Engine swap from a 350 to a 454 questions

ottawamerc

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Sep 16, 2004
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Hello all
I'm swapping out my freshly rebuilt SBC 350 to a used 454 in my 87 SeaRay 268DA. The 350 is the 3rd engine in this boat and I can see why, it's way under powered and working to hard. I don't want to blow this fresh engine so I have done lots of research and the next available engine is the 330HP 454 which owners say is good combo for this boat so here I am! I just bought a used 454 complete for $3K and I'm going to sell my 350 for hopefully the same as it cost me $3K to do the rebuild alone then hopefully the only cost is my labor to install (free) It has a Alpha outdrive and yes I know its underrated for the 454 but seems like many have this combo and as long as you don't beat on it it should last. I don't want to spend $$$ on a Bravo outdrive. First question is, the 454 had thru the hull exhaust and my boat has the Y pipe which I plan on keeping. Will the metal turn down elbows off of the 350 fit the 454 manifolds/risers? and #2 is the motor mount locations the same, including the mounts themselves? Off of the SeaRay web site I see that that model and year had an Alpha outdrive with a 1:50 gear for the 350 and a 1:32 for the 454. The 1:32 gear is no longer available so it looks like I will keep the original 1:50, the original prop is a 15 1/4 X 15 but I might have to change that for the 454? The boat also came with a 16X16 prop do you think this will match it ok?

Sorry for the long post but looking forward to your replys

Thanks Scott
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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The pork chop motors in front of alpha drives was a searay offering..... That only lasted a few years because of the high warranty of the gearsets failing.

Yes, the y pipe is same between the sbc and bbc
 

ottawamerc

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Thanks for the reply Scott, what about the turn down elbows and rubber couplers?

Scott
 

Scott Danforth

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elbows should work, if the couplers bolt to the perimeter of the flywheel, make sure they are the same.

none of your SBC brackets will work on the BBC.
 

ottawamerc

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So I picked up the engine today and it seems good. It has the coupling for a Bravo drive is it the same as the Alpha? Size and splines? Also he had the gimbal for the Bravo still, is the inside transom flange the same as the Alpha or would I need that part too/
 

ottawamerc

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Also the new 454 has a much smaller Thunderbolt ignition box than my last one, are they any good or could I use my original 350 control?
 

Scott Danforth

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you will need a 454 / alpha combination control box. the bravo has cone clutches where the alpha has a dog clutch. because of the dog clutch, the ignition must be momentarily grounded to cause the engine to stumble to get the drive in and out of gear. the Bravo box doesnt have that

the 454 has a different advance curve than the 350. I personally would source a bravo 3 drive and sell the alpha, then use the control box, coupler, transom shield, etc. that is on the 454
 

Bondo

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Also the new 454 has a much smaller Thunderbolt ignition box than my last one, are they any good or could I use my original 350 control?

Ayuh,..... Ya don't wanta use the 350 T-Bolt ignition box,.... I don't think anyways,...

The little triangular T-Bolt boxes are just as good, or better than the older bigger aluminum box units,....

It has numbers on it, What are the numbers on the one on the 454,..??
It could be a T-Bolt IV, or T-Bolt V,....
Different advance cures are also available,.... total advance will be stamped in the numbers,...
Check the numbers on the 350 unit too,...

If this is just the T-Bolt ignition boxes, 'n not 'puters for Efi, Scott has a moot point,.....

The T-Bolt will work on an Alpha drive, just wired abit different,....

If it's a 'puter box, Efi, 'n ignition, Scott is Right,....
 

ottawamerc

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Thanks Bondo thats one bit of encouraging words on my little project so far. The new 454 is carburated as well, no EFI so sounds like its a plug and play!
 

ottawamerc

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Ok so everybody that I ask about this keeps telling me I need to get a Bravo setup, so I finally after kicking and screaming decided that for once I should listen to the many that have said "GET A BRAVO" so I did :) I have driven many hundreds of miles to gather all parts but I should be set for next year BTW anyone need a fresh rebuilt 5.7 and great Alpha drive?????

Now I need to study what I need to know how to change everything out.
 

ottawamerc

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What should I look for when searching here "how to swap to a Bravo" ? I searched yesterday for awhile and I didn't find much, I figured there would be lots of info on the subject.
 

achris

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Remove alpha drive. Remove 5.7 engine. Remove nuts holding the inner transom plate on. Remove inner transom plate. Pull gimbal housing off the outside of the transom. If there are 6 bolt holes, then drill 2 new holes up the top. Offer up the bravo gimbal housing to the transom, fit inner transom plate and tighten the nuts. Drop engine in, align engine, fit bravo drive. Go fishing. :D

Basically, everything Alpha comes out/off. Then everything Bravo goes on.

Chris. ....
 

ottawamerc

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Sep 16, 2004
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Ok so update time and more questions... I have installed my new 454, transom assembly and Bravo 1 out drive. I have it running now on muffs but I noticed that the sea water pump intake hose was collapsed with the engine at idle. I turned the garden hose up to full flow but it still had the same result, for a intake hose it seemed pretty pliable? I wondered if it should have a spring inside like automotive hoses or is it just gone weak?
 

Pete104

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1. Did you get the 2 holes drilled at the top of the gimbal hsg?

2. You want 11/4" wire wound hose on the intake side of the sea water pump.
 

ottawamerc

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Sep 16, 2004
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Yes I did drill those 2 holes, that was the easy part. I was very happy to see the transom was dry and solid too! So as for the suction hose what I ended up doing was using 1 1/4" rubber hydraulic suction hose that has steel reinforcement. I tested it on the muffs again and it worked perfect although it was now sucking the garden hose down even at full flow!!!! man these Bravos pump alot of water!!! I bought the hose at Princess Auto ( Canada's version of Harbor Freight) for $30 much cheaper than a Mercruiser part. On a side note: I cant believe how tight it was to shoe horn that 454 into my 268 Sundancer's engine compartment those are BIG engines.
 
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