anuther dumb??

bondomerchant

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Jul 6, 2009
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is it possible to hang a a 77 motor in a 78 seaswirl an make it work with the later outdrive??the 77 had the elect shift the later didnt or should i keep looking for a pre 77 boat
 

mkast

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Re: anuther dumb??

What engine was originally in the hull? What is the replacement engine?
 

bondomerchant

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Re: anuther dumb??

well heres the scoop 78 seaswirl with 305 chev that runs but is getting water in the oil the other boat i have is an 77 century electric shift with an awsome 302 motor but bad upper gearcase what i was wondering is can ya hang that 302 in the other boat an use the later outdrive on it did omc change the though the hull deal that much ?? when they changed the rest over to the hydra shift?? if not i might better off than messing with the motor btw i havnt bought the other boat yet but other that the motor it seems ta be real nice 18 ft open bow my century was a 19 ft closed bow with extremly low hrs on the motor
 

Bondo

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71,083
Re: anuther dumb??

Ayuh,... About Anything is Possible...
But,..
You're going to have Fitment Issues going from Chevy to Ford, not the difference in years...
 

bondomerchant

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Re: anuther dumb??

are ya talking from the hull ta the motor ?? im not afraid of glassing the mounts so much the outdrive is my biggest concern ive done a considerable amount of glass work over the yrs biggest concern is will that later outdrive will hang off of that 77 thru the hull part i dont mind tinkering a little thanks for the replys though i might be better off seeing if i could fix the motor 2 i really was curious ta what the pitfalls of switching the motors would be ive got a fully equipped bodyshop ta pull the swap of this thing easy enuff but mabey id be better off fixing the 305 hmmmm
 

Bondo

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Re: anuther dumb??

Ayuh,.. If you're Not scared of Glassing,...

Fill the transom,+ start Fresh with Any other outdrive than those Stringers.....

Mercruiser quit the Ford motors way back in the late 70s, or early 80s....
Volvo hung with Fords up to the early 90s I believe....

Parts,.. Marine Parts for the Fords are Wicked Expensive...

SBCs are the poor man's choice,...
There's BaZillions of 'em out there,...
 

WizeOne

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Mar 23, 2008
Messages
2,097
Re: anuther dumb??

well heres the scoop 78 seaswirl with 305 chev that runs but is getting water in the oil the other boat i have is an 77 century electric shift with an awsome 302 motor but bad upper gearcase what i was wondering is can ya hang that 302 in the other boat an use the later outdrive on it did omc change the though the hull deal that much ?? when they changed the rest over to the hydra shift?? if not i might better off than messing with the motor btw i havnt bought the other boat yet but other that the motor it seems ta be real nice 18 ft open bow my century was a 19 ft closed bow with extremly low hrs on the motor

The answer is Yes! You can switch the '77 302 to the '78 Seaswirl intermediate housing and outdrive, but you would need to get a new coupler and intermediate drive shaft. The 302 would have the adaptor plate that would be required to bolt it up to the intermediate housing but the extra thickness requires a longer drive shaft.

Ostensibly, you could remove the drive shaft from the electric shift intermediate housing and use that along with the matching coupler already on the 302. BUT, the '77 used a fine spline shaft and coupler that was more subject to wear, so be sure to inspect them carefullly.
 

bondomerchant

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Re: anuther dumb??

thanks alot so your saying i can use my intermediate housing with the newer outdrive if i change the shaft outta the 77s outdrive right???
 

flargin

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Aug 13, 2008
Messages
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Re: anuther dumb??

Would it not be easier to pull the broken 305 + outdrive, and replace it with the 302 + outdrive. then you have the motor you want, with the outdrive already married to the outdrive...

You can the 305 and sell it, or rebuild and sell

cost you an arm or a leg either way...
 

WizeOne

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Re: anuther dumb??

Would it not be easier to pull the broken 305 + outdrive, and replace it with the 302 + outdrive. then you have the motor you want, with the outdrive already married to the outdrive...

You can the 305 and sell it, or rebuild and sell

cost you an arm or a leg either way...

He really wouldn't want to do that as the 302+outdrive is an electric shift system.

That being said, he confuses me in his last post. I will restate. You can use the earlier 302 motor with the later chevy setup. Your 302 has the adaptor plate that will mate it too either of the intermediate housings. Beyond that, your later 305 intermediate housing has a shorter drive shaft because the chevy motor did not need the adaptor that the ford needs to mate to the intermediate housing. As well, the chevy coupler with larger spline size, will not mate with the ford flywheel. You either need the longer large spline driveshaft with matching ford coupler, or you have to pull the longer small spline driveshaft out of your electric shift intermediate housing.

You may also need to get new connector sleeves to hook the exhaust manis to the intermediate housing. Your '77 ford uses log style manis with the port one being reduced to a smaller diameter. Your later intermediate housing most like has two exhaust recepticals that are both the larger diameter.

I am not familiar as to what style of exhuast mani's the chev uses. I personally do not like the 305 chev. Wouldn't own one. Some would say the Ford Marine motor components are hard to come by. I say, balderdash. True outdrive parts are getting harder to come by but not OMC Ford motor components.
 

bondomerchant

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Re: anuther dumb??

He really wouldn't want to do that as the 302+outdrive is an electric shift system.

That being said, he confuses me in his last post. I will restate. You can use the earlier 302 motor with the later chevy setup. Your 302 has the adaptor plate that will mate it too either of the intermediate housings. Beyond that, your later 305 intermediate housing has a shorter drive shaft because the chevy motor did not need the adaptor that the ford needs to mate to the intermediate housing. As well, the chevy coupler with larger spline size, will not mate with the ford flywheel. You either need the longer large spline driveshaft with matching ford coupler, or you have to pull the longer small spline driveshaft out of your electric shift intermediate housing.

You may also need to get new connector sleeves to hook the exhaust manis to the intermediate housing. Your '77 ford uses log style manis with the port one being reduced to a smaller diameter. Your later intermediate housing most like has two exhaust recepticals that are both the larger diameter.

I am not familiar as to what style of exhuast mani's the chev uses. I personally do not like the 305 chev. Wouldn't own one. Some would say the Ford Marine motor components are hard to come by. I say, balderdash. True outdrive parts are getting harder to come by but not OMC Ford motor components.

wow thats some good stuff now ya got me thinkin thanks a million i will definitly keep ya posted an i agree with ya a hundred %%about 305smabey ya can clear me up on the intermediate housing though can i use the ford one an conecct to that with the output shaft outta my electric **** outdrive that part has me confused a little
 

bondomerchant

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Re: anuther dumb??

or are what ya saying is that i could use the intermediate housing from the 305 with the 302 with the right parts thanks again:cool:
 

WizeOne

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Re: anuther dumb??

Ok, one more time. All of the respective intermediate housings are the same dimensions. They are apparently made to bolt straight to a chev bell housing pattern. You look and see on your 305 setup. I do not think you will see an adaptor plate between the motor and the IH. Then look at your Ford/electric shift. You will see an approximate 1 1/4" aluminum spacer between the back of the engine and the intermediate housing. That is the adaptor and the extra thicknes is reason the the Ford drive shaft has to be longer.

Your electric shift drive shaft is the proper length and will obviously spline match the coupler on your 302 but as I said they were fine splined and if yours is anything like mine was after 30+ years, you would be hesitant to reuse it.

I got the later model ford large spline driveshaft and matching coupler off of ebay. They are probably the same splines as your later chevy but that shaft is too short and the coupler will not bolt to the Ford flywheel.

Got it now?;)

Be sure to scope out the differences in the exhaust sleeves between the respective exhaust manis and the intermediate housings. Your Ford probably uses a reducing coupler on the port side as the receiving sleeve on the electric shift IH is smaller that it is on the starboard side. But again, I am not familiar with the chevy plumbing.
 
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