Conversion From Sbc To Bbc With 4 Speed Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

junkyardjohn · 08-08-2005, 09:18 PM

Hi Guys & Gals.... I Have A 69 1 Ton 2wd Towtruck That I'm Going To Put An 85 Front End Under. I'm Also Replacing The 350 With A Fresh 396. It Has An Sm465 4 Speed. What I Need To Know Is Will I Need A Different "z" Bar Or Complete Clutch Linkage To Go From A Sbc To A Bbc. The Front Crossmember Assy. Is Out Of A 85 1 Ton With A Big Block, & I'm Going To Use The 85 Bbc Motor Mounts. Any Help Would Sure Be Appreciated As I Hate To Have Any Last Minute Surprises. Thanks John

sakohntr · 08-08-2005, 10:43 PM

JJ- The geometry is all the same as long as its V8. When i went to bb from sb i used the smallblock engine mounts. Some say you will have manifold issues but i was going headers anyhow. I also slid it up about 1.5 inches to make more HEI room. This required me to "shorten" the linkrod between the throwout bearing arm and Z bar. I also had to slide the outboard pivot (frameside which is a bracket bolted in) forward as well. Works fine.
Good luck

junkyardjohn · 08-08-2005, 10:51 PM

Thanks Sakohntr --- I Don't Mind Moving The Bracket Thats Rivited To The Frame, Or Shortening Or Lengthening The Ajustment Rod. Just The Answer I Was Hoping For. Thanks Again John

08-08-2005, 09:18 PM	#1
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,425	Conversion From Sbc To Bbc With 4 Speed Question Hi Guys & Gals.... I Have A 69 1 Ton 2wd Towtruck That I'm Going To Put An 85 Front End Under. I'm Also Replacing The 350 With A Fresh 396. It Has An Sm465 4 Speed. What I Need To Know Is Will I Need A Different "z" Bar Or Complete Clutch Linkage To Go From A Sbc To A Bbc. The Front Crossmember Assy. Is Out Of A 85 1 Ton With A Big Block, & I'm Going To Use The 85 Bbc Motor Mounts. Any Help Would Sure Be Appreciated As I Hate To Have Any Last Minute Surprises. Thanks John __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

08-08-2005, 10:43 PM	#2
sakohntr Registered User Join Date: Mar 2002 Location: Floodwood Minnesota Posts: 1,057	conversion JJ- The geometry is all the same as long as its V8. When i went to bb from sb i used the smallblock engine mounts. Some say you will have manifold issues but i was going headers anyhow. I also slid it up about 1.5 inches to make more HEI room. This required me to "shorten" the linkrod between the throwout bearing arm and Z bar. I also had to slide the outboard pivot (frameside which is a bracket bolted in) forward as well. Works fine. Good luck __________________ 1967 K30 Napco 292/SM420 original paint 30k miles 1968 K60 Napco 396/5spd. dbl frame 52" michelins 1969 K10 SWB GMC 454/4spd 6" 35's posi,hooks 1972 C30 longhorn,BB/AT,A/C,Tilt,Toolbox,lokr 1987 K20 Chevrolet Suburban. 6" lift. 5.7L/TH400 1979 K60 GMC Coleman 4x4, 427/Allison.

08-08-2005, 10:51 PM	#3
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,425	Thanks Sakohntr --- I Don't Mind Moving The Bracket Thats Rivited To The Frame, Or Shortening Or Lengthening The Ajustment Rod. Just The Answer I Was Hoping For. Thanks Again John __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST



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