Wanted: 75 Horses escaped my Buick

Discussion in 'Street/strip 400/430/455' started by Cutlass, Sep 5, 2019.

  1. Cutlass

    Cutlass Platinum Level Contributor

    200r4, beefed up by Extreme Automatics
  2. Bens99gtp

    Bens99gtp Well-Known Member

    I would love to put a th200 behind my race motor if I thought it would live, thecweight savings from a th400 would have to make several tenths for certain.

    Glad it was something stupid that gained your power back, but if your motor has 20% leakage, something isn't right there still
  3. Cutlass

    Cutlass Platinum Level Contributor

    I am with you, but I am getting to the conclusion, that most likely I was to cheap when buying the tester. The good thing is, that the leakage rate is almost the same on all the cylinders, but cyl3. I will keep an eye on it and maybe have the test performed at a dealership for confirmation.
    Yesterday I ordered the advance kit from Summit, will see how long it takes to get to my doorstep.
    Question: The Kits come with one bushing. This is meant to be a replacement for lost/wornout stock bushings. I can not adjust the total mechanical advance with this bushing, right? If I need to adjust the max angle of mechanical advance I need to weld & grind, right?
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    If there is currently no bushing on the advance pin, the bushing in the kit will reduce the amount of mechanical advance.
  5. Cutlass

    Cutlass Platinum Level Contributor

    Today was the day and I had the Buick back on the chassis dyno.
    For those who do not want to read the whole thread; in a nutshell:
    Last years measurement resulted in 196 PS @ 4270 1/min. Reason was my stupidity, I accidently mispluged cylinder 2 & 6 at the distributor cap.
    Along this year I did set the distributor according to Larrys thread and installed a Pertronix module
    Also I installed an AFR-gauge, ordered a bunch of jets and needles and tuned the QJ
    IMG_0631.JPG IMG_0632.JPG
    After being done the engine performance and response felt good. As we do not have dragstrips here I decided to put the GS on a chassis dyno again.
    He produced 301 PS @ 4460 1/min and 465Nm (342 lbf-ft) @ 4460 1/min. Those numbers are calculated back to the engine already.
    So I guess this (at least the power) is in the ballpark of what to expect from a stock Stage1 engine. Not so sure about the torque, though.
    EDIT: Double checked with the guy, operating the dyno. He said to not pay attention to the torque, as he was not able to do a proper 4th gear run w/o downshifting. He also said, that the powerfigure is probably on the low side, as most likely the secondaries didn't open completely/slow, as he always tried to prevent downshifts and therefore probably never made a 100% WOT run.
    Maybe I will take out my GPS unit and find an empty road to perform some 1/4 mile measurements to back up the dyno results.
    What do you guys think?
    Last edited: Sep 15, 2020 at 1:14 PM
  6. hugger

    hugger Well-Known Member

    Its easy to prevent a downshift ......just unplug the switch,...or disconnect the cable,...30 seconds top,....he must not be to familiar with old cars,..nevermind just seen where it was a 200r,...still tho you would just leave it 3rd the 1:1 gear and increase speed to 50mph to prevent downshift
  7. Schurkey

    Schurkey Silver Level contributor

    You need to use that leakdown tester on several "known good" engines to see how it reacts. Best if those "known good" engines have similar bore sizes to your Buick.

    The "indicated" leakage on the gauge has as much to do with the leakdown tester as it has to do with the actual cylinder leakage. Either your tester has an extremely small orifice between the gauges, or the manufacturer has color-coded the scale too generously, so that worn-out engines still "test" good.

    The only ways to know are to take the thing apart to measure the orifice, or to test and compare several engines that AREN'T having problems. Again, best if those engines have Buick-sized bores, and therefore Buick-sized rings. (Stroke doesn't matter.)

    150-ish psi cranking compression test results would be perfectly "ordinary" around here. Cranking pressure depends on a dozen or more factors. Compression ratio, cam timing, altitude, and cranking speed being among the most important.

    "Good luck" keeping a Turbo Hydramatic 200 of any variety behind a big-block. I know the aftermarket makes heavy-duty parts for them. I still don't trust 'em.
    Last edited: Sep 15, 2020 at 3:35 PM
  8. OZGS455

    OZGS455 Oh what a wonderful day!

    Well this thread was an interesting early morning read.
  9. Cutlass

    Cutlass Platinum Level Contributor

    @ Hugger: There are not many US-Cars around here, and even less Buicks. The guy with the chassis dyno is used to work on "younger" vehicles, mostly BMW.
    I did couple of 1/4 mile measurements with my smartphone and an external GPS receiver (same as last year) and also went to the same spot. Performed the test in both directions of the street. Best results for each way was 14:38 @ 95mph and 14:72 @ 90mph. Using several calculators on the net, all leads to about 300 HP @ flywheel, which confirms the dyno number (give and take). Somewhere I have read, that back in the days a magazine tested a stock Stage 1 with 13:43 @ 103.46mph. So my GS lost one second in 50 years; not too bad :)
    @ Schurkey: I am with you in regards to the gauge. I probably was to cheap, when I bought it. If I find time I will do the leakage test again, just out of curiosity. But for the time being I will drive the car as is. Maybe one day I will get into my piggy bank and get an engine from Jim anyway

    In regards to the transmission, I certainly hope it will last, as I will not race the car on a regular base.
  10. stump puller455

    stump puller455 1970 GS 455

    This is why i had jim at trishield build my new engine... it makes great hp .. if i had a local shop build it and saved $ some how i would holding the short end of the stick

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