Value of a 400/402 big block?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,017
Reaction score
10,054
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
I know there are better options for building big power, but say a guy had an opportunity to get a good running 400 big block out of a ‘72 C10 for say, cheap….
Seems like a cool engine to drop into any square. Particularly an older one.
Obviously it’s worth whatever a decent running takeout motor is at a minimum, but cool factor, semi-period correct, and a big block…
I have no current use for it, but seems like I can’t pass it up for a couple hundred bucks considering my buddy is looking to get it out of his shop.
If I don’t take it, he’s liable to trade it for a set of headers or something….
 

Shorty81

Baby Boomer
Joined
Mar 19, 2018
Posts
2,885
Reaction score
5,145
Location
North West ohio
First Name
Darren
Truck Year
86
Truck Model
K20
Engine Size
496
I know there are better options for building big power, but say a guy had an opportunity to get a good running 400 big block out of a ‘72 C10 for say, cheap….
Seems like a cool engine to drop into any square. Particularly an older one.
Obviously it’s worth whatever a decent running takeout motor is at a minimum, but cool factor, semi-period correct, and a big block…
I have no current use for it, but seems like I can’t pass it up for a couple hundred bucks considering my buddy is looking to get it out of his shop.
If I don’t take it, he’s liable to trade it for a set of headers or something….
I'd pick that up in a heartbeat.
 

Dooley

Full Access Member
Joined
Mar 19, 2014
Posts
365
Reaction score
951
Location
North Coast
First Name
RW
Truck Year
1988
Truck Model
V30
Engine Size
454
If it was close I would grab it.
My 1972 GMC 3500 Wideside had one stock.
I wish i still had that truck. Factory in dash tach.
402, 8.5' long pickup box, under bed right side tool storage box, and auxiliary left side 18 gal. fuel tank.
 

Salty Crusty

Full Access Member
Joined
Apr 10, 2020
Posts
211
Reaction score
230
Location
Texas
First Name
Gary
Truck Year
1986
Truck Model
c1500
Engine Size
565
There's a reason many reject a 396/402 in favor of 454's: POWER

Even the 4.250" standard bore big blocks have issues with the big combustion chambers of big block heads, many builders notch the tops of the bores to help it breathe. This problem is magnified with the smaller bore 396/402 block. This causes problems with fuel efficiency and emissions. And you won't make as much power as an LS 5.3.

Now take that 3.766" stroke out of a 402 and drop it into a 454 block and you'll have a 427. Short stroke/big bore, the recipe for power.

It's sitting around in his shop for a reason...
 

45tt

Full Access Member
Joined
Aug 14, 2020
Posts
272
Reaction score
1,021
Location
Florida
First Name
MJ
Truck Year
1975
Truck Model
GMC Sierra Grande K15
Engine Size
350
I recommend picking it up, even if you just flip it for profit.

I had one in my old 72 Custom Camper and I loved it.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,017
Reaction score
10,054
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
@Salty Crusty
For sure. He’s building a bigger, easier to build engine. For all the reasons you mentioned basically.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,017
Reaction score
10,054
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
I recommend picking it up, even if you just flip it for profit.

I had one in my old 72 Custom Camper and I loved it.
Yeah, can’t really just flip it on him. Bro code, right?
But thinking more about buying a cool solution to a problem I don’t have yet…
I wouldn’t want to build it either. Have looked into it and bang for the buck isn’t there compared to other/easier options. iMO
I may just find an excuse to hang a boat anchor on my engine stand for an undetermined amount of time. Lol.
In the meantime, as long as it’s not going anywhere it looks better taking up space in his shop than mine!
 

Salty Crusty

Full Access Member
Joined
Apr 10, 2020
Posts
211
Reaction score
230
Location
Texas
First Name
Gary
Truck Year
1986
Truck Model
c1500
Engine Size
565
And in a few years, you'll get to pass it along to another friend..and so on, and so on....
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,141
Reaction score
24,084
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
When I was younger, a guy I know offered to sell me the 396 (402) from his '70 Nova SS. It ran and performed nicely. I still kick myself for not buying it.

I also kick myself for not trying to buy the 4-speed from him as well, lol.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,017
Reaction score
10,054
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
And in a few years, you'll get to pass it along to another friend..and so on, and so on....
Right? Probably after I have to build a cart to roll it into a moving van or something ridiculous!
And that’s why it’s still in his shop, but I’ll probably do something silly and buy it anyway
 

Salty Crusty

Full Access Member
Joined
Apr 10, 2020
Posts
211
Reaction score
230
Location
Texas
First Name
Gary
Truck Year
1986
Truck Model
c1500
Engine Size
565
^ been there, done that...if it's cheap, no harm, no foul. You might find somebody with a late 60's muscle car that wants it, it's a great feeling to facilitate someone's restoration.
 

Allan Abley

Full Access Member
Joined
Mar 15, 2021
Posts
53
Reaction score
21
Location
Hudson, Wisconsin
First Name
Allan
Truck Year
1986
Truck Model
Silverado C10
Engine Size
305
Sounds like it is hard to pass on an offer like that.
 

JeffK10America

Supporting Member
Supporting Member
Joined
Oct 31, 2020
Posts
316
Reaction score
675
Location
Easley sc
First Name
Jeff
Truck Year
1985
Truck Model
K10
Engine Size
350
I’ve experienced a 402 .. like to have one now for my chevelle . There good engines !
That’s a good buy for that engine!
 

Turbo4whl

Supporting Member
Supporting Member
Joined
Oct 30, 2019
Posts
2,898
Reaction score
6,534
Location
Downingtown, PA
First Name
Wayne
Truck Year
1974
Truck Model
Jimmy
Engine Size
350
The 1972 402, if it still has the factory heads will have the same heads used on the 454s. Fully quenched combustion chamber that work just fine with hi-dome pistons. The earlier heads did have hot spots.

You will need to machine and add hardened exhaust valve seats. Mild RV cam will build lots of torque!
 

Latest posts

Forum statistics

Threads
42,201
Posts
911,213
Members
33,695
Latest member
1998_K1500_Sub
Top