change engine from chevy to ford

Shorty

New Member
Jun 26, 2016
20
Western PA
Boat Info
1998 240 Sundancer
Engines
5.0 EFI
Was Just wondering what All I would have to change to change the 305 gm to a 351 Ford in my 98 240 Sundancer.
 
Would the Mercruiser outdrive even mate up to the Ford block?

Considering all of the differences between Ford and Chevy, your better bet would be to upgrade to the 5.7L Chevy, you could probably reuse a lot of parts.
 
besides the differences between Ford and Chevy mentioned by LTD.330 if you don't know the differences between car engines and marine engines you might want to do a little research on this subject before attempting this.....there are many differences because they live in different environments and have very different loads placed on them....this subject has been discussed many times in this forum so maybe even read the archived post for some info....

bottom line is a typical car engine would likely die a quick death if used in a boat...also the electrical items on a car engine are not 'spark protected' so it would present a significant explosion hazard if gas fumes accumulated in the engine room...

cliff
 
Was wondering because I am being given a complete 5.8 from my brothers boat when he upgrades to a 5.9 cummins.
 
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I wouldn't do that for 2 reasons.
  1. Every time I have ever worked on a Ford engine, I've ended up having to bang the heck out something with a big freaking hammer. There's no room to swing a hammer in a bilge.
  2. I want to use my boat on a regular basis. "Fix Or Repair Daily" isn't very relaxing.
:p
 
I rebuilt 2 351 Windsors for a Welcraft Nova project in the 80's. Ended up using 2 Jasper remans due to the condition of the original Merc 302's. The main differences are in the gasket set.........stainless steel head gaskets, all freeze plugs are brass, not mild steel...and this means you have to start with a short block, not a complete motor or a long block. Other differences are the camshaft....power and torque curves are completely different between a truck and a marine application, the carburetor bowls need to be vented internally, not to atmosphere, The starter motor and solenoid must be ignition prrotected, the alternator must be internally regulated and ignition protected.

The change you comtemplate can be done, the parts are available, but it won't be cheap.
 
I'm still confused. Is the engine from your brother's boat a 5.7 GM or a 5.8 Ford? If it is a Ford, sell it and use the proceeds to get a 5.7 GM. You will be a lot happier in the long run.
 
I'm still confused. Is the engine from your brother's boat a 5.7 GM or a 5.8 Ford? If it is a Ford, sell it and use the proceeds to get a 5.7 GM. You will be a lot happier in the long run.

at first I thought the OP was wanting to put a car engine (Ford 351 cid) into his boat but after re-reading the thread I think his brother has a boat with a 5.8L (351 cid) marine Ford engine that he is going to remove and give to the OP....the OP wants to know if he can make the 5.8L Ford marine engine fit in his 240DA....he has a 5.0L GM marine engine in the 240DA now.....so he would not only be going to a larger more powerful engine he would also be going from GM to Ford engines....not sure if the Ford engine would mount to the outdrive without modification or if the outdrive could handle the extra power and I am sure the motor mounts would have to be changed.......it is not stated but based on the year of the 240DA and the engine size I would assume the boat has an Alpha One Gen II outdrive.....I suppose all the instruments and gauges would work with the Ford engine but not sure if any senders/sensors would need to be changed....

cliff
 
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That's why he should sell the 5.8 (Ford) and buy a 5.7 (GM). Anything other than that would be a parts "rabbit hole" and actually hurt the remaining value of the boat.
 
at first I thought the OP was wanting to put a car engine (Ford 351 cid) into his boat but after re-reading the thread I think his brother has a boat with a 5.8L (351 cid) marine Ford engine that he is going to remove and give to the OP....the OP wants to know if he can make the 5.8L Ford marine engine fit in his 240DA....he has a 5.0L GM marine engine in the 240DA now.....so he would not only be going to a larger more powerful engine he would also be going from GM to Ford engines....not sure if the Ford engine would mount to the outdrive without modification or if the outdrive could handle the extra power and I am sure the motor mounts would have to be changed.......it is not stated but based on the year of the 240DA and the engine size I would assume the boat has an Alpha One Gen II outdrive.....I suppose all the instruments and gauges would work with the Ford engine but not sure if any senders/sensors would need to be changed....

cliff
I will get everything from mounts Alt, Starter and exhaust Manifolds. It is hooked up to a velvet drive right now. So Probably would only need bell houseing and a hub that has the right spline to go to the Alpha 1.
 
Bell housing will not match. You will create a one of a kind boat and ruin the resale value. Sell it and get a Chevy marine engine.
 
+1 on the Frankenboat

Hopefully, the OP realizes this project is a bad idea. It will be cost prohibitive to retrofit a Ford Engine onto a Mercruiser outdrive. Will the current outdrive support the increased horsepower?
 
Another vote for keeping things simple. I'm all for projects and DIY, in fact they can be downright fun! But sometimes they're just not worth it in the end. It's your boat and of course do what you want, but just make sure you think it all the way through.

Is your current engine bad?

As far as the HP, goes... how much extra, if any, will you gain? Your current engine has 240HP AT THE PROP, not at the crank. What year and model 351 is it... how much HP does it have... how old is it - how much HP does it STILL have?

FYI, if your current block is bad, 305 short blocks are a dime a dozen.
 
Sell it! Not worth the aggravation, and buy a 5.7, Merc 260. Very common and proven marine engine. Easy swap also.
 
The reason for wanting more HP is this Boat has always been under powered. And the ECM is bad on the chevy and I can't find an ECM for less than $1500. And I am not willing to spend that kind of money on the chance that will fix the problem.
 
have you tried a lower pitch prop on the 240?.....does it have trim tabs?.....both of these things can make a real noticeable improvement in the performance of a boat as far as getting up on plane quicker and easier....

cliff
 
Yet another case ill
Will the current outdrive support the increased horsepower?
the highest HP 5.8 makes is 300 HP. I doubt that engine is the 300HP model. there were only a few made. the Alpha drive is good to about 300 HP.

shorty, what you are thinking about doing is a really bad idea. You came on the site asking for advice. You've gotten plenty of it....but not what you wanted to hear. Go ahead and do it but have the nads to come back and tell us about all the problems and costs you've experienced.

What I said earlier comes from 50 years of boating and 10+ years on this forum. The most cost effective way to make a boat go faster is to buy a faster boat.
 
I'm a Ford guy have owned a lot of small block Ford's over the years. I would NOT swap a Ford into your boat, mainly due to the parts availability issues and the fact that almost nothi ng will bolt up. I'd go with a 5.7 as it should be a direct drop in and parts for 5.7s are everywhere and reasonable.
 

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