Big Carbs and Altitude

Discussion in 'Race 400/430/455' started by NOTNSS, Feb 13, 2002.


    NOTNSS Gold Level Contributor

    I'll be upgrading to a BG HR220 fuel pump soon and am considering swapping out the 800 Qjet for a Demon 1000cfm unit at the same time. Are there altitude concerns other than jetting? As in, vacuum being too low and such? Too much carb?
    I wanna get snotty but don't want to spend $$$ where unnecessary.

    The combo is (future additions in parentatsis):

    .038 455
    11:1 Ross - zero deck
    B4B dual pattern
    800 Qjet (1000cfm Demon downleg)
    Stage 1 fuel pump (BG HR220)
    Iron Stage 1 heads - 260/190cfm
    224/236 494/506 cam (TA "Street Dominatior" cam: 238/248 - 520 @.50)
    Stock rocker assembly (TA 1.6 or 1.65 Roller Rockers)
    TA 1-7/8" headers w/2.5" Flowmaster & 3-chamber (will add 'X')
    Stock rods polished/shot peened w/ARP bolts.
    Oil mods done. Pan baffled.
    VP400 w/1600/3200 stall
    3.55 posi (3.89 Ford 9")
    Hotchkis upper control arms, air bag, boxed lowers.

    Best et with current combo. 4000lbs. w/driver:
    13.01 @ 4500' altitude. No 60' times or trap speed (back woods track).

    Critique the whole combo if you'd like. Tell me where you'd make upgrades. (I know about the heads... someday Stage 2 aluminum).

  2. Adam Whitman

    Adam Whitman Guest

    Gary, we have a similar combo other than I have the TA intake and 10.25:1 compression. My car went about the same with the Q-jet (I don't know for sure because I did the trans, 1000 CFM BG carb, and drag shocks the same winter). All this gave me .1 in the 1/8 @5200' elev with a maybe some more to be had with more tuning.

    I did notice the car felt lazier down low without the small primaries of the Q-jet. I would make a guess that you won't go any faster unless you go to a TA intake, and then only maybe. Hell, the TA intake might be worth more than the carb.:confused:

    NOTNSS Gold Level Contributor


    You sure give me a lot to look forward to... hahaha.

    It's come to my attention that the Demon is NOT preferred over a good old Holley 950HP. Saving some bucks, too.
    I'll plod along and eventually be able to post my results. Hopefully all the changes I'll be making soon will get me deep into the 12s.
  4. Adam Whitman

    Adam Whitman Guest

    I have the silver claw which was before the Demon. It was supposedly better for whatever reason. I know a friend bolted one on a 502 with no problems, but later had to drill air-bleeds and fiddle a lot to make a demon work. Not sure why, but that is the story I got. If you're going to go for the 950, you might keep trying to find a good TQ. It seems most everybody agrees that they work well.

    I don't think I'd hurry to replace the carb until you have the other mods done. I'll be putting my Q-jet back on once I get the throttle shafts re-bushed and the trans working reliably. What's Revr'nd Jim think about the B4B Vs. TA intake?

    NOTNSS Gold Level Contributor


    Helena? I thought you were in Salmon. I'll have to give you a hollar on one of my trips to Butte to see Mom (and camping). Don't know that I'll have the GS with but sure hope to drive or haul it up there once and race in Anaconda. Is that where you're running 1/8?

    Problem with sticking with the Qjet is that I'm no carb tuner so plan on dyno time in SLC with a REAL tuner to dial it in. Don't want to do it twice with two different carbs. CW seems to be that bigger is almost always better with the Buicks. And with the cam swap, electric pump, etc., I should be able to consume more fuel.. a lofty goal.. hahaha.
  6. Adam Whitman

    Adam Whitman Guest

    Yeah, Anaconda is where I go to race, though not very often so far. I'm back to working in Salmon but get back to Helena fairly often; Butte is about half-way.

    There is a guy that's buddies with our PS "friends":laugh: that does of the newer style TQ to make 1000 CFM if you can't find an older one. The 71-up Q-jet is nothing to scoff at, especially if you have a tighter converter and taller gears. Probably the main downfalls of the double-pumper. The Q-jet can also be modified to do around 1000 CFM. Get David Vizard's book "cams, intakes, and carbs" or something like that, it shows how. And, if you ruin a Q-jet, usually someone will give you a couple more to practice on. :Do No:

    Give me a holler anytime you get up this way. By the way, the 429? 'stang that was here is gone.
  7. buick535

    buick535 Well-Known Member

    Gary, I don't know about that, I have run both holleys and demons and have had both apart, there is no comparison in quality between the 2. In my book , the demon wins hands down. Jim Burek
  8. rlracing

    rlracing Member

    A carburetor should be like a woman. Besides being attractive, it should be:
    a) responsive
    b) reliable
    c) forgiving
    d) easy (to work on)

  9. Adam Whitman

    Adam Whitman Guest

    don't you mean
    a.)high maintenance
    b.) constantly needs attention
    c.) make too much noise
    d.) need replaced often

  10. Nitro71455

    Nitro71455 Procharged 455 boost baby


    I can tell you my experance at this altitude with a 800cfm Q-jet and the 950hp holley. Our motors are almost the same with the exception of.....................................

    10.5 compression
    SP1 intake
    TA 1.60 rollers
    Crower .522 intake .525 exhast
    3.73 gears
    X pipe 3 1/2 to 3 to 2 1/2 system (Dr Gas)

    My car runs every bet as good with the Q-jet as with the holley. The holley has a little more topend, but the Q-jet makes up for it on the bottom. The times are pretty much identical with the G-tech. I can tell you that the Q-jet gets 2 to 3 MPH better!!!! The only reason I keep the holley around is for NOS :Brow: . If it wasn't for that, I would have sold it long ago!

    Just my 2 cents. If we hookup and race this year, I'll bring the carb if you like and you can try it out.


    OUTRAGEOUS Well-Known Member

    Adam, you must have the same carb as me!!!!!LOL! Randy
  12. NOTNSS

    NOTNSS Gold Level Contributor


    Now that sounds like a plan.. slap a Holley on there for kicks in Wendover...

    My combo will be getting closer to yours if/when I do the swap to the TA St. Dom. cam (238/248/520) and rollers. Possibly 3.90 gears from the 3.55, too. Randy in Wendover will get a bang outta seeing 3 GS cars running instead of just mine. He calls it "the bad buick" or "the parade float" (from when I raced (and beat) my pals 13.8s Judge with 4 people in my car.. haha. You listening Kirkland?
  13. JohnK

    JohnK Gas Guzzling Infidel

    No Gary, I'm not listening. Been out in the garage working out. Doing the TH400 bench press, ha ha. Baby needs a new VP torque converter. Wish I would have known that while the engine was out! Winter teardown season is drawing to a close - we finally got a 1/4" skim of mud on top of the frozen tundra here. I still need to do a converter r&r, and build a rear end, and finish breaking in that engine before I can seriously start beating the hell out of the car. It'll be soon though....
  14. Steve Reynolds

    Steve Reynolds SRE Inc

    Iwent the BG220 hot rod pump last year after my holley blue finally gave out (4 years!). Thought I would go one better with the BG, but I ran into a lot of work! The BG pump requires a #10 return line to avoid overheating on the street. I tried placing the pump in the same location as the Holley, but the BG would not prime! I relocated the BG To the rear of the tank (rear sump). There are NO restrictions to this pump, and it still loses prime on occasion, when the brakes are applied hard. There was no gain whatsoever by spending all this time and money. To top it off, the pump runs hot when cruising on the street. My car runs low 11's in full street trim. It ran the same E.T. and MPH with the Holley pump. I would check out the options for fuel pumps. There are a lot of good pumps out there now that are less expensive, and will give the same results as the BG 220 HR. BG makes great products, but I would say that they are geared more towards strickly race aplications. Just my 2 cents
  15. NOTNSS

    NOTNSS Gold Level Contributor


    Good info. Not what I want to hear, but maybe what I need to hear. My concern is that I get a pump that is made to run continuously, since my car is 90% street (for now anyway).

    I tried the Holley Blue and it worked fine but is pretty loud, which leads me to concern #2.. is there a relatively quiet pump that will fit the bill. I've heard the Mallory 140 is very quiet but don't know about continuous use, and it's not much less $$$ than the BG.

    I was just about to order the BG unit; I'll hold off awhile now. Gee, I could get a Holley Blue and another for a spare for the cost of the BG.

    I'm tossing around having the mechanical Stage 1 pump in line and the electric on a switch to run it only at the track or when pounding mud holes (MG quote) in the Shivies around town. My concern there is if the diaphram in the mech. pump gives it up, I'll be pumping fuel into the crankcase.

    BG 220HR?
    Mallory 140?
    Holley Blue?
    Other suggestions?

    Dang, like choosing a cam, almost. :Do No:

    Thanksb Steve.
  16. Dennis Halladay

    Dennis Halladay Well-Known Member

    I used a mallory comp 140 on my street strip car for 5-6 years and never had a problem. Went as fast as 10.20's on nitrous and never touched the low pressure switch. Finally went to a comp 250 pump for 2000 racing season, now only a race car. The comp 140 got a repair kit and new brushes and now runs my waste oil furnace, runs aprox. 18 hours a day 7 days a week. These are quiet, dependable and can feed a very healthy engine without a problem. Car didn't pickup enough to say so with the 250 pump, but it does make a lot more noise. If you use an electric on the street go with the bypass regulator to hold down the heat and the pump will last longer.
  17. NOTNSS

    NOTNSS Gold Level Contributor

    Thanks Dennis. I know there are a lot of Mallory pumps being used out there. Sounds like the way to go. I guess a guy could buy a Holley Red or Blue as backup to limp home with if it ever fails on the road.

    Oh, I assume it would be easy to run with -AN fittings?
  18. NOTNSS

    NOTNSS Gold Level Contributor

    Ok, I'm putting a sump in my tank and have the Mallory 140. I'm planning to mount the pump and the filter behind the rear bumper, one on each side of the tank spout. With the setup I'm looking at the pump inlet will be below the bottom of the tank but the Mallory filter has the inlet on top so will be a bit above the bottom of the tank.

    Can the filter unit be mounted upside down to solve this?
    Is it really an issue with the filter inlet above the tank bottom?

    I prefer to not have it all hanging out from under the car if at all possible. They'll both show a bit under the bumper already.


Share This Page