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#41
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#42
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I don't think BES owns the approach but I appreciate your candor.
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#43
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Have been running my 4.5" stroke Scat crank for 12 years. Has seen I would guess at least 25,000 street miles and I get out to the strip a few times a year. Two different times I melted pistons back in 2006 and 2007. Been running at least a few 8 second passes each year since 2008. Short block has been together for the last 9 years, and it's a 1970 factory block, Eagle rods and Ross pistons. This is with a turbo.
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#44
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Quote:
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65 Lemans Street Car - 521, T400, 3.70 9". 10.13 @ 135. 3770 lbs. Drag Week ‘14, ‘15, ‘17 63 Lemans Race Car- 8.81 @ 151, 5.60 @ 123(SOLD) 67 Bonneville ragtop 74 Firebird - 455, e heads, TK0600 in process |
#45
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6.7" rods, short block hasn't been apart in 9 years.
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#46
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How many are running a 4.75 crank?
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#47
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How about the MOLNAR 4.375" and 4.65" Stroke Crankshafts?
Anyone have any information on experience with the MOLNAR 4.375" and or 4.65" stroke 3" main journal crankshafts? For instance the cylinder wall wear?
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1970 Lucerne Blue Firebird Trans Am, deluxe blue interior. Original Ram Air III, M-21, 3.73. Being built as a 4" stroke "434" with SR 614 Ram Air IV heads 1972+ Lucerne Blue 4-door hardtop "what if" T-41 Le Mans Sport GT/Grand Am concepts. Equipped with future 3" journal "455 HO"/"what if" prototype "SD 455". What if GM had continued production of the 1970-72 GM A body somewhere in the southern hemisphere? |
#48
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We've been building 4.375 stroke Pontiac engines for decades (not with Molnar crankshaft) and it makes great combination . No issues whatsoever. Not much experience with the 4.65 stroke.
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#49
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I destroked my motor from a 4.75 Ohio to a Molnar 4.375. Both used same 6.7 rod. Less side loading on the pistons and able to get the pin out of the ring land(no ring supports). Crank was spot on. Only about 2,000 street miles and 10 passes, but so far so good.
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65 Lemans Street Car - 521, T400, 3.70 9". 10.13 @ 135. 3770 lbs. Drag Week ‘14, ‘15, ‘17 63 Lemans Race Car- 8.81 @ 151, 5.60 @ 123(SOLD) 67 Bonneville ragtop 74 Firebird - 455, e heads, TK0600 in process |
#50
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My SG 4.500 crank is going on 3 years of racing with no problems. Mild 700 HP build shifting at 6,800 RPM. Had it checked and mag'd by the machine shop when first purchased and it was good to go.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon. |
#51
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Thank you. My goal for this build is 860-880 HP. There are many opposing views on this particular brand of crankshaft, even on the "other brand" sites but most, if not all speak of the final machining process being the deal breaker and speak little about strength. I have to assume that no matter which company finishes them if they are overseas forgings they are very similar in overall strength. I'm sure some have been broken and I have spoken to a few in the bowtie camp that have broken an overseas forging, but that's where the story ends. No hows or why they failed. Mr. Kinsler's information is priceless as we all know the level of power he makes.
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Jack Ferris RestoRacing LLC www.restoracing.com Sandy, UT --------------------------------------------------- |
#52
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Quote:
I read somewhere that such was required with the 4.5" stroke to avoid cylinder wall scuffing. Would very much like to see some stories of the 4.375" builds.
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1970 Lucerne Blue Firebird Trans Am, deluxe blue interior. Original Ram Air III, M-21, 3.73. Being built as a 4" stroke "434" with SR 614 Ram Air IV heads 1972+ Lucerne Blue 4-door hardtop "what if" T-41 Le Mans Sport GT/Grand Am concepts. Equipped with future 3" journal "455 HO"/"what if" prototype "SD 455". What if GM had continued production of the 1970-72 GM A body somewhere in the southern hemisphere? |
#53
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All the builds were performance deals so the the blocks were filled atleast to the water pump holes.
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#54
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#55
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So as to avoid the cylinder wall scuffing, is such a partial water jacket filling required for a 4.375" stroke. Or for a 4.25" or even 4.0"?
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1970 Lucerne Blue Firebird Trans Am, deluxe blue interior. Original Ram Air III, M-21, 3.73. Being built as a 4" stroke "434" with SR 614 Ram Air IV heads 1972+ Lucerne Blue 4-door hardtop "what if" T-41 Le Mans Sport GT/Grand Am concepts. Equipped with future 3" journal "455 HO"/"what if" prototype "SD 455". What if GM had continued production of the 1970-72 GM A body somewhere in the southern hemisphere? |
#56
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Stock block? |
#57
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Filling the block seems to help everything, from what we've seen in our experience. However the Boss Bird guys have had success without ever using block fill. I can't say it's a necessity but almost every serious effort stock block build we've done has been filled.
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#58
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#59
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Quote:
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'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120 '66 Pontiac GTO - 389, 4 speed street cruiser |
#60
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GTO JONES's
Senior Member How many are running a 4.75 crank? GTO Jones.......You are one of the few it appears.
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79 Trans Am WS6 71 Formula 72 Formula 71 Firebird 69 Firebird |
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