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#1
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Lost a lot of performance
I am slowly taking the streetcar from running 11.70's back to basically stock. I have not changed anything on the engine yet other than the carb. I took the th400 with race converter out and replaced it with a 200r4 OD trans and stock 12" converter. I also changed from a 750Holley DP to a 750 Holley vacuum secondary carb. I did not think it would lose that much performance. Seat of the pants feels like I lost 100hp. Just very surprised.
Guess the $800 race converter was worth every dime I paid for it. |
The Following 2 Users Say Thank You to Mike S For This Useful Post: | ||
#2
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A converter of the needed stall to get a given motor into a cam’s power band has a big time effect.
For every 200 to 300 rpm you gave up in stall speed you probably need to go up 5% more in rear gear ratio to get that 1st gear punch back..
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I do stuff for reasons. |
#3
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How’s it in gear idling? Is the cam big enough it’s surging?
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#4
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Lost a lot of performance
Eginemasters did a dyno test of 750 Brawlers recently. DP vs vacuum secondary. Can’t remember the exact numbers but there was a noticeable loss with the VS on peak power. I’ll see if I can find it.
ETA, I’m too dumb to link it on Tapatalk. It’s episode 121. Double pumper was up 20 HP over the vacuum secondary at peak on a 500 HP small block Ford of some kind. It’s a pretty good episode. Murf Last edited by Murf; 01-09-2023 at 06:32 PM. |
#5
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The cam that's in the 455 now is 236/244 at .050 on 112ls. Installed straight up. I don't think it has enough bottom end for the 1800 stall. Also have to check the spring on the secondary's in the carb. I still have the 3.73 gear in the back. When it's in 4th with the lock up the rpms are at 1600 at 55mph. In a month I will be pulling the 455 out and installing a 400 with a 68 cam.
Just surprised at the difference the right converter can make. The one that came out was a custom ATI tree master that stalled about 3800. It use to smoke the tires from a roll. |
#6
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Re-install the good carb. Sell the weak carb for beer money.
Feelin for ya on the TH400 converter removal. I got lucky with the Stock 4L80 Converter. |
#7
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Does your 200r4 have lockup torque converter capability? If so you can run an aggressive converter and have it lockup under light throttle. Best of both worlds.
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#8
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Quote:
On my first 67 Firebird, which had a 326 with too much cam, going from a stock torque converter to a "3000" (which flashed to MAYBE 2800 behind the torqueless 326) knocked nearly 2 full seconds off the e.t. (from high 16's to high 14's).
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'73 T/A (clone). Low budget stock headed 8.3:1 455, 222/242 116lsa .443/.435 cam. FAST Sportsman EFI, 315rwhp/385rwtq on 87 octane. 13.12 @103.2, 1.91 60'. '67 Firebird [sold], ; 11.27 @ 119.61, 7.167 @ 96.07, with UD 280/280 (108LSA/ 109 ICL)solid cam. [1.537, 7.233 @93.61, 11.46 @ 115.4 w/ old UD 288/296 108 hydraulic cam] Feb '05 HPP, home-ported "16" D-ports, dished pistons (pump gas only), 3.42 gears, 275/60 DR's, 750DP, T2, full exhaust My webpage http://lnlpd.com/home |
The Following User Says Thank You to Lee For This Useful Post: | ||
#9
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I am a big fan of having the right converter for the application. The "right one" for my car put it on the rear bumper pretty much.
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Clutch Guys Matter _______________________________________ 53 Studebaker, 400P/th400/9" 64 F-85 72 4-4-2 Mondello's VO Twister II 84 Hurst/Olds #2449 87 Cutlass Salon 54 Olds 88 sedan |
The Following User Says Thank You to Mr Anonymous For This Useful Post: | ||
#10
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I switched my low 11 second ‘63 Lemans over to a 200-4r from a TH350 last year. I bought a TSP converter through Cliff Ruggles. Haven’t had it to the track yet but doesn’t feel like I’ve lost any power. It’s a lock-up and with 3:90 gears I’m 2200 rpm at about 75mph. According to Cliff the converter clutches will handle full power lock-up after 1-2 shift. Hoping for some track testing next year.
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Tom 1963 Lemans -428 +.030, SD Perf KRE heads, turbo 350, 9" Ford 3:90, 11.01@121 1956 Chieftain gasser, 461 stroked 400, SD Perf ported E-heads, turbo 400, Dana 3:70 10.40@125 |
The Following User Says Thank You to Tom63LeMans For This Useful Post: | ||
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