OPINIONS: 400 sbc top end upgrade

[xxblade31]

Hi all
Looking for some help upgrading my existing 400 gm 330817
My engine runs good and looks to be rebuilt a while ago. but wanted to put on some new heads and maybe a cam for some more punch.
What I can tell: headers 3 inch exhaust, performer intake, Iron heads
Holley single pumper, small cam

Any combo recommendations would be appreciated.

Another Idea
Cost wise it maybe cheaper instead of a complete rebuilding the 400 just buying a 383 pre built motor. thoughts on that would be awesome too.

[68Gold/white]

What condition is your engine in, currently? Stock? Rebuilt once?
This will help.

[The Chainsaw]

If the bottom end is in good shape, I would run the Brodix Race-Rite 200cc heads and a Comp Cams XR300HR.

That same combo in my 68' chevelle ran 11.17@119mph multiple times on 89 octane. The torque curve was awesome even though I had my doubts when the engine builder suggested that camshaft. Peak hp was at 5700rpm and ran best when shifted about 6300rpm.

That exact combo with the larger Brodix Track 1 227cc heads ran mid 12's in a 71' shortbed, but those heads were definitely too large for the combo.

Both those motors were around 10 to 1 compression.

[xxblade31]

Well thats it. I bought the truck like it is. The motor runs good. Leaky though.
Trying to figure out if some new aluminum heads and cam would be worth it.

I identified the block today. I will check the heads see if the last guy did anything different to it other than stock.

It runs strong. Just looking for more.

Ive read about vortec heads etc. I like the 400 kinda different then normal sbc. bigger like to keep it. But new atk of blueprint maybe more cost effective.

[xxblade31]

Thanks chainsaw

thats what im looking for. Head cam combo. what is the best way to check the bottom end? pressure test?

[praisegeetarman]

400's are good motors with the addition of a good set of heads, a good cam, headers and intake. Keep the RPM's down. They don't like revs. The long stroke and short rods are a bad combination for higher RPM's.

[xxblade31]

68 gold and white
I dont know if the engine was rebuilt more than once this is how i bought it. I has nice exhaust and performer intake with holley carb. It looks like some one did alot of work on the truck it has belltech drop kit c notch weld in tranny is a turbo 350 and seems to shift good and drive smooth. I think the work was done some years ago though. As when I got it there were weeds grown up under it. and the brakes were toast. The truck would roast the 15 inch steelies but with the 20's i need more umph.

[68Gold/white]

Find out what heads are on it now. You might have heads that will work. THere's many ways to do this, even on a conservative budget.

[fwayne]

One thing to look out for. True 400 engines have siamese'd cylinder bores with steam holes. You have to make sure the mating heads are built for the application. Otherwise you get hotspots, and an engine that detonates. Especially if it has been bored over.

as PRAISEGEETARMAN said these are good engines. Keep it under 5500 RPMS and it will be a bruiser. Slap it around with stock bottom end over 6,000 much and you'll have problems.

[stsalvage]

I have a thing that.If your thinking of a full on rebuild to get some extreme performance out of your 400 Sm block You might want to.Look up this.

I have been told that there are 3 engine combo's that put almost no where or tear on a motor and they run flawless.

1 of them was the 327

It had grate RPM's and it would not hurt the motor.

this one we all know is thy best motor GM ever built the 1969 DZ302 or what some really know it as the the DZ301.


Now your block the guys that run roundy round car's Love this combination

Most of the guys that run this they use the 2 bolt main blocks and run displacement caps meaning angle caps.They can almost squeeze over 1000 Horse power out of this combo with the right heads the rite carb and a 1800.00 Knife crank some call them scat cranks.

They use a 5/8 rod and a 350 crank this motor A DESTOKED 372 standard bore or the 377 30 over.

Best thing to do if you run this combo have your drive shaft re bounced and get a 9 inch rear end cus this combo likes to brake things.

It is once of the truest bounced engines out there the 383 can't even touch it you Have the 400 Cub's or bore the 383 is only working with the 350 block.

You will burn the tires off but if you can get a rolling start with a truck you will hunt down anything as long as you got enough carburetor a Demon 850 would handle that morot combo.For street use get a mild cam.

But if your any where close to any dirt track racing stalk to them guys.

400 blocks even if there 60 over sleeve them then you will have a motor that will never where out the rings will and your pistons will But a sleeve is stronger then the rings and the piston.

I have a guy out here on the west coast ran 9 races on a sleeve motor all he did was change the rings and hone the bore.

But look up the destoked 372 standard bore or 377 30 over bore.its one hell of a combo

[praisegeetarman]

Originally Posted by fwayne

One thing to look out for. True 400 engines have siamese'd cylinder bores with steam holes. You have to make sure the mating heads are built for the application. Otherwise you get hotspots, and an engine that detonates. Especially if it has been bored over.

Yes, this is correct. The 400 heads have steam holes in them that standard sbc heads do not have. I have drilled the steam holes in non-400 heads before and had really good success, but I think most modern aftermarket heads can be ordered with the correct holes already in them.

Keith

[xxblade31]

thanks for tips everyone.

What are some good heads ? Will the patriots work. I have read they flow good and there cost effective. I looked up the brodrix heads $1700.00 set

What cam ?? Thanks for the suggestions.

I am going to check out the heads this weekend and do a pressure check on the block. Make the decision on the top end or the complete. If i do the complete I will take the advice and do the scat crank and build the nice motor.
Any idea on what the costs are for say the destroked motor ?

I rode in a 600 hp truck! It was unsafe the thing wouldn't even stay on the road. The guy punched it almost into a tree. I do want it streetable.

[midniteblues]

this thread intrests me as not to long ago i picked up a fairly low mileage stock 400ci. same cast # as yours. mine is a 2 bolt block from 76.

it ran well so i put it together and am gonna run it for now and plan for up grades in the future.

from what i read the vortecs, performer eps intake and a 468 cam is a nice combo.

stsalvage has a good opinion on the combo but i'm looking to build for low end torque for the 4x4.

[xxblade31]

yea, I talked with a machinist today what the guy was telling me made me run 10,000.00
Think I'll be doing the top end too.

I did learn alot got to see what splayed caps were. And he said patriot heads were crap.
Brodix were the way to go. I will have them pressure checked and drilled for steam holes prior to install.

There is a builder on ebay jim white i think for 5500.00 i get a dart block scat crank etc.

http://www.ebay.com/itm/CHEVY-SBC-40...-/371536383818

whole engine for a lot less. This is another option

[The Chainsaw]

Dart has some nice options for entire short blocks or even some decent budget-friendly heads.

You get what you pay for when it comes to this kind of stuff. I would NEVER trust anyone offering a Dart-blocked SBC for $5,500.

I would also look into the Brodix IK 200cc heads. I believe they are around $1400 for a pair from Summit Racing.

[rigid]

I'm with chainsaw on this one . They may be using the SHP block which is around half the price of the little M . I have used both on dirt track cars with good luck . Had a 650 hp dynoed engine with the SHP with no problems
The little M will be around $2500 bare before any machine work . Another option you may consider is PBM . They have some nice stuff for a little less money .

[xxblade31]

So I'm clear. You guys checked out the link and think that motor is bs ?
What are nbk heads ?

[Mrturner1]

Originally Posted by xxblade31

yea, I talked with a machinist today what the guy was telling me made me run 10,000.00
Think I'll be doing the top end too.

I did learn alot got to see what splayed caps were. And he said patriot heads were crap.
Brodix were the way to go. I will have them pressure checked and drilled for steam holes prior to install.

There is a builder on ebay jim white i think for 5500.00 i get a dart block scat crank etc.

http://www.ebay.com/itm/CHEVY-SBC-40...-/371536383818

whole engine for a lot less. This is another option

Wow....I just read that whole add and that is an amazing engine.

[rigid]

sorry , I missed build link the first time . I would agree that is a pretty nice piece . It is the SHP block , but like I said earlier , I would use one again . I have used every part shown it the build sheet except the heads . It looks like the are something newer to the builder . The components in the head build are also good parts .
I may have missed it , but what are your intentions with the truck ? If you are just wanting to drive down highway and spins the tires once in a while this is a heck of an engine for that . Unless you can do the work and or assembly yourself not providing any cores , I doubt you could a much better deal .
Make a list of the parts shown and search online for costs , I bet it adds up pretty quick . Good luck

[xxblade31]

I like it too. The heads are a little questionable. But buy the time I pay for heads and cam with the old block its at least $2500.00 to $3000.00 to have it done.

I also checked out the Dart short blocks those are good too. Then I can buy a better head set. but that costs more. Well I'll let you guys know what I decide. Thank you for all the input.

[xxblade31]

Hey a question. Will I have to change the fuel pump to electric ? and what size carb would I need ? I guess I can ask the builder too.

[SoCoC10]

If I remember correctly, Hot Rod magazine built a low RPM torque monster 406ci on a budget. Used the splayed caps to convert the 2 bolt block to a 4 bolt. Used cast iron Vortec cylinder heads drilled for steam holes. A Lunati .550 lift cam for 400HP and 450LBS of torque.

I used the Vortec heads and same cam on my Chevelles 327 and it ran great. Plans were to build a 406ci but a LQ4 came my way and now my Chevelles LS powered.

[xxblade31]

thanks to you all for the help. I took the truck in to talk about the engine upgrade and the mechanic told me I needed posi. it would be a waste to put that engine in a non posi truck.. Checked and I do have posi. Awesome.

It seems my engine is a good rebuilt 400 with stock heads. Still not sure if just a top end upgrade would be enough?

So, I am finishing the rear wilwood discs next.

Had a question how many amp alternator should i put on? I do have a big amp and sound system. Other than that its oem. I know this is not the right thread for that. Thought i would ask.

Thanks again

[Mrturner1]

Originally Posted by xxblade31

thanks to you all for the help. I took the truck in to talk about the engine upgrade and the mechanic told me I needed posi. it would be a waste to put that engine in a non posi truck.. Checked and I do have posi. Awesome.

It seems my engine is a good rebuilt 400 with stock heads. Still not sure if just a top end upgrade would be enough?

So, I am finishing the rear wilwood discs next.

Had a question how many amp alternator should i put on? I do have a big amp and sound system. Other than that its oem. I know this is not the right thread for that. Thought i would ask.

Thanks again

Powermaster makes a nice 105amp alternator, they have the highest idle amperage rating which is great because the highest load will be at idle. I have a 120 amp alternator that doesn't make much idle amperage, and when I'm sitting at stop lights and the electric fans come on, I have all sorts of annoying issues.

Also for a big stereo system it's a really good idea to get a capacitor, which basically collects amperage from the charging system and feeds it to your stereo at a consistent rate whether your charging system takes a big hit all of the sudden, for example, a part of a song with big deep bass notes while headlights are on and E-fans all come on at the same time.

[Jarwood]

Building a 400sbc stroked to a 427.(bored .30over)
forged crank-Eagle
h-beam rods
AFR heads
fast fuel injection
March belt set up
3/8 push rods
Milder Cam cause of clearance

I can't wait to hear that puppy!