Rebuild sbc 400 in K10 or Crate motor?

[2018GMC]

Hi All,

I want your recommendations on what to do with the motor in my 1979 K10. See my signature for specs. The truck runs fine now but drinks gas and was only 180hp but 330 tq new in 1979. I would like to get it to 400hp 400tq so I can have a smile on my face when its drinking gas.

 

Here are some options.

 

1. Rebuild current 400, up compression ration, Dart or Vortec heads, etc.

 

2. Buy a zz383 or similar from Chevrolet Performance. Warranty is a plus but will cost more than a rebuild.

 

3. Buy a 383E for my 97 that is currently running great and take the current 350 out of 97 and put in 79. I believe it should bolt up to Turbo 350 transmission. I would need to do an electric fuel pump, get a wiring harness, intake, computer, etc from junk yard. This would be time consuming and more work than a crate motor but I would have a Fuel injected motor in the ol 97.

 

What do you recommend? I would like to keep budget 3K - 6K.

 

 

 

Here's a few pics because posts are better with pics!

 

 

[2018GMC]

According to the local landfill scale, the truck weighs 5,080 lbs with both tanks full.

[Hantke]

well if you don't want to rebuild the 400 give it to me for my '66! haha, but i'd rebuild that 400, those are beasts!

[Chris]

5.3 crate or used junkyard 6.0 with a new manifold and a carb

[2018GMC]

well if you don't want to rebuild the 400 give it to me for my '66! haha, but i'd rebuild that 400, those are beasts!

LOL, I thought it would be cool to keep the original 400 in it so I may go that route. But just weighing my options. I'm sure someone else has been here before and has advice on what they did or what they wished they did.

 

The 400 does burn some oil on startup but not enough that I have to add any between oil changes. I think it is the Valve guides leaking? But I want more power!!!

[atsbob]

Nice truck you have! Get a crate motor from GM.. IMHO..

[2018GMC]

5.3 crate or used junkyard 6.0 with a new manifold and a carb

 

A LS would be nice, but I would need the matching trans and transfer case? Which then means fabricating new motor and transmission mounts, Shift linkage, etc.

I currently have the NP203 full time 4x4 chain driven transfer case. I converted it to part time 4X4.

[Chris]

 

A LS would be nice, but I would need the matching trans and transfer case? Which then means fabricating new motor and transmission mounts, Shift linkage, etc.

I currently have the NP203 full time 4x4 chain driven transfer case. I converted it to part time 4X4.

Holley/hooker make mount kits. Trans is adaptable

[2018GMC]

Nice truck you have! Get a crate motor from GM.. IMHO..

 

Thanks! I was going to sell it awhile back but I just couldn't do it. Now its time to put some $$$ into it.

[2018GMC]

Holley/hooker make mount kits. Trans is adaptable

 

I will look into that. What kind of mpg city / highway do you get with your 6.0?

 

Besides 2500 / 3500 trucks, the GMT800 Denali Yukon XL's had 6.0's correct?

[Hantke]

LOL, I thought it would be cool to keep the original 400 in it so I may go that route. But just weighing my options. I'm sure someone else has been here before and has advice on what they did or what they wished they did.

 

The 400 does burn some oil on startup but not enough that I have to add any between oil changes. I think it is the Valve guides leaking? But I want more power!!!

 

Around my parts people go out of their way to snatch those up, a lot of dirt track guys run them aswell, they can be built up pretty and be pretty sweet engines, I'd 100% say rebuild and tune up that 400 any day

[Chris]

 

I will look into that. What kind of mpg city / highway do you get with your 6.0?

 

Besides 2500 / 3500 trucks, the GMT800 Denali Yukon XL's had 6.0's correct?

HD, all denalis, silverado SS, and Escalade. I can manage close to 20 hwy and my normal commute in town about 20 miles a day with a lot of stop lights and 10 miles of freeway a day gets me about 14ish. Depends on my mood and A/C

[Badass69]

I would never...... ever buy a GMPP crate engine. A friend of mine owns an engine shop and I have personally got to tear down some that come in and just wow....... Junk. Failures are failures but these things are failing from just piss poor build quality. This goes all the way from your basic Goodwrench crate 350 up through the big blocks. Metal chips from not deburring, improperly installed main caps, valve seats ground crooked or falling out, piston to wall set to tight and scuffing etc. Very very poor workmanship, ill fitted parts and GM's warranty is utterly bogus. For the amount of money those things are to buy and all the fancy paperwork they show up with it sure doesn't mean much. I haven't seen an LS crate apart yet but I don't see how they would be any different. I have a crate L76 6 liter I sold to a friend but we are going to tear it down and measure it all before he ever runs it..... not to mention delete the afm and whatnot.

 

Build the 400 if you want to stay with a SBC as they are a fun engine. We put one together that ended up in a circle track car but it's a nice mild mannered engine that makes around the power you are after. It has basic Vortec heads on it, a marine spec'd hydraulic roller cam ( modest split duration... I think 218/224 on a 112 lsa) and 9.5:1 compression. The owner chose an aftermarket crank and rods for the build as he started with a bare block and forged pistons. The engine makes good torque honestly and great mid range power..... peters out just over 5 grand. The Dart Iron Eagle 165 S/S is basically a production Vortec head in a heavier duty casting with a normal intake manifold bolt pattern. But there are a thousand different opinions on a Gen 1 small block lol.

 

An LS would make more power though, run smoother doing it and be even more fun but it's all what you want. You can easily LS swap for your budget. A cam and headers equipped LQ4 will make the power you want..... plop on some 243 or 799 casting heads found off of every Gen IV 4.8 or 5.3 and bump the compression to 10.3:1 and have even more fun!

[ifixedit]

1994Vmax offers some good advice. A junkyard LS will make 400 hp pretty easily and run very smooth, the bigger the LS, the easier the 400 comes. If you stick with your original small block 400 the key is getting the right cam, and better flow and the compression bumped up (mostly from the right heads), from there it all depends on where you want your power to start. The cam profile recommended would work well, keep your LSA in the 112 degree range, it will idle smoothly and you will make nice bottom to mid range torque which is what you want for a heavy vehicle. The HO 350 cam profile and similar grinds are good torque makers and places like Summit are good places to shop for stuff reasonably priced. If you want a lopey idle then a higher stall converter will be in order for an automatic trans and your power starts to move upstairs. Either the iron Vortec or Dart heads mentioned are very good power makers, both are much better than any other stock chevy iron head even from the 60's, but with the vortec heads it requires center bolt valve covers, special vortec bolt pattern intake, self aligning rocker arms and your lift is limited depending on who you talk to at around .480 + or -. They also have pressed in rocker arm studs. For not much more $$ I'd go the iron Eagle head route, you should be able to get an assembled set for around $900. With 64cc chambers and a stock bottom end with the pistons down in the holes a bit and dished pistons you should end up around 9.0 to 9.5:1 compression, do some bottom end work and get flat top pistons up at deck height and things get better. Hot Rod did a junkyard 350 a number of years ago where they yanked a 350 out of a 77 Impala (hardly performance oriented) didn't nothing to the engine other than bolt on parts, and got just over 400 HP using vortec heads, carb, intake, cam, headers, etc., none of it was anything special, so 400 HP is very realistic. If you feel the bottom end of your 400 is in good shape, bolt on the parts mentioned and have fun!

[2018GMC]

Thanks fr the repleys and keep them coming! I keep getting all nostalgic about keeping the 400 and building it so I will probably go that route. I am also seriously thinking about putting a 700R4 built to withstand 400hp and tq or 500 hp tq to replace the old Turbo 350. I hear I will ether have to move everything ahead 3in and keep stock front and rear driveshafts. Or leave engine in original position and move crossmember back 3 inches and get new front and rear driveshafts.