Since aluminum is the sacrificial anode in this pairing, a small aluminum fastener in a sea of receiving cathode will quickly corrode away to the point of failure. But in the reverse, the small amount of cathode in an SS fastener can't receive enough of the surrounding aluminum anode material to significantly damage it. I thought that was fastenating... see what I did there? (IMG:style_emoticons/default/lol-2.gif)

Interesting idea on the SS cheese heads. Might be a good option for the most visible and accessible screws. I wondered the same about locktite or anti seize.

I used standard antisieze (copper base IIRC) as a barrier and haven't had any issues with corrosion or loosening. In fact I took some out after 15+ years of install the other day and they were still tight, but unthreaded easily.

Definitely a worthwhile change. I don't even want to think about how much time I spend drilling out the originals and retapping. (IMG:style_emoticons/default/barf.gif)

[euro911]

I used the S/S Allens (from 914 Rubber) on the 'BB's motor.




That reminds me, I need to add another set to my cart for 'HOWARD's motor (IMG:style_emoticons/default/idea.gif)

(IMG:style_emoticons/default/type.gif)

[worn]

Death to the cheesheads !!! I replaced every one of them with SS socket head screws.
MUCH easier to deal with.
Barefoot

The only downside that I find is that you can not retrieve them with a magnet. In some applications the softness of the season fastener is an issue.

[Mikey914]

The screw are 316 stainless, so yes a magnet will not work. As far as softness does 316 has more nickel in it so it's not a soft alloy. More than adequate for sheet metal. The Allen head actually will take much more torque than a cheesehead screw.