Mercruiser 7.4 Aluminum Intake Manifold - Speedwake 2.0
 
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post #1 of 8 (permalink) Old 05-31-2016, 11:26 AM Thread Starter
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Mercruiser 7.4 Aluminum Intake Manifold

Hello,
Got a 97 7.4 Merc with oval port heads. My cast iron intake manifold rusted pretty badly in the water passages and I would like to replace it with aluminum intake manifold to go along with an fresh engine rebuild. I am going with a new full freshwater cooling kit as well as aluminum exhaust manifolds. I saw a thread on here about the edelbrock intake manifolds, I have an edelbrock 1410 carb already. Which manifold should I go with? Part number etc. I did the search on here and aluminum manifolds were discussed, no part numbers listed however. I have plenty of space for taller manifold and better spark arrestor. Appreciate any help. Thank you.
It's going into 1997 SeaRay Sundancer 270DA. Engine has been re-powered to 400HP.
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post #2 of 8 (permalink) Old 05-31-2016, 08:42 PM Thread Starter
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Anyone?
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post #3 of 8 (permalink) Old 06-01-2016, 08:47 AM
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The Edelbrock RPM air gap is a pretty popular one.

http://www.jegs.com/i/Edelbrock/350/...f80aAhs48P8HAQ
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post #4 of 8 (permalink) Old 06-01-2016, 08:48 AM
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Lots of folks with better and first hand info than myself, but see this one mentioned LOTS
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post #5 of 8 (permalink) Old 06-01-2016, 03:31 PM
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Have run both the RPM and the air gap the only difference was the air gap cost 100 dollars more and had to cut and install a spacer in the water hose coming from the thermostat hsg as the air gap it raised its position a couple inches. My question would be more aimed at are you running the peanut port heads as they are crap. I do have a set of aluminum Glenn Marine center riser exhaust manifolds for sale maybe 4 hrs fresh water usage.
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post #6 of 8 (permalink) Old 06-01-2016, 03:51 PM Thread Starter
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Quote:
Originally Posted by RSCHAP1 View Post
The Edelbrock RPM air gap is a pretty popular one.
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Originally Posted by turbo2256 View Post
Have run both the RPM and the air gap the only difference was the air gap cost 100 dollars more and had to cut and install a spacer in the water hose coming from the thermostat hsg as the air gap it raised its position a couple inches. My question would be more aimed at are you running the peanut port heads as they are crap. I do have a set of aluminum Glenn Marine center riser exhaust manifolds for sale maybe 4 hrs fresh water usage.
Yeah...
Mine has that weird center square intake? hole in the middle of the head? I don't know why builder went back to the peanut port heads... Though honestly it's inside of 1000lbs(optimistic) heavy Sundancer. Better flowing heads would have hardly mattered I guess. I would rather them be aluminum if anything... I decided to go with the Edelbrock 2161, because it looked closer to the stock 200lbs cast iron one
Got it for 150 bucks of eBay...

Trubo
Do those manifolds fit the 7.4? Because I am trying to replace my manifolds and risers with HGE aluminum, but they are not center rise?
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post #7 of 8 (permalink) Old 06-01-2016, 04:08 PM
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I ran them on my 7.4 with SS risers. When I PURCHASED THE BOAT IT HAD the RPM intake and a marine 830 Holley which is fresly rebuilt and also is for sale. I tossed the peanut port heads on after a few years and went with a pair of Eddelbrock roval port heads. Kept the factory 7.4 cam. Then tested its performance with the rpm intake the air gap and a torker II.

Pic of exh manifold the rest are on a memory stick at the moment.

The biggest improvement was the heads guessing close to a 100 HP improvement.

Should also mention with the eddy heads and the rpm or Air gap engine ran about the same as it did stock withthe peanut port heads. The Torker II with the eddy heads was a unbelievable improvement but wouldnt recommend it with peanut port heads.
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Last edited by turbo2256; 06-01-2016 at 04:12 PM.
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post #8 of 8 (permalink) Old 06-01-2016, 04:39 PM Thread Starter
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Turbo you're a bad influence. I like you. Man that manifold looks sexy. Reason why I am getting all new kinds of manifolds is that I am doing fresh water cooling. So I wanted something rust, etc free. Could you PM me more details on those manifolds, I think I am interested!
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