Guest Anonymous Posted November 19, 2001 Share Posted November 19, 2001 So I'm looking around for a carb to stick atop my hot 327. I want something in the neighborhood of 600-650cfm with vacuum secondaries to run with a single-plane I'm modifying myself, so booster signal strength, and thus carb metering accuracy, is of the utmost importance. I also don't want to spend an arm and a leg on the carb, which rules out BG/Demons and expensive carb modifications. After doing a bit of research, it seems like the Holley 4010/4011 seems like a very good carb... Aluminum body construction, shaves 6 lbs of weight, not to mention annular boosters and a shiny exterior. Now aren't annular boosters the best for anything short of an all out race car? Having them already in the carb would save me a pretty penny, avoiding me the expense of having to go to a carb shop to have them put em in. Only problem is, they don't seem to be making these carbs any more, and they are comparatively rare, so finding parts might be a hassle. Other than that, does the 4010 have any disadvantages over the 4150/4160 family? Also, how does a Q-Jet/Edelbrock/AFB compare to the Holley? They are supposedly easier to tune, but the Holley's have a much bigger aftermarket, and are more tweakable right? But what about metering accuracy and booster strength? The Q-jet has one within another, does that make its signal especially strong? Again, booster strength/efficiency is very important, because it governs throttle response, mileage, and low-end torque... Or am I wrong? One more thing. How much, if at all, would a spreadbore to squarebore adapter cost in terms of airflow? Are there any inherent advantages/disadvantages to a spreadbore compared to a squarebore? Seems to me like a spreadbore would get slightly better mileage above 10" vacuum due to smaller pumping losses and greater signal strength? Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted November 19, 2001 Share Posted November 19, 2001 for 1320 or curvy stuff? For curvy (ie. fore/aft hung floats) stuff I loved my edelbrock squarebore performer (600?). Easy to tune with independent idle/primary/secondary circuits.....their tuning guide complements it nicely as well. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 19, 2001 Share Posted November 19, 2001 Aah Yes, forgot to mention, this is gonna be for a daily driver with the occasional visit to the local road course. So I'd want fore/aft hung floats to prevent fuel starvation under heavy g's? Quote Link to comment Share on other sites More sharing options...
pparaska Posted November 19, 2001 Share Posted November 19, 2001 Yes, if you go Holley, get center hung. The new Avenger series has this. It's basically a jazed up 3310. I'm using a 3310 750 vac secondary carb. You can get this same type of carb in a 650 I believe. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 21, 2001 Share Posted November 21, 2001 Thanks for the responses guys. Again, I'm building a 327 with ~400bhp give or take, and want the best driveability/throttle response/mileage I can get, hence the choice of a 600-650cfm vacuum secondary carb. Anything less would be too small I think. So far I've heard nothing but good things about annular boosters. Do they have any disadvantages I should know about? A lot of Holley carbs I've seen have the standard booster (with the bar inside the venturi), and it looks pretty nasty... not at all conducive to flow. Do all the newer Holleys come with annular boosters or is that not necessarly true? So its pretty much a toss up between the Q-jet, Edelbrock/AFB, and the Holley 4xx0. From what I understand, the Holley is more of a race carb, better for WOT tuning, whereas the others are give up a couple horses here and there, but are more well rounded, and better suited for driving on the street. Is that right? As for the others, what distinguishes the Edelbrock from the Carter and the Q-jet? The Q-jet is kinda ugly, and seems really complex inside. How, if at all, is the Edelbrock superior? Does it give anything up to the Q-jet or Carter? Thanks Quote Link to comment Share on other sites More sharing options...
fl327 Posted November 21, 2001 Share Posted November 21, 2001 holleys are more geared towards high perf apps and need more tuning than edelbrocks q-jets can be made to be the great in between, giving great cruising performance and awesome wot response, simply because of teh more complex metering system they possess. these carbs get a bad rap that they dont deserve, they are a little harder to work with, but they deliver. theres Leonard. nothing like a holley double pumper to get the party started. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 21, 2001 Share Posted November 21, 2001 I think if anything a slightly bigger carb might be in order. I would personally use a 700 cfm mech sec, dp. You could probably even go 750, but the 700 is closer to the max an average 350 needs and definitely enough for the smaller 327. Just an opinion, and truthfully its hard to go wrong with any of those carb choices if you hang in there, understand the carb and get it dialed in. Out of box is just that, usually wrong and a guess at best from Holley, or Edelbrock or .... Good luck with the research, Lone Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted November 21, 2001 Share Posted November 21, 2001 I would suspect that since you are going to run a single plane manifold, that you will want all barrels to be the same size for best fuel distribution at high rpm. This would tend to eliminate the Q-Jet and one of the Holley 750/780 vac secondary's - the 3310 is the square-bore one (non-emissions). Of course, w/vacuum secondaries there is the chance that they won't be fully open even at redline - even on a 350. I seem to recall that the hot DP for the 351C Ford engine was the 700 DP - picked up a lot under the curve and sacrificed NO top end compared to the 750. I think the choice of a 650 vac would be close to ideal for a 327 - particularly if the barrels are all the same size, because the secondaries would probably be all the way open at redline. I would also suspect this could be the start of an interesting thread in it's own right.... Brad Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 22, 2001 Share Posted November 22, 2001 I have an Edelbrock for sale..... check out the for sale board....asking $80 Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 22, 2001 Share Posted November 22, 2001 Lone, I've heard repeatedly that a 750 or even 700 is waay to big for my 327, especially since I'll be using a single-plane and want to retain some manners around town. And Brad, let me get this straight. A Spreadbore is better for mileage/driveability, and the low end, whereas a Squarebore is better for high rpm power, right? . Isn't secondary opening decided by the stiffness of the spring in the vacuum diaghram? I don't think I'd have any problems with the secondaries not opening on a 600-650cfm vac sec carb... I posted the same question on the Chevytalk forum, and the guys there seem to be waxing lyrical about the Edelbrock, with its ease of tuning/optimization, throttle response, and metering accuracy. So at the moment, I'm kind of leaning towards that since the Q-jet is pretty ugly, both inside and out, as well as being a PITA to tune. The Holley is a great carb too, but the gains in power (like what, 5-10bhp?) are outweighted by its inferior driveability and mileage. (Edelbrock is a better all round carb right?) However I've heard that the Edelbrocks don't do well cornering due to their poor float design... That's not good at all, since my car is to be occasionally road raced/autocrossed. Does this mean my engine will cut out/bog under high lateral g's? Is there anything I can do to remedy this? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 24, 2001 Share Posted November 24, 2001 bounce (hope you guys don't mind) Quote Link to comment Share on other sites More sharing options...
Ray Posted November 24, 2001 Share Posted November 24, 2001 Funny question but what trans are you running??? if you are running an auto go with the vac secondary but if you are going with at stick I agree with the about on a 327 a 700 dp is great if you have enough cam and heads..... just my 2 cents.... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 25, 2001 Share Posted November 25, 2001 I'll be running a T5 manual. However I'm pretty set on using vacuum secondaries as they've shown to be superior on all but the wildest of engines. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted November 25, 2001 Share Posted November 25, 2001 I was under the impression that a center pivot float was better for the curvy stuff. Am I wrong? I ask because my afb has the fore/aft hung floats, and I thought the Idelbrock carbs were the same way. Anyway, I've used these well in side G's. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted November 25, 2001 Share Posted November 25, 2001 Spreadbores have the same amount of air flowing through the smaller primaries at low rpms, therefore have a higher amount of velocity and fuel atomization. Unless you are turning the vacuum secondary spring on the 750, the spring that comes stock will probably never fully open. I am of the opinion you are better off with a smaller carb w/all barrels the same size (on a single plane intake) and use the vac secondary spring that will open the secondaries fully at redline, that just bolting on bigger carb w/vacuum secondaries that may not fully open. I believe the fuel distribution will be more even, and the fact that you are utilizing ALL of the carb at high rpm (with smaller bores on all barrels) vs only a percentage of the secondaries on a bigger carb (with larger primaries ALL the time - there goes the fuel mixture velocity). I believe that given a little visualization, almost anyone can imagine the difference in airflow patterns between primaries and secondaries on a spreadbore, and a little more thought and visualization should bring the concept of using ALL of a smaller carb as being better than only PART of a larger carb. The larger carb will lose a degree of crispness due to the larger primary bores over the slightly smaller carb ALL the time, and you'll never fully utilize the secondaries. You simply wind up with more area under the curve with a properly sized carb/manifold combination. Dual plane manifolds tend toward the same distribution problems, but also usually have a better low end signal to cover up the effects of a larger carb. I think a lot of people go too big on carbs on a single plane intake when 'piecing' a project together. Go with what is documented in the real world as working well - and if you have a single plane intake, you may be surprised at how low you can go in carb size! All of this is JMHO, mind you.... Quote Link to comment Share on other sites More sharing options...
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