I believe there is more horse power left on the table with my engine.    It's tops at about 5000 RPM's right now, has seen 5200 with the wind at it's back.

 I put on a 750 Holley to get it on the lake.  I think I should have gone with an 800 - 850 double pumper.  My target was 52-5300 rpms, two people on board.  The carb is a tad lean yet and a jet change in the near future. 

I'm just curious what size carb  you guys are running on your 460's and at what RPM's?  My set up is:
750 Holley vac secondaries +  1 inch spacer
Edelbrock RPM air gap intake
Edelbrock RPM heads  with a stud girdle
comp cams xtreme marine cam 278
flat top pistons
mallory ignition,  + msd 6al
Hardin marine logs port matched

My boat is a 23.5 foot Glastron Carlson CV 23,  A impeller berkeley jet.

I believe it weighs around 2000 lbs. that's a number I've seen but not verified.  It's a day cruiser so it isn't a light weight.

The carb is still stock other than the secondary spring and 50cc acc. pump.  The plugs are on the  bone white side.  The mains are 70's  I plan on putting in 74's for a trial.

I didn't want to cut the carb up because I may be selling it.

In stockish Big blocks in the 450 ci range(give or take) I like 750-800's on a single plane, 800-850's on a dual plane.

A dual plane pulls from only 1/2 of the carb, so you need a bigger carb to get the top end.

Personally my 455 picked up a ton (500 rpm) going from a 750 vac to a worked 850 DP in the boat on a performer dual plane with no spacers.  

I would think you have what you need, I would suggest playing with spacers, secondary springs (I like the purple one, and these do change the CFM of the carb), primary jets, Convert the secondaries to a metering block style so you can change the secondary jets (unless you are lucky enough to have a 3310-1), mill the choke horn, convert to annular discharge, play with the ignition timing.  Also before you do anything make sure the carb is at least at stock jetting (nowadays primaries are 72's for a 3310, some came with 76's in the early days)


My fav carb is the 830 annular (9381) - anything I put it on makes the engine go faster it seems.  

I agree with the vac gauge (I have one in my dash in my boat), if you are pulling over a 1.5 in Hg at WOT, the carb is too small.

I would think you have what you need, I would suggest playing with spacers, secondary springs (I like the purple one, and these do change the CFM of the carb), primary jets, Convert the secondaries to a metering block style so you can change the secondary jets (unless you are lucky enough to have a 3310-1), mill the choke horn, convert to annular discharge, play with the ignition timing.  Also before you do anything make sure the carb is at least at stock jetting (nowadays primaries are 72's for a 3310, some came with 76's in the early days)


My fav carb is the 830 annular (9381) - anything I put it on makes the engine go faster it seems. 

I agree with the vac gauge (I have one in my dash in my boat), if you are pulling over a 1.5 in Hg at WOT, the carb is too small.

X2,
you have an RPM Airgap, which IMO is the best possible intake for your motor/application, which is why I don't thing bigger is better for this package. I would be really curious to see what the 74's do for you, I'm betting another 150-250 RPM if the rest of the setup is correct (you will be able to get more advance out of the ignition with a bit more fuel).

The secondaries have the yellow spring and are wide open.  I did the old finger test and there is nothing left. 

 I think I'll move the hoses inside the bulkhead.   There was no room on that side for
the filter is why the hoses and filter were where they are.

The spacer is the 4 hole which is what I ran on the old Torker intake, do you think I should
go to the open?

Both of our Spectra's run older 780 Holley's with the air horns milled flat and radiused.  Stock these come with dual feeds and dual metering blocks.  Notes from the 20' say 74 pri /78 sec jetting.

Usually can be had complete for $50 or less on ebay or craigs.


Cheers, Mark

The spacer is the 4 hole which is what I ran on the old Torker intake, do you think I should
go to the open?

A 4 hole spacer on a torker allows the single plane to work better on the bottom end - a 4 hole on a performer/performer RPM? That is a idle to 4500 RPM manifold at that point. I bet you have great throttle response though (and in a car you would feel great bottom end) and would give you better mileage. It never even crossed my mind that you would be running that combo.

Just take off the spacer and see how it does, then start adding open spacers. In my 440's in a car with a torker it seemed 2 inches open worked best, on a performer, I found it liked 1/2 to 3/4 of an inch.  Your combo WILL vary.

The performer RPM is setup to basically be a performer with about 5/8th -11/16th inch open spacer stock. No spacers on the RPM may in fact give you the best performance.

Keep in mind this is coming from some one that know's next to shit-nothing about mostly stock engines so take this for what it's worth.

1. ditch the 750 vac

2. replace wtih an 850 dp front power valve. Progressive linkage.

3. ditch the 4- hole spacer

4. replace with an 1"  open or better yet 2" Super Sucker spacer.

5. If the RPM Air Gap doesn't already have the plenum devider milled down( I think they do) mill the plenum divider down to 1" below the carb pad.

Sleeper CP

Big Inch Ford Lover ( 565" )

454 .030 = 460

Im running a 650 DP with a Edelbrock rpm performer intake

2sav

Your 650dp maybe a better choice than that 750 vac. I haven't liked vac sec carbs since I had a 780 on my 427 stroker motor in my '69 Mach 1. The engine would only rev to 6,200 +/-. Tried the different springs and nothing seemed to change. I swapped a re-built 850 I had and the first time I speed shifted that thing  was lucky I caught the engine at 7,200 rpm. That carb made that baby a different engine.

If you want performance get rid of the Vac carb.  Also read an article 20+ yrs ago in Car Craft or Hot Rod they had 4 builders build different big blocks and dyno them. The Ford guy put a 750 dp on his 460. At the dyno seccesion he didn't like the power #'s and put an 850 on the engine picked up 50 hp and I think it was only reving 6,500 if that much maybe just 6,000.

Sleeper CP 

I believe there is more horse power left on the table with my engine.    It's tops at about 5000 RPM's right now, has seen 5200 with the wind at it's back.

 I put on a 750 Holley to get it on the lake.  I think I should have gone with an 800 - 850 double pumper.  My target was 52-5300 rpms, two people on board.  The carb is a tad lean yet and a jet change in the near future. 

I'm just curious what size carb  you guys are running on your 460's and at what RPM's?  My set up is:
750 Holley vac secondaries +  1 inch spacer
Edelbrock RPM air gap intake
Edelbrock RPM heads  with a stud girdle
comp cams xtreme marine cam 278
flat top pistons
mallory ignition,  + msd 6al
Hardin marine logs port matched

More-so than the carburetor itself, your jet pump will play a big part in how may rpms you will be able to turn your engine.

That being said, I feel that even the bone stock marine-issue 460s should have a Holley 850 double pumper, Holley list # 4781, especially since these jet boat engines run at 5000+/- sustained, the bigger carb is the way to go.  460's respond well to a lot of air, a lot of fuel, and lot of spark...in the engine's stock trim.

The fact that you have a cam, heads, and compression makes me think that the Holley 850 is the minimum that you should have.  Also, the Holley 850 that I am suggesting has progressive mechanical secondary linkage, so you can troll about on the primaries and get decent fuel economy, and also open both primary and secondaries at will whenever you want top-end power.

I run about 1400 cfm on my 0.030" overbore 460 jet boat engine.

LO

The 850 will be on the way tomorrow,  what jets do you run?  Do you think 74 in the main and 76 in the back would be ok to start?
Thank you!

If you purchased a brand new Holley carburetor then start with the jetting as received. Do plug readings and go from there.

LO

If not I'd start in the upper 70's just to be safe. 76-78 or 78 squared. Is it a power valve carb ? If so the primary side can start at 6 jet sizes smaller than the primary, but play it safe and start 4 sizes smaller.

Sleeper CP

Any results on the 850 ?

Sleeper CP