Carbs

[Cas42]

Pro's and Cons welcome. I'm thinking about switching out the Holley 750 dual feed for an Edelbrock 750cfm. Do any of you have any experiences with doing the same? My boat is a 78 21' Tahiti Super Cruiser with a fairly stock 454. I bought the boat a year and a half ago and the only changes to the motor(that I know of) are the cam was changed, roller rockers were added along with an Edelbrock Performer 2-0.
Since I don't know what cam was put in, the former owner told me only that it's an RV cam, I'll be changing it out also but probably not until after this summer.
As mentioned in another post, I'm only taching out at 4400 max. I'm pretty sure I can get more rpm's, even with a fairly stock motor?

[Jetmugg]

My 2 cents - changing the carbs probably will not help, unless there is a serious problem with your Holley. You may very well want to check out the Holley internally, to make sure that it's okay, but I'm betting that it's usable. The cam swap will most likely be your best bang for the buck. You will be looking for a cam that makes the most power in the rpm range where you need it, which is currently at and above 4400 rpm. The "RV" cams are great for tow trucks, but lousy for jet boats. Forget about low end power when selecting a cam for a jet boat, what you really need is mid-to-upper rpm power. Also, don't listen too much to "car guys" with respect to camshaft recommendations, as they will tend to concentrate on low rpm torque. Many of the guys here are running very big cams by automotive standards, but they work great in jet boats.
It's also important to get the ignition timing and cam timing dialed in so that you can get the most power at the rpms's where you need it.
Steve.

[jim lee]

Personally.. (Only in m opinion..)
I hate the Edelbrock carbs. They are just renamed Carters and I hate those too. Why? 'Cause I'm not smart enough to get the silly things to run right on anything I've tried them on.
I first tried a marine Carter on top of my Tunnel ram on my Olds. Single carb tunnel. It ran like green caterpillars. Yuch. I tweaked and fiddeled. I was able to get it -better- It actually did -ok- wide open, but anything else was terrible. It always gave the feeling that the engine was toying with the idea of dying, any second now..
They want you to drill out or add lead to counter weights and things to change how the 2ndaries open etc etc etc. Sheesh! It was too much.
So I added a pair of old used Holley 660s and WOW!! What a difference! Huge power increase and it purrs like a kitten! A very thursty kitten, but a kitten none the less!
Just to be fair I tried the Carter on another jetboat. (The familly's boat, Ford 490 with a Torquer manifold) It had a Edelbrock on there that had been hit with a chemical fire exstinglisher, all corroded. I was in a hurry and didn't want to fuss with the Elelbrock, so I put my old carter on there (Both were set to out of the box stock settings) Runs horrible! Like on the Olds, Its -ok- wide open, It idles -ok- but midrange is all rough. (granted this Ford motor is not it very good shape, and I'm no carb guy.) But I'd much rather have the Holley than the Edelbrock.
The point of my diaribe?
I have rebuildable Edelbrock, Working Carter Marine 750?, Compete jet kit, tuning instrictions, silly nut drivers assortment and a printout with all the jetting cobinations that are possible (The don't put this in the manual, I made it up myself.) And I'll trade the entire kit and cabootle for a used working Holley 750 or 850 that I can plunk onto Julie's familly boat.
So there! :-)
-jim lee
[This message has been edited by jim lee (edited April 06, 2001).]

[spectras only]

Holley's are the simplest and easiest carbs to work with ,why change it? I still run my 1976 vintage 780 vacuum sec and only changed the gaskets once for the blue ones period.When I put a brand new 830 on my friends 460, it run perfect right out of the box. Some of my old salt boat dealers hate Holley's because some shadetree mech's wrenched on them before.Once you set up a Holley you leave it alone period.The other things you can do with a Holley is to change the metering block with a Percy unit that you can adjust the jetting from outside for different elevations.

[Timer]

spectras only, where can I get info on the Percy unit?
I have 2 Holleys with the bowls facing each other. Could you still change the jets from the outside with the Percy setup with this arrangement? Thanks.

[spectras only]

Timer , I have to call the local speedshop tomorrow to find out the manufacturer's address.I beleive the jets were adjustable from the top [ I hope ].Let you know when I found out.

[Cas42]

thanks for all the input guys. The Holley I have seems to work ok although it does drink a lot, maybe too much since 15 gal will last about 1 1/2 hours without skiing. I'm going to pull it apart this weekend to see what size jets and power valves are in it.
When I bought the boat, I got the original carb and the one that's on it. The original is a 780 dual feed but since the air horn was cut off, I decided to use the 750. I kind of like the use of a choke.
Right now I'm a little in between on what I want to do with the boat, I guess I'm a tweener. Anyway, I'm not interested in building a real go fast (yet), just want to make the most of what I have now....make sense?
The only thing I'm not fond of with this boat is the Panther jet. My old boat had a Berkeley and it just seemed to be a much better pump. I was also able to easily disconnect the pump, put a hose to the water inlet and do all the fine tuning in my driveway. I'm not able to do that with this boat/pump.

[Squirtcha?]

Cas42
Check out this article. I found it very useful when I rebuilt my Holley last year.
http://www.fordmuscle.com/archives/1...ey/index.shtml

[Cas42]

thanks Squirtcha, I'll be using it too

[spectras only]

Timer, get the Summit Racing catalog, go to page 85.There you'll find the Percy's metering block.The price is between 75-81 US$