What Carb for Poly Stroker

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You're a really smart guy. But your constant bashing of Holley style carburetors makes you look pretty ignorant. Holley and holley style carburetors have won more races and are on more vehicles than probably all other types of four barrel carburetors combined. Why not just say something like "it's been my experience that blah blah blah......." and leave it at that. Even a novice knows how many Holley and Holley style carburetors are out there and knows they aren't "best left in the box they came in". That just sounds stupid. Just tell people something like "I've not had the best tunning success with Holleys" and leave it at that, because hundreds of millions of people around the world.....including IN YOUR OWN COUNTRY OF AUSTRALIA where the toilets flush backwards have.

Lol. Harsh, but very factual. Wish I had that kind of diplomacy but God didn’t give it to me.
 
Lol. Harsh, but very factual. Wish I had that kind of diplomacy but God didn’t give it to me.
The toilet thing is kinda a private not private joke between Bewy and me. I like the guy. He'd be welcome for a cold one at my table any time.
 
I did not know that;
But looking at this
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I can imagine a spread-bore of some kind on there, without too much work.

The reasons I like a spread-bore for this combo are;
it's already a 10.8 engine and
the small solid cam is gonna have an early closing intake,
which means those two together, are gonna cause the cylinder pressure to climb, maybe too high for pumpgas. I mean, the Wallace calculator is predicting pressures between 182 and 190 psi!
But IIRC, the chamber design of that engine has no quench, nor squish, so
That leads me to imagine that it may be detonation-prone at lower rpms. IDK, I've never had a poly.
Small Primaries may help to keep the Effective compression pressure below the detonation limit, with pumpgas. Then, just adjust the secondary throttle-timing to be a lil lazy, and it might survive.
If a spreadbore is impossible, then second choice is a vacuum/AVS-type, secondary.
Altho, if it was mine, I'd be trying very hard to make a 750DP work, cuz if I break it, I can fix it.
What I'm really saying is that besides the TQ, I'm no fan of vacuum-secondary carbs, and in particular, not a fan of the 1850; unless it's for cruising in overdrive................. they work ok for that, if you know how to doctor them.
No matter what you choose;
Happy HotRodding
You're correct on being detonation prone on pump gas, and yes it could probably do with a bigger cam but that's the one that I had in there when it was a 318 and I was led to believe it would work ok with the stroker...which it does, but it's a bit small. The custom pistons have a small quench pad in them.
It runs great but if I put too much timing into it it pings. I'm at about 13° initial, 34 all in. If I add any more initial it pings. I've now switched to Manifold Vac Adv and put a limiter in the distributor on the vac adv mechanism as that was making the detonation worse.

I will consider a bigger cam, or maybe lowering the compression a bit with thicker head gaskets(?). I know when I do add in a bit more timing the engine seems to like it - aside from the detonation obviously. I was wondering whether I'd be better of at say 9.5:1 with a lot more timing, as when I've had the car at say 18° initial and tried it on my local "test" area it feels about 50hp more powerful instantly.

But this is all just thinking and considering options. The car runs absolutely great as is, no bad manners at all, has plenty of power and sounds good. But we're never happy of course - human nature, always looking to improve.

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You're correct on being detonation prone on pump gas, and yes it could probably do with a bigger cam but that's the one that I had in there when it was a 318 and I was led to believe it would work ok with the stroker...which it does, but it's a bit small. The custom pistons have a small quench pad in them.
It runs great but if I put too much timing into it it pings. I'm at about 13° initial, 34 all in. If I add any more initial it pings. I've now switched to Manifold Vac Adv and put a limiter in the distributor on the vac adv mechanism as that was making the detonation worse.

I will consider a bigger cam, or maybe lowering the compression a bit with thicker head gaskets(?). I know when I do add in a bit more timing the engine seems to like it - aside from the detonation obviously. I was wondering whether I'd be better of at say 9.5:1 with a lot more timing, as when I've had the car at say 18° initial and tried it on my local "test" area it feels about 50hp more powerful instantly.

But this is all just thinking and considering options. The car runs absolutely great as is, no bad manners at all, has plenty of power and sounds good. But we're never happy of course - human nature, always looking to improve.

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All in by what rpm? You may need to slow the curve way down around and below peak torque to get it out of tip in detonation.

More octane or a bigger cam would be the last options I would look at to fix that issue.
 
Hey guys I'm looking for some input on my next carburetor. It's a 66 Satellite with a 354 poly stroker. 3.58" Scat forged crank, Scat rods, Ross pistons 0.065 over, 10.8:1 compression. Poly heads with a little bit of porting, 1.94"/1.60" valves, Schneider solid lifter cam 264F (220° at .050, 0.450 lift). Topped off with a factory cast iron intake and currently a 1850 Holley 600 (vac sec). It's got headers, stepped from 1 5/8 to 1 3/4, 2.5" dual system.
Car is auto, 3.23 rear, used for hot street, cruising and at the track say 6 times a year. Weighs 3,640 lbs.
The car runs great with the Holley but I'd like to try something else. I've also got a 700 double pumper that I swap in and out and the car feels faster with the bigger carb (and made 7hp more on the chassis dyno, 341hp at the wheels vs 334hp with the 600) but the 600 is better on the street. I'm going to try the double pumper at the track early next year to see what difference it makes there.
There's so many choices my head's spinning.
I wouldn't mind trying an Edelbrock AVS2 but should I go 650 or 800? Normally I would think 650 but with the annular boosters would the 800 still work ok?
Or maybe a Holley 670 Street Avenger v/s?
Or a 650 double pumper?
Or a Brawler 680 v/s BR-67317?

I was leaning toward a 625 Street Demon but the reputation for poor build quality and a few design issues is putting me off.

Then there's boosters: straight, downleg, stepped, annular...man there's some choices out there.

I'm wondering what I'm leaving on the table with the 600 1850. I'd like the same reliability (super reliable), better low end and midrange, and maybe some more at the top (so basically more everywhere haha).

Any advice appreciated - I realise this is a very open question and one where brand loyalties are strong.

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Depending on your version of the 4778 700 dp your primary squirter size is 25 or 28
with a 727 that cam and 3600 lbs id start at 31 in the front and go as high as 37
have a friend stand behind the car if it blows black smoke and stumbles on a dead stop punch then catches and or starts to spin the tires you need more squirt after dialing in the squirters you move on to the cams/positions the power valve as well. get yourself a trick kit. properly tuned dp picks up low end as well that 600 vs is a pos on that motor other then cruising around
 
It's fun trying different carbs and i agree the Holley DP looks racey, but with that beautiful air cleaner on top no one will know the difference. After seeing what you have available now, instead of spending big dollars on another new one, i'd tune on that 700 some and i think you'd be happy.

Just a side note, the Holley 700dp was always one of the priciest carbs back in the day for some reason. I always tried to find them used but no one seemed to use them. I think that's a shame because it was the perfect size for a street rodded sm/small block like a 289/302 ford, 327 chebby or a 343 Amc.
 
600 Holley v Carter 625 AFB. Carter made more tq, more hp....& used less fuel doing it. There are more Toyotas & Kias on the road than Challengers. Does that mean they are better because more are sold......

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600 Holley v Carter 625 AFB. Carter made more tq, more hp....& used less fuel doing it. There are more Toyotas & Kias on the road than Challengers. Does that mean they are better because more are sold......

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If this is a response to post #25, point out where I said one was better than the other. I'll wait. Whichever carburetor someone has the best performance for "THEM" and they can tune it the easiest makes it the best one. Whether you like to admit it or not, that does not always coincide with your opinion.

I do wanna know something though. Does a counter clockwise flush clear out big turds better?
 
A-body guy, where exactly is the BS in my #32 post?????
More Challengers sold than Toyotas & Kias?
The AFB carb outperforming the Holley carb?
 
600 Holley v Carter 625 AFB. Carter made more tq, more hp....& used less fuel doing it. There are more Toyotas & Kias on the road than Challengers. Does that mean they are better because more are sold......

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Out of the box, Carters are more of a bolt on and go carb than Holley...

However Holleys are more tuneable once you learn how to work with them...
 
I didn't see mention of an aftermarket converter.
If you have a 2500 stall or better, I say ok on a double pumper.
Overall, a Thermoquad
 
The Holleys that are more 'tunable' than a Carter/Edel AFB/AVS cost a LOT more! [ Post #40.]
The Holleys that are a similar price to an Edel carb have fixed PVCR. On a Holley, this orifice adds the extra fuel for WOT. If it is too big, I guess it is bad luck....
If it is too small, it has to be drilled out. Also, many Hs only have a sec metering plate, not a sec met block. The plate does not have removable jets, so.....

With carbs like the Edel that use met rods & jets, you can find a combination that satisfies cruise as well as WOT requirements. Secs have replaceable jets for ease of tuning.
 
The Holleys that are more 'tunable' than a Carter/Edel AFB/AVS cost a LOT more! [ Post #40.]
The Holleys that are a similar price to an Edel carb have fixed PVCR. On a Holley, this orifice adds the extra fuel for WOT. If it is too big, I guess it is bad luck....
If it is too small, it has to be drilled out. Also, many Hs only have a sec metering plate, not a sec met block. The plate does not have removable jets, so.....

With carbs like the Edel that use met rods & jets, you can find a combination that satisfies cruise as well as WOT requirements. Secs have replaceable jets for ease of tuning.
No sir. That's just not true. The Quick Fuel Slayer and Brawler carburetors all have air bleeds on top, IFRs and power valve restrictors in the metering blocks. You need to get more familiar with what's available and stop spewing bad information.
This is what I have on Vixen.
QFT 450

This is what I have on Gladys.
QFT 650

Both of these choices are right in line with anything from Edelbrock and cheaper than some.
 
Well I pulled the 600 off to measure the diameter of the adapter holes, they were about 1 5/8". I noticed some of the cork gasket was encroaching on the hole so I pulled the plate off, tidied up the gasket and then took my dremel to the plate bores. I didn't go crazy but they were measuring 1 11/16" after I'd finished which was a slight improvement. The adapter plate bores now have a slightly coarse finish which might help with fuel atomization for that extra 0.1hp!
While the carb was off I thought I'd try the 700 DP again. It was running ok before except the off the line bog. I had it on my work desk and set the Transfer slot on the primaries to have the "square" or a slight piece of the slot showing. I'd read the secondaries should be showing the same so adjusted them too.
Put the carb on and it fired right up but was idling at about 1,000rpm even with the idle screw all the way out. Must be from me adjusting the secondaries (I'm running MVA)? I gave up at this point as I'm flat out in work and there's a big cruise this Saturday for a charity for Christmas so I need the car running good. Adjusting the T-slot with the carb inverted is fine when it's come from dry storage but to pull it off, drain it and still probably have fuel going everywhere didn't sound like fun so I just whacked the 600 back on there and took it for a spin.
Geez it runs good with that basic Holley on there, even on a 95° day like today. Geoff if you're ever in Queensland give me bell and I'll show you how good a car can run with a "leave-it-in-the box" piece of crap Holley. Then I would be grateful if you could show me how to tune a carb properly because I really don't know what I'm doing. I'll supply the beer.
After all the advice you guys have given I'm now tossing up between the AVS2 650 and a new Holley, either a 750 Vac Sec or perhaps a 650 DP?
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I always START with the secondaries adjusted all the way closed so they stick when closed and then adjust until they barely do not stick. I never expose the t-slot on the secondaries, no matter what the "experts" say. It's never worked "for me".
 
I wonder if clockwise or counter clockwise is more conducive to turd removal? I guess we may never know. lol
I have an idea, but I'll probably get reported and permanently banned so I won't type the idea.
 
66 Sat,
I would encourage you to run the 625 AVS2. It has annular boosters in the primaries, which brings you to a new world in throttle response. This carb has smaller pri bores than your 600 Holley [ 1 7/16" v 1 9/16" ] for better response & mileage, with bigger secondaries when you want the power.
Chrys cars used Carter 4bbl AFB & AVS designs during the glory years, including on the Hemi.
I don't have any more direct comparisons as shown earlier, but in Roger Huntington's American Supercar book, 9 supercars are listed. These are NOT magazine tests, these are his own, unbiased testing. Quickest was the 68 Plym which ran 14.6....with a 750 Carter AVS on a 440. RH estimated the actual hp at 330. 3.23 axle. A 69 Ford Torino, 428 engine, Holley 735 carb, ran 14.9 with a more helpful 3.50 axle. All the others ran in the 15s.
He says this of the 340, AVS powered [ p. 132 ] : '' One of the swetest engines of the era was the 340...'It combined power & quick response with good fuel economy.' A 'Cuda with a lowly 3.23 axle ran 14.8 @ 96 mph....big block territory for a stock engine.

I do not know how long you have been in Oz, but various Aussie muscle cars were compared & the results published in Top Aussie Supercars. The 340 Charger, AVS equipped, v the 351 Falcon GT with 830cfm Holley. The Charger was 150 lb lighter, but down 11 cu in.
" We managed to 15.5s in the Charger, while the Falcon was battling to break 16 secs. Our test crew felt that the Fal lost a lot of time below 40 mph [ throttle response? ] - an area where the Charger is pretty fast."

" The 340 is definitely smoother at high revs & it doesn't haver the 351's tendency to lose tune after hard use"
 
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