Small Block to Big Block
Thread Starter
Instructor
Joined: Aug 2017
Posts: 103
Likes: 17
From: Cornelius NC
Small Block to Big Block
Always like them so I recently bought a big block hood for my 65. Since the original 327 died years ago and was replaced with a 350, I have been kicking around the idea of changing the 350 out for a 396 or 427. I figure I would have to change the front springs out, unless I put in a big block with aluminum heads and aluminum intake manifold, then maybe I could get by with the same springs. What else was different? Would I need to change the rear end or the transmission? I have power brakes if that makes a difference. Thanks.
Popular Reply
Jul 22, 2021, 08:37 PM
Race Director
Joined: Mar 2018
Posts: 10,805
Likes: 2,230
From: Golden Colorado
Beg to disagree. Big blocks rock. Extra work, yes but you’ll never regret it if you do it right.
“ Gee I really wish I had a sbc instead of this big block”. Said no one ever.
“ Gee I really wish I had a sbc instead of this big block”. Said no one ever.
Safety Car
Joined: Mar 2009
Posts: 4,191
Likes: 951
From: Corpus Christi, TX
You'll also need to change the radiator support, radiator and fan shroud. Those are all unique to big blocks and the small block stuff won't fit. You will also need big block pulleys and belts. They are also not interchangeable with small block stuff. No need to change the rear end or transmission unless you plan to put huge tires on it and beat the snot out of it. Unless you have a weird PB booster, a factory one should fit with the correct valve cover on the driver's side (has a big "dent": in it to clear the booster).
Team Owner
Joined: Feb 2003
Posts: 54,155
Likes: 9,464
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
This topic has been beaten to death Plenty of old threads on this. And if you have the AIM it’s all there under RPO L36.
Race Director
Joined: Feb 2004
Posts: 11,046
Likes: 2,592
From: Del Boca Vista FL
Don’t do it. You will hate yourself. If you are looking for performance you can build a small block that will do everything the big block will do for you. Less expensive, less labor. From experience. Big blocks look great. They suck to work on in limited engine compartment space.
Burning Brakes
Joined: Jan 2019
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From: Newport Beach, CA
2025 Restomod of the Year Finalist
2025 C2 of the Year Finalist - Modified
2022 C2 of the Year Finalist - Modified
So it depends on what you want and there are many different ways to go depending on your tastes.
If you just want bragging rights to say you have a big block, then I cannot disagree with you. Big blocks do rock! If you simply want performance then maybe a stroked small block is the better way to go.
Drifting
Joined: Sep 2009
Posts: 1,767
Likes: 1,507
From: Willis, tx
Team Owner
Joined: Feb 2003
Posts: 54,155
Likes: 9,464
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
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Safety Car
Joined: Mar 2002
Posts: 3,780
Likes: 442
From: Southwest MI
As I’ve said before, there’s room for everybody here, we just have to understand we aren’t all the same/nor do we think alike. Either you got a little one, or you got a big one….. I never wished mine was smaller (Just a little comic relief 
).
).
Last edited by 66427-450; Jul 23, 2021 at 08:31 AM.
Burning Brakes
Joined: Dec 2010
Posts: 1,224
Likes: 361
From: Southington CT
There is no clear cut answer to this. My stroked 396 small block has more HP and torque than any original big block and weighs about 100 lbs less. So my car is better balanced and faster than any original big block with no real changes necessary to the suspension or running gear. However, if you want to stroke a big block, clearly you can make it more powerful and lighter. But you will then need to change the suspension and running gear because the car was not designed for that level of power.
So it depends on what you want and there are many different ways to go depending on your tastes.
If you just want bragging rights to say you have a big block, then I cannot disagree with you. Big blocks do rock! If you simply want performance then maybe a stroked small block is the better way to go.
So it depends on what you want and there are many different ways to go depending on your tastes.
If you just want bragging rights to say you have a big block, then I cannot disagree with you. Big blocks do rock! If you simply want performance then maybe a stroked small block is the better way to go.
I read your 396 SBC build posts. Dollar for dollar I would say my 496BBC in my 66 build was a touch cheaper and makes 100 hp & 100 TQ more with all off the shelf non custom parts and is dressed to look almost 100% like a factory L72 engine bay. As Corvette guys we can't bitch about cramped engine bays. This car platform has one of the most wide open engine bays around so SBC or BBC its really not even a talking point. You can make big power with a SBC these days, I have a 395 ci SBC in my Nova and it makes 813 hp/ 563 TQ which equates to 2.05 hp/ci but that is with zero off the shelf parts. BBC/SBC debate will go on even after we are driving electric cars, but I will say I don't think I ever heard one person say "Man I wish I kept that small block in the car"
Drifting
Joined: Sep 2017
Posts: 1,951
Likes: 748
From: CT
I have always been a BB fan, and my plan is to remove the small block in my 65 and install a GMPP ZZ427 with aluminum heads and the new Tremec 5 speed. There is quite a bit to do for the change over but In my opinion well worth the work. I have nothing against a small block my 365 is a strong high winding motor, but it’s not a BB.
Melting Slicks
Joined: Feb 2015
Posts: 2,571
Likes: 1,127
From: Huntsville AL & Hills of Southern TN
Racer
Joined: Mar 2019
Posts: 438
Likes: 185
From: Auburn Wa
My original 327 got boxed up years ago and I put a 350 crate motor in. My brother has a big block C3 with side pipes and it sounds awesome, he calls my 350 a "beginner motor". Well I'm in the middle of a body off right now and am waiting on my 383 to arrive. Got to love the big blocks but I never considered going that route.