60' times

Discussion in 'Small Block Tech' started by partsrparts, Apr 9, 2018.

  1. partsrparts

    partsrparts Silver Level contributor

    Hey guys, so I've had the car to the track 4 times so far this year with a best 60' time of 1.97 but usually 2.00-2.06, best 1/4 at 14.37@93.15mph. The elev. of the track is 5300' but the DA has always been 7200-7600ft.
    this computes to mid 13's at sea level, I feel that there is high 13's to be obtained with my set up, what is you guys take on this?

    1976 Skylark
    1968 350
    TA stage 1 intake
    Holley 750 DP
    TA HEI ign. set up per Larry's timing thread, 12 initial, 32 total at 3400 rpm
    TA 1 5/8 headers
    polished crank
    balanced rotating assembly
    stock resized rods
    JE 10 to 1 pistons @ zero deck
    custom ground cam from JW, flat tappet
    stock heads with new valves, guides seats and seals( waiting on alum. heads)
    JW special torque converter
    TH 400
    3.23 posi
    MT DR 255/75/15 @ 16lbs
    This last time out I opened the headers, put 18"x 3" extensions on and bumped the jetting by 2 sizes with really no change to ET or MPH and my 60' times never got below 2.06.
    It also felt a little sluggish until about 3500-4000 rpm.

    All input and ideas and suggestions are very much welcome!
    Thanks, Keith
     
  2. alec296

    alec296 i need another buick

    Reread Larry’s power timing thread. You should be in by 24-2600 if your getting full mechanical advance at 3400 it’s late. Get an air fuel meter to check if carb needs adjusting
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Get rid of those tires, they are absolutely killing your gear ratio.:) Those tires are 30" tall:eek:. Those tires are reducing your 3.23 gear to 2.82. Put some 26" tires on there to get your 3.23's back. At 93 MPH through the traps, you are at about 35-3600 RPM. You need more gear.

    Next time you go to the track, put the gear selector in 2nd, and leave it there. Go through the traps in 2nd gear. At least then you will get the engine up past 5000 RPM. Bet you it picks up big time.
     
    Last edited: Apr 9, 2018
    Harlockssx and alec296 like this.
  4. alec296

    alec296 i need another buick

    What’s going on with your 60 ft times also? 1.97? Are you spinning your wheels? What your reaction time? Pull your spark plugs and see if they are black.
     
  5. 300sbb_overkill

    300sbb_overkill Well-Known Member


    With a TH400, he should be able to put it in 1st gear and leave it there, those things will shift into 2nd when the RPM hit a certain speed while still in 1st anyway. Also the TH400 trans is slowing you down, a 200R4 would help a lot and even a TH350 will help a bit and your torque converter will even fit in a TH350.

    Partsrparts, before you think about getting the aluminum heads, it would be a good idea to get a good set of rods in there that can handle 6,500 + RPM without snapping in half. The sbb 350 Molnar rods should be close to the weight of the factory rods you have in there now(?) so you might be able to get away without having to rebalance?(have them weight compared if you do change them)

    More gear would help but without being able to spin the engine faster because of the rods, you wouldn't be able to take much advantage of that at the track or on the street without an overdrive if you drive the car on the street.

    After you get better rods in there, you can upgrade to a solid flat tappet for better RPM potential, team that with the single plane intake and now we're having some fun!

    A nitrous kit would make you faster, try to keep the RPM in check if you use the laughing gas. Also with a dual plane intake you're limited to a 150 HP shot.(good thing too because those '68 factory rods probably won't handle much more than that) With the new rods and the single plane intake you can now do a 500 HP shot if in you wanted to! You would no longer be limited to the 150 HP shot because of the dual plane intake.
     
  6. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Head porting needed.
     
  7. UPSTAGED1970

    UPSTAGED1970 Well-Known Member

    Do you happen to know the specs of your cam? Just curious to get a better idea of your set up. What is your converter stall rpm?
     
  8. partsrparts

    partsrparts Silver Level contributor

    Sorry, fat fingers, all in at 2400 rpm
    Sorry again, 255/60/15, 27" tall
    The first time out I forgot to put the shifter back in 1st after the burn out and it auto shifted to 2nd at 4000 rpm, I will hold it in 2nd the next time out to see what happens.
    My reaction times are crap, I'm trying to do too many things at once right now
    I'm financially handicapped right now and I can only try to make the best with what I have
     
    Last edited: Apr 10, 2018
  9. 300sbb_overkill

    300sbb_overkill Well-Known Member

    That's ok upgrades sometimes takes years, I seen you mention the new not yet released heads and want you to know what you needed with them for your engine to live and how to take advantage of them.

    Sounds like you have your timing pretty good so right now an air/fuel gauge if you don't have one of those yet will help optimize your carb for better 60 ft times.

    Can you list your cam specs?(or is it top secret?) Sounds like it may be a bit small if you're not gaining anything with open headers. If that's the case you would be better off leaving your exhaust hooked up.

    Also a nitrous kit can cheat you to better QM times if you want those before the upgrades, and they're not that expensive for the smaller kits. Besides you still have a dual plane intake so that will limit the amount of nitrous to safely use. Be careful though that laughing gas can be addictive.
     
  10. UPSTAGED1970

    UPSTAGED1970 Well-Known Member

    Your set up seems like it should be making plenty of power up near 5500 rpm. I would keep the shifts points at least there. Still feel that your rear gear is not enough. I'm assuming you're foot braking for the stall? You mentioned leaving at idle? You want to be getting through your traps at at least 4500- 5000rpm in 3rd. Take note of your mph change in your trap speed. This will tell you if your shift points, or any tuning adjustments, are improving your run. Don't worry about reaction time. Just focus on a good launch to your ET. You can always perfect reaction time later.
     
  11. partsrparts

    partsrparts Silver Level contributor

    If you expand the last reply I quoted from UPSTAGED1970 it has my TC stall, cam specs and a little more observations and info. I think I'm trying to do too many things at once.
    Another T&T this sunday and I'm going to try and do a plug chop and also focus on leaving at different rpm's and not worry about cutting a good light.
    Thanks, Keith
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Don't use 3rd gear. You need to shift at 5000 at the very least, and have the motor turning at least that as you go through the traps. You want the motor as close to peak HP as possible at the end of the track. Why install a cam if you aren't going to rev it higher.
     
  13. cjeboyle

    cjeboyle Gold Level Contributor

    At TNT your reaction time means nothing in regards to your 1/8 or 1/4 mile time. The clock doesn't start till you break the beam. Stage as early as you can to give yourself time to get on the converter, when you see the other car roll up to stage you can get on it as it won't be long till its launch time. I am no expert but as a fellow beginner these are the things I have been trying to focus on. Good Luck!
    Cliff
     
  14. Buick#455

    Buick#455 Well-Known Member

    Not to hijack this thread, but Larry how do you calculate that? I have 3:23 rear, running 295/55/15 DR with built th350. Just wondering what rear ratio is?
     
  15. UPSTAGED1970

    UPSTAGED1970 Well-Known Member

    Yes, I agree, if you can get through the traps by + or - 5500rpms in 2nd, by all means leave it in 2nd.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    The OP originally posted that he had P255/75R-15 tires which are 30” tall. That originally led me to believe that his 3.23 Gear was really a 2.82. He corrected that to P255/60R-15 which are 27” tall, much better. If he goes through the traps in 2nd gear, that would be 3.23 X 1.48 = 4.78 gearing. 336/27 X 4.78 X 93 MPH = 5532 RPM with no converter slip, so it should be doable.
     
    UPSTAGED1970 likes this.
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Since the circumference of a circle is directly related to the diameter by the constant pi, an increase in tire height varies directly with the circumference. If you divide original tire height by new tire height, and multiply by your gear ratio, you get effective ratio. Our GS cars came with tires about 26.6” tall. If you went to a 28” tire, as I did with a 3.73 gear, then 26.6/28. X 3.73 = 3.54.

    For the OP, the 1976 Skylark came from the factory with FR78-14's which are 26.30" tall. If his tires were indeed 30" tall, then 26.30/30.00 X 3.23 = 2.83.

    For the 27" tire, 26.30/27.00 X 3.23 = 3.15.

    For your car, a P295/55R-15 is 27.77" tall. 26.60/27.77 X 3.23 = 3.09
     
    Last edited: Apr 12, 2018
    MrSony likes this.
  18. partsrparts

    partsrparts Silver Level contributor

    So after looking at the cam specs and my set up is it the opinion of everyone that my power peak is about 5500 rpm? And is it that the stock heads won't flow much after 5500 rpm?
    Can anyone give me an idea on my peak HP and Torque numbers?
    Thanks, Keith
     
  19. 300sbb_overkill

    300sbb_overkill Well-Known Member

    The factory heads aren't necessarily the air flow cork as much as the dual plane intake is. A non-ported TA stage 1 intake is good for idle to 5,000 RPM range. If you dynoed your engine, you would see that it would probably peak around 5,300 at the most.

    If you want more RPM, then the new SP3 single plane intake would be the ticket. Just make sure you don't spin more than the factory rods can handle.(that is if your cam doesn't become the next choke point)

    You never posted your actual cam specs so we can't comment on those.
     
  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    The whole point of installing a cam is so the engine can breathe at a higher RPM where it can make more HP. You want the engine to be at or above at least 5000 RPM as you go through the traps. I don't know how anyone could give you your peak HP/TQ without putting the car/engine on a dyno. You could figure out the rear wheel HP to push the weight of your car to a 93 MPH trap speed.

    http://jmrdragracing.com/Tools/Est_HP_2_Weight.htm
     

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