Help me buy a manifold... 120HP Merc.

zbnutcase

zbnutcase

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Re: Help me buy a manifold... 120HP Merc.

The Sierra 4cyl manifolds seem to be decent installed a few of 'em with no fitment or warranty issues.
 
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Fordiesel69

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Re: Help me buy a manifold... 120HP Merc.

If I buy a sierra manifold, do I need to remove the head studs and install long bolts thru the manifold?
 
Fishermark

Fishermark

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Re: Help me buy a manifold... 120HP Merc.

Why would you need to do that? They mount the same way as the original.
 
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Fordiesel69

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Re: Help me buy a manifold... 120HP Merc.

From the pics, they appear to bolt all the way thru. Not sure if the pics is just a stock photo.
 
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fishrdan

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Re: Help me buy a manifold... 120HP Merc.

Fordiesel69 said:
If I buy a sierra manifold, do I need to remove the head studs and install long bolts thru the manifold?
Click to expand...

Nope, the head studs help you install the manifold, so you can hang the manifold of the studs while attaching the other bolts.

From the manifolds description;

This manifold is for most 1968-1982 Mercruiser 120 and 140, 2.5L and 3.0L, 4 cylinder engines with Rochester Carbureter and 5 bolt pattern.

The key word is MOST. There are several different port configurations for this type of manifold and you need to match up what you have, small/large intake ports, separate or siamese intake/exhaust ports. When I ordered a replacement manifold for my 140 several years ago they sent me the wrong one, small intake ports instead of my engine's large intake port manifold. Pull your manifold and make sure the ports look the same as the one pictured.
 
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Fordiesel69

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gbeltran

gbeltran

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Re: Help me buy a manifold... 120HP Merc.

I'd pm the guy and ask him to measure the ports, and compare it with measurements from yours, it looks the same to me, I don't think you will have to replace the carb plate, just the carb.
 
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fishrdan

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Re: Help me buy a manifold... 120HP Merc.

Your manifold looks a lot different than other 4 cyl GM engines I've seen before, so my stud comment was right/wrong. Leave the studs in as you want to use the same exact same style manifold you have now,,,, but if you did change manifold types (and you shouldn't) the studs would have to be replaced, different position, longer. But that's kind of a moot point.

The manifold ports between yours and the Ebay one look the same to me. Here are the different port styles:

marine-manifold-gaskets.jpg
 
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Fordiesel69

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Re: Help me buy a manifold... 120HP Merc.

Thank you for your time spent scanning that. This has been a miserable experiance. Why GM would make 4 different heads is beyond me.

17300 is the gasket that mine takes. I will call the seller and see if he can test the manifold, although I doubt anyone would want the hassel to sell a $100 manifold. The throttle linkage and carb rotation is what is going to kill that deal. That is why I hope I can unbolt the upper plate and use mine, but then there is that gasket to deal with now. Does anyone have that gasket #?
 
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Fordiesel69

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Re: Help me buy a manifold... 120HP Merc.

Well guys, if nobody has any other ideas, I think im screwed. I can;t be the only one with this problem. I am failing to find a match to mine. What is the next step?

Any places I could try to find a used one?
 
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