400 sbc in a ‘70 K10 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

zac · 08-09-2021, 09:27 AM

Maybe not the perfect forum for this but whatever. Been shopping for 400’s to put in my ‘70 burb. Truck is stock but needs more torque. It eventually occurred to me that GM probably never put a manual trans behind these. I see aftermarket external balance flywheels available. No problem with my SM465 and stock bell housing? Any other issues?

**kwmech** · 08-09-2021, 09:47 AM

Gm-- did in fact--put manual transmissions behind the 400 sb. Nothing wrong with an aftermarket flywheel. You can also put a 454 flywheel on the 400 if you are building your own and have it balanced accordingly, if you want to run a 12'' clutch (11-7/8). It will fit the 465 and bell. GM used the same bell both small and big block.

Where are you locating a 400?? Been looking for a good core for my 91 'burb. I'm thinking of going with a Dart Block

zac · 08-09-2021, 04:45 PM

Yeah, I guess saying GM always did this or never did that is always wrong…just got back from getting a stock bore 400. Been looking for several years, mostly on Craigslist. Facebook is so bad. Most of them damaged, already maxed out on bore, or sketchy in some way. It helps that my paramedic/firefighter friend has lots of down time and finds a lot of these for me. He found the one I just bought. I won’t bore you with all the details, but it was complete and disassembled, the guy knew absolutely what he was talking about. And I had to jump in my truck and drive two hours to beat other people there. $450 non negotiable. I knew this was the one if I was actually going to do it. And I happened to be off today. Patience and luck, I guess. Maybe it’s easier in other parts of the country.

Now the harder part is finding a decent machine shop. Anything in the Cincinnati, Louisville, Lexington KY area?

**kwmech** · 08-09-2021, 04:47 PM

Good score, have the block magnafluxed

**special-K** · 08-09-2021, 05:54 PM

That's great you got one. You'll like it. This is the small block 4wds needed. My '72 K/20 Highlander was a 400sbc/4spd/4.10/35" tires. I could have put a 2x4 under the gas pedal and it wouldn't matter. Great low end power. It hardly took any throttle to roll down the hiway

b454rat · 08-09-2021, 09:38 PM

Too bad so far away, I have block already done. Been checked and all the necessary stuff needed to be done. Ready to assemble..

**chevy71super** · 08-09-2021, 11:49 PM

I had a 79 square body K10 with a 400 SB and absolutely loved the motor's low end power.

**Warrens69GMC** · 08-10-2021, 12:43 AM

Quote:

Originally Posted by kwmech

Where are you locating a 400?? Been looking for a good core for my 91 'burb. I'm thinking of going with a Dart Block

They are still out there. I have a 400 standard bore in my stash.

doubleclucker · 08-10-2021, 06:09 AM

Try this, my buddy ran this for 15 years in a daily driver.

https://www.northernautoparts.com/Pr...ProductId=3906

zac · 08-10-2021, 09:10 AM

Thanks, I had no idea those balance plates existed. The guy I bought the engine from is retired but builds and sells engines to stay busy. Also drag races. He told me shops can internally balance a 406 but thought that would be overkill for me.

**kwmech** · 08-10-2021, 11:14 AM

Quote:

Originally Posted by Warrens69GMC

They are still out there. I have a 400 standard bore in my stash.

I have a 20 over block with a hole in #6 cylinder.. as much as I love the 400s I've had a few issues over the years with them. Surprisingly I've never had one overheat. I'm thinking the Dart Block may solve those problems

https://dartheads.com/shp-blocks/

plus it will take a factory roller cam set-up

**kwmech** · 08-10-2021, 11:19 AM

Quote:

Originally Posted by doubleclucker

Try this, my buddy ran this for 15 years in a daily driver.

https://www.northernautoparts.com/Pr...ProductId=3906

Balance plates are for automatics

BASE · 08-10-2021, 03:45 PM

Those Dart blocks are nice. The crate engine shortage has just about pushed me into pulling the trigger on one.

**kwmech** · 08-10-2021, 06:49 PM

Me too, issue is 2k for just the bare block, but I have everything else minus 1 piston. Then there is changing the cam to a roller. No way I would go through all that and not put a roller cam in since the block is already dialed for it.

doubleclucker · 08-11-2021, 06:37 AM

Quote:

Originally Posted by kwmech

Balance plates are for automatics

Wow go figure? buddy 's truck was a 400-SM465/NP205 guess he was wrong for those 15 years!

**Rickysnickers** · 08-11-2021, 10:13 AM

If you are looking at crate 400s, have you seen these? https://blueprintengines.com/collect...-hp-473-ft-lbs

**kwmech** · 08-11-2021, 12:42 PM

Quote:

Originally Posted by doubleclucker

Wow go figure? buddy 's truck was a 400-SM465/NP205 guess he was wrong for those 15 years!

Possibly

GMC71k20 · 08-24-2021, 01:38 PM

i highly recommend putting vortec heads and 6" rods on the 400, its an easy 500 ft/lb under 1800rpm with a rv cam

google the impersonator 406 magazine build

my thoughts regarding the original 400 blocks depend on your budget, machine shop connections and/or patience for engine swaps. the numerous anecdotes about cracked 400 blocks and heating issues that would could be avoidable if you pay for a dyno-test/warranty crate engine

i have an original block and vortec heads with 6" rods and the speedmaster intake. This makes the sm465, 4.10s and 35" tires very easy to drive.

**kwmech** · 08-24-2021, 10:14 PM

Quote:

Originally Posted by GMC71k20

i highly recommend putting vortec heads and 6" rods on the 400, its an easy 500 ft/lb under 1800rpm with a rv cam

google the impersonator 406 magazine build

my thoughts regarding the original 400 blocks depend on your budget, machine shop connections and/or patience for engine swaps. the numerous anecdotes about cracked 400 blocks and heating issues that would could be avoidable if you pay for a dyno-test/warranty crate engine

i have an original block and vortec heads with 6" rods and the speedmaster intake. This makes the sm465, 4.10s and 35" tires very easy to drive.

What was your final compression ratio with the vortecs?

08-09-2021, 09:27 AM	#1
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	400 sbc in a ‘70 K10 Maybe not the perfect forum for this but whatever. Been shopping for 400’s to put in my ‘70 burb. Truck is stock but needs more torque. It eventually occurred to me that GM probably never put a manual trans behind these. I see aftermarket external balance flywheels available. No problem with my SM465 and stock bell housing? Any other issues?

08-09-2021, 09:47 AM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,649	Re: 400 sbc in a ‘70 K10 Gm-- did in fact--put manual transmissions behind the 400 sb. Nothing wrong with an aftermarket flywheel. You can also put a 454 flywheel on the 400 if you are building your own and have it balanced accordingly, if you want to run a 12'' clutch (11-7/8). It will fit the 465 and bell. GM used the same bell both small and big block. Where are you locating a 400?? Been looking for a good core for my 91 'burb. I'm thinking of going with a Dart Block

08-09-2021, 04:45 PM	#3
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	Re: 400 sbc in a ‘70 K10 Yeah, I guess saying GM always did this or never did that is always wrong…just got back from getting a stock bore 400. Been looking for several years, mostly on Craigslist. Facebook is so bad. Most of them damaged, already maxed out on bore, or sketchy in some way. It helps that my paramedic/firefighter friend has lots of down time and finds a lot of these for me. He found the one I just bought. I won’t bore you with all the details, but it was complete and disassembled, the guy knew absolutely what he was talking about. And I had to jump in my truck and drive two hours to beat other people there. $450 non negotiable. I knew this was the one if I was actually going to do it. And I happened to be off today. Patience and luck, I guess. Maybe it’s easier in other parts of the country. Now the harder part is finding a decent machine shop. Anything in the Cincinnati, Louisville, Lexington KY area?

08-09-2021, 04:47 PM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,649	Re: 400 sbc in a ‘70 K10 Good score, have the block magnafluxed

08-09-2021, 05:54 PM	#5
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: 400 sbc in a ‘70 K10 That's great you got one. You'll like it. This is the small block 4wds needed. My '72 K/20 Highlander was a 400sbc/4spd/4.10/35" tires. I could have put a 2x4 under the gas pedal and it wouldn't matter. Great low end power. It hardly took any throttle to roll down the hiway __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

08-09-2021, 09:38 PM	#6
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,469	Re: 400 sbc in a ‘70 K10 Too bad so far away, I have block already done. Been checked and all the necessary stuff needed to be done. Ready to assemble..

08-09-2021, 11:49 PM	#7
chevy71super Registered User Join Date: Jan 2002 Location: So Cal Posts: 658	Re: 400 sbc in a ‘70 K10 I had a 79 square body K10 with a 400 SB and absolutely loved the motor's low end power. __________________ 71 Cheyenne Super 4X4 SB 72 Cheyenne Super 4X4 SB 72 Cheyenne 4X4 SB

08-10-2021, 06:09 AM	#9
doubleclucker Registered User Join Date: Jan 2014 Location: ONTARIO CANADA Posts: 130	Re: 400 sbc in a ‘70 K10 Try this, my buddy ran this for 15 years in a daily driver. https://www.northernautoparts.com/Pr...ProductId=3906 __________________ 100:1 low gear!

08-10-2021, 09:10 AM	#10
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	Re: 400 sbc in a ‘70 K10 Thanks, I had no idea those balance plates existed. The guy I bought the engine from is retired but builds and sells engines to stay busy. Also drag races. He told me shops can internally balance a 406 but thought that would be overkill for me.

08-10-2021, 03:45 PM	#13
BASE Registered User Join Date: Oct 2016 Location: St Louis, MO Posts: 194	Re: 400 sbc in a ‘70 K10 Those Dart blocks are nice. The crate engine shortage has just about pushed me into pulling the trigger on one.

08-10-2021, 06:49 PM	#14
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,649	Re: 400 sbc in a ‘70 K10 Me too, issue is 2k for just the bare block, but I have everything else minus 1 piston. Then there is changing the cam to a roller. No way I would go through all that and not put a roller cam in since the block is already dialed for it.

08-11-2021, 10:13 AM	#16
Rickysnickers Senior Member Join Date: Oct 2014 Location: Eagle, ID Posts: 3,067	Re: 400 sbc in a ‘70 K10 If you are looking at crate 400s, have you seen these? https://blueprintengines.com/collect...-hp-473-ft-lbs

08-24-2021, 01:38 PM	#18
GMC71k20 Registered User Join Date: Aug 2002 Location: mass Posts: 1,277	Re: 400 sbc in a ‘70 K10 i highly recommend putting vortec heads and 6" rods on the 400, its an easy 500 ft/lb under 1800rpm with a rv cam google the impersonator 406 magazine build my thoughts regarding the original 400 blocks depend on your budget, machine shop connections and/or patience for engine swaps. the numerous anecdotes about cracked 400 blocks and heating issues that would could be avoidable if you pay for a dyno-test/warranty crate engine i have an original block and vortec heads with 6" rods and the speedmaster intake. This makes the sm465, 4.10s and 35" tires very easy to drive.



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