Finish my 509
 

Long time lurker, first time posting, glad to be here. I have procured parts for a 509 project engine for my first powerboat. I have a Dart Big M block with forged rotating assembly. The pistons are flat top with 4.5cc valve relief. I would like 9.5-10 CR which means i will need 110cc heads or smaller i think. I have a hydraulic roller camshaft with the following specs: 234/242 .610/.632 112 If I can use it fine, if not, oh well. I want to get the most bang for my buck. With the research i have done i see that 310cc canfield heads are a good buy along with an airgap intake and 850 demon. My budget is pretty tight. i buy parts on ebay from money made on side jobs. $2000 for heads, $200 intake, $550 for carb. What can ya'll recommend for the top end of this motor. I'd like to see 600+HP with a nice broad torque. I hope to put this motor into a 26' CAT someday. Thanks for your input and once again, hi ya'll.

Re: Finish my 509
 

Use a Dart single plane intake. I've seen a lot of used ones on this site. Other than that, your choices are fine. Don't forget a good oil pan and cooler.

Re: Finish my 509
 

I've got a 10qt oil pan. Will i still need a cooler with that much oil? Will the single plane be too much with such a higher rpm operating range compared to a hi-rise dual plane. I've seen so much controversy over the two. My machinist says dual plane but he does not do strictly marine, mostly blown alcohol and other drag car types of motors. I like the input OSO has due to the marine experience. Thanks, Dave

Re: Finish my 509
 

I hear the Brodix Single planes out perform the Darts.
I am changing mine this winter from Dual planes to Brodix Single plane.

Mark

Re: Finish my 509
 

pistons .023" down from deck surface @ TDC: 8.97:1 with 110cc heads

pistons @ zero deck: 9.35:1 with 110cc heads

Based on 4.500 bore, 4.000 stroke, .038" gasket thickness.
Head volume figured with sparkplug in place.

mc

Re: Finish my 509
 

I know of a guy who built a 509cid engine with the same hydraulic roller cam specs as you, 950cfm Holley, 9.1 comp ratio, Air-Gap intake, Dart 308cc heads with only some clean-up around the bowl/valve areas and it made 563hp @5700rpm on Tyler Crocket's dyno a few years back. Not sure you will quite hit 600hp with a dual plane intake such as the Air-Gap on a 509 for what you're tyring to do. The Dart single plane intake might be a good option. Maybe others can help shed some light on the subject. Welcome, and have fun with your project.

Re: Finish my 509
 

Yes, you are still going to need the oil cooler.

The single plane is going to start making more HP/Tq at about 4000 rpm on up over the dual plane. Using 5500 as a WOT, the single plane is going to be showing ~25-30 HP more than the dual plane. In the 3000-4000 range, its going to be about even. remember, in a boat you really don't need to worry about the power below 3000 RPM, as that is the speed that most boats get on plane, compared to a car that will be spending a lot of time at that RPM. You will usually be cruising between 3-4500 in a boat, and when you want to go for it up to say 5500, the single plane will blow the dual away.

Re: Finish my 509
 

We put together a 509 for my sisters Chevelle , 502 crate motor bored out, 10.5:1 cr, Iron heads done to death, air gap intake single plane, 710/690 solid roller cam with 110 center line ( same as our 540 boat motors) 1050 street demon carb and all the other good stuff as far as hardware goes. 675 hp ,600 ft/torque. This car is a driver, full interior, all steel , 390:1 rear end and runs 10.90's when tuned for it. I would build this same combo for a Boat .

Re: Finish my 509
 

Would large oval port heads do me better than rectangular ports. For example, the large port AFR heads compared to their rect port heads. Also, should i ditch my flat top pistons for some small dome profile pistons? There seems to be more 118cc heads out their than 108 or 110 cc heads which i know you can custom order but i usually buy gently used stuff on ebay or where i can find it. Thanks, Dave

Re: Finish my 509
 

Anyone else with proven 509 combos? Thanks

Re: Finish my 509
 

Small Canfields are the best heads for your type build imho. Unported,I think the ovals would cost you a few horses up around 5000. Build a good valve train. Doyou have room in the budget for roller rockers? With al. heads and a cam that big , you could probably get away with a little more compression. A small dome about 10 cc would be good. 0 deck the block and you would be just under 10 to 1. The engine would run better but it would require better gas.

Re: Finish my 509
 

I'm seriously considering selling the flat top pistons i have and buying the small dome profile SRP to get me near 10:1. Seems to be more 118cc heads out there for sale than the 108 or 110cc heads i will be looking for. Dunno, we'll see. Does anyone have experience with the ProComp marine billet distributors with MSD caps that are on ebay for about $175? I know it is chinese stuff but it sure is a lot cheaper than the $325 MSD one. Thanks, Dave

Re: Finish my 509
 

As far as rockers go, i will probably go with the crane gold 1.7 series. Any other suggestions within that $ budget?

Re: Finish my 509
 

be american buy american chineese are screwing us every inch they can just my two cents

Re: Finish my 509
 

Be careful with high comp ratios for marine applications. With the way fuel quality is these days, I would try to keep comp ratio down....the quality of fuel seems to be becoming more and more questionable as time goes on. It's no fun trying to find special octane fuels for your boat especially right when you need it-----AND that's especially true of a marina! Or expect to carry lots of TORCO fuel octane boost additive with you.

Re: Finish my 509
 

Would 10.2 compression be too much. We have 92 and 93 octane fuel available everywhere here in central texas.

Re: Finish my 509
 

If everything is set up perfect, true 93 will be okay in 10-1 Don't get carried away with total timing. 32 to 34 MAX.

Re: Finish my 509
 

Hey Dave,

You might want to find bobl on here he is usually in the Nordic forums. He owns Full Throttle Marine in Austin Texas. You could pic his ear, he could give you some good ideas.

Re: Finish my 509
 

been there done that, i'll check with him again

Re: Finish my 509
 

I don't think you'll have too much compresion with the 110cc chambers. And I also think that you can make 600 flywheel HP with a decent cam (such as the one you have now) if you get the right heads and manifold to go with that cam.
My Teague/Merlin Marine 509 came with small-dome pistons (14cc) and a cam w/ 226 deg. int. & 234 deg. exh. duration and .587" int. and .610" exh. lift w/ 112 deg LSA.
With the Merlin VR 345 cc cast irons heads w/ 119cc chambers (these flow relatively poor IMO) this motor came from Bill Mitchell with a dyno sheet which showed it made 574 hp @ 5600 rpm and 631 ft.lbs of torque @ like 4800rpm. This was with the Merlin Marine single plane intake (which has slighly larger ports (exits) than the Dart manifold (but the Dart might actually outperform it).
For the best power I would suggest that you use the Dart 335cc CNC Pro-1 or AFR 315cc CNC heads and the Dart manifold. I think your engine would make over 600 HP with these provided you can get the heads machined to like a 114cc chamber and use the thinnest good quality gasket you can find (probably like .038").
A cheaper option is the Edelbrock Marine heads which come with Inconel valves but without springs and retainers.
These are available hard anodized coated in either an oval port with the 110cc chamber or rectangular port with a 118cc chamber. The oval will give you more compression but less power with your combo in my view.
If you don't have to have aluminum heads, give Valako Racing Heads a call and ask Jim Valako what it would cost you to port a set of Dart Iron Eagles and you might find that these would give you the most "bang" for the buck. In fact, just call Jim first and I'm certain he'll give you an honest opinion and damn good advice. And he can make any head flow better. I just had a set of AFR's done by him and I have no problem reccomending his work to anybody.
Just my 2 cents...

Re: Finish my 509
 

Man i appreciate all the advice. My machinist is very good at what he does but he builds mostly blown alcohol and other engines for mostly cars. He has built several marine engines as well and is hell bent on making sure i build for torque and not for horsepower which i understand, but, he is all about oval ports, dual planes, etc and from what i have seen here on the posts its about rect ports, single planes, etc. i know yall guys build alot of marine stuff so that is why i come to you to get the marine opinion. i dont want to piss off my machinist by not taking his advice. he wants me to get a large oval port head and oval port dual plane intake like the airgap style and put a 1-2"phenolic spacer on top. This motor will hopefully be going into a cat.

Re: Finish my 509
 

I like the price of the Canfields compared to the AFRs. I'll probably go with them. Are there any concerns with the raised exhaust ports? They state you need custom length pushrods. How much do those cost? Thanks

Re: Finish my 509
 

apples to apples, there is no comparison between Canfields and AFR's. you are talking two totally different animals here.

Pushrods cost the same no matter what length they are. "custom" just means that you have to use an adjustable length one to get the correct valve geometry set. Both crane and Comp have good articles on their web sites about checking this.

Re: Finish my 509
 

Remember who is going to be writing the BIG check to him. There is nothing wrong with the large oval ports. You can get some serious HP from them if they are ported correctly. They flow ok, put their strong point is that they have very good velocity.

Don't get too confused by all the numbers thrown around. For example, 2 sets of heads that both flow 390cfm @ .700 lift are not usually the same. The ones that do it with the smaller port are going to have better velocity, and make more HP. See my post above about Canfields and AFR's. Not saying Canfields aren't ok, because they are. But look at the runner size, and the flow. The AFR's have smaller runners and greater flow than the Canfields (and most other heads). Thats why they make HP, and thats why their price tag is what it is.