Drilling/Tapping of Manifolds

[haulnazz15]

Has anyone has success/experience with drilling and tapping holes in the cast-iron exhaust manifolds? I am probably going with the center-riser conversion on my engine and the water-fuel separator was mounted on a bracket to the old log-style manifolds. There is absolutely no other place to mount the separator on my boat due to the gas tank being about an inch from the port panifold, so there's no place in between the tank and the engine I can put it.

My thought was to just drill/tap two small holes on the front of the new manifolds to mount the bracket. I would be using a thread sealant and SS bolts. Does anyone see why this wouldn't work? I don't know if the cast-iron could be tapped successfully, and I wouldn't want to pierce the water jacket, although I don't need more than 1/8-1/4" deep or so.

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

Ok, no joy on that one huh?

I was also thinking what about having a couple of nuts welded to the outside of the manifold to receive the bolts from the brakcet. This seems like a little safer idea and should hold as well as drilling/tapping would. It would just push the bracket out by the width of the nuts welded onto the outside.

ANyone find any problems with that theory?

 

[John_S]

Re: Drilling/Tapping of Manifolds

I don't particularly like either idea. If you have to mount it to the exhaust, can you make a bracket to mount the other bracket to? Make something that mounts to existing bolts (or get slightly longer ones), either exhaust manifold mounting or riser bolts. Just a thought.

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

Well the issue is that there are NO bolts on the front or back of the newer manifolds, where the log-style can caps on the front/back of the manifolds which were held on by bolts. I can't think of another way to mount the fuel separator bracket except by creating a mounting point. There isn't any way to simply strap it to the manifold.

 

[JustJason]

Re: Drilling/Tapping of Manifolds

Why don't you just buy new fuel line and mount the filter housing someplace else. There's virtually no limit to the length of the fuel line.

 

[Bt Doctur]

Re: Drilling/Tapping of Manifolds

Really need some kind of pic to better understand your issue.
Having the gas tank that close is very strange too. You`ll never remove the old bolts??????

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

I suppose a pic would help, but let me see if I can explain it first. The fuel tank sits on the port corner of the transom and extends toward the center of the boat to within an inch or so of the port exhaust manifold, so there is nowhere to mount the filter/bracket unless I wanted to run a fuel line behind/underneathe the engine to the starboard side. Then, a line all the way back to the port side of the engine where the fuel pump is. (Ford 351w)

As you can see, that isn't really that pheasible. So in the interest of making things simple, I was going to try and mount the bracket on the port exhaust manifold just like it was from the factory, except the newer manifolds don't have an end-cap with bolts to secure it with. I'll upload some pics of the old setup, and a pic of the new manifolds to better explain what I'm talking about.

Alright, top photo is my engine/original setup. You can see the inline fuel filter which is right next to the big aluminum (or galvinized steel) fuel tank.

The next picture is a center-riser kit on an inboard 351w, but same idea. Manifold has a single hose fitting on the front, but no bolt/cap to secure the bracket.

 

[Bondo]

Re: Drilling/Tapping of Manifolds

Ayuh,... Please resize the pictures to 640x480,... These screw up my screen...

You can use the foreward manifold retaining bolt,+ another from the front of the head...
Maybe a piece of strap iron, with a few bends to make a corner bracket...

Don't drill or weld the manifolds....

 

[Howard Sterndrive]

Re: Drilling/Tapping of Manifolds

Don't drill or weld the manifolds....

ditto

in cast iron, you can hit a sand pocket or other weak spot with a drill
cast iron is goofy

 

[John_S]

Re: Drilling/Tapping of Manifolds

Does it have to be mounted to the engine? Not sure of the specific rules, but believe it just has to be "solidly mounted". Others here will probably know.




A couple of things you should check on:

- The fuel pump in your picture appears to be an automotive one, or at least the sight tube is hidden. You can see it on the 2nd ie inboard pic.

- Not sure if the inline filter before the water sep, is to the rules. I know you can't have it after the pump.

 

[sparky71]

Re: Drilling/Tapping of Manifolds

I converted from log style to center rise manifolds (Barr style)and i purchased a bracket to work with the center rise manifold.I believe it was right from barrs website.Not sure it will work for you but worth a try...would be better than drilling and tapping,eek...it was not very expensive either...hope this helps

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

A couple of things you should check on:

- The fuel pump in your picture appears to be an automotive one, or at least the sight tube is hidden. You can see it on the 2nd ie inboard pic.

Well, the fuel pump in my picture has a rather large protrusion with a sight glass on it (you can see it next to the fuel line running to the carb)

- Not sure if the inline filter before the water sep, is to the rules. I know you can't have it after the pump.

The inline filter will not be used on the new setup, we were trying to diagnose a problem out of the water. (ended up having mud/sand in our fuel tank from mud-dobbers/horses kicking up dust)

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

I converted from log style to center rise manifolds (Barr style)and i purchased a bracket to work with the center rise manifold.I believe it was right from barrs website.Not sure it will work for you but worth a try...would be better than drilling and tapping,eek...it was not very expensive either...hope this helps

I'll definitely look into it, as I'm gonna be spending $700 on all the manifolds/risers/hoses/etc, what another $50 or so for a custom bracket to fix my problem?!!

 

[sparky71]

Re: Drilling/Tapping of Manifolds

Look at barrmarine.net...you'll have to look around cuz it doesn't look like those mans you have are barr mans.still might work tho...think it is less than $50...good luck

 

[wire2]

Re: Drilling/Tapping of Manifolds

Cast iron does drill & tap readily (the chips look like black sawdust) but it's not a good idea on a manifold that constantly cycles hot/cold. There's no way of knowing how thin the manifold is at that spot.

If you prefer the bracket in the same place, consider a saddle mount on the manifold water inlet connection. Cut a 1?" long piece of 1" black pipe in half longitudinally, weld a piece of 1/8" sheet on the middle of it vertically, with holes to bolt the w/s bracket on. Paint it and clamp it on over the hose with 2 gear clamps.

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

I did go to Barr/Osco Marine and searched around and *may* have located something. It is listed as a fuel filter bracket which mounts onto the engine head (appears to be L-shaped) so it would relocated the filter basically over the fuel pump instead of to the right of it. If I can eyeball it and see where the bracket would mount, it may be the ticket and it was less than $15. I'm going to do some snooping when the new engine comes in today.

BTW, the manifolds I'm replacing the log-style with is a conversion kit from OSCO but the general idea is the same as the Barr models.

 

[haulnazz15]

Re: Drilling/Tapping of Manifolds

Look at barrmarine.net...you'll have to look around cuz it doesn't look like those mans you have are barr mans.still might work tho...think it is less than $50...good luck

Sparky, what does the bracket look like/bolt to? I found this part at ebasicpower oscflcr-fb and it is basically an L-bracket that bolts to the head. It says fuel filter bracket, but doesn't list exactly what its purpose is. you think this is what you have? It's only $11.