Osco or GLM man&riser,which is better?

crazy charlie

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May 22, 2003
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Well ,it is time for more PM.I did the man and risers on my port engine last season and I am going to do the stbd this year.Basic Power has Osco mans&risers&gaskets set for $539 and the same in GLM for $439.Anyone have a preference??? 1988 5.0 lx mercruiser i/o 230hp rwc and always fresh water flushed after each use.Charlie
 

Scaaty

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May 31, 2004
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5,180
Re: Osco or GLM man&riser,which is better?

I got both sides, manifolds, risers, gaskets, bolts, rubber, AND elbows for a GM350 with Sierra part#'s on the box off ebay for $550 shipped left coast. Search old post for more info if needed....salt will have its way in four years anyway.
 

KaGee

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Aug 14, 2004
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Re: Osco or GLM man&riser,which is better?

The GLM's carry a three year warranty Charlie... hard to beat that. Ebasicpower had some great package prices. My view is they are only going to last so long anyway, so might as well save a buck. Besides, Dennis Moore's design gives you MORE POWER! ARGH, ARGH, ARGH! (Tim Taylor imitation :D )
 

LANCLJ

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Sep 25, 2005
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Re: Osco or GLM man&riser,which is better?

GLM claims to give a performance boost due to the configuration of the manifold's runners (they "individulize" each port up to the top of the manifold, rather than each port dumping into a common chamber).<br /><br /> Also, going to a 4" riser, with GLM's design configuration, is also supposed to be a performance gain. With a 5.0 small block, you probably have a 3"(or 3 1/2") riser now.<br /><br /> Dennis Moore, who writes about performance marine engines, had a hand in GLM's design, and, obviously, he reccommends them.<br /><br /> If straight-foward replacement is all your after, then I'm sure the OSCO or SIERRA brands will be just fine.<br /><br /> There are a ton of places you can find new manifolds on the 'net. Of course, shipping is always a killer. You would have to weigh that against buying them in person from a local marine supply store. In my opinion, $540. sounds a little high for OSCO. However,I also like consistancy. So if you did one engine last year with OSCO, then ...........
 

crazy charlie

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May 22, 2003
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Re: Osco or GLM man&riser,which is better?

KG,I DID notice the 3 yr warranty when I was looking at them but they really should last at least 3 years dont you think.I have got way more than that out of any manifold I have ever run by fresh water flushing after every use.I called Basic Power and asked if they knew of any difference and they only stated that Osco is American and GLM is from China.I guess saving $100 aint so bad and shipping is free so I will see if anyone has any negative press on these and go from there.Charlie
 
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