4.3L - 1 Piece Manifold conversion - Risers??

BRG25

Chief Petty Officer
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Messages
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Searching the archives I found this old thread from 2006 regarding the conversion of the old 1 piece style exhaust manifold to the newer style.

http://forums.iboats.com/showthread.php?t=55787

I called Mercury today and gave them my engine serial number (0L642312) and they gave me the following part numbers which matches what Don listed in the post above.

2 exhaust elbows 807988A03
2 exhaust manifolds 99746A17
2 intermediate elbows 14478T01
1 installation kit 864293A02

Now the lady I talked to did not mention risers so are they not needed in my application?

Any tips on doing this job? Thanks.
 

BRG25

Chief Petty Officer
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Messages
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Re: 4.3L - 1 Piece Manifold conversion - Risers??

I guess I'm just confused...the service manual has 2 different diagrams, one with risers and one without so I'm assuming this is illustrating different manifold setups depending on what the owner needs. BT Doctor are you saying that the 807988A03 exhaust elbow has the riser built in? It's difficult to find pictures based on specific part numbers. I've attached pictures from the service manual to show what I mean.. Do I just not understand the terminology here?

Manifold1.jpg


Manifold2.jpg
 

nofuss

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Re: 4.3L - 1 Piece Manifold conversion - Risers??

hi the terms elbows and risers are used interchangeably in discussions about this type of manifold. however with the additional pair of elbows needed with this conversion it could be confusing.
Your risers, labeled as "a" in your diagram are the risers, they are in your parts list as " 2 exhaust elbows 807988A03" .
the second set of elbows are the extra part that you would need to make the conversion. 2 intermediate elbows 14478T01
I am presently in the middle of doing this conversion myself. I received my manifolds and risers today, and since i had to purchase the intermediate elbows from another dealer due to stock, I would not receive those until Wednesday.
if you need further assistance or pictures just let me know. I was not very familiar with this engine type so i did the research.

I bought after-market GLM parts. There is a kit available with all the parts for the conversion, but i opted to buy the parts separately as it saved me about $200
for pictures that show u the parts you need do an ebay search for the "mercruiser 4.3V6 1 piece to 2 piece conversion kit" you should be able to see pics of all the parts you would need.

let me know if u need any more help

Pernell No Fuss :)
 

nofuss

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Re: 4.3L - 1 Piece Manifold conversion - Risers??

ok I see what is causing the confusion, its the riser spacers listed as risers. for the conversion you dont need the spacers, listed as "b" 3 in exhaust risers. this spacer is used for a different application.

Pernell :D

see pic of conversion kit sold on ebay. this shows all that you need. its its GLM aftermarket and i know some people like OEM but it shows all the parts you need.

P :)
 

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BRG25

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Re: 4.3L - 1 Piece Manifold conversion - Risers??

Thanks for the information guys, I really appreciate it.

Pernell, I would be interested to hear how your conversion goes. Are you also converting from the 1 piece manifold? I'm not having any problems, however mine are original and about 10 years old, but I do not boat in salt water. They are still overdue to be replaced.
 

nofuss

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Re: 4.3L - 1 Piece Manifold conversion - Risers??

Not a problem at all, I am supposed to get the intermediate elbows tomorrow morning, and as such I plan to do the installation tomorrow. I would let you know how it goes, probably take some pics while i am at it too.
I am converting from the one piece, to the two piece, as the one piece is no longer available. however with the knowledge that i have now, i would have converted even if they were available, as maintenance is much easier with the 2 piece.
I bought my boat from florida and it was mostly used in fresh water, but was a 2000 boat with original manifolds. and now they have all failed my pressure test, so i guess yours may be not far behind, so now would indeed be good time to change out.
will let u know how it goes.

Pernell :)
 

nofuss

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Re: 4.3L - 1 Piece Manifold conversion - Risers??

Ok conversion completed, engines started and run well.
due to really bad weather i had to complete the installation today. and was not able to run boat. thunder showers :(

Firstly I will say unless you are quite mechanically inclined dont go for this GLM brand. My brother and I had some "fun" sorting out a couple casting flaws, and clearing threads to install water inlet elbow and blanks. There is another company in california that I was told sell much better aftermarkets but i wanted mine in a hurry, and luckily we could handle these defects.

the installation is pretty straight forward, however due to the weight of the manifolds I decided to make a tool to make installation easier. :cool:

I took 2 6" X 3/8" bolts that have the same thread as the manifold bolts and cut off the heads leaving them about one inch longer than the manifold bolts. then I put two blades in my hacksaw together, to make a wider cut, and cut a slot across the cut edge of the bolts, so creating 3/8" screw head bolts" ;)

ensure that you have the water inlet elbows in place and any blanking plugs that need to be installed before starting installation. :redface: If like mine, your engine is raw water cooled, you would most likely only need the elbow at the bottom, and all the other holes blanked out. (ensure that you have all the elbows facing the right direction, and install them to suit this.

after ensuring that the gasket face of the head was clean, i installed the two "screws bolts" into the outer holes in the head, running them in just hard hand tight. then i slid the gasket into place over them so that it lined up properly. Then i put the manifold in place over the bolts. then with the bolts supporting the weight in place, i install the 4 bolts in the free holes, just till they are securely in but not tight, next i remove the "screws bolts" the slot is to remove them with a screwdriver if they are tight to remove. some times they will be.
when the screw bolts are removed install the other 2 bolts and torque to speck, starting from the inside out.
next connect the hose to the water inlet on the manifold. if u have 2 engines, this makes work easier on the two outer most manifolds. does not make much difference in the center 2.
next i push the 4 " round bellows over the round end of the intermediate elbows, and installed 2 hose clamps in the groves on that side. (Note I did not remove my oval bellows from the Y piece when removing my manifolds, I just slackened the top 2 hose clamps and manifold bolts and lifted the manifolds out.) Then I rested the elbows oval end, into the oval belows, but did not tighten the clamps. next I pushed 2 hose clamps over the bellows, rested the riser on the manifold and slid it aft rocking it so it entered the round bellows and the elbow, until it reached the ridge in the bellows and lined up with the manifold. then i lifted the riser a little and slid the gasket between the riser and manifold, and then dropped in the bolts and tightened them up, to speck in a criss cross manner. ensuring that the gasket stayed properly in place while initially screwing in the bolts. When lining up the riser ensure that the bolts could be dropped in with the riser in place or you would have to drop them in and then position the riser. :redface:
Next tighten the remaining hose clamps in any order.
If your linkage is like mine, you would see that a screw and nut seem to line up with a raised point for a stud, I just removed the nut and the bolt goes straight into the raised point. the other two studs from the original manifold go back in the holes that they match.

note some kits come with 2 hose clamps for each bellows, get 2 more and ensure that each bellows has 4 hose clamps.

I think that is it basically any more questions just send me a message.

or i forgot, hook up water, test and enjoy your boat :D

Pernell No Fuss :)
 
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