Which flapper and manifold/risers do I need? 4.3 Mercruiser...

[CStradling24]

Hello and thanks for helping.

I am replacing the one piece manifolds that were on my 4.3 Mercruiser with the two piece set ups. Found a few sets on eBay that are meant to be direct replacements for the one piece manifolds including the exhaust bellows. They are made by GLM or Sierra. Is either better than the other?

Also I am looking for the flappers since mine are completely gone. I see two parts available.
807166A2 - which says to use with one piece manifolds.
807166A1 - which says to use with two piece manifolds.

My questions is which should I use? I am replacing my one piece with two piece manifolds but I am not changing the Y-pipe that these go into?

I think my engine is a 2000. Serial 0M007192

 

[achris]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

1998 engine (from the serial number) should already have the new style shutters, so you go for the A1 number.

Personally, I wouldn't use either GLM or Sierra... Both are cast in China and are known to be quite a bit thinner than OEM... And one of them (can't remember which) is renowned for the elbow surface needing to be milled because it's not flat. ....

Chris.....

 

[CStradling24]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

Considering mine came with the one piece manifolds I would assume thats they Y-Pipe I have? I looked up two pictures of them. It would appear that the 807166A2 version is more squared. I am going to go run to storage to look at my Y-Pipe and try to see if it looks squared.


807166A1


807166A2

 

[achris]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

The y-pipe is the same, one piece or 2 piece....

No, the shutters are the same in both 'kits'. The A2 number is the upgrade for the old style shutters (includes a mounting frame)... You have the new style, use the A1 number....

 

[CStradling24]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

Then what am I missing? The Y-Pipes part numbers are different as well. Upon googling pictures for them it would appear the one is a rounded the other is a little squared as well? Just trying to figure it out, I am definitely a newb but dont understand why the part numbers are different.

 

[achris]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

What are you googling? The y-pipes changed in about '96. The old style has a single shutter flap on a stainless shaft.. They had problems with those ones falling off... They changed the y-pipe (and shutter design), old pipe was -44266T1. The new one, which uses the 2 piece style shutter is part# -807166A1. For people whose shutters fell off the old style pipe and didn't need to change the whole pipe, the shutter kit is ....A2. If you have the new style pipe (the one you have being 1998) then the shutter kit number is ...A1.

HTH,

Chris.......

Edit:.... Embarrassed... :redface: :redface: :redface: Just did another check.... Oh, this is bad :facepalm:... The upgrade for the old shutters is not A2, it's A3... Oh boy..... The right kit for your y-pipe is, ouch!, the A2 number.... So very sorry for the confusion... I can post up the parts drawing if you like....

Humble apologies

 

[CStradling24]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

When you say new style, are you sure your not referring to 807166A3? Both A2 and A1 are on a stainless shaft.

According to mercruiserparts.com, my Y-Pipe is 807130A7. This is, according to their parts diagram, the Y-Pipe for the one piece manifolds.

Then for the two piece manifolds they list the Y-Pipe as 807130A4.

I can find pictures of the inlet where you put the flappers for both of them on eBay. 807130A7 looks to be more squared (just like the flappers for that one) where as 807130A4 looks to be more rounded.

 

[CStradling24]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

Hey no problem, I was sitting here beating my head in confusion haha. Hopefully this thread helps someone in the future. I searched several regarding these part numbers and there was no real difference for the A2 and A1 that I could find.

 

[achris]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

 

[CStradling24]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

The A1 and A2 part numbers are both the newer type like in my pictures. Just ones a little squared. I just checked my Y-pipe and I Need the squared ones. Im not sure what the part number is for the older flaps in your top picture.

 

[achris]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

... Im not sure what the part number is for the older flaps in your top picture.

Those shutters originally had the part number -14348A1, but they had a habit of falling off (shaft would wear through), and the replacement for them is -807166A3...

You can see the ring at the top is the mounting for them on the old style y-pipe....

HTH...

 

[FishHog]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

I have just went through this with my 1998 4.3L. I got confused and so did the parts supplier I use. I finally took my old shutter in and compared it to the ones they had in stock. A2 is what I need. A1 looks similar but is in fact smaller. A3 is what achris posted above.

 

[Rydnlow]

Re: Which flapper and manifold/risers do I need? 4.3 Mercruiser...

A2 is what you need. I just had the same problem with mine. The marina spec'd out the A1 and it was about 1/2" short of being wide enough. It was only 3" wide and I need a shutter that is 3 1/2" wide and more squared off. I tried to put the A1 in and it would have fallen right in. I called and had them order me the A2's and will exchange. I also had the single piece exhaust and the y pipe to go with it. I am currently changing to the 2 piece exhaust now also.