Run PCV Valve or evacuation on bracket car

Discussion in 'Race 400/430/455' started by Machinefarmer, Feb 10, 2015.

  1. Machinefarmer

    Machinefarmer Platinum Level Contributor

    I've pulled my 68 GS into the shop to make some changes for 2015. Car runs 10.30's with a very mild roller 470 JW engine, 10 to 1, 4:30 gear, 14x32 tire, QF 950. Car weighs 3100 with me. I need advice about plugging the PCV on the carb and installing evacuation "tubes" in the headers. I bracket race for the money and don't chase every tenth that might be available. Is the change to an evac worth any HP and more important, is it more consistent than running a PCV? Downside? Thanks in advance for any advice on this! Jim P in MN
     
  2. Briz

    Briz Founders Club Member

    I cant say anything about consensity one way or the other but I did pick up some time / MPH when I went with the header evac set up over the base PCV. I also installed a power evac pump pulling out of the PCV valve but that did not seem to make much if any difference.
     
  3. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    Maybe not so much about the money as it is about evacuating the crankcase. At WOT, which is where you are at most of the time, there is no engine vacuum, so a pcv system is basically useless. Without it you'll end up pushing oil out wherever it can get out. For a bracket car, I'd definitely go with the evac system.
     
  4. gmcgruther

    gmcgruther Well-Known Member

    If you can find an old smog pump, reverse the plumbing to make it a vacuum instead of a air pusher, you will pick up quite abit of et . I like the pvc because if you ever decided to get used oil from a top fueler, the oil has trapped nitro in it. When ran in a track only car with a tube running from valve covet to under carb or drilled hole in intake, the trapped nitro getts whipped out by the crank and sucked up through the intake and thus makes your engine wake up ;) the % of nitro is small, on the high end 12-14% max but man it does wake up any engine, especially on nitrous ;)
     
  5. 8ad-f85

    8ad-f85 Well-Known Member

    I've not used header evacs with any mufflers that aren't straight through. Not sure if it would load up a baffled muffler with oil over time.
    They definitely help power, better with reduced ring tension.
    If you are already on the bottom of a bracket, more power makes it easier to run your opponent.
    There's a reason you see the same name over and over on the board every year he participates.
     
  6. Skylard

    Skylard Well-Known Member

    3100lbs.
    where did you find 550lbs. Just curious in case i want to get there some day
    my 69 skylark hit the scales at 3880-230=3650 (1/4tank=30lbs)

    GLASS=
    hood
    trunk
    doors
    window glass
    fenders
    heads

    Cheers!
     
  7. 8ad-f85

    8ad-f85 Well-Known Member

    I've read somewhere recently that the one way valves from the kits do not last long. GM ones are cheaper and last quite a while.
     
  8. 69GS400s

    69GS400s ...my own amusement ride!

    Alum. heads and intake is about 1,000# right there .. or so it seems when you're wrestling the Irons off
     
  9. telriv

    telriv Founders Club Member

    Has to be MORE than that because as mentioned the heads are ALSO "Glass". LOL
     
  10. Jim Weise

    Jim Weise EFI/DIS 482

  11. Machinefarmer

    Machinefarmer Platinum Level Contributor

    Skylard, I don't think my race weight is much different than other dedicated bracket cars. My "post" 68 has glass hood and deck lid, no inner fenders, no interior other than plastic race seat. 8 point mild steel roll bar. No regulators, wiring and all glass is Lexan including the windshield. Manual steering box, fabricated trans cross member, Strange disk brakes at all four corners. In addition, I have moly A-arms with coil-overs in front. Rear is ladder bar with coil-overs too. PLastic fuel cell, one battery. I still have the brass and copper radiator and stock style start so I could find another 25 pounds replacing those. Car actually has scaled at 3070 with a half tank of fuel and me...I'm about 190ish depending on the season! Thanks for replys concerning the PCV; I will install and evac. Jim P
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Machinefarmer,
    Is your engine similar to mine? I remember Jim mentioning he sold an engine very close to mine that went in a 68 Race Car. Is that you?
     
  13. Machinefarmer

    Machinefarmer Platinum Level Contributor

    Larry, yes I guess that would be me. Bought the car as a roller from Pete in KS. Since then, learned the history of the car from the Midwest to Colorado. (its the No Hunting Car...great story!) Upgraded front suspension and brakes, replaced lots of stuff and did very well last season, after being away from bracket racing for almost 20 years. Used to run a 66 Special at Firebird in AZ. Probably had some of the earliest STG 1 heads from Mike back in the day....early 80s? Bought the 68 roller 1.5 years ago and scored the engine from JW. Mild 470, about 230-240 H roller that idles at 800. Pulls the front wheels a full 12 inches or more off a foot brake launch. I will run a delay box this year with an old school 4 wheel line lock and kick butt in bracket 1. Will run bracket 2 foot braking too, Happy with the engine....any more power and i'd be n the 9's which presents more tech issues and more $. I'm not sure what JW engine you have....but yes......I'm the guy with the California GS race car and JW 470! (I recently built a super hot 36 Ford with a home built 464 too!) Jim P
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    It's the engine in my signature. My car weighs about 4020-4050 with me in it and nothing in the trunk and depending on how much gasoline I have. Try to aim for half a tank at the track. I am also running a switch pitch and Gear Vendors overdrive, the heavy Buick factory chrome wheels, and 3.73's with a 28" tire (3.55 effective). I guess I'm doing OK considering.:grin:
     
  15. Machinefarmer

    Machinefarmer Platinum Level Contributor

    GMC....nitro fumes from used oil? Really. WTF....I asked the board for PCV verses an evacuation system advice for a bracket car (consistency is required!) and you post your idea to run used top fuel oil? I know we should all be civil here...but I'm going to say....and post it....out LOUD.

    don't be dumming down this site with your constant bull crap; at least stay off the race board....please.
    Jim P
     
  16. Machinefarmer

    Machinefarmer Platinum Level Contributor

    Larry, you are dialed in assuming 1000 lbs is a full second! I didn't dyno at your 602 and I run a very slight detune package with 31 degrees advance and a few other things to insure consistent traction and ets. I think I'm about 550hp. I 60 foot at 1.38 to 1.39. The 470 engine has been very consistent, low maintenance and runs cool. JP
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I'm going to ditch the switch pitch and I am having a fixed pitch transmission built this year. I'll spend some money and get a custom built converter. I think that will pick me up some. My best 60' to date is 1.62. I remember Jim told me your engine is a virtual twin to mine with a bit less head. My car is mostly a street car. Yes, the 470 is very reliable and mine runs nice and cool also. I can drive my car anywhere under any conditions.
     
  18. BQUICK

    BQUICK Gold Level Contributor

    I run PCV with MOROSO oil separator. Works for me.....
     
  19. buicksstage1

    buicksstage1 Well-Known Member

    :kodak: I did this dyno test on a stg1se 475 with a small flat tappet. With pcv, with Pan evac and re tested with pcv. I should be able to round up the dyno sheets next phone call.
     
  20. BQUICK

    BQUICK Gold Level Contributor

    I bet pan evac was worth 10+ hp over PCV.
     

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