Carburetor Replacement

[Bigbroadjumper]

Hello all, I need some advice on replacement carburetors. I have an old Magnum with SBCs, Dart 202 heads, stock exhaust. When I purchased the boat she had automotive carburetors (Holley) and I want to replace them with Marine. What size and brand would you recomend?
Thanks

[Sam]

600-650 would work well.

[Ranman]

It's hard to say. What HP are the motors? I would think that if the engines are 250-300hp, you wouldn't need much more than 500cfm. I'm sure others will provide a more accurate estimate. It's very easy to over carb an engine. Bigger does not always mean better.

[BUIZILLA]

Holley # 80551 is a marine designated 600cfm, direct replacement, for engines up to approx. 300 hp.

J

[MOP]

I picked up a 4 barrel setup for my 16, I am pretty sure its a 650. It came off a stock fresh water setup that Art from Babylon Glomed to get the cool little ski. Moody got the trim/tilt off the same boat. What did the older 302's have?

[Ranman]

BUIZILLA,

You seem to know a bit about performance engines. I'm not saying you are wrong, but why would that be the best choice? Is it because it's the only marine unit available? It's the best value price wise? Does a 300HP engine really need 600cfm? I'm not tryoing to be sarcastic, I'm seriously wondering. Would you have to jet that 600 down some to make it work well?

[Bigbroadjumper]

Thanks for the input. I spend most of the time running around 3000 - 3200 RPMs. What do you think about the Edelbrock Marine carbs? Summit Racing is selling new for about $280.
Bob

[BUIZILLA]

Ran, I just pulled that one out of the hat, since it is the only one that appears on the online catalog this week, and it seemed to suit a basic STOCK replacement parameter. I'm not suggesting it is the best choice, if there is a best choice..
That is best left to the end user.

The Holley online catalog is difficult to navigate sometimes, with the 3 browser definitions to choose from, and I noticed lately that several MARINE specific listings have vamoosed from the viewing theatre in one or more of the browsers. There were some 750's listed b4, as in 2 weeks ago, but I can't seem to find them now either. There were also more than 2 or 3 600-650's listed before as well. It appears Holley consolidated listings by using a more universal throttle lever/fuel inlet to cover a wider audience and less listed numbers. I would think out of the box jetting would be pretty close for the STOCK application as requested.
I have no working usage of the new Edelbrock carbs to date, so I can't comment on those.

J

working on surge brakes....again

<small>[ March 26, 2003, 06:54 AM: Message edited by: BUIZILLA ]</small>

[JimG]

My last three boats have had Edelbrock/Carter carbs. I can't vouch for the ultimate performance vs. Holleys, etc. But IMHO, they are the best "out of the box' carbs I've ever seen for reliability and easy cold starts. I bolted a new one on my Donzi last Friday, and it's a whole new boat...

JimG

[BigGrizzly]

BBJumper go with no more than 600 cfm for that application. My 351 clevland actuall runs better with a 600 than a 700 CFM unit. My 302 16 has a 500 on it and Forrests little green giant 302 has a 450 on his and I clocked him at 69 on my GPG. As for Edelbroc vs Holley I have both a 600 and 750 in both brands and have swapped then both on the dyno and at the lake and jetted them on my engines with similar results the 600 being better in everway to the 750cfm. None have giving me any trouble. the only problem is getting use to the fuel metering rods for jetting. If it were ne I would replace with the holly as close to your as possible. That way there no suprises. Oh yea someone is soon to kick in with the blown power valve problem. That is not an issue anymore unless you have a high compression engine with a locked advance that
baclfires bigtime

[Bigbroadjumper]

Thanks for all the input, it has been a big help.

Bob