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#1
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All 68 RA cars had the 4 bolt main block, diff cam, heads, and 4.33 gears, or 3.90 in Birds
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#2
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1968 L74 MT uses the 068 cam, #111149 distributor, #7028267 carb and 3.55:1 std gears.
1968 L74 AT uses the 067 cam, #1111270 distributor, #702268 carb and 3.55:1 std gears. 1968 L67 (RA) MT uses the 744 cam, #111149 distributor, #7028275 carb (early), #7028273 (late) and 4.33:1 std gears. 1968 L67 (RA) AT uses the 068 cam, #1111270 distributor, #7028274 carb (early), #7028270 (late) and 4.33:1 std gears. 1968 L67 (RAII) MT uses the 041 cam, #1111941 distributor, #7028273 carb and 4.33:1 std gears. 1968 L67 (RAII) AT uses the 068 cam, #1111941 distributor, #7028270 carb and 4.33:1 std gears. |
#3
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i used to know all of this off the top of my head now that i am old i cant remember whats the difference between the 744 and 041 cam?
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#4
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744 wasn't much more intake lift than 068 ( around 408 or 410)
But had more .... whatever - duration , lobe separation , overlap , ICL , ,,, 041 was a bump stick A lot more lift and yadda yadda Around .450 range intake lift with 1.5 rockers , around .500 range intake lift with 1.65 rockers Another oldie just shooting from the hip |
#5
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
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#6
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thats right wasnt the 744 the cam they used in the 4 speed ra3 cars in 69
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#7
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Interesting note on the 7028273 and 7028270 carbs. They first appeared on the 68 RA I (late) and RA II engines. They are also listed for the 69 RAIII engines according to the GTO Association Illustrated Indentification Guide (Eric Whites book). The 69 RAIV engine was 7029270 and 7029273. Normally the 4th digit is the last digit of the year in this era. Is the book wrong?
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#8
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With this and another post, I am going to chime in;
Quote:
Unitl recently I too was confused with how an HO differed from a Ram Air car... At the time the 'HO' was intended as a nominal increase in power from the std 4bbl engine (which I believe normally carried RPO L78), and acted as a stop gap between the L78 & RA engine; Prior to 1969 L67 was "the" Ram Air RPO code; I'm going to try to keep things simple by first looking at the offerings at the beginning of the 1968 model year: (cams, smaller to larger; 066-067-068-744-041) L78(mt) = 2-bolt main block, D-port #16 heads, standard exh manifolds, 067 cam, std air cleaner L74(mt) = 2-bolt main block, D-port #16 heads, standard exh manifolds, 068 cam, std air cleaner L67(mt) = 4-bolt main block, D-port #31 heads, RA exh manifolds, 744 cam, ram air induction **Automatic version of the above engines received a one-step-down camshaft** I need to take pause here, because I want to punctuate the differential gearing which Kenth posted; The RA cars always came with 4.33:1 on the GTO (and 3.90:1 in the Firebird) - while the HO had more street friendly gearing. I would think that for day to day driving, this was the biggest differentiator. So, compared against your car an early 1968 Ram Air GTO would have had: 4-bolt block, a bigger cam, cold air induction, RA exhaust manifolds, and lower gearing. Not to be contradicting, but I'd wager a guess that if lined up together, there would be a substantial difference in E/T's between your car and a RA car (assuming both cars had the same prep). Late in the 1968 model year the Ram Air option quietly changed to what we know as the RAII; In essence it changed the heads, and upped the cam from a 744 to a 041. It has been written that the RAII was essentially a stop-gap to the forthcoming RAIV; Starting in 1969 the RPO L67 was for the round port RAIV. This was around the time that Pontiac muddied the waters; The "HO" (RPO 'L74') became the Ram Air III, and essentially was a 1968 400-HO with RA exhaust manifolds, and cold air induction. The 1969-L74 maintained the conventional 'D'-port heads with the smallest combustion chamber size; Early 1969 RAIII/mt cars came with the (previously RA spec) 744 cam, but later in the model year, the 744 was no longer used, and the 'HO' (068) cam was the standard cam (at this point in time the automatic cars stopped receiving smaller cams). The 1969 'L74' did not require the low gearing of prior RA cars. I could be mistaken, but believe some early 1969 literature still referred to the L74 as an "HO". (Hopefully this post didn't have too many errors in it.)
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#9
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Kenth about this part of this post:
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If I have a correct understanding then no 1968 RAI should have ever been assembled with either a 270 or 273 application quadrajet.
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#10
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Early and Late is the differential between Dport and Roundport. As best I know of.
Better verbage would have been Early .... and Very Late. 68 HO (WS) had same standard axle ratio as Base (WT) 3.55 And the same air cleaner. But either of those engines could have been ordered with 3.90 or 4.33 at small charge (after upcharge for posi) 68 RA cars were shipped with standard air cleaners and closed scoops. Selling dealers were to make the mods and install RA for their customers, with supplied material from PMD in the trunk. 7029273 came with Ram IV release , and eventually co-joined with Ram3 production. |
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#11
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Never knew that 1969 Tempest 350 H.O. also used the 744 camshaft?
From 1969 Tempest AMA specs: |
#12
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Can't imagine that. It was about as much as I'd want in a 400!
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