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#41
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#42
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Great post, Dennis. Thanks.
I was surprised by such a strong exhaust flow influence. I have read that about these engines on many PY threads but always assumed the exhaust flow benefits were about higher HP builds. Wrong again, Mike... !! And sorry for diverting but I'd be upset if I had paid to resize rods and they weren't stable. I would NOT expect this. Good to know! I wonder why? Maybe they creep a little under the loads of new rod bolts? Seems unexpected so thanks for sharing this too. Mike |
#43
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A few years ago you post up a W72 that made 371 HP. It had 8.75:1 CR and the Summit 2800. Were those the only differences from this engine? 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 |
#44
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Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#45
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The XE 262 I put in my 78 motor was a FUBAR initially. Outer cam journal was too big to fit in the motor! It was 0.002 too big compared to every other journal on it and other cams I have. I had to pay for shipping to get the old one back before they would grind a new one so I just paid for a new one and then they refunded that when the old one went back. It ran OK just not any better than the 2801.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#46
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Dennis |
#47
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" Long story short, Dan rebuilt the original numbers matching engine with .040" over Icon forged pistons w/4.5 cc valve reliefs that are .006" out of the hole and with .045" x 4.328" Felpro head gaskets to provide .040" quench depth. The 6X-4 heads were minimally cut for trueness and measured 92.45 cc's average for a final static compression ratio of 8.75 to 1. Dan replaced the cast rods with forged Eagle H-beam rods. New 1-pc valves (2.11/1.66) with CC dual springs were installed. A Summit 2800 cam (204/214/112 @ .422”/.444”) with new 'old' Crane hydraulic lifters along with a new Melling 60 psi oil pump. The one modification was the use of old factory D-port ram air exhaust manifolds with the 2.1" outlets with Pypes 2.5" mandrel headpipes. The original 17058263 Q-jet on the factory cast iron intake with the EGR system and plumbing were reinstalled. The base runs were made with 42 degrees total timing in by 3000 rpm, 45 primary rods/74 jets/CH secondary rods on an I hanger. The 3rd (and best) base pull made a corrected 360.3 hp @ 5000 rpm/456.1 lb-ft torque @ 3600 rpm (351.2 hp/444.5 lb-ft uncorrected). The correction factor was a low 1.026 as the weather conditions were very good...low humidity, high barometer, and very cool temperatures (65 in dyno cell). After rejetting the carb to 40 primary metering rods/72 jets/DA secondary rods on an 'I' hanger (same total timing at 42 degrees), employing the 'big' dyno room dumps for the headpipes, and installing the air cleaner base, the max hp jumped to 371.4 hp @ 5000 rpm/459.2 lb-ft @ 3600 rpm (362.0 hp/447.6 lb-ft uncorrected) on the final pull (#14). The highest torque reading was on pull #13 at 460.3 lbft. " Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#48
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Dennis |
#49
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I thought the custom XE262 with shorter seat duration would be the ticket for a low compression 400 , just nothing spectacular. Idle was about the same pull in the car about the same, although the 6X-8s were bone stock on that motor and the 6X-4s I have cleaned up the pockets and port matched. Same Performer intake and late HO/RA 2.5 manifolds and exhaust system. Dual cats and 2.5 mandrel. They were still using a sniffer here then and I needed the cats to clean it up.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#50
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The 2800 and 2801 are hard cams to beat for a near dead stock low compression 4bbl 3.75 stroke experience RPMs wise then a bit more torque from a touch more lift
3.75 stroke 9.5 compression and up could use more camshaft than 2800/2801
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If your not at the table you're on the menu A man who falls for everything stands for nothing. |
#51
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Dennis |
#52
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Here are the stock 6X intake flow numbers in relation to the cams spoke of in this string.
.400”///// 199.3 .450”///// 202.2 .500”///// 206.3 To make 371 Hp it took 199 intake cfm, or 3.98 cfm per CID . This fits in well with the accepted industry formulas for making hp.
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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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#53
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If you want to wake up the low comression 400, you can't go wrong with an Elgin E-923-P (same assummit 2800) from Amazon fot 118.82.It's what I got on Ebay 15 years ago from a guy on Ebay for $10. If you would like I have a new set of 16 Melling ifters will sell you a for $50 Plus shipping.. I have the cam and will give it to you for the shipping... PM me
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1979 Trans Am WS-6 .030 455 zero decked flat pistons 96 heads with SS valves 041 cam with Rhoads lifters 1.65 rockers RPM rods 800 Cliffs Q Jet on Holley Street Dominator ST-10 4 speed (3.42 first) w 2.73 rear gear __________________________________________________ _______________________________ 469th TFS Korat Thailand 1968-69 F-4E Muzzle 2 Last edited by track73; 11-22-2023 at 11:10 AM. Reason: typo's |
#54
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While your in there, look over the timing chain & gears, perhaps a new harmonic balancer & water pump?
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