Engine Swap Question

[el_coqui]

I own a 1990 305 I/O mercruiser with an Alpha One drive. The block and manifolds cracked, due to incorrect winterization. I purchased a used complete 350 with a Volvo outdrive. I'm not interested in using the outdrive but just the engine. Since I'm not familiar with the condition of the accessories of the motor, I swapped from my the 305 to the 350 the alt, WP, starter, PS pump, fuel pump and wire harness. After all this I noticed that the valve covers on the 350 are the old style valve covers, with the four hold down bolts on the lip. My 305 has the bolts in the middle of the cover. I don't know what year of the 350. I haven't pulled the 305 from the boat yet and don't really want to until the 350 is ready to be put in. I planned on swapping the flywheel from the 305 to the 350 during the engine swap.

Is this swap going to work? Do I need a different flywheel, coupler, input shaft, etc? Anything else you guys can think off.

Thanks in advance for your help.

 

[Bondo]

Re: Engine Swap Question

Ayuh,... What is the 350's crankshaft bolt pattern,..?? 3", or 3, 1/2",..??

Using the Volvo manifolds are going to be a Problem with the merc drive...
Using the Volvo coupler may be a Problem...
Using the Volvo flywheel cover is gonna be an issue...

Matter of fact, using Anything beyond the Long Block is gonna be an Issue...

 

[HT32BSX115]

Re: Engine Swap Question

Howdy,


As much as I would use the long block only.......What's the matter with using the Volvo Penta transom and drive?

It should all "fit"

 

[ringmaster72]

Re: Engine Swap Question

You should only need a flywheel for the older motor. I had a 1990 4.3 that I removed and put in an early 80s 350. After 87, the flywheel is different because of the one piece oil seal. So, you just need to get a flywheel for a pre 87 small block.

 

[el_coqui]

Re: Engine Swap Question

Using the Volvo manifolds are going to be a Problem with the merc drive...
Using the Volvo coupler may be a Problem...
Using the Volvo flywheel cover is gonna be an issue...

Matter of fact, using Anything beyond the Long Block is gonna be an Issue...

I'm not planing on using any of the Volvo stuff except the manifold, that I thought were matched to the engine not the outdrive. I compared them to the cracked ones and the only difference is that they don't have drain plugs.

As much as I would use the long block only.......What's the matter with using the Volvo Penta transom and drive?

The packaged came out of a 25' boat and I have a 20' boat. The set up for the Volvo, from the end of the outdrive to the front of the motor appears to be much longer than mine. Also I kinda like Mercruiser .

You should only need a flywheel for the older motor. I had a 1990 4.3 that I removed and put in an early 80s 350. After 87, the flywheel is different because of the one piece oil seal. So, you just need to get a flywheel for a pre 87 small block.

I hope you are correct. Where can I get one and what should I ask for?

Anything else you guys think I need o r be concerned about?

Thanks all for the quick response.

 

[el_coqui]

Re: Engine Swap Question

Not sure about the year of the 350. Just that it has the valve cover hold down bolts on the lip of the covers. I'll get the serial number and maybe someone here will be able to tell the year.

 

[TilliamWe]

Re: Engine Swap Question

Do you know if the 350 is an 1987 or newer? If so everything will swap over from the 305.

No it's not, because of the valve cover bolt arrangement that he has mentioned. It's possible that someone has installed old heads on a newer motor, but that would be silly. The center bolt valve covers came about in 1987, right when the one piece rear main seal did.

 

[el_coqui]

Re: Engine Swap Question

OK guys the serial number is VH284832, can someone look it up or instruct me how to.

 

[gbeltran]

Re: Engine Swap Question

The easiest way to tell is to just take the flywheel off the 350. If it's perfectly round and has a one piece rear main seal that you can see then everything from your 305 will fit. If it's got more of a flange back there then you will need a flywheel and a coupler. Or take it off and post a pic, then we can tell you if it will work with what you have.

 

[el_coqui]

Re: Engine Swap Question

I found a web site http://www.autorevival.com that decodes casting numbers and here is what I came up with for the 350.

Casting_id -190
Casting_number -14016379
Casting_cid -350CID
rated_hp -
year -1977-79
Deck -
main_caps -2 or 4 Bolt Main
info-

WOW, I didn't realized this motor was so old.
Where do I go from here? How can I find what flywheel I need? Once I get the flywheel will the coupler from the 305 fit?
This is getting complicated for me . I hope someone here can guide me.
Thanks

 

[JaseBosto]

Re: Engine Swap Question

I found a web site http://www.autorevival.com that decodes casting numbers and here is what I came up with for the 350.

Casting_id -190
Casting_number -14016379
Casting_cid -350CID
rated_hp -
year -1977-79
Deck -
main_caps -2 or 4 Bolt Main
info-

WOW, I didn't realized this motor was so old.
Where do I go from here? How can I find what flywheel I need? Once I get the flywheel will the coupler from the 305 fit?
This is getting complicated for me . I hope someone here can guide me.
Thanks

You might want to consider a newer 350, and selling this one. I'm sure its not what you want to hear, but a newer one would make more sence to me...

 

[ringmaster72]

Re: Engine Swap Question

Im pretty sure any flywheel(manual tranny, NOT a flexplate) older than 87 will work. Although, I would measure the bolt holes where the coupler bolts to make sure it is the same diameter. I found one at a local junk yard for 40 bucks when I did mine.

 

[Bondo]

Re: Engine Swap Question

Im pretty sure any flywheel(manual tranny, NOT a flexplate) older than 87 will work. Although, I would measure the bolt holes where the coupler bolts to make sure it is the same diameter. I found one at a local junk yard for 40 bucks when I did mine.

Ayuh,... I believe your Right,...
The bolt pattern of the coupler matches that of the clutch pressure plate....

 

[el_coqui]

Re: Engine Swap Question

Im pretty sure any flywheel(manual tranny, NOT a flexplate) older than 87 will work. Although, I would measure the bolt holes where the coupler bolts to make sure it is the same diameter. I found one at a local junk yard for 40 bucks when I did mine.

Ayuh,... I believe your Right,...
The bolt pattern of the coupler matches that of the clutch pressure plate....

If I understand this correct, I can get a manual flywheel from a 87 or older car and it will work? I just have to match the bolt pattern of the coupler of the 305 to it.

 

[ringmaster72]

Re: Engine Swap Question

You are correct. For some reason, I have it in my head that there are different diameter flywheels. That is the only reason I even mentioned measuring. But, you should have no trouble finding one.

 

[JaseBosto]

Re: Engine Swap Question

It appears to be an older engine....So with that said, can you put your newer 305 heads on? Correct me if I am wrong its been a while since I've been inside a gm engine, but aren't 305 and 350 heads the same?
Reason I say all this, is because newer heads typically flow better = more power.

 

[Starcraft Enterprise]

Re: Engine Swap Question

It appears to be an older engine....So with that said, can you put your newer 305 heads on? Correct me if I am wrong its been a while since I've been inside a gm engine, but aren't 305 and 350 heads the same?
Reason I say all this, is because newer heads typically flow better = more power.

The 305 heads will usually have smaller cc combustion chambers, raising his compression, but could cause detonation problems.
As far as flow, if they was 1996 or later heads instead of 1990 heads, they would be Vortec heads and have a little bit better flow characteristics.

If you pull off a valve cover, you can check the casting #'s to see if the heads are decent and make sure that they are a good match for your block. (correct cc's for a 350, etc) Hopefully they are not casting # 462624 which was common for that time period. They are a thin casting that cracks easily and flows badly. They was used alot on 180 hp smog automobile engines of the time. I replaced a set on a 1985 Volvo 350 just because of the casting #'s. So unfortunately, they also made it onto marine engines too.
Better pull off both covers on an engine that old to also make sure both heads are the same casting #'s, alot of strange things can happen to an engine in 30 years.
Here is my favorite site for checking casting #'s. http://www.mortec.com/castnum.htm

 

[el_coqui]

Re: Engine Swap Question

I do need to pull the valve covers and check the casting numbers. When I was power washing the motor to put a fresh coat of black on it, one of the heads was painted red the other was black, so????

 

[Starcraft Enterprise]

Re: Engine Swap Question

I do need to pull the valve covers and check the casting numbers. When I was power washing the motor to put a fresh coat of black on it, one of the heads was painted red the other was black, so????

That does not automatically mean a bad thing. One could have cracked and a correct replacement was used or ?
When checking the casting #'s you are just verifying what you have. Determining risks to see if it would be better to replace a head now before adding on all of the labor of replacing it while it is in the boat or ruining a day of boating when it cracks while you are on the water and possibly ruining the entire engine. Also, you are checking to make sure the replacement head (the black one?) has the same cc combustion chamber as the other. You don't want one bank of cylinders with X compression ratio and the other bank with a different compression ratio.

 

[el_coqui]

Re: Engine Swap Question

Here is an idea. What if I take the volvo flywheel that is on the 350 to a machine shop and have it centered, re-drilled and balanced to accept the mercruiser coupler.

Could this work?