Osco risers question

[Dreamweaver]

With 351s I have what is left of Osco CRR-1 risers which have a 10 degree down and have run across a set of Osco CRR-3 which have a 30 degree down.
Are these okay providing there is clearance or is there a rule to replace exact? I need two complete sets of exhaust systems sans the manifolds and they are at a good price. Thanks.

[prowlersfish]

I don't see any problem as long as you can get the exhaust hoses hooked up

[Dreamweaver]

I ended up getting them off of ebay New in the box sitting in somebody's garage for years for a c note,now I just need another set and a bunch of elbows to complete the system.

Another question,there are the risers then inline the rubber collar then a 3x12 aluminum pipe then rubber collar to the 90 degree,in the 1996 survey it mentions that the aluminum pipes are a no-no but they are still there and are in good condition are they okay to have or are the cast iron required?

I am going to have to have this re certified to have it renamed and transferred when it is done,does the Coast Guard flag this or is it considered unsafe or even a remote possibility of being unsafe?

[prowlersfish]

I don't see a issue , just see what the new survey says . ( they make aluminum marine exhaust manifolds )

[larryeddington]

My f28 is in shop getting repowered with new 318s as we speak and we are tossing all the old exhaust after the risers. My risers are different than your as they turn 180 straight down and went into the old mkII mufflers.

We are installing a 4 inch fiberglass muffler on each side, only one that fits between the water tanks and transom. As it stands now using a 4" 90 degree molded elbow to turn exhaust from muffler to engines, will use a fiberglass wye and some other items to complete. The f28 is a real bugger to pipe exhaust, and I do not know what the 351 setup looks like, post a picture I am curious.

Here is my old setup:

[Dreamweaver]

That set up looks restrictive or uneven back pressure on the engine,was that stock?

[Dreamweaver]

Here is the 351 set up,the pictures makes it look like lots of room.




This boat sat outside uncovered for 5 years and is showing a water level line that comes just below the valve covers,I drained the fluids and soaked the engines with marvel mystery oil and was able to free them up.

But between the salt water use and sitting the exhaust is pretty crumbly.

One of the risers.


The new ones.


The original risers would have had a lighter drop,I think the new ones will give me more clearance to install the strainers.sorry about the cell phone picture quality.

[larryeddington]

The mufflers are no longer available, and I will bet the ones you have are, gutted anyways. You can use stainless muffler pipe and bend to suit. I am installing one small centek 4 inch x 16.75 inch muffler on each side out the transom. Will collect exhaust from each riser then through a wye and out muffler.

Yes what you see is exactly as the f28s come from factory with 318s. I have 2 of them 77 and 78 both identical and seemed to work correctly.

Suggest you give me a call at 903-896-1610 when convenient. I have been working on f28 rebuild for a while and you can pick my brain as little as it is.

[gettaway]

Dreamweaver, I mean no disrespect, but....

with your engines siting that deep in water for 5 years, Id think you may be in for more than new exhausts, maybe a repower?

[Dreamweaver]

Dreamweaver, I mean no disrespect, but....

with your engines siting that deep in water for 5 years, Id think you may be in for more than new exhausts, maybe a repower?

Not seeing any disrespect,the engines on their own I could rebuild in my sleep its just everything else that surrounds them I look here for others experiences,knowledge and been there done that aspect.

Surprisingly the internals held up pretty well,the only place water could have entered would have been the crank shaft seals but they seem to have done their job well,low hours on factory engines to me is better.

The suspect part to me is the Vee drives or more so the flex plate because the starters were relocated to the top and no sealing plate installed in their place,I will have to separate the two if only to inspect.

I am just going to replace everything new on the externals of the engines anyways so if it is necessary for re-power I can just transfer everything over,the bad part with 351s is the parts are not as common as a GM 350 or Chrysler so in order to maintain a realistic budget I buy stuff when it becomes available,like the gen-set,it was the last thing I needed to buy now but for $250 with 100 hours it can sit in the corner until its time comes.

This boat was stripped basically,which I prefer because it forces my to just buy it new from the start and hopefully stop a lot of the future gremlins,yea I know keep dreaming lol but it looks good on paper anyways.

Richard