Close



Results 1 to 25 of 25

Thread: What's this?

  1. #1

    Default What's this?

    What's this?




    Anybody?

    I know what it is, and have been looking for one for a long time, and finally got one, to complete what I have sentimentally hung onto for a very long time. Posted as a conversation piece. We'll see if anybody knows... I'll spill the beans later...
    Last edited by Walking-Tall; 07-18-2017 at 11:35 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  2. #2
    FEP Power Member 306gt's Avatar
    Join Date
    Aug 2005
    Location
    Plymouth, Ma.
    Posts
    1,477

    Default

    Holley 3 bbl base plate. Never seen one in real life. Only heard about them. I can't imagine they worked very well. If they did they would still make them today.
    85 G.T. All motor
    337 c.i.d 11.44-120 mph

    88 L.X. Hatch 5.0L H.O.
    5-speed. 13.41-102 mph on E.T. Streets winter beater

    1984 1/2 G.T. 350
    13.09-106 mph

    1979 Pace Pace car 2.3L Turbo (Daughter's Car)

  3. #3
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,211

    Default

    Holley 3160 PN #3916 950cfm or # 4604 1030cfm carb.


    eg http://www.ebay.com/itm/HOLLEY-3-BAR...-/151780115351

    It was a really good pre Dominator 4500 carb often used in a really good Buick, Oldsmobile, Mopar, Ford or COPO 427 Big blocks. They made these vac sec muthas for about 3 years before the 4500 Dominator and spreadbore 4165/4175 carbs became common, and then replaced them with the 4150/4160/4165/4175 versions in vac sec and mech sec form.

    Rory428 from http://fepower.net/simplemachinesfor...p?topic=1347.0

    Over the years, I have owned both versions of the Holley 3 barrels, and ran them on my Fairmont. They ran great performancewise, but lacked some of the part throttle drivability of later Holleys. They were basically a 3310 780 Holley with the material between the 2 secondary butterfies of the baseplate and main body cut away, and a single, large oval secondary plate installed. They used a large angled vacuum secondary housing, similar to a Chevy or Mopar 3x2 barrel unit, although the length of the vac diagphram rod is different. As mentioned, the sec. diagphram is onbsolete, not sure about carb kit availability either now. They used a funky cable operated manual choke flap, with no choke tower. To tella 950 vs 1050 cfm 3 barrel, check the secondary venturi area. A 950 has 2 booster, like most other Holley 4 barrels, but a 1050 has 2 simple brass tubes, with no booster bell to get in the way. Kinda crude, but it did work well at WOT.

  4. #4
    FEP Senior Member
    Join Date
    Jan 2011
    Location
    Vancouver BC Canada
    Posts
    774

    Default

    Funny, I was just going to reply, and noticed the previous post had my quote from another forum!
    1978 Fairmont 2 door sedan, 428CJ 4speed. 9.972ET@132.54mph. 1.29 60 foot
    Replaced the FE big block with my 331/4 speed in my Fairmont, best 10.24ET @128 MPH.
    1985 Mustang LX hatchback NHRA Stock Eliminator 302 4 speed best in legal trim 12.31@107 mph, but has gone 11.42@115 with aftermarket intake, carb, and iron Windsor Jr. heads.New for 2012! 331 cube SB Ford, AFR 185 heads, solid flat tappet cam, pump gas; 10.296ET@128.71 mph, 1.37 60 foot.
    1979 Zephyr Z7, all original 302 auto, 2nd owner.

  5. #5
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,211

    Default

    Quote Originally Posted by mcfairmont View Post
    Funny, I was just going to reply, and noticed the previous post had my quote from another forum!
    That's because , can I say it without disrespecting you, your McFamous, Mr McFairmont!
    You've done some nice informative work as R427!

  6. #6

    Default

    Yep, it's a Holley 3-barrel throttle base plate, for a Model 3160, List#3916-1S, 950cfm (rated, at the time, at 20.4 inches of water... let that marinate for a minute, and consider that all have been rated at 28 since sometime afterward...) vacuum secondary. Technology continued after these, as has marketing, advertising, and snake-oil, but progress has not... is as much as I'll say right now regarding these (and others of the time, calibrated very well) not still in manufacture today.


    Some words from others:


    bigjoe1 Wed Mar 04, 2009 2:12 pm I had one of the very first prototypes back in 1967-- They are very good if you dont need the double pumper setup-- They were rated at 950 CFM, and the usually made more Hp than an 850 CFM in their day-- I still have some spare parts for them--They were very goog for street racing because of the vacuum secondary they made traction come on much more smoothly from a dead stop--It was always 5 or 10 more HP than an 850
    JOE SHERMAN RACING


    Tuner Wed Mar 04, 2009 6:48 pm

    Joe, were you with Edelbrock during the development of the 3 barrel in collaboration with Holley? I was working at a speed shop when they finally became available and sold a few dozen of them (at least) in the next few years until the double pumpers made them “obsolete”. It was disappointing when we couldn’t get new ones anymore. I was lucky to have some experience with the 3085 3bbl (’64 Race Hemi), so when the 3916 showed up with its quirks I was a leg up out of the gate.

    The original 3916 got kind of a bad rap because they were calibrated a little too lean. That lead people to assume the bog was because the carb is so large when actually all it needed was larger secondary metering plate fuel restrictions and larger PVCR’s with a high flow power valve (Joe, do you remember the “400-A” PV?). Close attention to the secondary spring was necessary because it is somewhat application specific.

    Also, the 3916 came with a 30cc accelerator pump which was barely enough for a 327 with the 180 C3B Edelbrock intake that was engineered to use with the 3 barrel. That required the upgrade to the “REO pump”, so called because the original application of the 50cc pump was a 2bbl on a huge (450 CI?) 6 cylinder REO truck engine.

    Because of the unique location of the secondary discharge nozzles, the 3 barrel has to use the 4160 type metering plates in the secondary. The angle channel exit from the regular 4150 metering blocks doesn’t line up with the discharge nozzles in the carb body because the nozzles are closer to the centerline of the carb in a 3 barrel.

    The shortcoming with using any vacuum secondary carb on a nitrous engine is a backfire when the throttle is closed will bend the throttle shaft. The three barrel has so much more secondary throttle plate area, and less support for the shaft because it lacks the bearing in the center, that the damage will be worse from a smaller sneeze than would bother a double pumper. I would want to be sure the tuneup was such that the secondary was fully open before the N2O could activate. An RPM window switch is a good idea with nitrous on any engine, but in this case I think it would be particularly necessary. With a loose enough torque converter the secondary could be fully open below stall speed and the N2O isn’t necessary until the load can be applied fully so a window switch can help protect the carb.

    Because 3 barrels are so large it was very rewarding to get one running well since they always made more power than a smaller carb. In the daze before the “rules” were cast in stone that “X CFM be used with Y cubic inches for Z RPM”, we put as many of the largest carbs available as would fit on any engine. Before double pumpers became available, I did several dual 3 barrel tunnel ram and cross ram manifold jobs and it was all good. Watch the vacuum secondaries open and the front tires come off the ground at the same time. When all the little holes are the right size, there’s (almost) no such thing as too big a carb. We used the Mopar Race-Hemi engine vacuum secondary carbs for inspiration and it all seemed so easy. Fun anyway.

    It’s too bad people had problems with them initially, but from my point of view it was a blessing they had the bog issues and other little quirks because it made a lot of opportunities to have unique engine tuning experiences that money couldn’t buy. Tuning 3 barrels would be good training for anyone who wants to be a carb tuner.




    bigjoe1 Wed Mar 04, 2009 11:01 pm I worked at Edelbrock, and they had a special deal with Holley-- The first two years that the carbs were on the market, you had to buy it from Edelbrock-- This was in 1967 andd 1968-- They sold very well-- about 2000 units as I recall--- How biut this--- they were 75 dollars--- A 3310 was 57 dollars
    JOE SHERMAN RACING


    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  7. #7

    Default

    Quote Originally Posted by xctasy View Post
    ... and then replaced them with the 4150/4160/4165/4175 versions in vac sec and mech sec form.
    Politely begs to differ on this, since 4150/60's were born in ~1957.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  8. #8

    Default

    When I was first learning to drive, I drove the old man's '66 Fairlane 500 sedan w/289, automatic, and 9-inch with ~3.50:1, that he had installed and tuned a 950cfm 3-barrel onto. It had crisp, instant off-the-mark and part-throttle drive-ability, got great gas mileage, and when that secondary opened at about 95 miles per hour in top gear, it felt as though the transmission had kicked down into another passing gear.

    Anyways, that's the sentimentality factor for me, the untouchable small block Ford sleeper Fairlane with the big honkin' Holley 950 on it that I had the privilege to drive, that left numerous people sitting wondering wtf just happened, lol. Years ago, one of my brothers left the original throttle base at some establishment to have it's broken off mounting ear welded, and the base plate went mysteriously missing. I've had the rest of it bagged and boxed for going on three decades since.

    I'll refurbish and reassemble this and re-box it, and it will be put to good use again on something some day.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  9. #9
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,211

    Default

    Quote Originally Posted by Walking-Tall View Post
    Politely begs to differ on this, since 4150/60's were born in ~1957.
    WT is totally right.

    A point of note is that the 950 and 1050 carbs were replaced by the 4150 and 4160 830 and 950 cfm versions of the 4150


    The cfm gap "filler" between the 750 and 780 cfm 3310 and the various versions of the 4500 Dominator, and the large size spreadbore RRP Q jet, Thermoquad and Autolite 4300 series was the totally strange 4165 and 4175 series replacements.


    It looks to me that perhaps Holley should have just made the 3-bbl become the top dawg, but Ford decided to make the 4500 series Mystery carburettor the One.


    That was because Ford decided Independent runner fuel delivery was gonna make more peak power. That's why, at the same time as contracting out Holley in 1967 to make the 4500, they at the same time pumped money into Autolite to make the illfated 1969 to 1973 independent runner inline 4-bbl Cross Boss Carbs.


    Ford actually made that bad boy work real good, but the anti trust legislation litigation ment that all Fords development work got taken in the Bendix Technicho and Presolite claims.


    In the Port on Port situations, such as Dual Quads and Tunnels Rams, and in line Daul quad Autolites, a critical air speed is the key to power, not CFM.


    Ford learned all that between 1964 to 1969, when they won Le Mans when suddenly 5 liter port on port engines made as much power as 7 liter ones when the formula was changed. Same when the SOHC Hemi and then the Big Block were banned from NASCAR.


    The carb development was stratospheric during that land on the moon space era...the 3bbl was the first plip on this first little Pony Car HP spike between 1966 and 1969.


    We are on the seventh wave now. They were

    Wave One 1966-1969 (actually greater than 271 hp to 375 hp, the top performers in the 330 to 375hp zone were equal to net hp figures fudged down, but it was Holley and Rochester 4BBL carburation that made those engines streetable )

    Wave Two 1974 to 1975 (when the 104 hp 171 V6 got replaced with the 139 hp 302 in the Mustang)

    Wave Thee 1981 to 1985, when Colt Corp released the Holley annular discharge and electric bowel vent carbs, which had both become, rightly or wrongly, FoMoCo patents.

    Wave Four was the 1986 to 1994 slow rise to the GT40 headed EFI 5.0 and 5.8's

    Wave Five was the Cammer era from 1994 to 2000, before the full strength Cobra 4.6 option was pulled, making its return look like a new wave from 2003 to 2004.

    Wave Six was the 2009 to 2013 superchraged era. For a time, the hp was again in freefall as Ford decided what to do with the supercharged engines.



    The proof of the importance of carb air speed to even 2-bbl and 4-bbl carbs was when Ford decided never to spend a dime on new carburettor devleopment. The VV2700 and VV 7200 were the last all new carbs ever (except the last spit polished 2150 HO 2-BBL) and from 1979, totally contracted out all carb development to Holley and then Carter in 1983 when Holley was close to going bust.

    The smallest hp spike, just 90 hp from about 119 hp 1981 to 210 hp in 1985, made the greatest change in acceleration, 18 seconds to as little as 15 seconds flat on a well preped 4180 series Holley 600 cfm 4-bbl.




    The problem with the 3-bbl is that it isn't easy to do suble 0 to 100 cfm air flow adjustments to venturi size to meet the optimized venturi size charts, unless you have a CNC lathe or perhaps a bridge port. The carb itself works great but only on big small blocks or small big blocks, and other carbs trounce it in certain low speed response situations.

  10. #10
    FEP Member brianj's Avatar
    Join Date
    Feb 2012
    Location
    Raymond, New Hampshire
    Posts
    2,892
    Blog Entries
    2

    Default

    Of course, you can buy a brand new Street Demon 3BBL. Pretty good carb.
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  11. #11

    Default

    Coming along fine, and in great shape for a 48 year old air/fuel mixin' mechanism. Throttle base and shafts cleaned up, and there's still only just normal running clearance, new "180" 1-3/4" primary throttle plates (one was missing when I got this throttle base), and 8 new throttle plate screws. Temporarily assembled. Brackets and linkages still need cleaned up.





    Last edited by Walking-Tall; 07-18-2017 at 11:42 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  12. #12

    Default

    NA to this thread.
    Last edited by Walking-Tall; 07-18-2017 at 11:46 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  13. #13

    Default

    Throttle base refurbished and she's sleepin' for now, until I've someday got something to use it on.
    It's date code is 863, which means the 3rd week of June, 1968.

    Last edited by Walking-Tall; 07-18-2017 at 11:48 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  14. #14

    Default

    Sometime in the mid-'90's I bought a (rebuilt, refurbished, whatever they called it and sold at the time) 3310-4 750cfm vacuum secondary from Summit. After about a week's run time, I decided it needed a different secondary opening rate spring. Long story, short, all three attaching screws for the vacuum secondary diaphragm housing snapped clean off in the body... was I pi$$ed. Recently the light bulb went off over my head...




    So, instead of trashing it...






    Converted the throttle base with double-pumper components and for "four-corner idle" duty:




    Shazzam... a choke-less, "four-corner idle", 750 double-franken-pumper :










    ... with adjustable (6-32 brass socket setscrews) idle feed restrictions, primary power valve channel restrictions (8-32 brass socket setscrews), and air bleeds (8-32 & 10-32 brass socket setscrews).
    Last edited by Walking-Tall; 10-31-2017 at 06:15 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  15. #15

    Default

    I'm pleased to say that the 750cfm double pumper above is going onto a 4-eye, a 1983 Mercury Capri with a 351W with a "Rollin' Thunder" hydraulic roller camshaft (235 & 238 degrees duration at 0.050 lift, 112 degree lobe separation, and 0.573" & 0.582" valve lift) in it! It's going to work so very well there!



    Last edited by Walking-Tall; 07-25-2017 at 12:52 AM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  16. #16

    Default

    Creating an adjustable IFR secondary metering block for the 950cfm 3-barrel, to go in place of the metering plate:

    The secondary boosters are closer together than a normal 4-barrel, and the main air bleed passages are lower and closer together too, requiring some epoxy surgery on the block and a custom-made metering block gasket...












    Preparing an alternate adjustable IFR & PVCR primary metering block:






    Last edited by Walking-Tall; 07-25-2017 at 04:07 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  17. #17

    Default

    Those setups deserve being ran with either no sound insulation on the hood or no hood temporarily just to hear. Run a nice open element air cleaner or for full effect temporarily no air cleaner at all...... let some young kid to hear an old V8 and carb sound like it's about to suck the atmosphere into a self-created black hole and make you both disappear. Lasting impression for sure.

    Ive had a few old Thermoquads and Holleys and Edelbrocks back when I was young. They each had themeir bright spots. I spent plenty of time with my dad too bending this and tweaking that to work an old Quadrajunk to tuning perfection on my brothers car. (73 350 Buick we switched over to flat top pistons and put a nice cam in).

    Laughable now but for some reason I thought a 360 degree rise Offenhauser intake was about right on my DO0E head 351W daily driver - and was a good idea. The damn thing ran hard for what it was but was very cold blooded due to runner length vs cold weather.

    One thing about having EFI now for all these years.... I do occasionally miss hearing a well tuned carb moaning out it's long song. I just might have to build something that will talk (moan) one of these days.

  18. #18
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,211

    Default

    I know why Holley's make power, and its the throttle size, arrangment, and the bigger, coarser fuel droplets. Mec Sec operation sure helps any engine.


    I've studied the Carter WCFB/AFB/AVS secondary opening scenarios, and delt with the VS 3310 on the street. I've never liked vac sec carbs, too unpredicable on a Detroit Locker axled 302 Boss or 351C 4V HO.

    Quadrajets are the best for racing, you can set them up just so. Thermoquads too. Demon 625's are a cross bread.


    ith four corner idle, and nice, large fuel droplets, a Mec Sec 3310 conversion seams like the right beast. Jet and metering rod carbs are more accurate and better atomisers, not better power producers.


    Well done on resurrecting the best medium block carb ever, it was a 396/402 Chevy request, and like 390 GT Holley 4bbl vac sec carb that became the BOSS 302 carb, it was a focus point of bringing the Holley into the emissions era on street cars. The 4350 Autolite/Motorcraft variants stopped all that good 650/750 mec sec development. I personally think Carter was right to stop giving Ford vac sec WCFB's, Carter knew that the secondaries had to be entirely machincal or gravitational, not vacuum operated they way the generation of Vac Sec Holley's were.

    I know the Vac Sec gives great mileage, but there was a lot of that triple booster development work going on at Holley, and Ford's Autolite Division had patented the Anular discharge, so suddenly, Holley, Autolite and Carter and then Rochester weren't cross fertilizing ideas anymore.



    I love 660 Center Squiter 1:1 secondary opening, but its hard to generate a progressive fuel delivery under load the way a Q Jet can.

    In our Internation Group A, FISA Group 2 Aussie and Kiwi race regulations, we got our 2900 pound Commodore 5liters into the 462 hp at 6700 rpm zone with a 725 cfm wet flow Q jet. The 650 cfm dry flow Mec Sec Mustangs never got past 390 hp. The difference in GM to Ford HP was the CFM flow rating. Each used the M 6250 A311 280/290 style cam, and the Holden the Crane version of the Wade 169 276 degree at lash cam, all 215 at 50 thou cams or near to.

    If the Mustang was allowed to use the 750 Mec Sec Holley 4bbl and a proper dual plane intake modified the way Holdens was, it would have picked up the hp.

  19. #19
    FEP Super Member xctasy's Avatar
    Join Date
    Jun 2012
    Location
    Dunedin 9011, New Zealand, South Pacific
    Posts
    3,211

    Default

    As my co poster on another forum said.

    intake velocity=torque=hp=easy to live with fun
    holleys are crude and very limited in tuning range

    Yes, but you CAN adjust EVERYTHING on them . With Carters, Qjets, Edelbrocks, Thermoquads and Autolites, some parts are still very hard to rework, and require a lot more work than a suck it and see Holley.


    I like your brass plug for every circuit treaments, Mike.

  20. #20

    Default

    Quote Originally Posted by erratic50 View Post
    Those setups deserve being ran with either no sound insulation on the hood or no hood temporarily just to hear. Run a nice open element air cleaner or for full effect temporarily no air cleaner at all...... let some young kid to hear an old V8 and carb sound like it's about to suck the atmosphere into a self-created black hole and make you both disappear. Lasting impression for sure.

    Ive had a few old Thermoquads and Holleys and Edelbrocks back when I was young. They each had themeir bright spots. I spent plenty of time with my dad too bending this and tweaking that to work an old Quadrajunk to tuning perfection on my brothers car. (73 350 Buick we switched over to flat top pistons and put a nice cam in).

    Laughable now but for some reason I thought a 360 degree rise Offenhauser intake was about right on my DO0E head 351W daily driver - and was a good idea. The damn thing ran hard for what it was but was very cold blooded due to runner length vs cold weather.

    One thing about having EFI now for all these years.... I do occasionally miss hearing a well tuned carb moaning out it's long song. I just might have to build something that will talk (moan) one of these days.
    Yup, inhale the clouds right out of the sky, lol



    Q-Jets can be dialed in to work very well.

    Sorta same here, with a SBC 350, with ported heads, a '69 GM "350-horse" hydraulic camshaft (that has pretty stout duration and overlap and moderate valve lift), and with a Torker II and 3310 750... she was a highway rocket, but pretty soggy down low, lol

    Last edited by Walking-Tall; 07-25-2017 at 04:05 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  21. #21

    Default

    Quote Originally Posted by xctasy View Post
    I know why Holley's make power, and its the throttle size, arrangment, and the bigger, coarser fuel droplets. Mec Sec operation sure helps any engine.


    I've studied the Carter WCFB/AFB/AVS secondary opening scenarios, and delt with the VS 3310 on the street. I've never liked vac sec carbs, too unpredicable on a Detroit Locker axled 302 Boss or 351C 4V HO.

    Quadrajets are the best for racing, you can set them up just so. Thermoquads too. Demon 625's are a cross bread.


    ith four corner idle, and nice, large fuel droplets, a Mec Sec 3310 conversion seams like the right beast. Jet and metering rod carbs are more accurate and better atomisers, not better power producers.


    Well done on resurrecting the best medium block carb ever, it was a 396/402 Chevy request, and like 390 GT Holley 4bbl vac sec carb that became the BOSS 302 carb, it was a focus point of bringing the Holley into the emissions era on street cars. The 4350 Autolite/Motorcraft variants stopped all that good 650/750 mec sec development. I personally think Carter was right to stop giving Ford vac sec WCFB's, Carter knew that the secondaries had to be entirely machincal or gravitational, not vacuum operated they way the generation of Vac Sec Holley's were.

    I know the Vac Sec gives great mileage, but there was a lot of that triple booster development work going on at Holley, and Ford's Autolite Division had patented the Anular discharge, so suddenly, Holley, Autolite and Carter and then Rochester weren't cross fertilizing ideas anymore.



    I love 660 Center Squiter 1:1 secondary opening, but its hard to generate a progressive fuel delivery under load the way a Q Jet can.

    In our Internation Group A, FISA Group 2 Aussie and Kiwi race regulations, we got our 2900 pound Commodore 5liters into the 462 hp at 6700 rpm zone with a 725 cfm wet flow Q jet. The 650 cfm dry flow Mec Sec Mustangs never got past 390 hp. The difference in GM to Ford HP was the CFM flow rating. Each used the M 6250 A311 280/290 style cam, and the Holden the Crane version of the Wade 169 276 degree at lash cam, all 215 at 50 thou cams or near to.

    If the Mustang was allowed to use the 750 Mec Sec Holley 4bbl and a proper dual plane intake modified the way Holdens was, it would have picked up the hp.
    Vacuum secondary woes disappear when sped up with a light spring, a removed ball if with standard transmission, or a 0.40" angled bypass hole drilled under/beside the ball with automatic transmission, but most importantly, secondary idle-to-main circuit transition richened up some with bigger IFRs and/or smaller secondary idle air bleeds. The larger vacuum secondary carburetors (1-11/16" & 1-3/4" throttle bore) also require the addition of the 45-degree brass signal tube (that Holley choose to omit in them some years ago to save a few pennies each... dumba$$ery, lol) into the primary venturi in order to be adequately signaled to work right and to fully open the secondaries.

    Then, the ho-hum function turns to...




    Anything can give great mileage on anything. There are even successfully dialed-in (primary idle feed restrictions, sometimes adjustable transfer slot restrictions if necessary, idle air bleeds, realistic part throttle primary jetting, and adequate PVCRs for WOT) large double-pumpers and Dominators on small blocks and even healthy V6s. It's ALL about dialed-in primary idle/transition circuit AFRs for what the combination wants/likes.

    You bet they would!
    Last edited by Walking-Tall; 07-25-2017 at 04:01 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  22. #22

    Default

    Quote Originally Posted by xctasy View Post
    As my co poster on another forum said.

    intake velocity=torque=hp=easy to live with fun
    holleys are crude and very limited in tuning range

    Yes, but you CAN adjust EVERYTHING on them . With Carters, Qjets, Edelbrocks, Thermoquads and Autolites, some parts are still very hard to rework, and require a lot more work than a suck it and see Holley.


    I like your brass plug for every circuit treaments, Mike.
    Airflow choked enough, velocity can equal pumping losses too.

    Thanks, bud. Adjustable in all the right places FTW!
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  23. #23

    Default

    Somewhat on topic... contacted/contracted to build an 800 double pumper for a 550+hp SBC '68 SS/RS Camaro... here's the "4-corner idle" answer:




    ... with only 5-6"Hg intake manifold vacuum at idle, and 2 or 3 times that at off-idle and cruise, an animal like this needs transfer slot restrictions, and will be very fuel efficient.












    Ready to rip

    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  24. #24

    Default

    Pardon the repetition, but I believe the following is useful to be posted in numerous places...

    A shamefully ridiculous example of why I tell folks in regard to Holley carburetors, "if you want a good one, get an old one":


    Posted at racingfuelsystems forum, entitled "Brand New Blunder #??? - A Heads Up..."

    "So a local (repeat client) fellow contacted me asking if I could fine tune his brand new spread bore vacuum secondary... that with a few miles of driving his '77 Malibu he found that it would hesitate upon light part throttle "tip in"...

    Observation #1 was a throttle lever bent over toward the main body badly, so badly that it was bent all the way down to the throttle shaft area and loose on the throttle shaft, obviously dropped before it went into the box, and bumping into the driver's side secondary link lever at wide open throttle as well... and a secondary stop bracket not allowing full wide open of the secondary throttle plates... idle screw backed out, fully shut primary throttle plates, he said still idled way too fast, primary lever and idle screw tip not even inline with each other (primary throttle shaft not fully installed/seated laterally originally), and quite open secondary throttle blades...

    Observation #2 was small appearing primary idle air bleeds, and large idle mixture passages and blunt-tipped idle mixture screws... so I told him it is a "reverse-idle" unit, and it'll have passage holes into the primary bores, blah blah blah how "reverse-idle" works etc... I don't remember where now, but online somewhere that sells these states that the 80555-1 4175 650 spread bore vacuum secondary has a "forward" idle circuit... I presume as opposed to "reverse"?... hmmm, okay...

    Observation #3 was NO holes/passages into the primary bores for "reverse-idle"... so, in a nutshell, it has standard idle main body and base plate, and a "reverse-idle" primary metering block and mixture screws... at first I got him back here and showed him all of their "quality control" and "attention to detail", and thought completing "reverse-idle" would be the best course of action to make it behave... but after some more thought about it, I decided against that, because it would mean blocking the large standard idle discharge holes in the base plate, drilling new small ??? size constant idle feed holes below the primary transfer slots, and drilling ??? size passage holes into the main body... so instead I drilled the idle mixture screw passages in the PMB with a #29 drill, tapped 8-32 thread on through the passage, and installed 8-32x1/8" brass socket set screws with 1/16" holes in them, so that regular sharp tip idle mixture screws can be used...

    Observation #4 was air bleed sizes crazy in contrast to the handful of these (other, older, LIST-7002 etc.) that I have dealt with before, as well as somewhat larger than usual primary idle feed restrictions at 0.029"... and #64 primary jets where #62's are supposed to be according to documentation...

    Here are it's original calibration details as I found/measured:
    - 0.029" PIFR's (?) & 0.035" SIFR's (#54 SMP - specs not listed anywhere btw)
    - 0.053" PIAB's (?) & 0.051" SIAB's (?)
    - 0.036" PMAB's & 0.040" SMAB's (?!)
    - #64 PMJ's (?) & 0.081" secondary main circuit holes (#54 SMP - specs not listed anywhere btw)
    - 0.057" PVCR's
    - 0.040" pump shooter (?!) and orange pump cam in position 2

    So I remedied the metering block like explained above, loosened throttle blade screws and shuffled shafts and blades around so they were correct, got out the brass and drills and created 6-32x1/8" 0.026" PIFR's (very mild stock replacement camshaft in rebuilt 350) and installed those in the block, installed #62 PMJ's, drilled and tapped and installed 10-32x3/16" 0.070" PIAB's, 6-32x1/8" (the secondary constant idle feed holes seemed a bit big at about 0.030", so I chose to create) 0.040" SIAB's and 6-32x1/8" 0.026" SMAB's, and installed new regular idle mixture screws and the orange pump cam in position 1... not having any "anti-pullover" shooters of other/smaller sizes on hand, the rather large 0.040" remains in it...

    A couple hours after picking it up, he was back at the door, beaming and grinning, telling me to come check out my handy work. He brought the car, and it was idling in the driveway slowly and nice and smooth, and he said it's working night and day real nice, and making far more sense setting idle speed and mixture... and when he left here, it launched real good, barking out the exhaust, lifting the nose of the car some and was off down the street, lol!

    Thought I'd share this with you guys who may end up dealing with one of these further enhanced (translation: EFFED UP) versions of the "new and improved" that come brand spankin' new outta that place and cost this fellow 750 smackers... for what? Nearly complete re-calibration necessary so that it will just FUNCTION correctly... pardon my french, but the pompous jackasses who apparently know-it-all really should be knocked down a few notches somehow... I wish..."

    So yeah, the moral of the story... stop buying expensive new garbage from giant monopolizing corporations, because contrary to their marketing and such, they do not know WTF they are talking about or doing there at all anymore.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  25. #25
    FEP Power Member gmatt's Avatar
    Join Date
    Jul 2009
    Location
    Chicago, south subs
    Posts
    1,817

    Default

    Weird coincidence. I had just seen this thread bumped 'back to the top'. My next move was to browse CL parts for sale(not looking for anything in particular), I do this all the time. Almost immediately see this listing:
    https://chicago.craigslist.org/wcl/p...990543266.html

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •