Going whacko trying to ID my engine

[Romeo1800]

I had my Mercruiser 228 engine replaced a few years ago with a rebuilt OMC GM engine. At the time I did not think about parts being different since I was under the impression the it was actually the same engine as the 228; however I now remember that the shop said it was a higher HP engine, maybe 300 or 350. I had forgotten that the parts maybe somewhat different. Well the boat has been in storage for the past 5 years (or so) and since I am now retired, decided to get it back into the water. The first thing I noticed is that the spark plugs are not what I used on my 228. So I started trying to identify the year and model of the engine.

Here is what I have found:

Block No; 3970010.... that can be one of the following:
1969 302
1969 327
1969-80 350
(according to a list I found on the web)

After much searching I found info on the web that told me where to look for further engine ID numbers.

Here's what I found on the engine to the left of the engine block:
T4F518384 followed by:
VO701TJY

None of these last two numbers can be found on any of the model number lists I have found on the InterNet.

Can anyone help ID this engine?

 

[Howard Sterndrive]

you know all anyone can know without disassembling it. That 3970010 block can be built as a 302, a 327, a 350, a 383 stroker. And it's been around since the 1960's so it may have been through a rebuilder at one time and had it's displacement changed via different crankshaft.

The most common use of the 0010 block in a boat is by far the 350 which makes 260HP in typical marine trim.

At the time I did not think about parts being different

external parts as far as maintaining the boat are NOT different. Tell the parts guy 228 with your old model/serial number and don't worry about it.

 

[Romeo1800]

Now that I read your post I should have said "... it was a higher displacement engine..." rather than higher HP. In fact what you mentioned about typical marine trim, sounds very familiar to what I remember the shop telling me what the engine was... 350 cu and 260 HP. I do remember it was a little more HP than what the 228 was so 260 sounds right. The 228 HP was 305 cu.

I hear what you are saying about not knowing without a tear-down, but one should be able to use the engine model number to ID the engine. I just don't see the same type of number listed that I found on my engine. According to the write-ups on the web, the ID numbers I found in the location mentioned should be the ones on the web lists, but mine are somewhat different than those listed.

I need to know timing specs, spark plug type (the one in are NGK but would normally go with AC or Champ), firing order and so on. It appears that all the filters are the same as I was using on my 228.

 

[Howard Sterndrive]

all timing specs, spark plugs and pretty much every other part or value you could ever possibly need for it is exactly the same as the 228.
And no, the numbers cast into cast iron cannot be modified when someone fits a different crankshaft into an engine. Regardless of the what the supergoogles say to you, no one knows what is inside that motor from any numbers on the block.
I could build that engine to 4 different displacements.. the numbers you see won't change.
If you can't sleep without knowing, pull it out, flip it over and take the oil pan off. The part number on the crankshaft will tell you what you got. Or take a head off and measure bore and stroke.
my bet is a 350 cid/260hp.

 

[Bondo]

all timing specs, spark plugs and pretty much every other part or value you could ever possibly need for it is exactly the same as the 228.
And no, the numbers cast into cast iron cannot be modified when someone fits a different crankshaft into an engine. Regardless of the what the supergoogles say to you, no one knows what is inside that motor from any numbers on the block.
I could build that engine to 4 different displacements.. the numbers you see won't change.
If you can't sleep without knowing, pull it out, flip it over and take the oil pan off. The part number on the crankshaft will tell you what you got. Or take a head off and measure bore and stroke.
my bet is a 350 cid/260hp.

Ayuh,..... Exactly,.... That's the Beauty of the SBC,.... With the mixin', 'n matchin' possible, the combinations are mind bogglin',...

The basic Specs don't change, same plugs, 'n timin',...