Exhaust Bolts
 

Replacing my stock exhaust with Gil aluminum manifolds. Grade 8 or stainless bolts?

Stainless. The torque spec is 25ft-lb, shouldn't need the extra strength and would lose corrosion resistance.

+1. Trying to remove exhausts i put on the hatteras 5 years ago. Bolt heads corroded down so it is a serious problemo.

and use antiseize

not a good idea using stainless with aluminum...disalike metals

How is that even a real concern? Your exhaust bolts should never be submerged, much less for prolonged time. Secondly, if it does bother you just add an anode (which won't do anything because your engine compartment shouldn't be flooded, but I digress). Sure, you could use an aluminum bolt but youve just moved he corrosion cell to another area.

Ideally wed use like materials always, but in reality that isn't always the case.

this always makes me laugh, so the stainless fittings threaded in for the water passages are ok but don't use stainless bolts to hold them on to the heads? Lol

Exactly! The galvanic corrosion stuff gets parroted because most don't understand it. You need ample electrolyte to make it work (what plants crave, lol). If your exhaust bolts are in that condition they're not even on your priority radar.

Like worrying about stainless seel valves, steel springs/retainers/cups, on aluminum heads....LOL.

However, if using stainless bolts in aluminum heads, please,,as noted above...use some antiseize. I prefer copper antiseeze because I just do.

i like the nuclear grade antiseize because,well because i get it for free.

I got all new stainless header bolts @ https://www.boltdepot.com/
Great prices, fast shipping.

I always like to let them go thru a heat cycle and while they are still warm give the bolts an extra quarter turn.

You could use blue Locktite or a non-metallic anti-sieze.

Ayuh,..... I was always an Anti-seize kinda guy, 'n have used mostly the nickle based anti-seize on 'bout anything, 'n everything, bein' a heavy equipment/ heavy truck Mechanic by day,...
Of course, as I transitioned into Boats over the years, I also carried with me my Anti-seize habits,...

'n bein' a freshwater boater up here in the sweetwater seas, I never had much of a problem with corrosion anyways,....

Over the years I've been postin' at iboats forums, I became very good friends with Don Sindledecker, the rather famous Don S, who unfortunately, pasted away 2 years ago this July,......
Don spent most of his career in Ketchican Alaska, movin' down to seaside Washington state for his last few years,....
Anyways, Don S was a Loonnngggg time Saltwater boater/ Mechanic,....
Don S always called Never-seize, Ever-Seize,....
After much discussion on the matter, I tried Don S' routine, which is to coat bolt threads with,... Quicksilver Perfect Seal,... aka: Form-a-gasket, #3,.....
Now that several years has past, 'n I'm removin' bolts I bathed in Perfect Seal, insteada Never-seize, I can tell ya,.....
Perfect Seal, seals the threads, 'n pretty much Stops corrosion,...
Much, Much Better than Never-seize,....

While I still use Never-seize on occasion, Perfect Seal, aka: Form-a-gasket #3 is my "Go To", rather than Never-seize,....

I have been using grade 8s on my gils for 6 years in fresh water with no issues at all

The stock bolts that came from Merc with Gil exhaust were SS Allen head socket caps.

And stainless and lowes grade steel bolts are just as dissimilar to aluminum anyway.

Most of the hardware stainless bolts around here are as soft as chapstick. Buyer beware.