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Big Dave Apr 19th, 09 04:59 PM

SBC to BBC conversion '68-'74
Installing a BBC in place of a SBC in a 1968-'74 Nova consists of changing the following parts:

Frame Stands (unique to year and motor)
Radiator (copper-brass 19"x23" wide core by 4 rows thick, 1969 tank code IO) return hose connector bent 45° if equipped with A/C straight if equipped with solid tappets (no A/C was ever used in any high performance solid tappet motor)
Radiator Shroud ('67-'68 Short WP GM-PN 3916637 '69 Long WP GM-PN 3947619)
Radiator Support Bracket
7 blade fan 18 inches in diameter GM part number 3947772 (SBC used a 4 or 5 blade)
7 blade fan thermal control clutch
Heater Core
Heater Core Box
Bell Crank (Z-bar)
Clutch Linkage
Muncie Offset Shifter Bracket (1967-"68)
Muncie Hurst-supplied shifter (similar to the over-the-counter Hurst Competition-Plus model, but differed in the following ways: Slip-in "bayonet" style round handle. No adjustment bolts. 1969-'72 used a unique Hurst style aluminum shifter mounting plate.
TH400 Transmission Cross-member GM-PN 3912573
Muncie Transmission Cross-member
Alternator (14 AMP's bigger)
Battery (again higher AMP-Hour capacity)
Battery cables (heavier gauge wire)
Fuel Line tank to sub frame exit (3/8" instead of 5/16)
Return Fuel Line (only if equipped with the 325-350 horse 396)
Rochester QuadraJet stainless steel heat riser cross over block off plate
Intake Manifold (aluminum high rise #2161 4.85" max)
Valve covers, chrome plated or painted orange, with oil drippers (no dimple on drivers side that's for the Corvette)
Fuel Pump 6415748 high capacity
Fuel filter (larger than SBC to act as a fuel reserve)
Fuel Line to Carb (Holley is different than Q-Jet)
High Torque Starter Motor 1108400
Starter MotorBrace 354353
396-427 Flywheel 361950 11" clutch 14" diameter 168 tooth
454 TH 400 Flexplate (externally balanced) 3992069 168 tooth
Power Steering Pump (return line pointing to drivers side)
Alternator Brackets (year and model specific)
Cast iron Harrison A6 air conditioning compressor brackets
Big block accelerator rod or cable (and mounting bracket)
Cast iron exhaust manifolds (are not reproduced)
Headers have to fit the application and most aftermarket heads have raised exhaust ports Caveat Emptor
Dual 2-1/2" diameter tail pipes (minimum)
Front coil springs 327 lbs per inch stock (or an Eaton #MC-126)
Sway Bar (lager diameter than the SBC)
Five leaf rear springs 150 lbs per inch
High Perf. deep groove set for short water pump 67-68:
3858533 crank - double deep groove, Z/28 and HP
3765947 crank - double deep groove, PS drive insert Z/28 and HP
3770245 water pump double deep groove, HP V8
3720616 water pump pulley spacer shim - reinforcement
481042 PS pump - single deep groove perf, HP V8
[High Perf. deep groove set for long water pump 69 (All 69 and later GM pulleys are of the deep groove type).
3941105 PS pump - this is stamped steel, not cast iron
3956668 crank- two groove
COLOR=blue]392456[/COLOR] water pump single groove
3829387 Fan Generator pulley-single deep groove 43/64" shaft

This is part one of many. Part numbers are for reference only as many of them are no longer valid; and parts are out of production. I will attemp to get a repop part number from several different sources and pictures of the parts to answer a lot of futer questions.

Finding parts is more challenging than I first estimated I have been searching for hours an no one site ahs all the parts but my list of reproduction parts is growing. When I find them all I will continue with my next post.

One of the things the factory did when you ordered the Heavy Duty Suspension (part of the SS package) was to add gusset plates and weld in reinforcing pads in the body were the frame mounts were and were the chassis bolted to the car in anticipation of heavy duty use that grandma's Nova never got because it had a six banger in it.

Big Dave

brian oneil Apr 19th, 09 05:19 PM

Re: SBC to BBC conversion
Thats alot of good info Dave :thumbsup:. Now I wanna big block :yes::yes::D:D

jlowery78 Apr 23rd, 09 05:04 PM

Re: SBC to BBC conversion
Lots of great info. I made the swap last year on my 69 that originally came with a small block 350. Pulled the mouse out and dropped the rat in, a 454 big block. Everything went smooth as silk. I used the stock small block frame mounts, and also used moroso solid motor mounts for a small block. Didn't have to change out the heater box, car doesn't have ac as well. Bought cheap flowtech headers from summit racing. I'm running a turbo 350 tranny with a B&M holeshot 3000 converter. Ford 9" with 3.89 gears. Puts a grin on my face every time I drive it. This engine has a massive torque curve.

bigblockshock May 28th, 09 09:48 PM

Re: SBC to BBC conversion
do you guys know if small block are the tall and big blk are short or vs versus in the middle of puttin a 468 in a 69 nova

71BBNOVA4sp May 28th, 09 10:04 PM

Re: SBC to BBC conversion
once you go rat you never go back
nice info :D

Philip May 28th, 09 10:46 PM

Re: SBC to BBC conversion
The big block mounts are 2 different sizes, I think the drivers side is taller than the passenger side.

B73nova Jun 21st, 09 01:27 PM

Re: SBC to BBC conversion
Hey Dave, I have owned bowties for a long time but this is the first nova...I have a 73 and I was putting in my bb today when I noticed 2 things....1- the mounts dont work, I have the moroso solids for bbc but they are not lining up with the frame mounts.........2- I need more height for factory crank pulley not to hit on this normal? I think the car had a sb in it before can you help me:(

Philip Jun 21st, 09 01:40 PM

Re: SBC to BBC conversion
To put a BB in a 73 and 74 the 70 BB mount system has to be used to move the engine to the right and up. Some of the after market frame stands are junk so choose wisely before purchasing.

B73nova Jun 21st, 09 01:58 PM

Re: SBC to BBC conversion
Hey Phillip, So I can buy what name brand? and where from. I thought moroso would specify this but I guess not so I guess my pulley clearance and oil pan problem will go away

Philip Jun 21st, 09 02:20 PM

Re: SBC to BBC conversion
Brian I am not 100% sure of who has the best mount (I am a 4th gen guy cause everything fits nicer:) ). A lot of the Camaro guys like dealing with Ricks Camaro. They sell 67-68 BB stands and the 69stands. Not sure what would be different except maybe the part number stamped into them.

B73nova Jun 21st, 09 02:22 PM

Re: SBC to BBC conversion
thanks Phill I will try them first, this just baffled me. my 68 chevelle didnt have this issue and i was sure it would fit right in my nova live and learn i guess

Philip Jun 21st, 09 02:24 PM

Re: SBC to BBC conversion
I called a friend that just installed a BB in his 67 Camaro. He bought his stands from Firewheel Classics. I helped with the install and the engine fits great.

Philip Jun 21st, 09 02:29 PM

Re: SBC to BBC conversion
Brian it is the rear steer issue that makes it tight. The steering box location is the biggest problem area. My buddy, whose name is Brian also :), used the shorty headers on his. The long tubes interfered with the manual clutch linkage. He also smoothed the fire wall and is installing a Vintage Air heat and AC unit to make for more room under the hood.

Big Dave Jun 21st, 09 02:46 PM

Re: SBC to BBC conversion
Hey Philip was that a factory A/C Camaro? IF so the lower half of the box for the A/C evaporator is worth it's weight in gold as it is not being reproduced and is much in demand over on Team Camaro.

Big Dave

Philip Jun 21st, 09 02:50 PM

Re: SBC to BBC conversion
Yes it was, I'll find out what he did with the stock system.

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