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Bought the wrong port tunnel ram and was just told I can run a rectangle port intake on an oval port head doesnt make sense to me. Anyone have any experience with this ?
 

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Bought the wrong port tunnel ram and was just told I can run a rectangle port intake on an oval port head doesnt make sense to me. Anyone have any experience with this ?
Ask the guys who deal with Dyno's a lot. That combo usually makes more power then the oval port manifold does. I am sure Bob or Steel will say something.
 

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83 Crusader - 468 BBC
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Bought the wrong port tunnel ram and was just told I can run a rectangle port intake on an oval port head doesnt make sense to me. Anyone have any experience with this ?
Please post your findings...I am interested and curious as well :)Unsure
 

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sqaire port tunnel ram

we have done it in the past had good results it was allways on a mild mannered set up . Just be sure to use square port gaskets
 

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It will definitely work. I can't see it being the most efficient though, especially on the top end. I ran this combo years ago when I needed a motor to just get the boat wet with so I threw my T Ram on an old wore out Suburban 454 just to finish out the year. It actually didn't run that bad. Just remember to use the intake gaskets that match your intake or you'll have a massive vacuum leak.
 

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It will work just fine. I ran a rect port intake on oval port heads for three years. Would I do it on the motor I have now? No, but for a 450-500 hp deal used to cruise on the water it wont make a difference.
 

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Yea it works. I have a rec tunnel on a pair of ovals and it works real well on my set-up although my heads have been worked a bit on the intake side. Lots of guys have done it and most wouldn't want to admit but let er rip. I have found that it will acctually wakes up the bottom end a pinch, kinda like a velocity thing. Just use the right gaskets!!! Mark
 

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Single Carb Tunnel Ram Question

Has anyone had issues with running a single carb tunnel ram- issues being the fuel mixture is not consistent through out?? I'm looking to run this set up, but have a few people tell me not to because of it leans out the front and back cylinders? Any constructive thoughts/info on this would be greatly appreciated!
 

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Has anyone had issues with running a single carb tunnel ram- issues being the fuel mixture is not consistent through out?? I'm looking to run this set up, but have a few people tell me not to because of it leans out the front and back cylinders? Any constructive thoughts/info on this would be greatly appreciated!
Alot of factors come to play on this question? Engine size,cam specs and intended carb. Not to mention boat and what you are trying to get out of it. Of Course everybody wants the most bang for the buck but I have done it and made it work. The biggest factor is a LARGE plenum manifold with a single shot carb?. With that being said the squirters and jets need to be stepped up to kill the initial hit from the peddle. As most people have learned with a single top tunnel is that they have a large hesitation on the hit simply because of the plenum which is mostly air and a touch of fuel will toss a big bog on off throttle response. So to cure that issue what would you do. M
 

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Since this is a jet boat thread, lets state the bottom line here first. IF you are running a stock pump, you may be limited in rpm that you will realisticly see, due to a stock pump's very nature, around 5500-5600 is my recollection. On our dyno at work, we've found that the oval ports well out pull the rectangular ports up to around that same 5500, where the rectangular ports start to show gains at the higher rpms. I've never purposely run a mis-matched intake/head combo to know , but indications are that if you're running a hot lake or river boat, and not an all-out racing rig turning 7000 rpm with a loosened up pump, shoe, grate, nozzle, etc, the Oval port big Chevy heads are the more efficient flowing , and the aftermarket ovals even more so. Run a matched oval intake to keep velocity high. ( Remember, you're trying to "ram" the air/fuel charge in ). Many builders have even run a slightly larger head port opening as opposed to the manifold's, to create a manifold "lip", to minimize reversion. Running the biggest and baddest components just to have bragging rights often results in an engine that isn't running well. My engine building motto.....Give each particular engine what it tells you it wants, not what you want to give it.
 

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Rectangle intake/oval port head

rumor has it, the air fuel mixture will bang into the intake area surrounding the smaller oval port in the head thus knocking the air-fuel mixture out of suspension causing a loss of power...if anything, when port matching intake to head, some want the port in the intake slightly smaller as to alleviate this problem...:)
 
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