2.5L Pre-Alpha to 3.0 Alpha One Motor Swap

[pigrge]

Eureka!!! I think I found a solution to the following problem:
I have a 1982 Sea Ray with a pre-alpha transom assembly, the motor was shot, as discovered when the head was removed and the pistons were in horrid condition! So I decided to swap it out for a 1986 3.0L Motor Serial # OC305017. Easy swap right? Not sooo much, but I am making some headway, I will have to change the coupler and the whole back side of the motor cover, the cover that encases the flywheel, as I found out that pre-alpha and alpha 1 those are different. The biggest problem that I have had thus far however is the exhaust. This has been a big thorn in my side, as the 3.0L motor has an exhaust riser that comes at an angle and joins to an exhaust tube on the transom assembly with FOUR boltls and my exhaust tube only mounts to the transom assembly with three. SO after coming to MANY dead ends and marine shops that do not want to help out with this dilema, I decided to tackle the problem all on my own, and here is what I came up with. Up to 1982 I ASSUME that all of those outdrives were all Pre-alpha outdrives, because all the the exhaust tubes from thre transom assembly had three bolts, and all of the exhaust risers came straight back from the manifold. HOWEVER there were two different sizes of manifolds that were made. The manifolds for the 2.5L were actually smaller bolt patterns that the 3.0 or 140h.p. models. So all I have to do is grab an exhaust manifold with the part number 76351A04 and gasket 52076 and simply drill out the extra two bolts that are used for that specific riser and I will be set!
I would like some input from the higher ups here on my project. Has anyone ever tried this before? Sooo far there hasnt been alot of love on this subject but I am hoping that now that the boating season is back in full swing, someone will chime in! Thanks fellas, after this problem is solved, it is on to figuring out that dog gone shift and throttle set up! Have a great one!

 

[mkast]

Re: 2.5L Pre-Alpha to 3.0 Alpha One Motor Swap

The problem with finding a donor boat with a complete power package is?

 

[Bondo]

Re: 2.5L Pre-Alpha to 3.0 Alpha One Motor Swap

HOWEVER there were two different sizes of manifolds that were made. The manifolds for the 2.5L were actually smaller bolt patterns that the 3.0 or 140h.p. models. So all I have to do is grab an exhaust manifold with the part number 76351A04 and gasket 52076 and simply drill out the extra two bolts that are used for that specific riser and I will be set!

Ayuh,......

Prior to this quote you're talikng about Downpipes,+ then you're talking Manifolds, Risers,+ Downpipes.....

Now,.... In this quote,.... Please explain,... Exactly,.... Where these bolt patterns are Different, between your part #s, which I'm not familiar with.....

From My experince,... You should be able to bolt your original Manifold,+ Riser onto the new motor,+ Along with the original Downpipe, flywheel cover,+ coupler,...
It should Bolt right Up.....

 

[pigrge]

Re: 2.5L Pre-Alpha to 3.0 Alpha One Motor Swap

My original carb was junk, my original exhaust manifold was cracked, not around the water passages, but on an exhaust passage, BTW, this is where I determined my hissing noise was coming from on my post titled, 2.5L Teapot! So, original manifold was junk! Hence the going to the entire new motor as alot of the parts on the old motor are bad. Everything else will bolt right up.
As for the explanation of the difference in bolt patterns, the difference is as follows,
the 1982 Motor has an exhaust Manifold (part # 63122A14) that has a choke stove which heats up a spring in the carb allowing tension to relax opening the choke as the engine warms up. The parts for this choke stove are almost next to impossible to find, although I did find most of them, I was unable to locate all of them. The bolt dimensions as measured from the inside of each bolt, front to back is 2-5/8" and from side to side is 2-1/8". That exhaust riser/elbow has a part number of 55538A2 with the gasket number 27-39915 and that only goes to 1982 in the 2.5L motors ONLY.
The new 3.0L motor the measurements are front to back 2-1/2" and side to side is 2-3/8". The part number for that year exhaust manifold A60235A04 and uses exhaust gasket 27-997772. This gasket goes for motors with exhaust risers that go straight back, (I assume all the are pre-alpha boats) AND risers that go away from the motor and a 45 degree angle.
So after some researching, I found that in 1982 the 140's were actually put out with the same gasket number, (27-997772) with a different part number for the exhaust riser, 76351-A04 indicating to me that the exhaust riser SHOULD pair up with my pre-alpha transom assembly exhaust tube AND my Alpha one exhaust manifold, saving me a TON of money by NOT having to change out my freshly rebuilt pre-alpha outdrive, and, saving a TON of headache!!!!! I hope this explains it a little bit better and maybe save the next guy from having to do alot of extra work!!!!
I spoke with one guy at a marine shop and he said he just did that to a customers boat and didnt have to time to do the research and just opted to update the whole thing transom assembly and all. Le me know what you guys think! Thanks in advance.
Some may wonder by the way, why am I putting soooo much money and time into a 1982 Sea-Ray with a 3.0L? I guess, it is just my crazy sentimental side, wanting to have a boat that I KNOW is done right. If you have kept up with some of my postings you know I am also, redoing to deck, stringers and transom. All for the love of it, I guess!!! So please, dont be cynical! Thanks!