I have 509's , I am running the Crane big hyd roller cam,( 7 something ) pro 1 heads tricked out by Jim V. and Lightning headers with the Dart single plane intake and they will all day at 600 RPM in gear. Holley HP 950's for carbs.
Before the Crane hyd cam I was running a big solid flat tappet cam. Same results. ( idle quality that is ) ( The Hyd roller is smother )

i got hydr.roller cam's. i don't know why my builder is so worried about the idle then. everyone else is running a single plane intake it seem's.i think he's trying to give me a nervous brake-down. i'm already a couple week's behind on these thing's and the intake's are the last piece here. everything eles is ready to rock.

Mine were rectangle ports that were welded up to match the ports of the heads. The floors of the heads were 'wedged' and then ported. they look like a cross between oval and rectangle, but the ports all match.

Tinkerer I have not forgot about the DYNO but Jim has been pretty busy and I decided to tear down my other engine last night and redo it completely. So I might not be going to the dyno till later, if at all. I do want to go when Jim pulls his and I will let you know.
You done with the Toy Box yet??
Jason

Idle quality depends alot more on cam choice than single vs. dual plane. If your cam choice is reletively conservative, a smaller single plane like a Dart will idle great at 800rpm. My old 454-420hps came from Merc with single planes, Wiend Xcelleraters and they would idle all day at 800rpms. They had square port heads also.

Yes again on the cam on idling....the intake is going to have very little on idle quality....low end power...now thats another story....I still feel ovals are the best choice on boats...unless the cubic inches way up there...and even then I have seen some 600 + motors with ovals making some unreal low mid power...right where we need it....Rob

had both a 850 BG, and my new one which was stolen was a 1050 nickerson stage 5, now going to a custom one from DEAN GELLNER with a intake custom ported. so in 2months we will see I hope if not then more stuff will be changed head work cam.going for 725 to 750 from 670 with the nickerson/ 647with bg merlin heads

flange was 4150 2'' rise dart single plane

114 or 112 cam will be fine I had a 110 it was snroty but I am going back to a 110 with a better carb it will be fine plus I have stainless marine exh dry so THE 110 WILL WORK.PLUS i WANT TO GO BACK TO RACING AGAIN in opa 600/500 class. merc uses the dart intake single on there 500hp for years. my boat with the 114 cam still throws you back when you hit it from 3000 to 5000, it set up for 5400 to 5600rpm but had it running at peak 5800 to 6000 for half hour when testing with to small a prop 26b1 needed a 28 or 30 lab hit 83.2gps figured its good for 86 with a 30 lab.

sounds like the 741 633 lift mine is a isky with 622 .

12YRS i SPENT WITH A BUILDER he did some race boats , but mostly cars. So after talking last year to the big boys and there big power .the guy for me is DEAN GELLENER MR.HORSEPOWER. BEFORE you buy them call him for the cost of the intakes he gets good prices and have him match port it. hes going to do some magic like like jim v does on heads. for me on a new intake custom porting