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RickSE
04-19-2000, 11:53 AM
Does anyone have any experience or advice on buying a new 4-barrel carb. Jegs has the standard marine Holley 600 cfm and the Edelbrock 600 & 750, but I don't like the standard 4160 Holley and don't have any experience with the Edelbrock. I boat at high altitude and would prefer to use a carb bigger than 600 cfm. I have a 96 2-barrel 350 (215 HP?). Does anyone know of a good place to get marine carbs. I'd like to find a place that stocks the Holley 650 marine carb.

GeneS
04-19-2000, 01:51 PM
I bought the 750 marine from Edelbrock through the Jeg's catalog. No complaints at all. Carb works fine.

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Gene Schmidt
'74 X-18 "Chi Chi"

Forrest
04-19-2000, 04:19 PM
The Edelbrock is actually built by Weber . . . the same as MerCruiser uses on many of their Hi Perf carburated engines. Great carb, but make sure that you get the marine version.

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Forrest

AVickers
04-19-2000, 04:59 PM
Isn't the Edlebrock actually the old Carter AFB (and ThermoQuad) with a new name?

If it is, it and the Q-Jet both use a variable surface-area jetting principle (tapered needles moving in and out of the jets) to vary the mixture as the engine RPM, vacuum, and load changes. They tend to be very forgiving if they have been purchased for a specific application and they are used for that. However, if you change them out to a different application and want to change their operating parameters, things get complicated on both. Re-jetting these carbs is a bitch! Not only can you change the jet itself, you can change the diameter of the needle and its taper. I have found that it’s best to simply leave them alone to adjust themselves… Both also use secondaries that are preset to come in as the vacuum in the manifold dictates. The Q-Jet uses needles in the secondaries too, but if I remember, the AFB has fixed secondary jets. In the case of the AFB, the air butterfly is counterweighted, in the case of the Q-Jet, the air valve (as it is called) is spring loaded. Both are completely mechanical... And, unless there’s something wrong with them or they’re not correctly sized for the application, they are bulletproof.

For boats (as opposed to cars) they are great! This is because the parameters of boat operation are rather simple and predictable. No hills, no valleys, no passing, no radical reversion cams with a lot of overlap, etc. Mostly just a hole shot up to plane and leveling off, or (in the case of most of us Donzi guys) PUNCHIN' IT HARD & RUNNIN’ FLAT OUT! Make sure the carb has the volume to support the engine running at WOT and you’re in like Flynn.

My thinking and experience with these two carburetors is that, although both are good, the Q-Jet is preferable because is has very efficient primaries and will return better overall fuel efficiency -- as long as you stay out of the secondaries. Both AFBs and Q-jets adjust themselves as altitude changes. You may have to dink with the idle mixture on both, but when running in mid- and high-range at any altitude, they’ll not need to be re-jetted or adjusted in any way.

The Holley is also mechanical, but it is much easier to adjust the parameters as to the conditions under what will happen when. Put a radical cam in your engine, and you can change the power valve to compensate for having no vacuum at the low end. Put it on a larger engine and you can change the jets and springs to move more fuel through it and have the secondaries open earlier (or faster). Got a flat spot when you punch it? Put in a bigger accelerator pump or a larger nozzle. You can change the power valve to vary the vacuum required to richen the mixture (They even make two-stage power valves that come in a little bit under light load and open up all the way under heavy loads. If you have vacuum secondaries, you can also vary the spring rates in the dashpot to have them come in earlier or later). You can also change the check valve out to have the secondaries come in more quickly or more slowly when they begin opening. You can also vary the accelerator pump shot and duration and you can easily change out the primary and secondary jets with predictable results. At higher altitudes, the Holley will adjust for load and for when the secondaries will come in, but it will sometimes need to be re-jetted for general running. Not hard to do, but something that will need to be done as opposed to other carbs that compensate...

My thinking regarding the Holley (and I really like these carbs for cars and trucks) is that at times they are too adjustable for mere mortals to mess with. This is especially true for boats ‘cause, as I said, they operate under some fairly simple conditions. There are so many parameters that can be changed on Holleys that unless you simply take them out of the box and bolt them on, you’ll go nuts trying to set them up properly – especially from scratch. If something out of whack, you can adjust for it, but these carbs are difficult to diagnose and troubleshoot. In fact, the only more difficult carburetor to work on, in terms of setting them up from scratch, is the Weber.

I've used all three on Boats and Cars and all work very well when they are set up properly. Out of the box, I tend to prefer the Q-Jet… It’s as simple as they get – hell, it’s only got two gaskets! But it takes some skill and concentration to rebuild. The Holley is easy to rebuild, but it’s got a lot of adjustments and parameters to fiddle with if you’re “tuning” it. The AFB is as simple as the Q-Jet, but I don’t think the primaries are as efficient… As for rebuilding, I think they are easier than Q-Jets, but more difficult than the Holley. As for running, AFB are also simple and bulletproof. The only down side to either the AFB or the Q-Jet is that the floats are relatively difficult to adjust… Some Holleys can be adjusted on the engine with it running. The AFB and the Q-Jet both have to be disassembled…

When the carbs get old and sit for long periods of time (like on a BOAT), I think the advantage goes to the AFBs and Q-Jets. They don’t have any diaphragms or o-rings to harden or break and the float bowls on both are split horizontally at the top (remove the top cover and there’s the floats). As gaskets age on a Holley, the bowls may start leaking. And you can just about be assured that the o-rings on the transfer tube will age and start to leak along with the o-rings on the needles (if so equipped). Over the years, I have experienced failures in all of these areas with Holleys and they will disable you…

In fact, now that I think about it, I wonder why I use Holleys at all???????

There you have it. My tome on the most common of boat carbs... http://206.150.187.82/ubb/eek.gif

Hotboat
04-19-2000, 05:13 PM
Just put a 600 cfm Edelbrock (1409)on a Century V-drive that I have just built. Works great and looks better than a Holley. The marine version will fit the square-bore intake.

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Hotboat

AVickers
04-19-2000, 05:22 PM
Well,

I saw Forrest's post and wanted to see what's been happening in carb technology lately. I have a set of DCOE Webers on my Triumph and love them, but they were the most complicated carbs I have ever had the "pleasure" of dealing with...

Was surprised to hear that Weber is now manufacturing old Carter/Rochester designs, but I'm sure if they do, they'll be done to the highest levels of perfection.

Anyway, I wanted to confirm that the Edlebrock is what I remembered it being so I took a shot at a Web Page and sure enough, there is one...
http://www.edelbrock.com

They have some information about setting their carbs up and some stuff on high altitude. Very informative:

High Altitude

Altitude has a direct effect on the operation of most carburetors. As the altitude increases, the air becomes less dense so a carburetor, originally calibrated at low altitude, delivers too much fuel and the engine runs richer. If the preceding tuning procedure is performed on an Edelbrock Performer Series carburetor, a proper high altitude calibration will result. If the vehicle was calibrated at lower altitude, however, and is to be driven at high altitude temporarily, it is not necessary to repeat the complete calibration procedure. Instead, use the rule of: "2% leaner per 1500 feet" and the Calibration Reference Chart for your model carburetor. For example, with a #1405 at baseline calibration (location #1 on the chart) and intended operation at 6000 ft. altitude, you would want 6000 divided by 1500 x 2% = 8% leaner calibration. That would be location #24 on the chart which would require only a rod and jet change.



[This message has been edited by avickers (edited 04-19-2000).]

RickSE
04-19-2000, 06:09 PM
Thanks guys, some good info. It's going to be a hard decision. Due to my warranty I will be leaving in the original cam, so I don't want to waist money on a carb that will be uselsss when I can make changes. I tend to favor the Holley carb but avickers' info on the Q-jet & Edelbrock is leaning me in the other direction. Plus the fact that a marine Holley 750 is $460 while a Edelbrock 750 is less than $300. Like I said my bigest problem is altitude. The closest lake to my house is at 7000 ft. Lake Powell is 3700 ft. and Lake Havasu is 500 ft. This makes tuning a real bitch, so I need a carb that I can adjust easily.

AVickers
04-20-2000, 07:02 AM
My thinking at this point would be that the Edlebrock/Weber would be the ticket. Priced right and the book that appears to come with it (or that you can download) is much more complete about setting them up than what I ever had years ago -- when all my hair fell out futzing with needles and jet sizes (I still think I have my needle/spring kit somewhere...)

Anyway, if you can compensate for 6000 feet of altitude (requiring an 8% leaner mix) simply by replacing two needles, that would be the way to go. Needles come out of the AFB like cake. Flame suppressor off. Two screws and covers (Small screws and samll covers -- smaller than a dime. Be careful not to drop them down an open choke!) Slide the plungers/needles out. Replace them and button it all up.

Less than 5 minutes!

OOPS! If the jet needs to be replaced too, then you're in for a longer session to change things. Perhaps changing only the rod (a.k.a. needle) would compensate between the 7000' and 3700' lakes...

When you go to Havasu, you'll have to take the cover off the carb to change out the jets.

[This message has been edited by avickers (edited 04-20-2000).]

GeneD
04-20-2000, 07:17 AM
avickers...
Wow!!
I say, what you said.
Awesome tech review.


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GeneD
007
Melbourne, Florida

BillG
04-20-2000, 08:02 AM
You could also look into the Holley models 4010 and 4011 . They come in 600, 750, 650, and 800 CFM. The 4010 has a square base like a Holley and the 4011 has a Q-Jet base. The jets are easy to change, just remove the top and they are accessable. They are probably the easiest carb to work on I have used.

AVickers
04-20-2000, 09:08 AM
I tried to buy a couple of the 4011s last year and was told they were discontinued????

Still in the catalog, but the one I wanted didn't appear to be available anywhere. I finally went w/ spreadbore 4160s.

RickSE
04-20-2000, 10:02 AM
BillG, I was wondering about Holley's new carb but as avickers states, they may have been discontinued. Although Holley shows a picture of one on their marine web site, they don't seem to list any part numbers for them, only 4150, 4160 & Dominator style carbs. I'm going to call their tech line again today and ask about the models you mentioned. Once again avickers, your info is causing me to seriously consider the Edelbrock, I really appreciate the info.

BillG
04-20-2000, 05:08 PM
In the Holley web site go to marine carbs and try part no. 0-84018 ,0-84022, 0-84023, and 0-84024.
Good luck

RickR,GroveCity
04-20-2000, 09:12 PM
Rick
Check out www.jegs.com (http://www.jegs.com)
They can probably get a 650CFM Marine carb special ordered.
They have a 650CFM automotive double pumper Holly for $275 (might be too big for your motor)

The way it works with Rat Motors

Holly= Excellent Performance, Good Economy

Cater= Very Good Performance, VeryGood Economy

Q'jet= Good Performance, Excellent Economy

I use a 9381 Holly Automotive race carb(830CFM) with Annular Discharge Nozzels, no choke(Choke horn milled off), four corner idle, on my 420HP 454. It's awesome http://206.150.187.82/ubb/eek.gif
I installed marine style vent tubes. Those 30cc pumps throw the fuel to it!
Old timers like me call this carb a Dual Line Double Pumper or a 4150.


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RickR mailto:riggerb@aol.comriggerb@aol.com</A>

[This message has been edited by RickR,GroveCity (edited 04-20-2000).]

[This message has been edited by RickR,GroveCity (edited 04-20-2000).]

RickSE
05-05-2000, 05:19 PM
Well this week I finally made a decision on a new carb. Holley has a Model 4150 600 CFM marine carb (#080559, $386 from Jegs) that should suit my needs pretty well. I heard a lot of good things about the Edelbrock but decided to go with the Holley 4150 since I know it best. I checked into the newer Holley models 4110 & 4111, but they have been discontinued. I will also be installing an Edelbrock Performer manifold and changing my 19P Quicksilver prop to a 21P Revolution-4, 4-blade.

With the Mercruiser 2-barrel, 19P quicksilver, 2 adults and a half tank of fuel at 3700 ft. elevation my speedo reads 53-54 MPH @ 4500-4600 RPM.

Anticipating a 40 HP increase from the 4-barrel and with the new 21P 4-blade, I am being told to expect approx. 58 HPH @ 4500 RPM. I'm hoping for a little more and will be elated if I can hit 60 at this altitude. I honestly believe with some carb tuning and a light load I will be able to do so. If anyone is interested I will post some numbers once I get the boat on the water.

Hotboat
05-05-2000, 10:07 PM
Very curious to hear the results. I think 40 hp for a carb. change is optomistic. Hope it works for you.

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Hotboat

GeneD
05-06-2000, 08:40 AM
Yeah, that was my first thought too, but I was too intimidated to say anything.
But...with a carb change and manifold change, that might be possible.
I remember back when I was 22 and I changed out my 2 bbl for a 4 thinking I was going to get tire ripping performance. I was very disappointed.

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GeneD
007
Melbourne, Florida

Craig
05-06-2000, 01:31 PM
On the Holley web site under "marine" they have a good description of the marine differences as well as a handy RPM @ WOT / Estimated HP / Recommended CFM (carb size) chart. By that chart it seems 600's and 650's may be bigger than needed for a lot of small blocks, but I guess that doesn't matter a lot. It seems like the popular (and therefore readily available) marine Holleys fall in that range (600-650 CFM). I bought a marine Holley 600 recently and got it with Vacuum Secondaries. It seemed like, at first they weren't opening at all. Holley recommended lighter secondary springs, which I did. They open now but disappointingly slow. I think I preferred my old mechanical secondary carb. The quick acceleration when you punched it was nicer. I can't think (now) of why you would want vacuum secondaries.

BillG
05-06-2000, 03:06 PM
If the secondaries are not opening or don't open all the way the engine can not use the extra cfm's. Overcarburation is very easy to do. I have run my 351 HO motor with a 650 Holley and a 2 barrel Ford Carb. the rpm difference was about 200. Holley has an excellent book for tuning their carbs. It will open your eyes about how big a carb you can run.
Good luck
BillG

AVickers
05-07-2000, 01:48 PM
I tend to agree that the vacuum secondary units are much easier to work with and essentially "size themselves" depending on application, but, at this point, I'm wondering about the results of swapping out my Q-Jet with a Holley on my 18' (both are "vacuum secondary" carbs and both exceed what I think are the CFM requirements at a given RPM). My boat actually runs better with the old Q-Jet than with the new 600 CFM Holley marine. In fact, lots better...

A word about Vacuum Secondaries and why I'm sold on them:
The nice thing about Vacuum Secondary Carbs is that, unless they're really messed up, they won't "overcarburete" your engine. "Overcarburetion" occurs when the air mass flowing through the venturi is so slight that the venturi effect diminishes (vacuum inside the venturi drops off) and fuel isn't sucked into the airstream. This, in turn, causes a lean condition in the engine -- sometimes resulting in a bog (e.g. when the secondaries open on a mechanical, progressive-linkage design that's just too much for the engine) or, in extreme cases, even backfiring through the carb. This leaning-out is compensated for on mechanical-secondary Holley carbs with a second (usually huge) accelerator pump that comes in as the secondaries open.

With vacuum-controlled secondaries, the second (usually larger) throats come in when they're necessary to provide more air/fuel mixture while maintaining adequate mass velocity through the carb and, therefore, an adequate venturi effect inside the appropriate throats -- Holley uses a vacuum-controlled spring-loaded diaphragm to open the secondaries; Q-Jets use a spring-loaded valve to meter the air into the secondaries (which open progressively by the linkage), Carters use an offset counterweighted butterfly valve to open the secondaries. The presumption is that if the engine doesn't need the air, the carburetor won't provide it...


A word/question about carb sizing:
Interestingly, if you run the numbers, really big carbs don't seem to be necessary for the operating range of most marine engines (at something like 5000 RPM)...

For example, at 100% volumetric efficiency (which won't happen), a 350 cu. in. engine spinning 5000 RPM will move 506 CFM:
(350 X 5000 / 2) / (12 X 12 X 12)= 506

At 6000 RPM, the engine will move 607 CFM.
(350 X 6000 / 2) / (12 X 12 X 12)= 607

The big question in my mind is, "How fast does/can a boat engine in front of an outdrive turn?????"

Which leads to my next question: "What's the ideal prop speed????"

For example: If you want your boat to run 70MPH and you're using a 24p prop, you'll need to turn the prop at about 3850 RPM (given 20% slippage):
((70 / 60 X 5280) / 2) / .8 = 3850

If you have a 1.68:1 drive ratio in the drive (Volvo 280), you'll need to spin the engine at something like 6500 RPM to go 70 with a 24p prop. This is at the upper limit for a reliable Mouse and not really within the range of a 600CFM carburetor (if my numbers are right). At the 6000-RPM limit for a 600 CFM carb, you'd be turning the prop at 3571 and pushing the boat at something like 65 MPH – if you could get it to wind that tight…

Now for my own experience:

With a 780 CFM Q-Jet --
At WOT; my engine [SB 350 w/ a Volvo 280 w/ 1.68:1 ratio, on a cool day (55 degrees) in relatively smooth water, with a 15 X 24p prop] turns 5200 RPM -- about 56 MPH. On a "normal" day (90 degrees) it'll turn around 5000 RPM -- 54 MPH.

With a 600CFM Holley --
The most I've seen on the turn dial has been 4600 RPM with the Holley -- 50 MPH.

Obviously, all other things being equal, I'm getting better performance out of the Q-Jet than the Holley.

So, is the Holley really running out of breath? Or is it simply not set up right? Or, on either carb, is it that I'm not yet into the secondaries and the mixing efficiency of the triple-venturi primaries on the Q-Jet is so much better than the Holley that my engine makes more HP because of a better air/fuel mix?

Anybody out there got any thoughts????

I ran a 21p prop for a while and the WOT RPM didn't go up like I thought it should. However, the prop had almost no rake so I couldn't really tell what it was doing. The hole shot was better (obviously), but with this prop, I didn't have the bow lift that usually comes with a high-rake prop. My guess is that the wet area of the hull was greater with this prop, so it was taking more power just to keep things moving the same.

I've thought about trying to scrounge up a 26p or 28p prop to see what my RPM will do, just to see if I'm at the power max for this engine, but I haven't conveniently come across one yet, so no data on this front. My thinking is that if the Rs stay constant, then there's still power available. Essentially, my engine would be breathing-limited and the only way to make a substantial improvement would be to install a different carb and/or manifold and/or cam and/or headers and to open up the ports and valves to allow more efficient airflow through the engine at this RPM range. If the Rs go down with the higher-pitch prop, then more power would need to be extracted across the range and the best way to do this would be to increase the compression ratio -- pretty easy w/ domed pistons.

I just don't know if I have the energy to do all this stuff -- to a boat that I'm probably going to sell anyway...

Currently, I've got a big block setup on my new 22' and at 5000 RPM; it's theoretically doing something like 69 MPH (1.32:1 drive ratio and a 24p prop). I've seen 4500 on the turn meter, and felt like there was a lot more there, but the water was rough and getting air wasn't in my wife's afternoon plans... http://206.150.187.82/ubb/eek.gif

It, too, has a crappy speedo, so it's all theory at this point. I guess GPS is in my future.

GeneD
05-08-2000, 08:31 AM
Hmmmm...
Great theorems.
I'm wondering about your calculations on the airflow in a 350. It sounds right, but then why do racers put bigger carbs on? I'm thinking just to add more fuel?
I agree with your evaluation of the Q-Jet and the Holley. Though I'd rather have a Holley, the Q-Jet is very efficient on stock motors.


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GeneD
007
Melbourne, Florida

PaulO
05-08-2000, 10:28 AM
I agree with Gene. I have played with the air flow numbers when sizing carbs in the past and, for some reason I can only guess at, those low numbers don't seem to do the trick. Always wondered why all those millions of Q-Jets that GM put on every small block flowed 780 CFMs when, theoretically, the need was about 550 or less for most factory SBCs. I wonder if it has something to do with the amount of pressure difference ( vacuum ) that it takes to extract the maximum advertised CFM out of a particular carb actually creates too great a drag on the engine to get max HP/RPM. Or, it could be just economics. It may be cheaper to build 2 million Q-Jets in a "one size fits all" config. Sorry, just thinking out loud.
PaulO

AVickers
05-08-2000, 10:29 AM
Airflow: Assuming 100% volumetric efficiency:

Each revolution of the crank will draw 1/2 of the cubic inch capacity of the engine -- 4-stroke engine intake every other stroke.

At 5000 RPM in a 350 you'll have 175 Cubic Inches of air moving through per revolution: 875,000 cu. in.

Convert to Cubic Feet (CFM)-- Divide cubic inches by (12X12X12): 506.37 Cubic Feet.

As for larger carbs, I can see it in automotive use, the engines in a flat-out bracket or drag racer will crank upwards of 7500 to 8000 Rs. This would require a top-end carburetor in the range of a 750 to 800 CFM for a Small Block. Plus, I don't know how effeciently a carb is at air/fuel mixing: Are they more effecient at 80% of their rated capacity???? 100%??? Where's the sweet spot?

Also, there may be something beyond 100% volumetric efficency at certain RPM ranges as the scavange effect of headers or the ram effect of tuned intake manifolds kick in (but I doubt it -- my thinking is that the only way to exceed 100% would be supercharging).

Anyway, for boats, this, too, might be relevant, but 4500 to 5500 Rs appears to be at the top for the boats we're in and I don't think many/any of us are running optomized tuned port intakes or wet headers...

Is anybody out there turning more than 5500 with their motors??????

RickSE
05-08-2000, 10:50 AM
Gene, big carbs are for high RPM's or big cubic-inch engines. I run a 750 CFM on the 400 SBC in my drag car and shift at 6800 RPM.
All this will be a very interesting test. I know I'm being a little aggressive in the HP estimate but I'm basing a lot of it on the HP ratings of 2-barrel(210HP) and 4-barrel(260HP) engines in 96, given in the Merc. manual. I think what is really going to hurt me though is the cam. I'm pretty sure that in 96 the 2-barrel and 4-barrel engines had a different cam. In fact I believe the 4-barrel had a roller and the 2-barrel did not, I'll see when I open up the engine. I can not change the cam though until my warranty runs out, in Oct. 2001. I'm going to start off by running the existing 19P prop and see what gains I have made, then switch to the 21P and compare. If all this fails then I'm going to RIP that damn 350 out and put my 450 HP 400SBC in the boat.

AVickers
05-08-2000, 11:23 AM
That's what I'd do! Except I've been unable to come across what I would call an "affordable" 400 ci SBC.

Be sure to change out the cam to a marine (non-reversion) unit! Otherwise, it'll suck steam...

Barry Phillips
05-08-2000, 12:19 PM
Rick R: I have a 350 2 barrel makeing 250hp
spinning a 23 pitch Mec. Vengenace prop.
The boat runs a radar confirmed 65mph with
a full tank of gas and one passenger. I am
very interested in how the Holly performs,
scince I am thinking of doing the same thing.
Performace Marine a much respected tuner
on Lake George suggested a 750 CFM Holley
on top of a Edelbrock Torker intake, plus
bumping up the rev. limiter to 5000rpm.
I would suggest a 23 pitch prop, I tried a
21 pitch Mariage Plus on my 18 and lost
3 mph.
SO-SLO

RickSE
05-08-2000, 01:20 PM
SO-SLO, What year is your 350? Thats pretty good performance out of a 2-barrel. One problem I ran into on my 96 350 is that Edelbrock only makes one intake manifold that will fit, #2104 Performer. The four center bolts on these heads are canted, and Edelbrock does not make a Performer/RPM or Torker manifold that will fit this configuration. Mercruiser is probably still using these heads since the next generation head from GM was the Vortec. GM stopped using these heads in 95.

Barry Phillips
05-09-2000, 07:30 AM
RickS: Performance sugested the Performer
intake and if hatch clearence allows the
the RPM would be better, sorry for the
misstake. The boat is a 1998 Classic 18.
I ordered it in 97 with the 5.7LS motor
rated a 275hp. The MPI rated at 300hp was
$3000 more. The boat was dlivered with a
5.7L 250hp, the dealer did manage to get
me a Bravo 1 drive as a $200.00 option.
The Bravo was only being ofered with the
Magnum at the time, what a deal! Janson
at Performance Marine thinks this motor
was a good choice because it is identical
to the Magnum except for the intack, MPI
digital ignition and 5200rpm rev limiter.
He feels the Vortec heads flow well and
can left alone for now. Because I am on
a budget he sujested a 750CFM Holly,
bumping up the rev limiter or a high
performace ignition and budget allowing a
tuned exhaust system. A a new prop would
be last on the list. I am really not
disapointed with SLO-SO's performace as it is though, with 3 aboard and 35 gallons of fuel, GEOO clocked it at 61.5mph with the speedo
indicating 62mph. I have seen 67mph alone
in it with a light fuel load, 20 gallons.
A guy in a 24' 454 Checkmate told me I am
running 68mph, he was impressed it was only
250hp. Rick I would still think about a
23 pitch prop it well compliment your new
found power. Keep us posted, good luck.

SO-SLO

RickSE
05-09-2000, 10:29 AM
Barry, my plan (if everything works) is to utilize the following props:

21P for high altitudes, 2000-5000 ft.
23P for altitudes below 2000 ft.
19P for ultra high altitudes above 5000 ft.

I live in Arizona and our highest Donzi worthy lake is at 7000 ft., the lowest is at 450 ft.

Sounds like you have a good setup. The Vortec heads have a lot of potential. I wasn't sure if they had made it onto a marine engine yet. Yours also should be a roller cam motor. Plus since you already have the Bravo your set for life.

Emmo
05-09-2000, 11:27 PM
Remember this formula-
the heat of the meat is directly proportional to the angle of the dangle and the square of the hair.

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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>