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#121
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Good info, thanks. They were floating somewhere OVER 5000. I dialed in the governor to 5000 and no more valve float. |
#122
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Basically what I’m saying if you over gear first and second you’ll experience exactly what your experiencing. Especially with that cam and the Crower 60919 might not be any better, well maybe initially. So there’s trade offs. All bottom end and no mid range. The motor after the shift now needs to get back up to peak torque. So it’ll feel like a locomotive. T-400 will keep it in power band and peak torque range.
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#123
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Oh boy that explains a few things valves floating, sure it felt better once that issue was resolved. But definitely 700R4 gearing isn’t helping.
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#124
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Anyone have the @50 dur and valve lift specs on the 60919 crower cam.
Thanks GT |
#125
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For Pontiac 428-455 engines from 1955 through 1981
Basic RPM Range: 2000 to 6000 Valve Lift Intake: .470 Valve Lift Exhaust: .470 Intake Duration: 304 Exhaust Duration: 316 Intake Duration at .050”: 231 Exhaust Duration at .050”: 240 Lobe Separation: 112 On cam card Gets installed @ 108. Those numbers are with 1.5 rocker with 1.65 rocker it’s 520 lift and actually picks up a little more duration not sure on exact duration with 1.65. But thinking around 236 and 246 duration.
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Last edited by Gach; 01-25-2024 at 01:57 AM. |
#126
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A 50 CC pump should not be needed on any Pontiac motor that’s running a duel plane type of intake .
Your just crutching something else that’s wrong with the carb by using it.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#127
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I’m sure the Crower cam would do great but the risk of wiping a lobe during break in would be enough for me to correct the obvious issues in this build before throwing in the towel. As already mentioned, degree in the cam with a new timing chain, swap in a Performer RPM and work on the current carb or a 68-72 factory intake and well built Q-jet.
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Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears ‘66 Lemans, 455, KRE D-Ports, TH350, 12 bolt 3.90 gears '64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears (Traded) '69 LeMans Vert, 350, #47 heads: Non-running project |
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#128
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I found a like new Performer RPM locally for $300 and am going to pick it up. Of course the car isn't doing anything until the snow melts. It's on casters up against the garage wall currently for the winter. I'm finding the idea of lowering my shift point via the governor to pick up more speed intriguing as well.
I stumbled upon this in another thread: "My first 455 ran a full .5 quicker at the track when shifted at 4600, compared to 5000. It was still "pulling" at 5000, but a torque motor needs to be where it is making torque to run the best." - Lee Last edited by General Z; 01-25-2024 at 10:26 AM. |
#129
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First the computer can only show you somethings, but you must really test for the best results.
Second while you hear engine torque is so important it is really torque at the rear wheels that accelerates the vehicle. Lets take the dyno sheet posted in post #68 and extent it to 5800 RPM Now lets look at torque at the rear wheels in each gear. Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
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#130
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#131
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People have ran mid/low 12's with that combo, nothing wrong with it. SHOULD blow the tires away anywhere in first gear, and possibly in 2nd.
Either there is a defective part (worn cam lobe, for instance) or the tune is WAY off. About 1 car in 5 that I work doesn't even have full throttle - start there if you have not verified.
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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 |
The Following User Says Thank You to Lee For This Useful Post: | ||
#132
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People have ran mid/low 12's with similar combos, nothing wrong with it. SHOULD blow the tires away anywhere in first gear, and possibly in 2nd.
Either there is a defective part (worn cam lobe, for instance) or the tune is WAY off. About 1 car in 5 that I work doesn't even have full throttle - start there if you have not verified.
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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 |
The Following User Says Thank You to Lee For This Useful Post: | ||
#133
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Good morning,
Got a plan: 1. Wait for spring, because the car is put away for the winter. 2. Drive it with my G-Tech and note the data. 3. Confirm if secondaries are opening. 4. Install the vacuum secondary spring quick change kit I ordered. 5. Swap to the RPM intake. 6. Drive with G-Tech and note the data. 7. Assuming secondaries were, or are now opening, try springs. 8. Determine if the above made enough difference to make me more satisfied with the car, while keeping in mind that it's a family, street cruiser. 9. Pull the engine to address the oil leak and also get into internals, depending on the above data. 10. Tinker with transmission governor, to possible lower the shift point. |
#134
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General Z - just remember the RPM intake is 1" taller than the regular Performer and stock 4-bbl intakes, so check to make sure your air cleaner set-up doesn't have an unexpected collision with the hood on your Firebird.
Dennis |
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#135
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OP- I have an RPM in my bird with a 1” drop base and use a 14x3” element, clears hood but not by much. Definitely measure.
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Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears ‘66 Lemans, 455, KRE D-Ports, TH350, 12 bolt 3.90 gears '64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears (Traded) '69 LeMans Vert, 350, #47 heads: Non-running project |
The Following User Says Thank You to grivera For This Useful Post: | ||
#136
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You still need to take a look at your distributor. Confirm your initial timing, mechanical timing and total timing. You should also confirm TDC matches the mark on your balancer. Very easy to do all of these. you can verify this before driving season comes. Are you running a vacuum can on the distributor and if so do you have it connected to a vacuum source?
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68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
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#137
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Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
The Following User Says Thank You to Stan Weiss For This Useful Post: | ||
#138
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Thanks. My car is a 67 Firebird with a 400 hood. Currently running one of those spreadbore to squarebore spacers which is like .85" and the bowtie overdrives plate for the kick down cable. I have a drop base air cleaner and a 3" tall filter. Hood clearance is probably 3/8"+ right now.
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#139
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While you change the secondary spring, you really should also richen the secondary jets a few sizes on your 750 Holley. You could start by reading your plugs, but normally on big CID’s on a 750 you want want to go up at least 2 jet sizes. My guess is a 750 on a 455 needs closer to a 2 to 3 jet increase front and back from the base factory setting. The carb is big enough, but it is set up out of the box for smaller cubes. With the engine running very lean all those other performance upgrades just send the performance sideways.
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#140
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Yes, thank you for the reminder. I need to do the compression test. |
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