( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six )

[73 Dolphin]

Hello all.

getting ready to drop the engine back into my old 22' 1974 starcraft chieftain.

When I got her the gimbal housing was trashed. So I put on another gimbal assembly.
It also was from another 165 powered boat of the same era.

The only difference I see between the two gimbal assemblies is that the original
just had an blank space under the exhaust mount. The new one has two ports.

It will take either the 3 bolt oval mount exhaust or the 4 bolt exhaust which encloses
the two ports.

I have the 3 bolt exhaust.
I'm guessing I need to get the 4 bolt exhaust , but as it will take either I'm a little confused.

It seems that if I use the 3 bolt then water will just rush in the ports as soon as I put her in
the water.

Any thoughts would be much appreciated as I'm ready to drop the engine in as soon as this
is resolved.

Thanks !

 

[73 Dolphin]

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

It always seems that after searching for days and finally posting a question, I get an answer from another source as soon as I post !
I'll post the answer in case this will help someone else.

It seems that this gimbal housing is set up for a V8 ( hence the two extra ports for the Y pipe) and also the straight six.
Seems I need to block off the holes intended for the Y-pipe and all should be good.

If you can confirm this or disagree please let me know.

Thanks.
Paul

 

[haulnazz15]

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Sounds right. Those bottom two ports are relief ports. I'm not sure about the ability to block them off, but as long as you get it sealed up I assume it would work.

 

[73 Dolphin]

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Thanks. That's what it looks like. I'm pretty sure this was a gimbal and pipe combo from the same boat
and that those ports were just as they are now, but I've through a few parts boats and cant be 100% sure.

What am am 100% sure about is that will be a lot safer to just plug them now and not when I'm at the dock
and the engine is in the way !

 

[haulnazz15]

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Well, as long as you can ensure the plugs would be permanent, and that the exhaust pipe could be properly torqued/sealed to the transom using the 3 bolts instead of 4. Wouldn't want a leak coming through those ports.

 

[Fishermark]

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

Re: ( pre ? ) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line si

I don't think you have the right combination. It sounds like your original looked like this:

Does your new transom assembly look like this? (Forget the writing on the picture - has nothing to do with this post)

The two are not interchangeable - you cannot simply use the wrong pipe and hope to plug up the holes.

 

[smokeonthewater]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

no his new one has 5 holes..... that one is a later model unit the O/P is SLIGHTLY mistaken in that the V8 actually uses all 5 holes on those and not the 4 bolt patterns of the newer 3" exhaust model you pictured or the 4" model in which the top two holes are at the same height as each other.

IIRC the relief holes on the older ones can be plugged with freeze plugs and I think it's from the outside of the boat but might be inside.... make sure to clean the holes, use BRASS plugs and coat with locktight before driving in. Do not use steel freeze plugs.

 

[smokeonthewater]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

something just occurred to me..... the V/8 motor mount pads on the gimble housing may be spaced wider than the I6 pads.... check first that they will even line up with your bellhousing and that the exhaust won't hit the bellhousing.... I used a V8 gimble housing with a 165 but I had to use the V8 bellhousing AND the V8 input shaft (different length) plus I had to run through hull exhaust and cap the gimbal housing with a plate because the exhaust tube wouldn't fit with the engine in place.

 

[haulnazz15]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

Good call, Smoke. Definitely would be good for him to figure that out before he embarks on putting the engine in.

 

[Will Fish]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

I'm in the process of doing the same since my 292 blew last fall (going back to the 250 though toi save fuel $$$. In any event, I bought a newer style housing that has the "upside down U" looking exhaust. I had to purchase a new exhaust tube (the inline 6 and 4's are the same), and a new flywheel cover from a 3.0L since the spacing on the transom plate goes from about 14.5" to 9.5" (I do not remember the exact measurements.

something just occurred to me..... the V/8 motor mount pads on the gimble housing may be spaced wider than the I6 pads.... check first that they will even line up with your bellhousing and that the exhaust won't hit the bellhousing.... I used a V8 gimble housing with a 165 but I had to use the V8 bellhousing AND the V8 input shaft (different length) plus I had to run through hull exhaust and cap the gimbal housing with a plate because the exhaust tube wouldn't fit with the engine in place.

Smoke - What do you mean by 'input shaft'? Are you talking about the spline attached to the universals from the outdrive? I did not know there was a difference between a V8 gimbal vs. Inline 6; an Alpha is an Alpha, except for Gen II.

 

[haulnazz15]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

True an "alpha is an alpha", but the yoke attached to that alpha comes in different lengths depending on engine option used. If your existing input shaft is too short/long, it merely means purchasing a new shaft and replacing the existing one so that it mates with the coupler correctly.

 

[smokeonthewater]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

yep^ the shaft that slides into the coupler can be different

 

[smokeonthewater]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

now that I think on it a little more... the difference was in the inner transom plate.... The mounts were different and I had to use the V8 inner plate with my V8 gimbal because my I6 donar was a 1976 and the gimbal had a different bolt pattern than my 1980 gimbal housing (and my transom)..... If you are still using the same inner plate then I BELIEVE that you will be fine with your exhaust and your input shaft.

 

[smokeonthewater]

Re: ( pre ?) alpha one gimbal exhaust. 3 bolt vs 4 bolt. Help please.(165 in-line six

O/P, I did just a little more research, and the gimbal housing you have won't work.... the original had exhaust relief ports drilled into the exhaust passage and your new one has them drilled into the openings below it.... If you simply block them you will have too much exhaust back pressure and idle and low speed.... possible even burning valves in the engine.... I have found a possible solution for you but it is against forum rules and you don't accept pm's.... If you are interested in the details, change that setting and send me a pm.