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Discussion Starter · #1 ·
Just picked up a jet boat with a 454 and looking for recommendations on which carbs to run on a tunnel ram 450s or 600s.

Engine has oval port heads with a small cam. Any feedback would help.

Thanks Nitroman
 

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AKA Blownjet 468
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I've used pairs of 600 vac. sec (1850's) numorous times with good luck,
just remember to equalize the secondary diaphrams, and you should be
fine. I wouldn't use 660's, (on anything)
 

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Holley 600 or 650 classic double pumpers are what we recomend. I'll sell you a set of either used for $250.00/pair, if you want them rebuilt we can do that cheap for ya too. Kit price and $125.00 for both rebuilds. TIMM 623-877-8553
 

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I've used pairs of 600 vac. sec (1850's) numorous times with good luck,
just remember to equalize the secondary diaphrams, and you should be
fine. I wouldn't use 660's, (on anything)
Why no 660s? Just curious. I'm running them and they seem OK, but I have nothing to compare them to.
 

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AKA Blownjet 468
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1,193 Posts
IMO, 660's are more of an old school race type carb, 1 to 1 linkage,
1 centrally located squirter, fed by 1 pump. ok if you plan on running
idle to full throttle , but if your interested in drivability, there not the carb
of choice. sure, you can tune a holley out of almost anything, but my choice would be the 600vac.secondaries, for what you said you had.
If you had a little more motor-ie: compression/cam/etc, I'd opt for the
650DP's, as stated earlier. ( just my opinion, 660's belong on the shelf,
along with the magneto's, just outdated technology imo):)
 

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I did a test a while back on my boat. Switching from dual 450dps to 660 centersquirters I picked up 3mph, 396bbc with rectangle port heads, solid cam, etc etc... A impeller. The 450's kicked the living snot out of the 660s for gas mileage though.
 

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IMO, 660's are more of an old school race type carb, 1 to 1 linkage,
1 centrally located squirter, fed by 1 pump. ok if you plan on running
idle to full throttle , but if your interested in drivability, there not the carb
of choice. sure, you can tune a holley out of almost anything, but my choice would be the 600vac.secondaries, for what you said you had.
If you had a little more motor-ie: compression/cam/etc, I'd opt for the
650DP's, as stated earlier. ( just my opinion, 660's belong on the shelf,
along with the magneto's, just outdated technology imo):)
Let's not start on the mags again!!!:D
 

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underdogs.

For the look an function. 450s are hard to beat. They are not going to give you all out performance, but they are good on mpg, easy to start, very simple carbs.

I ran a set on an river boat that I had for years with great results, and loved them. For a smaller motor like you are talking about with low compression, small oval heads I would go with the 450's. JMO
 

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Resident Ford Nut
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I did a test a while back on my boat. Switching from dual 450dps to 660 centersquirters I picked up 3mph, 396bbc with rectangle port heads, solid cam, etc etc... A impeller. The 450's kicked the living snot out of the 660s for gas mileage though.
RPM change ?

On my dads 418" smblk we ran a test on the dyno with only the primaries working on the 450's I think it lost only 20 some hp running only on the primary side. I'll see if I can find the dyno info tomorrow.

We were all surprised.


S CP :D
 

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northern member
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611 Posts
I've used pairs of 600 vac. sec (1850's) numorous times with good luck,
just remember to equalize the secondary diaphrams, and you should be
fine. I wouldn't use 660's, (on anything)
i agree , don't know what you think a small cam is but have used them with a 250*- .600" cam use the plain diaphram spring they work good. make sure the accelator pumps are giving a full shot . sec. plates are a bit of a pain but if your careful you can drill them to fatten them up.
 

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RPM change ?

On my dads 418" smblk we ran a test on the dyno with only the primaries working on the 450's I think it lost only 20 some hp running only on the primary side. I'll see if I can find the dyno info tomorrow.

We were all surprised.


S CP :D
I'll beleive it.... just cruising the 660's sucked! They took a ton of gas, and couldn't quite get them cammed right. What they wanted for WOT, and cruising throttle, were two different tunes. And it was a back to back test.
 

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Resident Ford Nut
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Hi Tony,

Did you pick up any rpm with the 660's ?

S CP :D
 

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I'll beleive it.... just cruising the 660's sucked! They took a ton of gas, and couldn't quite get them cammed right. What they wanted for WOT, and cruising throttle, were two different tunes. And it was a back to back test.
May have something to do with the fact that the 660s don't have power valves, ya think?



 

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79 Sanger Picklefork
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840 Posts
450's

For the look an function. 450s are hard to beat. They are not going to give you all out performance, but they are good on mpg, easy to start, very simple carbs.

I ran a set on an river boat that I had for years with great results, and loved them. For a smaller motor like you are talking about with low compression, small oval heads I would go with the 450's. JMO
I had dual 660'S a couple of years ago. Ran great just went through a ton of fuel. With the advise of Widowmaker, who at the time had a boat with dual 450'S I took off the 660'S and now run 450'S..never looked backed. Lost a little power but I can live with it...Once you get them dialed in they are really simple..
 
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