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  1. #1
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    Default Starving after 4200 rpms???

    Ive got a completely new 468 with a TA 212 cam with a brand new 750 "JET" Quadrajet on it. The motor is great, but it seems to be running out of fuel at WOT once it passes 4200 rpms. The plugs also look pretty lean even after 1000 miles on it. Im wondering if anyone knows what size primary jets a 800+ Quad would have it? I have not opened mine up yet but Im thinking they would be 73 or 75 and Ill need 80's Any thoughts?
    Last edited by Thomaswarlord; 07-30-2012 at 02:35 PM.

  2. #2
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by Thomaswarlord View Post
    Ive got a completely new 468 with a TA 212 cam with a brand new 750 "JET" Quadrajet on it. The motor is great, but it seems to be running out of fuel at WOT once it passes 4200 rpms. The plugs also look pretty lean even after 1000 miles on it. Im wondering if anyone knows what size primary jets a 800+ Quad would have it? I have not opened mine up yet but Im thinking they would be 73 or 75 and Ill need 80's Any thoughts?
    If it is running out of fuel, you first need to inspect the fuel lines from the tank all the way to the fuel pump and carburetor. Look for kinks in the metal line, and bad rubber hoses back near the tank, and fuel pump. You may need to also drop the tank to inspect the filter sock, but that is the last thing I would check.. They can collapse and hinder fuel delivery. How old is the fuel pump, and are you using the Stage1 pump? There isn't one jetting recipe for all 800's. Q-jets were all calibrated differently depending on the engine, and year.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  3. #3
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    Default Re: Staving after 4200 rpms???

    Im running a Edelbrock 10lb inline electric fuel pump. With new 3/8 line from front to back. She runs real hard and fast, melting the tires through all of first gear, but the second it gets just over 4k it flattens out. Not like an ignition miss, it feels alot like running out of fuel, then shifting to 2nd gear lowers the rpms and it instantly goes wild again. You may be right about the sock, or maybe my floats a hair to low? I think Ill unhook the fuel line this weekend and try a volume test. I think I should get just over 1/2 gallon in 30 sec, does that sound right?

  4. #4
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by Thomaswarlord View Post
    Im running a Edelbrock 10lb inline electric fuel pump. With new 3/8 line from front to back. She runs real hard and fast, melting the tires through all of first gear, but the second it gets just over 4k it flattens out. Not like an ignition miss, it feels alot like running out of fuel, then shifting to 2nd gear lowers the rpms and it instantly goes wild again. You may be right about the sock, or maybe my floats a hair to low? I think Ill unhook the fuel line this weekend and try a volume test. I think I should get just over 1/2 gallon in 30 sec, does that sound right?
    One pint in 30 seconds or less is the spec for the mechanical pump. Where have you mounted this Edelbrock electric fuel pump? A regular Stage1 mechanical is all you need. I don't like electric pumps, but if you want to run them, the right way is to sump the tank, and mount the pump low so that fuel gravity feeds to it. An intermediate set up is to use your electric pump as a pusher pump up to the Stage1 mechanical pump. I would do that if I was you.

    There are mechanical pumps that will supply all the fuel you need. There is no need for an electric, and I bet the one you have isn't going to do the job as well as a regular out of the box Stage1 pump.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  5. #5
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    Default Re: Staving after 4200 rpms???

    Its mounted on the inside of the frame rail, halfway between the trany cross member and the tank. Ill look into a stage 1 pump. The only reason I went to a electric was the old engine would percolate the gas in the float bowl on hot days and make for long crank time to refill. Having the "key on" pump was my solution at the time.

  6. #6
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by Thomaswarlord View Post
    Ive got a completely new 468 with a TA 212 cam with a brand new 750 "JET" Quadrajet on it. The motor is great, but it seems to be running out of fuel at WOT once it passes 4200 rpms. The plugs also look pretty lean even after 1000 miles on it. Im wondering if anyone knows what size primary jets a 800+ Quad would have it? I have not opened mine up yet but Im thinking they would be 73 or 75 and Ill need 80's Any thoughts?
    Not sure why anyone would put a smaller carb on any 455+ than what came with them from the factory. If you are looking for better fuel economy you would probably be driving a V6. If you are looking for performance I would run a bigger carb, lets say 800+ cfm. There are great carb tuners who can get darn close by just giving them the engine specs. You will only get 10 mpg, and less when you go WOT! Get a V6 for economy and a big carb for fun. Remember most speed limits are 70-75mph and blowing the tires off on the street is illegal! BTW TA lists the power range to only 4900rpm on that cam, so maybe you only want to putt around. lol

  7. #7
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    Default Re: Staving after 4200 rpms???

    Not sure why anyone would put a smaller carb on any 455+ than what came with them from the factory. If you are looking for better fuel economy you would probably be driving a V6.
    I used that carb because it was new, and I needed a carb. It was for my old 350 but I sold that engine this spring. So since I had a brand new engine, with no carb, and I didnt have more money for another carb, it made perfect sense to use the one I had. I care ABSOLUTELY NOTHING about gas mileage. And the range is actually 5500

  8. #8
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    Default Re: Staving after 4200 rpms???

    The 750 carb is fine for your TA212 cammed 468. It might go faster with a bigger carburetor, but at least you don't have a Carter AFB or the Edelbrock equivalent. Mounting that electric pump like that is going to lessen it's effectiveness, and I wouldn't be surprised if that is ENTIRELY your problem. I would pull that pump, go to the parts store and get a Stage1 pump. Airtex makes it, and they are about 40.00.(Airtex part #40664) Put the Stage1 pump on and see if your problem disappears. Depending on what the Edelbrock electric pump actually is, you may be able to use it as a pusher pump mounted to the front wall of the trunk, above the rear axle, and teed into the fuel line. Honestly, I don't even think you need that though. The Stage1 mechanical is all you need.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  9. #9
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    Default Re: Staving after 4200 rpms???

    Thanks Larry that sounds like a good idea! Ill try that before I crack open a new carb. Thanks for the advice.

  10. #10
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by Thomaswarlord View Post
    Thanks Larry that sounds like a good idea! Ill try that before I crack open a new carb. Thanks for the advice.
    I merely stated what the TA catalog stated. POWER RANGE IS 4900RPM, With the right springs I would not be surprised if it wouldn't turn 6000 in the lower gears. A 625 would also be "fine" but your motor wouldn't perform to its potential. As far as elect fuel pump, don't waste your time. A Stage 1 fuel pump is plenty for most street strip applications. My 72 Stage 1 NHRA record holder race car had a stock fuel pump. My 11 sec. street car 70 built Stage 1 had a 1000cfm Thermo Quad that I turned 6500 rpm with a stock fuel pump. My brothers street car 70 built 455 turned 7000 rpm and used a Stage 1 fuel pump. Over 99% of all street buicks only need a stock Stage 1 fuel pump! To save money for now keep the 750 and have it professionally tuned, and use a Stock Stage 1 fuel pump. Everyone needs to stop out tricking themselves!

  11. #11
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by ken betts View Post
    I merely stated what the TA catalog stated. POWER RANGE IS 4900RPM, With the right springs I would not be surprised if it wouldn't turn 6000 in the lower gears. A 625 would also be "fine" but your motor wouldn't perform to its potential. As far as elect fuel pump, don't waste your time. A Stage 1 fuel pump is plenty for most street strip applications. My 72 Stage 1 NHRA record holder race car had a stock fuel pump. My 11 sec. street car 70 built Stage 1 had a 1000cfm Thermo Quad that I turned 6500 rpm with a stock fuel pump. My brothers street car 70 built 455 turned 7000 rpm and used a Stage 1 fuel pump. Over 99% of all street buicks only need a stock Stage 1 fuel pump! To save money for now keep the 750 and have it professionally tuned, and use a Stock Stage 1 fuel pump. Everyone needs to stop out tricking themselves!
    Ken,
    There is some contradictory information in the TA catalog, and the website. My 2007, and the new catalog, say the power range of the 212 is 1900-4900, but the website says 1500-5500.

    http://www.taperformance.com/proddet...rod=TA_212-455

    I do agree though, the Stage1 pump can supply enough fuel for most street BBB. I went with TSP's billet CV mechanical pump because I didn't want to take any chances, and because it was so pretty
    Attached Images Attached Images
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  12. #12
    Join Date
    May 2012
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    North Carolina (336)
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    Default Re: Staving after 4200 rpms???

    I have the ta street/street mechanical fuel pump. And its not keeping up. I didn't put the shim pieces in the bolt holes. Could this be my problem?
    Brandon

  13. #13
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    Default Re: Staving after 4200 rpms???

    Call me stupid but he doesn't even know what jets are in the carb?? Before you start changing fuel pumps and setting up pusher pumps, just jet the carb and see what happens??? You can change fuel pumps but if you still have small jets in there, it won't matter one but just my 02

  14. #14
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by dentboy View Post
    Call me stupid but he doesn't even know what jets are in the carb?? Before you start changing fuel pumps and setting up pusher pumps, just jet the carb and see what happens??? You can change fuel pumps but if you still have small jets in there, it won't matter one but just my 02

    Jetting will not make a car nose over. When the pump cannot keep up with fuel flow requirements, that is something you cannot mistake for anything else. It is not likely that the jetting is that far off anyway because it was built with performance in mind by Jet. The way he installed that electric fuel pump, it is almost certainly the problem.

    http://www.jetchip.com/JET_Carburetors.asp
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  15. #15
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    Default Re: Staving after 4200 rpms???

    when you say it is noseing over ... is it just not pulling hard or is it bogging ?

    Mark
    MAY THE TORQUE BE WITH YOU

  16. #16
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by ick View Post
    when you say it is noseing over ... is it just not pulling hard or is it bogging ?

    Mark
    I said that it was nosing over. He said it felt like it was running out of fuel.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  17. #17
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    Default Re: Staving after 4200 rpms???

    It hits 4200 rpms and just runs out of fuel, like pinching off a garden hose, turning off a faucet. It has a 2400 rpm stall converter, so rpms jump up fast and she takes off great. But at WOT with the rear end smoking and shes tearing down the road right around 4200 rpms, just as im getting ready to grab 2nd gear, it just falls flat on its face, like hitting a brick wall, then a second later as rpms drop its like the carb fills up again and shes off. It dose not feel like any kind of ignition miss Ive ever felt. So Im ruling that out. It felt just like choking off the fuel supply for a second. I think Larry is on to something, Ill check everything BEFORE the carb first. I was able to get that stage one pump for $27 so Ill change it too any way. Like I said earlier, the electric pump was there to try and solve a different problem with the older SBB that was in there.

  18. #18
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    Waring, Tx
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    Default Re: Staving after 4200 rpms???

    The quadrajet has a small fuel bowl. When I build one for a big block Buick, I always use a high flow needle/seat and set the float level on the high side. I would start there. That is where a big restriction probably exist in the jet build.
    Mark
    72 Skylark "GSX" Convertible 462, SP 400, 4:10
    72 "GSX" 464, TH 400, 3:42 10.71@126, street tires and mufflers
    Buick Quadrajet builder
    Join "quadrajet power " on Facebook
    mark@texasextremeracing.com

  19. #19
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by carmantx View Post
    The quadrajet has a small fuel bowl. When I build one for a big block Buick, I always use a high flow needle/seat and set the float level on the high side. I would start there. That is where a big restriction probably exist in the jet build.
    Good call. A fuel pressure test and volume test would be a great start, but both of those may check out fine even if the needle & seat is the restriction.

    Devon
    Fuel & Brake Systems Engineer
    "I can live with doubt and uncertainty and not knowing. I think it's much more interesting to live not knowing than to have answers which might be wrong." - Feynman
    "Good data is precious. The problem I have is when some damned fool fails to use it properly." - Slingerland

  20. #20
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    Default Re: Staving after 4200 rpms???

    He said that it was a Jet built carburetor, but there are several versions that they build. One has the .135 Needle/seat.

    http://www.jetchip.com/JET_Carburetors.asp
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    1967 BT Switchpitch ST-400, Gear Vendors OD
    with TSP 3200/1800 converter
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's
    11.67 @ 115.49 MPH
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  21. #21
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    Default Re: Staving after 4200 rpms???

    Heres the exact carb I bought.

    http://www.jetchip.com/Shop/shopdisp...pp=10&catID=36

    Rochester Q JET | Stage 2 | Passenger Cars
    Part #: 35002

    A Stage 2 has all of the features of a Stage 1 plus features fully recalibrated idle, off idle, main, accelerator pump and high speed circuits to match any modifications done to the engine such as intake manifold, headers, ignition or mild cam change. A Stage 2 features improved idle quality, instant throttle response and maximum torque and horsepower for street-strip vehicles, tow vehicles, RV's and watercraft with modified engines.

    This Carburetor is intended for 305,350 & 400c.i. Chevy Passenger Car engines with mild performance upgrades such as:
    Dual Plane Aluminum Intake Manifold
    Headers (1 5/8" - 1 3/4")
    Compression Ratio 8.5 - 9.5:1
    Mild Porting on Cylinder Heads or Performance Heads
    Camshaft Specifications: Duration @ .050 Min. 210 Degrees, Max. 220 Degrees
    Lobe Seperation Angle 110 - 112 Degrees

  22. #22
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    Wisconsin
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    Default Re: Staving after 4200 rpms???

    Tomas ,

    I would do a volume test ,if it passes you will know that the fuel pump,sock & lines a good to go. I ran my 69 GS Stg1 with a 455 & C118 KB camshaft to 6000 +rpm with a Stg 1 pump & had no sign of laying down on the job.



    Mark Campbell
    MAY THE TORQUE BE WITH YOU

  23. #23
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by LARRY70GS View Post
    Ken,
    There is some contradictory information in the TA catalog, and the website. My 2007, and the new catalog, say the power range of the 212 is 1900-4900, but the website says 1500-5500.

    http://www.taperformance.com/proddet...rod=TA_212-455

    I do agree though, the Stage1 pump can supply enough fuel for most street BBB. I went with TSP's billet CV mechanical pump because I didn't want to take any chances, and because it was so pretty

    I have seen the TSP billet CV pump referenced a number of times, but I cannot find anywhere to buy one. I went to his website, but it seems to just be a place holder site for now. Or am I confused (again) and not looking for it correctly.
    Where did you get the picture and is there a link to the pump for cost and availability?
    Jon Baker (just like the guy in CHiPs)

    1967 skylark, 455, th400, in process
    2003 Regal LS. Not a v-8 or supercharged, but I still like that car. Heck of a stereo in there now too.

  24. #24
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    Default Re: Staving after 4200 rpms???

    Quote Originally Posted by Houndogforever View Post
    I have seen the TSP billet CV pump referenced a number of times, but I cannot find anywhere to buy one. I went to his website, but it seems to just be a place holder site for now. Or am I confused (again) and not looking for it correctly.
    Where did you get the picture and is there a link to the pump for cost and availability?
    Just contact Jim via his profile: http://www.v8buick.com/member.php?11-Jim-Weise

    Devon
    Fuel & Brake Systems Engineer
    "I can live with doubt and uncertainty and not knowing. I think it's much more interesting to live not knowing than to have answers which might be wrong." - Feynman
    "Good data is precious. The problem I have is when some damned fool fails to use it properly." - Slingerland

  25. #25
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    Default Re: Staving after 4200 rpms???

    Jon , give Jim a call @612-532-2207 I have not used this pump but I have not heard any neg about it . Robb Mc also offers a great mech fuel pump @ around $200.00

    Goog Luck

    Mark

    ---------- Post added at 10:18 PM ---------- Previous post was at 10:12 PM ----------

    Sorry Devon ,I did not see your post.

    ick
    MAY THE TORQUE BE WITH YOU

 

 
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