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#1
03-05-2021, 12:47 PM
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Dyno Results 462
Just had this sent to me a few days ago.
Don't know all the details, but it used #16 iron heads, lowered compression to around 10 to 1, custom ground HR cam, RPM intake and a later Pontiac carb I did for the owner. No mention of head porting in any of the specs they sent with the carb. The cam is a smaller HR, 284/296 @ .006", 236/242 @ .050", 112LSA, .520/.540" lift. Didn't quite make 500hp but near 600ft lbs and over 500ft lbs from 2600rpm's to the end of the pull is pretty impressive........Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#2
03-05-2021, 12:51 PM
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Looks like a nice successful build.
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#3
03-05-2021, 01:50 PM
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Agreed, I really had little to do with it aside from checking out the carb the customer was using on it. He rebuilt it with a kit/custom tuning parts I sent him, just wanted me to give it a look over before the dyno session. Just goes to show us how much power can be made with the factory iron heads, and pump gas friendly as well.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#4
03-05-2021, 01:53 PM
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Nice wide torque band without question!
Seeing as the motors still holding onto 500 ft lbs even up at 5200 rpm I am going to venture a guess that the heads are ported, can that info be found out ? Also what carb was this Cliff and do you happen to know what intake was being run. Judging by the dyno test safe fat BSFC numbers there’s still more HP to be had out of that motor!
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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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#5
03-05-2021, 02:04 PM
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They didn't do any tuning (carb) that I know of and the "dip" in the curve is from not running enough fuel pressure.
The Q-jet has an undeserved bad reputation from not liking a lot of fuel pressure, which was only true on the very early models and correctly by 1969, but to this day folks think they will give issues much past 5psi which is what they were using for these dyno runs. The later carbs are EASILY good with 7-8 psi even using larger fuel inlet seats in them. I run a .145" seat at 7.5 psi and have for over 20 years now without a single glitch anyplace......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
| The Following 5 Users Say Thank You to Cliff R For This Useful Post: | ||
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#6
03-05-2021, 02:05 PM
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Quote:
I wondered about the dip. Thanks.
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 frittering and wasting the hours in an off hand way.... 1969 GTO, 455ci, 230/236 Pontiac Dude's "Butcher Special" Comp hyd roller cam with Crower HIPPO solid roller lifters, Q-jet, Edelbrock P4B-QJ, Doug's headers, ported 6X-8 (97cc) heads, TKO600, 3.73 geared Eaton Tru-Trac 8.5", hydroboost, rear disc brakes......and my greatest mechanical feat....a new heater core. 
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#7
03-05-2021, 02:07 PM
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Can incorrect valve springs cause a dip like that?
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
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#8
03-05-2021, 02:16 PM
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Most likely they sucked the bowl a tad low just past peak VE as they were only using 5psi and pushing all the fuel past one N/S assembly......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#9
03-05-2021, 02:19 PM
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"Also what carb was this Cliff and do you happen to know what intake was being run."
Not sure but it may have been the RPM. I did the carb about a month ago and having bad cases of CRS and DGS these days!......LOL..... The stock intake would have been adequate for that power level. The 428 build we did a few years ago with about the same compression and 236/242 @ .050HR cam made 497hp/540tq with my iron intake on it and fell off to 491HP when we bolted the larger RPM on it.....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#10
03-05-2021, 03:12 PM
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Yes Scott, a fast dip like that could be due to valve springs at what some call there fuss point/ spring surge. Zone.
This where they loose control of there own mass, no less the valve train, but then many times recover very fast. It’s commonly accepted that if more then one is seen on a graph of a pull, especially above 5000 rpm that spring life will be quite short and if you hanging on the edge of having enough valve to piston clearance things are going to get very expensive if you get my drift?
__________________
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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#11
03-05-2021, 05:28 PM
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Quote:
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#12
03-05-2021, 05:50 PM
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Stop putting words in my Mouth, as I did not say that it definitely was the case on that dyno pull, I clearly said it “could “ as in just that it was a possibility when dips like that show up that fast and then go away in a very narrow section of rpm,
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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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#13
03-05-2021, 05:55 PM
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Quote:
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#14
03-06-2021, 01:00 PM
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Really nice build. Any idea what it's going into? Would love to hear any track results if it gets there
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
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#15
03-07-2021, 09:40 AM
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Pretty sure into a 68 GTO and it will be raced "on occasion" so we may get some numbers on it at some point.
They didn't have the rest of the drivetrain selection made so I don't know the rear gear ratio or type of transmission, etc....
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#16
03-07-2021, 10:39 PM
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Why did they stop the pull at 5000 rpm?
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#17
03-08-2021, 07:50 AM
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Don't know because I had nothing to do with the build or the dyno session.
Most likely they tightened up the brake to get a good idea of power (torque) below 3000rpm's. On the dyno I've used in the past this would have had it quit early as well. The build was pretty much a stroker "kit" supplied by one of the big Pontiac shops. I may have actually contributed to the engine, at least as far as the cam choice goes. 15 years ago they would have sold him a Comp XR276HR or something close to it on a tighter LSA. I had a talk with one of the owners and sent them a copy of the dyno sheet below, and since then they have been using different lobe profiles and wider LSA..........FWIW......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#18
03-08-2021, 08:57 AM
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Impressive TQ curve. The 4000 rpm dip is quite evident for questions, which leads to a low fuel delivery (as mentioned), or a dwell problem leading to spark delivery (points dizzy).
Glad it was evident to be fuel psi. hope they pick a 2.73:1 to 3.08:1 12-bolt posi with TH400. That would be an excellent cam for my Spare engine build going on; planning for HFT 230/240 range, but a Roller of this duration (and perhaps less Lift for 700 mile towing) would be satisfying. |
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#19
03-08-2021, 09:45 AM
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Quote:
 Someone heeded your advice? That's crazy  Duplicating a combination that likely couldn't be improved upon much is something I look at here, all the time....Thanks!!!
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... 
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#20
03-08-2021, 08:01 PM
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Ya, everyone once in a while someone takes my advice and I've never had single complaint when it comes to cam selection for these engines. Well, that's really not true as I had a customer last year that I helped out with a big Olds engine that LOVES the power it makes, and that it easily manages pump gas at 10.6 to 1 compression.....his complaint.....it idles too smooth!......LOL....
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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