First Jet and Full of Questions

[jrork]

Hi Everyone,
We have just picked up a 78 Brendetta with a 454BBC/Panther.
I have three questions that I hope you can answer.
>The boat currently has a 650 doublepumper that needs to be gone through. Setting in my garage I have a sweet Holley 3310, 780cfm vacumm secondaries with very little miles on it.
I also have a 600cfm and a 750cfm Edelbrock carbs as well if you would think one of those would be better.
My gut feel is to throw the 780cfm Holley on the boat as I would think that once I got the vacumm secondaries dialed in, it would be a sweeter running engine but I'm curious
What would you do? Do we need a "Marine Application" carb?
>My next questions surround the Distributor. The boat has a Mallory Dual Point with no vacumm advance. I know we quit using these non-vac distributors on the street years ago but are they still recommended for jet boats?
>I also have a new MSD ignition box and am curious if this might be a nice addition to the boat?
I don't want to set a speed record. I just want it to run tight and have some fun.
Thanks to all of you for your help and knowledge..John

[Max_182]

jrork:
My next questions surround the Distributor. The boat has a Mallory Dual Point with no vacumm advance. I know we quit using these non-vac distributors on the street years ago but are they still recommended for jet boats?
>I also have a new MSD ignition box and am curious if this might be a nice addition to the boat?
I run constant flow injection so I know as much about carbs as I do about Apple computers!
But ignition is another story. The Mallory dual points come in a 4 lobe and an 8 lobe version. The four lobe is superior IMO. But the real difference in spark energy between a magnetic system and an MSD (Cap discharge) is enormous. Run the dual point distributor to trigger the MSD. It's no contest. The points will never wear out as there's no primary voltage going through them. They're just a trigger.
Vacuum advance is a moot point on boats most of the time. Not only do you not want that much advance, but you will rarely ever have much manifold vacuum anyway. You rarely see a HP boat running more than 36 degrees or so on gas.
Rk

[Taylor LP]

Here's my thoughts, others may disagree so you decide........
1. Since you already have it go with the 780, a 454 will handle that and more with no problem. You may have to play with the secondary springs and acc. pump to dial it in, but it should be worth your time. The main thing with marine carbs is the J vent tubes to keep fuel from sloshing out in rough water. More important if your engine is covered, fumes go boom! Nuff said. I think you can pull the J tubes out of the 650 and put them in the 780, but not 100% sure. Some guys here like the Edelbrock carbs too. I find the Holleys easier to tune, but that's just me.
2. Most everyone agrees, no vacuum advance is needed on jets. Just make sure the total timing is ok.
3. MSD couldn't hurt. Especially if it has a rev limiter. Could save your engine, and since you already have it why not. Just don't expect to see any performance gains on a mostly stock engine.
JMO

[Hotcrusader76]

Stick the 780 on the boat and run it. They actually flow more than a 650DP and a quicker set-up in comparison.
Good luck
~Ty

[jrork]

Thanks guys.
The 780 it is. Years ago we would install vent extensions in the fuel bowl that we called "Whistles" to control the fuel during acceleration. Assuming you can still find them, would you recommend them.
On a side note, is there a general rule of thumb regarding what to set the timing at?
Thanks again....John

[jrork]

Please bear with me as I try to learn how to post an image on here.
This is the project. http://www.***boat.com/image_center/showphoto.php?photo=20570&password=&sort=7&thecat=997

[sleekster]

i like to set my timimg as far advanced as i can till it spark knock's.