warlockjer

Am removing 420 mega blower and intercooler from a 454, actually a 496. Am wanting to go to a single 4 bbl carb and manifold. Talked to about eight different mechanics and my answers a split between the two , single or double plane manifolds. Motor is in a 29 warlock with 1.36 gears and a 28 prop, which I know I will have to change. Also they are split between mechanical and vacuum secondaries. I do not run the boat real hard so do not need alot of top end. Any help or suggestions would be greatly appriciated.

WETTE VETTE

Go dual plane with a 750 vacuum secondary holley. That will provide good all around performance for skiing, tubing, and cruising. I suppose if you really cared about top end you would keep the blower!!

KAAMA

iTrader: (1)

I agree with Vette on the dual plane, but in reference to the carb, most usually use the mechanical secondaries for marine use vs vacuum. 750cfm is adequate enough for a 454 though.

Dave F

I'd use Edelbrock's Air Gap dual plane with the 750 mechanical secondary.

That manifold can flow more than enough air for your WOT and create the torque for your low rpm range.

DAVE

Dennis Moore

When I was working at Hallett boats I was piecing together a copy of a Merc 500 HP Carb engine out of spare engine parts we had sitting around our shop. It was going into a prototype boat we were building (we needed something with good power for our first few test runs). I didn't have a Dart Single plane intake manifold (the one that comes with the 500 HP) so I installed the GM rectangle port dual plane (I even sent it out and had it powder coated blue). Nick Barron (the owner of Hallett) mentioned that he felt we would be down on power without the single plane Dart and I disagreed. He is a very good friend of Vic Edelbrock and gave him a call. Vic stated that the best single plane will give up 40 horsepower at 5,000 rpm to the dual plane but would be at least 40 horsepower more powerful at 6500 rpm.
Since we were only going to run the engine at 5000-5200 rpm I was vindicated (good thing, because it wasn't cheap getting that dual plane powdercoated!). The engine ran VERY good with the dual plane manifold. When we installed a production engine into the prototype boat we sold my pieced together 502 HP engine to a guy who wanted more power for his 21 Hallett. He used the boat at a high elevation lake (Lake Arrowhead) and was very pleased!
I hope this little story informed or at least entertained someone!
Sincerely
Dennis Moore

formula31

Interesting, Edelbrock was the ones who suggested the single plane torker 2's for my enignes and I have been running them for years. They must have had too many of them around. I woudlnt have any problem changing them but I have deck clearance issues. Do intake manifold manufacturers use a standard when listing deck heights?

tomcat

I haven't posted for a while but I couldn't resist this recurring question. I have made the back to back swap between the GM dual plane with open spacer and the Dart single plane on 454/420s. I saw no difference in a boat propped to run 5200 RPM...but the Darts look faster at the dock!!

The only other reason I can think of to use the single plane intake is if you think they might help mixture distribution issues with a blowthrough carb. It might also be good to use them to reduce low RPM torque on a blowthrough system to increase drive life.

BTW, it's nice to see Dennis Moore on the board. Welcome...with the winter months coming up for some of us, the bench racing will really heat up soon.

Dennis Moore

I am looking for topics to write about for FAMILY AND PERFORMANCE BOATING Magazine and thought this would be the best place to get them. Keep up the comments and I appreciate any suggestions. I am purposely going to be a little controversial to provoke a response from intelligent people like you so keep this in mind (and don't tell anybody).
Sincerely
Dennis Moore

RLW

Dennis,
In regards to your request for topics, why not do a report on what would be involved on removing a Supercharger and going back to normally aspirated (NA). Things to take in to consideration like carb choice, intake, timing, heads, and possible cam selection (if applicable) etc.
Take Warlockjer's engine, a 496".
I too have a 496" that came with a intercooled B&M 250 and have thought about going the simpler route of NA.
We have all seen the articles on supercharging but not desupercharging. It seems that there are some of us who would consider doing it with the right guidance.
Is it that hard to go back to NA?
Thanks for being part of the board!

warlockjer

Thanks for the advise. Looks like I will go with the dual plane and 750. What would a 420 mega blower with PFM inter cooler and 2 Holley 850s be worth???? Polished of course...........