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Big Block swap help (1/9)
 5/2/04 8:04pm
OwenLifetime Member
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HOUSTON, TX - USA

Vette(s):
1976 L-48 coupe


Joined: 11/15/2002
Posts: 296

I am considering an engine swap on a '76. SBC 350 out, BBC 454 in. What are some of the items I need to be aware of concerning mounting, exhaust, starter, water pump, etc? What items are interchangeable?
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Big Block swap help (2/9)
 5/2/04 11:43pm
cthulhuLifetime Member
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Hot Springs, AR - USA

Vette(s):
69 Conv #'s Match 427, TKO-600, 3.36HD-Posi, T/T, PS, PB, PW, SP, Lthr, Comp Mag 270 & Pro Rlr Rockers, Edel Air-Gap RPM, BG SD 750 MS, MSD 6AL+Tach Dist+ Blaster SS+Wires, Hly Bl Fuel Pump, K&N, Jet-Hot Hkr Side-Pipes,Steeroids, Al Rad, Spal Fans


Joined: 4/24/2004
Posts: 3208

Ive never swapped a SBC for BBC in a vette. Your direct engine accessories will need to be replaced. (exhaust manifolds, water pump, intake etc) but you can keep your distributor as it is the same in BBC as SBC. make sure you use a correct "corvette" oil pan. get the gm ls7 pan from gmpartsdirect (part #14091356). be sure to get the windage tray studs too if your block doesnt already have them.

also be prepared to have NO room under the hood..

in fact you need to be very mindful of intake/carb clearance. without a BB hood ... there isnt much room for a carb and a decent intake.
Big Block swap help (3/9)
 5/2/04 11:46pm
cthulhuLifetime Member
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Hot Springs, AR - USA

Vette(s):
69 Conv #'s Match 427, TKO-600, 3.36HD-Posi, T/T, PS, PB, PW, SP, Lthr, Comp Mag 270 & Pro Rlr Rockers, Edel Air-Gap RPM, BG SD 750 MS, MSD 6AL+Tach Dist+ Blaster SS+Wires, Hly Bl Fuel Pump, K&N, Jet-Hot Hkr Side-Pipes,Steeroids, Al Rad, Spal Fans


Joined: 4/24/2004
Posts: 3208

also... the radiator needs to be beefed up
Big Block swap help (4/9)
 5/2/04 11:48pm
cthulhuLifetime Member
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Hot Springs, AR - USA

Vette(s):
69 Conv #'s Match 427, TKO-600, 3.36HD-Posi, T/T, PS, PB, PW, SP, Lthr, Comp Mag 270 & Pro Rlr Rockers, Edel Air-Gap RPM, BG SD 750 MS, MSD 6AL+Tach Dist+ Blaster SS+Wires, Hly Bl Fuel Pump, K&N, Jet-Hot Hkr Side-Pipes,Steeroids, Al Rad, Spal Fans


Joined: 4/24/2004
Posts: 3208

and stay away from "universal" brackets for alternator and power stering.. try to get "real" brackets for a earlier model vette
Big Block swap help (5/9)
 5/2/04 11:54pm
charlie c
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MEDINA, OH - USA

Vette(s):
1977 dark red,buckskin int. 355small block ,built


Joined: 1/30/2003
Posts: 111

Owen; what happened to the blower motor??
Big Block swap help (6/9)
 5/3/04 8:05am
Gunslinger
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Frederick, MD - USA

Vette(s):
1969 convertible L71 427/435 4-speed black interior


Joined: 9/8/2003
Posts: 3398

You'll likely need to replace the front coil springs with those rated for the heavier engine, as well as front and rear sway bars like factory big block cars did.
Big Block swap help (7/9)
 5/3/04 8:57am
OwenLifetime Member
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HOUSTON, TX - USA

Vette(s):
1976 L-48 coupe


Joined: 11/15/2002
Posts: 296

Thanks for the input. I am having problems with the blown 350. I suspect a cracked block but won't know until later this week. I have a fresh 454 available and am considering a swap if the sbc is trashed...

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Big Block swap help (8/9)
 5/3/04 10:12am
markdtn
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Joined: 6/16/2003
Posts: 252

I would stay away from the BBC in a Vette unless you are just dying to have one. 1) W/ SBC the weight distribution is very close to 50/50 2)Unless you mod the hood you have to use an intake that is practically a valley 3) Cooling is much more an issue than a SB car 4)Pulleys and brackets are not cheap for this swap. 5) Probably have to change front springs. 6) Harder to work on than a SB. 7) Have you priced exhaust manifolds? $500+ for good repros or use headers

I would swap in late model fuel injection. Lot more bang for your buck. TPI is easy (that's what I have), LT1 is not bad, LS1/6 is more difficult, but not impossible. See www.corvettefaq.com The TPI can use existing exhaust, accessories, etc.
Re: Big Block swap help (9/9)
 12/7/18 3:04pm
70big4speed
Former Member

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chesterfield, MI - USA

Vette(s):
1979 L48 Auto red on red 1971 Coupe 350 auto 1970 454 4-speed Coupe sold 1977 350 auto sold


Joined: 2/16/2015
Posts: 34

I am also converting my 1971 Coupe from 350 auto to 454(468) 4-speed. Mine is a project car I bought without an engine or trans so my expenditure will be close to just restoring her with the 350 auto or darn close. Anyways, nobody has mentioned drive line issues such as trans slip yoke, differential yokes(3) and half shafts. I have 454 half shafts already but now have to contemplate issues with small block standard yokes and drive shaft(s) I have a 4-speed drive shaft so I think thats fine and my input yoke on the differential is fine. My Muncie M21 I have is a 27 spline output and I have a yoke for that, GM standard slip yoke, but wonder if I have to go beefier on that. I do plan on heavy duty u-joints all around. This 454 has been bored .60 over and I want to use a cam just 2 steps over a stock 70 LS5 spec. Holly 750 and performer intake. I wouldn't think my horsepower and torque will end up crazy or even close. I hoping for around 425 h.p. and 450 ft/lbs.

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