riser bolts too long

[hoodooman]

Morning,
I'm converting my 1998 4.3 i/o from the single piece batwings to a brand new two piece genuine mercruiser setup. the riser bolts i received in my kit are approximately 1/8 - 1/4 inch too long. they bottom out in the exhaust manifolds before tightening up on the risers. should i add washers under the bolts or cut them? threads are all nice and clean. this is the last issue i figured i'd have.

thanks for any input. my first time doing this job.

 

[Bondo]

Morning,
I'm converting my 1998 4.3 i/o from the single piece batwings to a brand new two piece genuine mercruiser setup. the riser bolts i received in my kit are approximately 1/8 - 1/4 inch too long. they bottom out in the exhaust manifolds before tightening up on the risers. should i add washers under the bolts or cut them? threads are all nice and clean. this is the last issue i figured i'd have.

thanks for any input. my first time doing this job.

Ayuh,...... Welcome Aboard,....... I'd probably cut the ends off, 'n clean up the threads after, myself,....

 

[Lou C]

A good thing to have, when doing jobs like this, is a set of thread chasers, both for threads and bolts, it will make your life a lot easier and avoid grief in the future! You want to clean up those threads where you have to cut them.
Good for you changing them before they leaked and ruined an engine.
I never had leaks with my OMC version of the same thing, but of course they became NLA, so I made my own conversion kit using Barr Marine aftermarket elbows and manifolds and Volvo Penta exhaust hoses/down pipes. Cost a bit more but fit like factory and no leaks.

 

[hoodooman]

Thanks for the input so far fellas. Guess I'll cut the bolts and chase threads. Conversion project has been moving along nicely until this hiccup. Put in new valve stem seals, fuel pump, impeller, blower hose this year. I've only ever worked on this boat. Just a Bayliner 1850, but has sentimental value. Bought from my FIL and he recently passed. Cosmetically, she's a cherry. Hopefully I can get her all back together for the season.

 

[airshot]

Are you sure the blind threaded holes are not filled with crap ? If used and aged, sometimes manifold holes get filled with rust and crud making them more shallow. Often a drill into the hole will bring out the crud, not going to drill into fresh metal, just check to be sure the hole in not filled with crud. Then run a tap into that hole to be sure the threads are good all the way down. Not an issue cutting off some of the bolt, add a nice changer after cutting, you should be good to go.

 

[hoodooman]

Are you sure the blind threaded holes are not filled with crap ? If used and aged, sometimes manifold holes get filled with rust and crud making them more shallow. Often a drill into the hole will bring out the crud, not going to drill into fresh metal, just check to be sure the hole in not filled with crud. Then run a tap into that hole to be sure the threads are good all the way down. Not an issue cutting off some of the bolt, add a nice changer after cutting, you should be good to go.

Thanks for the input. All parts are brand new and the threads and such are nice and clear.

 

[Scott Danforth]

Im with Bondo on this one, use a razor wheel and zip off the end..... dress them on the grinder

 

[hoodooman]

The bolts in my kit came with what looks like red loctite already on them. Is that a requirement?

 

[Scott Danforth]

I would use blue loctite or dip them in permatex #3 vs red

 

[Bondo]

Ayuh,.... Permatex non-hardening liquid for me,.....

 

[hoodooman]

So I called multiple fastener stores (fastenal, etc.) and no one had the correct grade 8 studs. Ordering them online would take a long time. You guys know how it goes with ordering parts for a project. It's hard to get all of the required parts on time to complete a project in the correct order. For example, I also ordered new mercruiser approved valve stem seals for my 4.3. while it's apart. Of course this needs to be done before the exhaust. Two weeks went by and they didn't even ship! All that time my new manifolds are sitting at the house. So, I went to autozone and bought FelPro seals which were a perfect fit to try and get my project back on course.

Anyhow, I shaved 5/16" off the bolts and they all torqued to spec (33ft lbs) just fine now without bottoming out. Now I just need to connect my upper bellows and elbow to the y-pipe and I *should* be off to the lake for a sea trial! I'll let you know how it goes.

As I mentioned I'm no boat mechanic and have never done marine exhaust before so we'll see how this pans out.

 

[Bondo]

For example, I also ordered new mercruiser approved valve stem seals for my 4.3. while it's apart.

Ayuh,.... Now that, is a waste of time, 'n money,.......
It's a Chevy motor, built with Chevy parts,....

Fel-pro is quality replacement stuff,....

 

[Scott06]

As I mentioned I'm no boat mechanic and have never done marine exhaust before so we'll see how this pans out.

Its not rocket surgery, if you are a decent shade tree mechanic with some tools, get the factory engine and drive manuals and ask questions here.

X2 what bondo said internal motor parts are stock GM stuff. the accessories that go on the long block are marine specific items. These engines are same parts on same line as chevy truck and industrial engines were made on.