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Sbc 350 GLM exhaust Porting
I was thinking about buying a pair of GLM exhaust manifolds and porting them out to match my AFR heads I know you guys are gonna think I’m crazy But the manifolds aren’t that expensive a lot cheaper than aftermarket and I figure if I can open them up should work just as good right ? Die Grandor Some Bose noise canceling headphones And a beer and have at it what do you guys think. open up the ports to a 1 3/4 or 1 5/8 you know if thes room |
Make sure to grind enough away to get into the water jacket. Water injected exhaust ports are the "hot ticket" right now...
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You spent bucks on AFRs and Im guessing a nice cam to go with them, but you want to skimp on decent exhaust and grind on some cheap manifolds... Give it a try, maybe it runs good, worst that can happen is it reverts and destroys the motor......
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I hear you AFR heads plus a cam and then cancelling that all out with a close matched poor flowing OEM exhaust manifold and riser.
Actually you are going backwards ---- did you know your cork in the system is the stock exhaust riser as well. Its the same riser and gasket a 175 hp thru 190 hp V-6 mercruiser uses. Wanted to pass that info on |
Ok guys your right I’ll get some headers thanx for setting me straight :lolhit: |
If you trying to save a few bucks, search the parts pages on here, fb etc for some used stainless marines, etc.... you do not have to send 5 grand on fancy exhaust but you need something better than stock.
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Originally Posted by phragle
(Post 4625533)
You spent bucks on AFRs and Im guessing a nice cam to go with them, but you want to skimp on decent exhaust and grind on some cheap manifolds... Give it a try, maybe it runs good, worst that can happen is it reverts and destroys the motor......
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Originally Posted by Ryan00TJ
(Post 4625599)
I ran unported GLM aluminum manifolds on my old 383 SBC. Risers were Imco 4" dry to transom. This setup supported 475hp and 80.5 gps speeds. Sure a set of CMI's would probably outperform the above setup. Don't waste your time porting the GLM's. The restriction is on the riser as stated above.
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anything cast will always have room for improvement
looking at the cross section there looks to be a little bit of room to open up in the ports. but with that said your mileage may vary https://cimg5.ibsrv.net/gimg/www.off...90765c2d21.jpg I don't know what cam you're running, but if its it is a stock cam i would port these a little. at least clean it up, port transition, casting flash, radius, smoothing things out. If you start removing lots of material I would be a little more cautious. |
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