Engine tin screws, Just need 4 Options

[rjames]

What size are these things? I just need four of them so I don't want to order a full set (which is how they are being sold by the various 914 vendors).

[Literati914]

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?

[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

[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.