Hello, I am the proud new owner of a 1989 Baja 250 Sport with a mercruiser Big block 454 7.4 and I need a new exhaust manifold. I have looked all over the engineblock etc and cant find any serial numbers to identify the engine to order parts. Does anyone know what model/type/version I should refer to when researching parts?

Also when replacing the exhaust manifold, do I need to replace the riser and elbow or just the manifold?

Any help or suggestions would be appreciated. Got a great deal on the boat and cant afford to bust out another thousand!

you should do all manifolds and risers . More tgat lijely you have 4 inch risers 15 degree. and center outlet manifolds. Post a photo

https://marineenginedepot.com/exhaus...lds-and-risers.

This should be your serial number range, list cast and stainless, either will work
https://www.mercruiserparts.com/454-...8-1988-1992-0b

I have the orig exh manifolds/risers from my 1990 454's I'm not planning on ever re-using. They're very heavy so shipping might be an issue. Need to see pics of what OP is trying to replace and what part of the country he's in.

BTW, in the Mercruiser link posted, looks like those manifolds are for a SBC, or at least the head/manifold gasket appears to be for a SBC.

Good catch. Mercury has a habit of using generic pictures in many of the catalog images, especially on the older pages. The part numbers are correct.

The stainless elbows are no longer made, just the cast iron now.

BTW BAM, your site is having issues, might be fixed now. Last few days except today, I would enter a serial number and it would take me to a different motor

Just FYI

Thanks I'll look into it