What Carb for Poly Stroker

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66 Sat

66 Sat

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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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I'm not sure if you've even got any options on an intake, but I'm big on reworked Quadrajets, if that isn't delving too deep into "the dark side". Hey, Q-jets were originally designed and built by Carter.
 
OK thanks for all the replies, AVS2 650 is looking like a good choice but will it work with the square bore manifold I have?
20181023_135048a.jpg

I am going to open the up the center section and port the manifold as per Gary Pavlovich's advice but that might not be for some time.
 
You're kinda unclear on the cubic inch displacement.....at least to ME. You say 354 stroker. Does that mean it is a 354 NOW or that you began with a 354 ? Is 354 the current displacement? Chrysler did make a 354 Poly engine, so that's why I ask.
 
RustyRatRod said:
You're kinda unclear on the cubic inch displacement.....at least to ME. You say 354 stroker. Does that mean it is a 354 NOW or that you began with a 354 ? Is 354 the current displacement? Chrysler did make a 354 Poly engine, so that's why I ask.
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318 poly. 3.58" crank. 0.065 over. 354 current cubic inches, as opposed to 4" crank and 390+ cubic inches.
 
66 Sat said:
318 poly. 3.58" crank. 0.065 over. 354 current cubic inches, as opposed to 4" crank and 390+ cubic inches.
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A 750 Thermoquad would work well on it, but I don't like having to stack up adapter plates. Since the Holley bolts right up and works and you like it, why not stick with it? Hard to beat the little 1850. If I was going to do something different, I'd look at the Quick Fuel Brawler in a 650 double pumper. They are some of the most tuneable carburetors on the market. But I think I'd really leave it alone. Have you worked on getting a good hot curve in the distributor?
 
Since it seams to like more carb, if going the avs route, i'd probably just step up to the 800, as long as the 1.75 bores will work with a little massaging. It might sound like a little much by most standards, but i think it would be tunable enough to give you the best of both worlds.
 
Hard to beat a Holley 750 vacuum secondary in any of the million variations that are now available.
I have an old 3310 that I bought in the early 90's and still have it. It is my problem solver carb for all of my buddies who "think" they have a carb problem. Now granted I had the choke horn milled,screw in air bleeds,and a rear metering block put in before it was tuned on a dyno motor.
 
OldmanRick said:
Since it seams to like more carb, if going the avs route, i'd probably just step up to the 800, as long as the 1.75 bores will work with a little massaging. It might sound like a little much by most standards, but i think it would be tunable enough to give you the best of both worlds.
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I would also endorse that. The AVS is very similar to the Thermoquad in that an engine can stand a larger CFM since they only allow what the engine demands.
 
RustyRatRod said:
A 750 Thermoquad would work well on it, but I don't like having to stack up adapter plates. Since the Holley bolts right up and works and you like it, why not stick with it? Hard to beat the little 1850. If I was going to do something different, I'd look at the Quick Fuel Brawler in a 650 double pumper. They are some of the most tuneable carburetors on the market. But I think I'd really leave it alone. Have you worked on getting a good hot curve in the distributor?
Click to expand...
Leaving the 1850 on there would be the sensible choice. But nearly everything has been done to the engine with performance in mind, and I've still got the most basic 600 Holley on there that you can get. It just seems a little...boring, and doesn't look impressive (I know, that sounds pretty lame). This is my hobby and I work hard so like to spend a bit on the car where I can. The car is definitely stronger with the 700cfm double pumper, but has a big stumble off idle, which I'm working on fixing. The double pumper also looks way cooler with the dual inlets.

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I would endorse the 3310 750 were it not for the fact that these newer Holley types like the Quick Fuel were so incredibly tuneable. With the 3310 and the older style Holleys, you're "stuck" with the idle circuit and power valve circuit you have. These newer style carburetors have idle and high speed bleeds on the outside, idle fuel rectrictors and power valve restrictors in the metering blocks. They are infinitely tuneable in comparison.
 
So if I went the AVS2 route will I need a different adapter plate?
I've currently got this one, not to clear the butterflies but because the bolt pattern is different on the older manifold
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Will the larger AVS2 secondaries clear those holes?

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Have you tried tuning on the double pumper, jets, power valves, or accelerator cams? Since it seems to like more carburetor than the 600, I'd play with the 750. In my opinion, the Holley is much easier to tune and change per your situation. PM me if you need any information about Holley parts and pieces,
 
Look at the overall combo & remember what you built the engine for: predominantly street driving.

I could you build a great performing TQ that will tear your head off when the secs open...& give great economy. But I ain't going to Qld to dial it in for you.....

Your cam is mild-ish, only about 8* more 050 duration than the 340/275 hp cam. That is going to limit top end, getting pretty tired by 5000 rpm. So why put on a 6000 rpm carb on a 5000 rpm engine? Throttle response & mileage will suffer.

Holley's [ & clones ] are best left in the box they come in.....

The ideal carb for YOUR combo is the 625 AVS2. It will bolt on directly without an adapter. A 800 AVS will not fit without opening up the bores in the man...or using an adapter.
Your 600 H has 1 9/16" pri & sec bores. The 625 AVS has smaller primaries [ 1 7/16" ] for better throttle response & bigger secs [ 1 11/16" ] & has more total air flow. I have only heard good reports about the 625 AVS2. Edel changed the design of the AVS from the original Carter design which was a positive move in my opinion. They added venturies to the secondaries, originals did not have these.
I have been involved with the install of two Street Demon carbs. One worked well, one had a flat spot that was never able to be overcome, even with ph calls to Holley tech.
 
66,
Just to add to above. When I said the AVS will bolt on without an adapter, I was comparing the small gap between the two sec bores, on the carb pad & the carb itself [ pics you posted ].
If the blades clear, you do not need the adapter because the dual bolt pattern on the AVS allows for direct bolt on.
 
I run the BIG TQ on my 318 winter motor. I luv it.

I wouldn't run any less than the 750DP on that small-cammed engine, unless it doesn't have much for cylinder pressure, then a 650 DP. But in both cases, only because it's on a square-bore intake.
My carb of choice would be the TQ on a spread-bore intake/no adapters; I love those carbs. But a close second would be a Q-Jet, again on a spreadbore intake/no adapters. I would pay extra for a spreadbore intake.
BTW, I'm not dissing your cam selection; at 10.8 Scr she should be a real stump-puller.
 
Unfortunately There are no spread bore manifolds for the Poly A engines.
 
Darter6 said:
Unfortunately There are no spread bore manifolds for the Poly A engines.
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I did not know that;
But looking at this
1701114042950.png

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
 
Bewy said:
Look at the overall combo & remember what you built the engine for: predominantly street driving.

I could you build a great performing TQ that will tear your head off when the secs open...& give great economy. But I ain't going to Qld to dial it in for you.....

Your cam is mild-ish, only about 8* more 050 duration than the 340/275 hp cam. That is going to limit top end, getting pretty tired by 5000 rpm. So why put on a 6000 rpm carb on a 5000 rpm engine? Throttle response & mileage will suffer.

Holley's [ & clones ] are best left in the box they come in.....

The ideal carb for YOUR combo is the 625 AVS2. It will bolt on directly without an adapter. A 800 AVS will not fit without opening up the bores in the man...or using an adapter.
Your 600 H has 1 9/16" pri & sec bores. The 625 AVS has smaller primaries [ 1 7/16" ] for better throttle response & bigger secs [ 1 11/16" ] & has more total air flow. I have only heard good reports about the 625 AVS2. Edel changed the design of the AVS from the original Carter design which was a positive move in my opinion. They added venturies to the secondaries, originals did not have these.
I have been involved with the install of two Street Demon carbs. One worked well, one had a flat spot that was never able to be overcome, even with ph calls to Holley tech.
Click to expand...
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.
 
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