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View Full Version : OSCO vs MERCRUISER HEIGHT



raritan
01-28-2006, 06:02 PM
Can anybody give me the height of the Mercruiser exhaust manifold. I would like to know if the top of the mercruiser riser is even with the top of a holly carb. I have clearance problems on my 16. Any help appreciated

Lenny
01-28-2006, 06:14 PM
Merc is 13 5/8", top of riser to bottom of manifold. 4" flange version.

I just happen to have a new set here to measure from... :)

raritan
01-28-2006, 07:24 PM
Thanks for the reply. What I need to know is this:

1. Is the Mercruiser riser level with the top of a Holly carb
2. How much higher is the Mercruiser then the Osco riser.

T

Lenny
01-28-2006, 09:05 PM
Raritan, sorry, I can not bolt 'em on to the motor to check.

First off, what intake manifold are you using for a comparison?

Do you have a spacer on the intake manifold?

Are you using the "low" style flame arrestor?

The only constant (leaving out all these other variables) is the bottom of the exhaust manifold to the top of the rise elbow. If your "X" dimension is unchanged it should be the same as all others.

Open the engine hatch, put a straight edge across the hole, and measure depths and locations. You should be able to get all the answers from this.

MOP
01-29-2006, 12:27 AM
Not sure if this helps, I had Osco's on my 302 Ford they just touched the hatch bit not enough to break through the gel in 3 years.

phil

raritan
01-29-2006, 02:45 PM
Thanks for the help.. I have OSCO's with 3 inch outlet and have just about 1 inch between top of manifold and hatch. I planned on replacing Oscos with GLM aluminum which are just like mercruiser. Lenny, Do you have something more specific like the distance from the middle of the bolt hole to the top of the manifolds. That might help. I do have an extra engine cover but really dont wanna cut into it if I dont have to. I just want to get rid of the excessive weight.
I can be reached at thomas@yellville.net also

raritan
01-31-2006, 08:29 PM
Howdy,

I still need help with these dimensions. Please look at my last post and see if you can help.

thanks

Lenny
01-31-2006, 09:39 PM
Middle of the bolt hole that bolts the MANIFOLD to the head, to the top of the riser (4") is 12" give or take a 32nd... this is Merc...