660 Holley #4224 opinion?

[SCOBRAC]

Ok,

I know I have railed in the past against overcarburation and that in particular 600 cfm vacuum secondary are a big compromise at best and at worst. Well you know.

So I have lived with my Holley 9660 450 mechanical secondary carbs on my 427 and am well, not impressed. Yes they run well and seem perfectly happy but I can tell there is more to be had.

Shelby is said to have muttered something like "too much is just enough" and I am inclined to believe him. Is it possible, despite the mathmatic formulas to the contrary the C5AE 715 cfm carbs were just enough "too much".

I still refuse to go with a vacuum secondary but have any of you got an opinion of the 660 cfm Holley #4224. 50cc accelerator pumps, 25cc center squirter with 1:1 mechanical secondaries???

[Excaliber]

I'm running two of them on my 427. There EXPENSIVE drag race carbs. No power valve and the "secondaries" are VERY close in size to the primaries. The secondaries are slightly bigger, but it's hard to tell "looking" at them.

The mechanical linkage is VERY FAST. Center Squirters all right. The accel pump shoots into all four barrels at the same time. Thus the linkage is set up to open the secondaries when the primaries have just barely opened a little. Everything about these carbs is "fast". BIG accel squirt IS needed to avoid stall. Linkage travel distance is kind of far, keep pushing down eventually the pedal will hit the floor board and the carbs will be wide open.

I hate them! I've done ALL the tricks to make them more street friendly, it's just not in their nature. They flood REALLY easy on even modest cornering or modest braking. The go in straight line really really good however. They LOVE to run wide open throttle. Two 660's are 1320 cfm. Normally I would say that's "too much". But for MY motor setup it's "perfect"! I run high 11's at 120 plus in the 1/4, and thats taking it "easy" on the car. I DID re-jwt from 75 to 68's (total of 8 jets, all same size) and that actually HELPED performance.

If they didn't LOOK so cool and RUN so fast on the drag strip I'd sell 'em and go with something else. But there so bad, there good! I'll keep 'em, love/hate relationship.

OH, I forgot to mention the "idle circuit",,,,,, wait, they don't have one thats worth mentioning.

[steelcomp]

Slick is right...those really aren't the right carbs to run on on a road car. They are a drag race only tunnel ram designed carb, and were really designed for WOT use only. Boat guys love 'em, but because of the "liquid hook up" many of the problems are covered up. Besides, most guys that run them in boats are always wide open.
Why no vac. secondaries? I had a pair of 1850 600 vac sec carbs in a dual 4 application that were a pair of the best carbs I ran. There's a couple of things you need to do to them, but they were EXCELLENT! Double pumpers have their application, but for the most part, a good set up w/ vac secondaries is much more driver friendly on the street and will give you just as much bang for the buck.

[SCOBRAC]

Hmmm... I feared this might be the case. Maybe I will look into rejetting and reworking the secondary system in the 600's. The last 1850 I had was on a 1.2 liter rotary engine. (I only rail about being over carburated I didn't say I never did it) I just hated that carb. Not for what it was, but what I needed to do to it to make it work. It worked really well after a ton of trial and error. I got almost 150 hp per liter out of that 12a rotary. Now every time I see an 1850 I think about it. It was still a 188 hp 2400 pound car, that was double the factory HP.

I actually have already bought a pair of these carbs from a racer who ran them on an FE and had them reworked for road racing, air horns milled, rejetted etc. I was a little leary of the 50cc (x2) accelerator pumps going off at once. Who knows maybe I can make them work with 30cc pumps to get the thing to be more managable off idle. Probably not.

I got them thinking the WOT would be impressive and it will be I'm sure. He's got 76 jets in them now and that seems really large. I was thinking 68's too. I'm wondering whether your flooding during cornering and braking isn't due to the fuel level being a bit high. Thats a common problem with road racing carbs. There are baffles that you can install in the bowls to stop it if lowering the fuel level creates a starvation problem.

I too was inspired to buy these for the bad boy factor. I wish Holley would produce more carbs without choke assemblies, these don't have chokes but the hir horns being milled off really sealed the deal.

They are expensive new almost $600 each. I got this reworked pair, freshly rebuilt, refinished etc. inc. shipping for $485.

[steelcomp]

Michael,
Leave the 5cc accelerator pump the way it is. You might go to a smaller nozzle which will give you a little less gas, but over a longet duration, and nyou can play with pump cams as well, but you need the big pump...it's feeding all four venturies at the same time. It's no different than a double pumper, since primaries and secondaries are coming in at the same time. You're not going to get very good drivability with these, but they ought to work good under WOT.

The 1850 600Vac sec. carb will be jetted good enough out of the box. What you want to do is open up the power valve passages about .010-.015" more than stock, and re spring your vac. sec. diaphragm to get the secondaries full open by 3000rpm. You can buy spring kits for them, or just cut 1 1/2 coils off the stock springs. A balance tube between the diaphragms is a good idea as well, but not necessary. You won't be disappointed in these carbs when they're set up right. And they'll be very driveable!
Just my thoughts.

[decooney]

Michael,
In addition to trying jetting changes, do these carbs by chance have the removable discharge nozzles for primary and secondary? Have you tried changes to these along with experimenting with different accelorator pump cams? Maybe try this after exhausting all rejetting attempts.

Also, as orginally equipped I noticed there is a pretty good jump down in original jet sizes / stock rear metering plates between these 4224/660s (Primary 76 jets) you have as compared to the 1850/600 carbs (Primary 66 jets). As a guess... If they are still 76s in the front, I'd be tempted to jump down and try the 66s. The standard 600s run the (F)66,(R)plate 134-9, 6.5 Power Valve from Holley... I'd be curious to know how it works out once tuned a bit more. Good Luck.

[steelcomp]

I don't want to get into an arguement here, but you don't want to change the 660's jetting 10 sizes. You can't compare the two carbs. The 76 jets in the 660s is the stock jet size for that carb. If there are removable jets and a secondary metering block, someone has modified these carbs, but the stock secondary metering plate, as it were, was equal to a 76 jet size, so there isn't really any difference as far as stock calibration. These carbs out of the box are set up a little "fat", as to be safe. Remember, a carb is calibrated to provide a certain amount of fuel for the given size and metering of that carb. Although the 600 vac. secondary carb is similar in size, and the primaries are almost identical (ventury sizes the same, throttle plates a little bigger on the 4224) the callibration is completely different, mainly because the 1850 runs a power valve. This is worth about 6 jet sizes. (If you were to remove the power valve from the 1850, you'd need to go up to 72's)

Do these 4224's have idle mixture screws in the secondary metering blocks? If so, they've been converted to four corner idle, which will help, if you choose to use them. (and they were done right)

Bottom line is, the best place to start with any carb, even if you're running multiple carbs, is to start with the stock setting(s). Make small changes, and make one change at a time or you'll never know what change had what effect. Document your changes in minute detail. What ever you do to one carb, do to the other. Don't buy any more carbs or anything else because they seemed like a good deal or for the bad boy effect. There's a reason someone is getting rid of them. When carbs get modified, it only takes one hole in the wrong place, or one wrong part to turn an expensive carb into a paper weight. The "bad boy" effect won't be so bad when you try and drive these carbs, and they stumble or fall on their face untill the motor catches up, and the guy next to you is GONE! To put it bluntly, these are the wrong carbs, and you're going to spend a lot of time and frustration trying to get them to do something they aren't designed to do. And milling off the air horn dosen't really help anything. Some say the flow bench will show the opposite. But it looks cool.

BTW...I'm not sure what manifold you have, but make sure the (660) carbs, with the added secondary metering block, will fit. they might not.

[Excaliber]

I guess carbs were modified. I DO have the idle mixture adjustment screws and the removable jets. The 68's seem to work much better than the originals and 1/4 mile times are as good or better also.

I GOT to have the BIG accel pump shot or she WILL stumble. I adjusted the accel cam so I have a "little bit" of throttle travel before it kicks in. That was to avoid flooding the engine by just "touching" the gas pedal getting in or out. The accel pump is VERY aggressive.

I've got float level BELOW specs AND the baffles! It helps, but I won't be running any SCCA events with THESE carbs. I'm starting to like the drag racing thing though........

[SCOBRAC]

Hmmm... Maybe I can sell these to a guy witha boat.

[steelcomp]

try ebay...they should go pretty easy.

[SCOBRAC]

I'm going to thrash around with them for a while. I think they might be just enough of too much of a good thing . I think the squirter volume (these have 25cc squirters x2 with 50cc pumps) as well as reduced accelerator cam profile will make them more civilized for street use.

I hadn't considered the lack of a power valve when considering jet changes. I may want to leave well enough alone, one step at a time. For the price it will be a fun exercise, I will keep the 450's handy though. They worked really well on the 428 with the hydraulic cam and are ok on the 427. There is just more to be had, of course that always comes at a price.

Thanks for the prospective. I will let you know how it works out.

[Excaliber]

,,,,as I mentioned earlier, attempts to reduce the accell pump shot resulted in a mean stumble when "flooring it". Apparently they need all 50 cc?

[chopper]

I posted the following on a previous thread, dealing with my experiences with both carb models. The CFM numbers were for a stock displacement 428, as I recall:


"FWIW, my experience with the Holley 1850s was less than optimal. I fiddled around with them for several years and was never really satisfied with how they ran. I could get them to run at low speed or at high speed but not together. I went with the 6224s, swapped the metering blocks from the 1850s (which have the power valves) in place of the ones which came with the 6224s (which have the power valve holes blocked) and played with the jets until I was satisfied. I ended up with #72 jets in the primaries and secondary plates equivalent to #76 jets in the secondaries. I hooked up a vacuum gauge directly to a port in the manifold, duct taped the gauge to the dashboard and recorded the manifold vacuum in each gear at 1000 rpm intervals; lowest vacuum was at idle at 10.5 inches. Based on that I installed 8.5 power valves. Seems to have worked out OK but was certainly a frustrating and expensive way to go.

To expand a little on what Mr. Scobra said, if you run the numbers from Holley, you could get a dual-quad setup using the 450-cfm mechanical secondary Holleys (model 0-9776) and have plenty of carburation for your engine:

http://www.holley.com/HiOctn/ProdLi.../FMSC/FMSC.html

Inputing the numbers in their formula, you need about 805 cfm if you run your motor to 6500 rpm and assume 100% volumetric efficiency. The 450 cfms are considerably cheaper than the 660-cfm 6224s, $175 each versus $455 each for the 6224s.

Incidently, if you get to fiddling around with the power valves, be aware that just because the package says "8.5" doesn't mean the valve opens there. I have one of those little power valve testers and a hand pump and took it to Loper's with me when I bought the two valves in the car. We went through about a dozen before I found two that actually opened at 8.5 inches. Range of actual opening vacuum readings was from 6 to 12 inches. The guys behind the counter were a bit miffed that I did it until they saw the variations for themselves.

Also, if you elect to go with a dual 1850 setup, be aware that you will have to get the little caps for the secondary dashpots which have the nipples which allow you to hook the two secondary dashpots together, to ensure that they open at the same time. Holley wants about $65 apiece for them. One of the guys I work with rebuilds old BMWs for a hobby, and we took the dashpot covers which came with the carbs, drilled horizontal holes; inserted small-diameter stainless steel tubes and epoxied the tubes to the covers with some really good industrial-strength epoxy. It solved the opening-together problem but the I couldn't solve the not-opening-all-the-way problem. That's when I finally went back to the mechanical secondaries on the 6224s. Hope this rambling is of some use to you."


In final summary, I'd have to say that I agree with the assessment that the 6224's are drag racing carbs and as such are not optimal for the street. However, I never could get the vacuum secondaries to open properly, so I've come up with some "yankee ingenuity" to modify these to work. My biggest problem now, as listed by others on this thread, is some bogging down during rapid decelerations and a slightly smaller bog when going around corners hard. But, when I say GO, it goes. Like everything in life, it's a compromise.

[steelcomp]

We noticed considerable leaning in the mid range with the 1850s on the dyno, but as I stated in my earlier post, if you do a simple mod they work seamlessly. I never had a problem with them not opening all the way either, if treated to a spring change. (That's why they make different springs for them)

As far as the "CFM" chart... that dosent mean a thing in the real world. It's a guide line for minimums (for a given VE), not maximums. Honestly, a motor is only going to move a given amount of air for a given dispacement at a given RPM, and it really dosen't care how many carbs you put on it. Carburetors pose a restriction, even at the proper CFM for a given engine/RPM. Now, of course you won't force more air into a naturally aspirated engine with a bigger carb. What you will do is reduce the restriction which will allow the engine to "breathe" better. As always, there is a trade off when going to bigger carb(s). But as long as there is ample air signal to the carb for it to provide proper atomization, the engine will use what the carb will allow it to use. For example, if you took the chart and your average performance motor, say a 496" BBChev, turn it 7500, that chart calls for aprox. 1100 cfm @ 100%VE. Why do we get another 65-70 hp by near doubling that? (two Holley 1050s) We might be at 110% VE, which with the formula, would call for 1220 cfm. Still not close.
See what I mean? Honestly, the better carbs would be the Ford 715CFM vac secondary carbs. Ford's engineers didn't just pull those out of a hat. But a 427 at 6500 only needs about 880 cfm. according to Holley. I've talked to their Tech guys a few times, but they don't offer information "outside the box", so I quit calling.
If it were me, I'd get over the antiquated dual four barrel thing and put a good single on it. Lets face it, it's a replica.

[Excaliber]

Well there is one good reason to stay with the dual fours.

They look really cool and they replicate what was somewhat common on the originals.

Most of us are having fun and not seriously racing, so "looks" are a part of the equation.

I would like to run a little SCCA so maybe I'll pick up single carb\manifold for "fun". But I'll keep the 2X4 also!

[steelcomp]

Slick, That was two reasons.

I know, there's few things that look cooler under the hood than a pair of holleys! Messin with them is half the fun! I'm just trying to help keep it fun, not frustrating. This stuff just isn't that difficult.

[Larry Hampton]

I have had a pair of 660's on my race 289 (.060" over) and they ran great, so I'm not sure (or I haven't experienced) about the not overcarbing a motor. I can't remember what we ran up front, but I think they were in the 68-72 range. The car was a '69 R-code Mach I and had a Jerico, 5.67 gears, 9x30 slicks, weighed 3000#. The motor had a Offy 360 T/R, full roller, 12.7:1 TRWs, '69 351w heads, aluminum rods and cast crank. Launched @ 6400 and shifted and crossed the line at 8000. I was told that was the best induction setup for a drag 289/302 (660's and Offy 360) and I can't say I was given bad info as the car ran 11.08@119.

One piece of advice I was given when shopping for 660's was to look for unmodified carbs. I understand milling the horns off does more harm than good on these carbs (from what I've heard). I was also told to make sure the linkage hadn't been modified to where it was no longer 1:1 and to check for sloppy throttle plate shafts. I bought a pair of stock carbs for $400 back in '94. I plan on sending them to Pro Systems after I get my 390 stroker built for my '63 Fairlane NSS car.

I really don't know nothing from nothing when it comes to carbs, all I can say was this was the situation I had, what advice I was given, and that it worked for my application. I've also heard that the 660's aren't that great for a street car. They should work great on my FE for a drag only car though and I think is probably the prefered carb for a drag application. They may end up in stock form on a 489" Shelby blocked drag motor that has run 8.4xs with a single 4bbl (1050 I think) in a '64 Falcon. Right now intake is preventing that from happening I believe.

Larry

[steelcomp]

660's were designed for one application...dual four barrel on a tunnel ram manifold for drag racing or marine use. For that, they work great. And you're right about getting them in stock trim. From there, a competant carb shop can do wonders. A guy in his garage reading Hot Rod Mag, on "how to modify your 660 Holley" is most likely going to end up with trouble, figure it out after hours of frustration, and sell them on ebay. The next poor sucker doesn't stand a chance.
You're also correct about milling the choke horns off.

[carbide]

I have a 428CJ stroked to 462 with extensive head work and a .565 lift hydraulic roller. I'm running the Dove 2x4 tunnel wedge and a pair of the 4224 Holleys. On the dyno it was running lean until I changed the jets from 76 to 84 where it made 579.9 HP and 565 torque. After putting it in my Cobra I found it wouldn't run under 1800 RPM without stumbling which made it very unfriendly to drive on the street but at WOT it was great. In an effort to make it drivable and maybe get my gas mileage above 5, I have since gone back to 76 jets but haven't had a chance to really see if they make a difference in drivability. Hopefully now it won't burn my eyes as much if I crank it in my shop.
Before I stroked it changed the cam and bumped the compression to 11/1, I ran 2 of the 600 Holleys and it was very streetable. I may wind up going back to them.

[dcdoug]

Hi Carbide, just FYI, this might be better posted as a new thread, since this thread was last updated 9 years ago.....