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#1
11-22-2025, 04:28 PM
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1970 455 "HO" Engine question
Did the higher compression 455 from the 1970 GTO, w/ the 64 heads, come with log exhaust manifolds or the HO / Ram Air 3 400 versions?
I believe the standard log versions but wished to make sure.
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79 Trans Am WS6 71 Formula 72 Formula 71 Firebird 69 Firebird |
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#2
11-22-2025, 05:17 PM
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Log manifolds.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/3.08 2002 WS6 Convertible LS1/4L60E/3.23 1966 VW Type 2 Single Cab Pickup 140hp 2276 1956 VW Type 2 Panel Van 36hp 1200 1957 VW Type 1 Beetle 180hp 2276 |
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#3
11-24-2025, 02:27 AM
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2x on the logs .
I have an original car that still had the lock tabs on the exhaust manifold bolts. |
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#4
11-24-2025, 08:33 AM
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If they had only used a 87 cc ra4 head,, aluminum intake,ra exhaust manifolds and ra 4 cam on that 70 455. Wouldn’t of been much to touch it.
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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. 8.45 @ 88.1 mph on slippery street tires.Bad 2.19 60ft.Owned since 86' |
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#5
11-24-2025, 04:45 PM
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I suspect the fact that they couldn't sell the 455 in the F bodies was a reason they didn't make a true high-performance version of the 1970 455. Also, the long stroke of the 455 on the stock bottom end of the 1970 455 wasn't compatible with the high rpm characteristics of the RA IV cam and valve train.
The closest to that was the 73-74 455 SD, it doesn't take much to imagine what 25% more compression and the high lift duration of the RA IV valvetrain would have done to the power band.
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My Break Away Squad 1969 Fbird (base OHC, 350, 400HO & Sprint Cvt’s - 400HO & TA ht’s) 1969 Custom S 2dr ht 1969 LeMans (2dr & 4dr ht & Cvt) 1969 LeMans Safari wagon 1969 GTO (2 Cvt, 2 ht & Judge ht) 1969 Cat (3 Cvt’s & a 2dr ht) 1969 Ventura wagon 2 seat 1969 Exec 4dr post 1969 2 Bonnie Cvt's & 2 wagons 1969 Bonnie Brougham (4dr ht & Cvt) 1969 Grand Prix 2 SJ’s 1969 2+2 2dr ht (Canadian) |
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#6
11-25-2025, 08:46 AM
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Quote:
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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. 8.45 @ 88.1 mph on slippery street tires.Bad 2.19 60ft.Owned since 86' |
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#7
11-25-2025, 06:29 PM
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RoundPort heads and IV cam with 1.65 rockers will spin past 6,000+ rpm
That's why most Ram4 cars have replacement engines. Guys would have been doing the same thing with their 455's if Pontiac put all the goodies with them. Which they should have, and had plans to, but didn't. Would have been a lot of warranty repairs even with better rods. 067 and 068 camshafts with stock springs were like built-in rev limiters |
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