1983 johnson 150 head differance

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Painterx

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Hello I have a set of heads 1983 johnson 150hp (328325)that the previous owner stripped the spark plug holes and put tread savers in crooked. now I found a set of 1981 johnson 150hp (325557) heads local.can someone tell me what the differance would be on the 2.will the 32557 heads be fine on my motor without any tuning or major mods.
 
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emdsapmgr

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Re: 1983 johnson 150 head differance

Can you post a picture of the head firing face from both heads? I know the 557 heads are the low compression (bathtub) heads. Seems OMC changed the heads and carbs changed mid-year in 1983. Possible head compression changes may have required rejetting of the carbs and new/different carb part numbers. (switch from high compression heads to low compression heads.) You need to be careful with this change to make sure you match your carbs to the right heads.
 
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Painterx

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Re: 1983 johnson 150 head differance

Here's the 325556 port. image.jpg 1981 (j150tlcla)

Here's the 328324 port. image.jpg 1983 (j150tlcte)

On ********** parts list I can't find any difference in the 2 motors except these heads and carb bowls.
 
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emdsapmgr

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Re: 1983 johnson 150 head differance

Both heads have the same head configuration. I don't see much real difference. The other heads should be ok.
 
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Painterx

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Re: 1983 johnson 150 head differance

That's what I sayed if there is a difference you can't tell from the naked eye.but I don't want to put 100 bucks into gaskets and find out I have to reject carbs and timing.there has to be something I'm missing the 150,175,200 all have the same block pistons heads only difference I see is the carbs.
 
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emdsapmgr

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Re: 1983 johnson 150 head differance

You are correct, most of the difference is in the carbs. The 175/200 do use larger carbs which flow more fuel. The 200 block is ported differently-makes more hp at higher rpm's. The 200 also uses special rubber intake filler blocks for added hp.
 
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Painterx

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Re: 1983 johnson 150 head differance

Found it the 328324 and 328325 are 1/16th thicker in the firing face than the 325556 and 325557 everything else are the same.if I run 2 head gaskets on the 325557 and 6 they would be fine.but I'm not going to do that lol that double gasket just smells trouble.i ran 2 gaskets on a race quad and every 6 runs it would blow.
 
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