Electric shift sterndrive identification

[salvageyard saviour]

I'd like to know what the HP rating and gear ratio is for this drive.

tag on side says Model 981231 / serial J16L (attached photo) Welch plug on top has same model number

I unbolted it from a 72 350 SBC . They were in the bed of a pick up so I have no idea about it's history. Didn't see any labels on the motor for model. It has the bracket on the side for the steering.

Searching I find a lot for models 99XXXX and a few threads here that start but the posters leave before any answers.

 

[Scott Danforth]

about 250 hp max

 

[salvageyard saviour]

Do you say that just because it was bolted to a 350 ? or by the model number ?

I have no history of this drive and don't even know if it was the correct one for that engine. The adapter is a different color than both the engine and intermediate & drive. Maybe a clue things were changed in the past.

If I count the teeth on the upper gears, what should I see if this was a correct match ?

 

[Scott Danforth]

that drive was behind a 307 originally. all the electric stringers behind v8's blow up past 250hp.

 

[kenny nunez]

The highest HP electric shift OMC ever made was known as a SX245 which was a 307. I only saw a few of them. Pretty rare. The torque of a 350 used easily will hold up if you do not try jumping waves or wide open starts with a smaller boat.
I have used 350s on some electric shift models that held up but the customers were careful not to overload the boat.
If my foggy memory is right the ratio was 1.41 on the V8 models.
Try to post more pictures.

 

[salvageyard saviour]

Aren't there gear ratio differences between the drives for the V8, V6, inline 6 & 4 ?
I don't want to assume this is not for the 120 and 165 HP.
If the engine adapter is changed, can they be put on a wrong engine application ?

 

[salvageyard saviour]

Oops, sorry Kenny. Just saw your post. What pics would you like to see. Which parts of it ?

 

[Scott Danforth]

Just an FYI - the 2.5 and 3.0 4-bangers have the same bolt pattern as the in-line Chevy and the SBC's so yes, its possible to bolt a V8 to a 4-banger drive and visa-versa

 

[salvageyard saviour]

I guess I haven't worded it right. That's what I'm trying to find out. How do I tell the difference between the drives ?
How can I be sure this one is meant to be bolted to a higher HP ? Does it matter ? or am I just snipe hunting ?

 

[Redrig]

Not sure if this helps answer your question or not , but on the electric shifts ALL of the lower units are the same gears , the change for HP and gearing is done in the upper .

So yes , you want to match the upper v8 for v8 , and upper 4 banger for a 4 banger .

So if you pulled the entire drive off a v8 and put it on a v8 , you shouldnt have a huge change in overall ratio and be able to use the same prop.

 

[Scott Danforth]

Based on the model number you provided, its from behind a 307 V8

 

[salvageyard saviour]

Thanks, That's what I understood but I'm not that sure on what I "think" I know.

SouthCog mentioned in a past post about 12/18 gears. I've seen websites listing gear sets from 12/16 to 12/20. I don't know what ratios are for what HP uppers. My model number seems to be not listed as it's before 1973.

Yes, this drive was setting in the back of a pick up with a 350, But I want to be sure it IS meant to be on a 350 before I start buying seals and parts for it.

I've seen another 350 that had an Electric shift that had 120 - 150 HP stamped on the welch plug. That boat had a cracked block and rotted stringers. So I don't know if it ever ran like that.

Thanks Scott, Just saw your post.
That's just what I needed. When I open it up I guess I'll just count the teeth and I'll know the rest of my question.

I couldn't find any info on the 98XXXX model numbers

 

[southkogs]

I'm 90% sure the 98xxxx# you're referring to is the part number on your upper gear case housing.

The 225HP and 245HP both ran with a Chevy 307, but they never used a 350 like Kenny said. Gear ratio on the 225 and the 245 were the same - 1.16:1 overall - upper 21:16 - lower 15:23 . (Redrig is right, all of the lowers are the same ratio)

Likely you've got a frankenmotor there.

I'm not sure how comparable the Ford 351 is to the Chevy 350, but the 235HP was a Ford 351 and had the same gear ratios as the 225 & 245. So, I'm guessing the mashup should work?

 

[salvageyard saviour]

Oops, A bit dyslectic. That's 21:16 gears I saw before. Again not positive but they go to 21:20 ?

I did know the 350's didn't show up till 85, well after the Electric shifts. I've just never seen a 307 in a boat yet. So I didn't mention it.

The first post has a picture. It's a little hard to see in pic, but positive it says MOD. NO 981231 below that SER. NO. J16L

Again, I just want to be sure. When I open the top I should only count 21 and 16 teeth to be correct for V8 350 (307) HP range

Or is this not counting teeth all and just weird ratio magic that I'm completely lost on?

 

[southkogs]

All of the details that I have are electric shift. I didn't collect much on other Stringers, so I don't know when they introduced the 350. But as far as I can tell the electric shift never had 'em. Up until '74 it the V8s were pretty much all 302 and 307. They introduced the 351 in '74 and that seemed to hang in until they went to newer shift systems. I don't have past that.

I'm not sure why it does, but you're right - it looks like it says model number. It's possible they had model numbers for the stern drives on some of 'em. But with OMCs, you go by the model number of the whole enchilada usually on a tag on the engine (which you don't have). Up until '72 model numbers would read something like XUFM-21, or JUFM-10s in '73 the numbers switched to look like 990206F 1973 (and as far as I know, all the model numbers up through 1980 start with "99").

The 165, 175 & 190 had a 21:19 gear ratio in the upper and the 140 had a 19:20 , but there was no 21:20 that I can find.

Correct on the counting (and I'm no expert) but the gear ratio is the counting teeth. Ball gear : pinion gear. There is a way to do it by counting rotations (turn the ball gear by hand/wrench) and count the number of rotations vs. the number of complete rotations of the shaft on the bottom of the upper. I've never had to do it that way, so I'm not sure how the math works properly - I should think that in a 21:16 it would mean if you turn the ball gear 21 times the shaft should rotate 16.

 

[kenny nunez]

You can never be sure what drive you have until you open up the upper and check the gear set.
OMC used the same upper ratio for the 4 cylinder and the V6 Buick engine until 72. Also the drives were the “high profile” style. 73 on most were the “low profile “ style. At the time however the Chevy V8s were still produced with the “high profile” drive. The gears are the same and can be swapped around. I converted a few V6 Buicks to V8 because the boats were too heavy and the V6s did not last. Consider. 24” deep V Sea Bird with only 155 HP. Typical boat builder joke. 100 gallons of gas, 4-6 adults plus ice and tackle and you get the idea.