400 sb help me build - The 1947 - Present Chevrolet & GMC Truck Message Board Network

brad20653 · 08-02-2003, 01:15 PM

Tell me everything i need to make this take off like a jet ? Give details from boring to cam to valves everything tell me what i need to do ??

**kwmech** · 08-02-2003, 01:49 PM

I've built quite a few 400sb's and what works for me is NOT boring the block as large as you can the first time, have the machine shop see if they can do a minimum cut. What I mean by this is have them actually measure and see if they can go 10 or 20 before just making a 30 or 40 cut right off the bat. If you want longevity of the engine keep compression to a reasonable level such as 8.5 to 9.5. I have found out that 400's on the street seem to like a large combustion cyl head such as 72 or 76 cc. A do not I have also encountered is using a 2.02 head you loose some bottom end and use lots of fuel. What has worked for me has been just a 1.94 with a 1.6 exhaust. Use the 350 connecting rods for a few more rpms. Balancing is very important make sure your machine shop knows what they are doing. Crane and comp make some nice cams for all kinds of applications I personally like crane cams. For a long rod 400 I have used their 268 Not a lot of lope, still has good vacuum and a lot of pull, use quality parts and have fun. A good open exhaust is also important 3'' single flows well. The last 400 long rod I built took about $2200. to put together. Strong puller and I get about 12mpg when driving with a light foot.

Jefe · 08-02-2003, 05:02 PM

Just built my first 400sb last year. Went pretty much the opposite direction. Did the 350 rod deal though, little longer stroke I believe. Bored it out .60, 2.02/1.60 stainless valves with the stock heads opened up to accomodate such large valves. Stock crank just ground down .10 and polished. Really large cam 292comp cam, like around .510 lift I believe. Hydrolic lifters and roller tipped rockers. Make sure you get hardened EVERYTHING you can if you plan on running it hard, ARP bolts and such. Very very choppy idle but if tuned right with enough spark and fuel, it will move quick! I recomend HEI of course with a hot hot coil, high output with large wires. I'm running a Holley 750 double pumper with a little larger jets to pour it in. Single plane intake for sure, try Victor Jr. or Torker II. Not a really really high compretion ratio though, to keep it cool, and still run on pump gas. Make sure that the steam holes are drilled properly in the heads. And get a 4 core rad for sure with a good shroud and large enough and properly placed rigid fan. AT LEAST 2 1/2 inch exhaust with a good flowing muffler and no cats. Gas mileage will suck hard, but it will be quick so who cares? Have Fun!

Douglas.

And if running a huge cam ask the machine shop about the cam/piston rod clearance. They might have to grind on the rods a little.

Low69CST · 08-02-2003, 07:21 PM

I just built my first 400. haven't got it on the road yet, but breakin the motor in, it sounds more wicked then I thought it would. I'm no expert, but what i've learned is most performance stuff is guaged on 350's and when thats put on a 400, it doesn't let it breathe as much as it needs. So, I put a Victor Jr. intake. I also went to Dart Iron Eagle heads with 200cc chambers. Again, when i researched it, i learned stock GM heads choked the motors down too much and most magazine build ups used 215 or 220 cc intakes, but due to cost reasons i had to stay with 200's. Also, if y ou gonna be running dailly on pump gas, u need to get 76 cc heads and then your compression will still be on the high side. You may even want to go to a slight dish piston. Another thing you may want to go to is a 5.7 or 6.0 rod. Stock 400's have 5.565's (?) and it creates a poor rod-stroke ratio. So if you buy pistons, u may want to go with one for a longer rod. I'm using a 284XE Comps Cam along with a 3000 holeshot coverter. Cam gives it a good lope and when you open the barrels it revs very quick. The carb i'm using now is a 650 double pumper which is way undersized for this motor. But it was free and i'm in college. Later on I'm planning to go to a 850 dp. I'm extremely happy with the results I'm getting from my motor, hope my input helps.

Stroker · 08-02-2003, 10:09 PM

Originally posted by brad20653

Quote:

Tell me everything i need to make this take off like a jet ? Give details from boring to cam to valves everything tell me what i need to do ??

As you can see there are a number of way to build a SB Chevy. There are a few thing we need to know before anyone can really point you in the right dirrection.

First off how do you plan to use your truck? Daily driver, Street/Strip, Drag only, Towing, Weekend Cruiser, ect....

Second how much can you invest in the truck to make it "take off like a jet" ? The engine is just one part of the equation. It's not difficult to build 500+ ft lbs of torque with a sb 400.You will then have to focus on getting the truck to hook up. If it hooks up well, the entire drivetrain will also have to be built to take the abuse.

brad20653 · 08-02-2003, 10:34 PM

ill drive everyday, what do you have in mind

brad20653 · 08-03-2003, 07:53 AM

ttt

Stroker · 08-03-2003, 10:14 PM

As already mentioned cylinder heads are one of the most important engine componets if HP is the goal. This is the basic combo I would recommend for a strong streetable 400 sbc. AFR 190cc heads, Comp extreme energy 274 cam, performer RPM intake and a 750 carb of your choice. Compression ratio of 9.5-10.0 and 1 3/4 full length headers in front of a performace exhaust system using an H or X cossover. Longer rods would be a nice addition not so much as a HP maker but should help the bores last a little longer, a properly prepped stock crank and rods (ARP bolts) should hold up without any problem, but I think something like the SCAT cast steel crank and the SCAT or Eagle sportsman rods are a worthwhile upgrade and considering the machining cost of the rods and crank are not really that much more $$. With a 2400 rpm stall and 3.73 gears you'll need some sticky meats to plant the power for sure. Here's a link to with a simular combo in a 350 installed in a little lighter car. Your truck being a little heavier will make good use of the additional stroke and bore.
http://www.prestage.com/Product+Reviews/159.aspx
Check out some of AFR's dynoed combos here.
http://airflowresearch.com

Good Luck........Stroker

08-02-2003, 01:15 PM	#1
brad20653 Senior Member Join Date: Jul 2003 Location: So. MD Posts: 218	400 sb help me build Tell me everything i need to make this take off like a jet ? Give details from boring to cam to valves everything tell me what i need to do ??

08-02-2003, 05:02 PM	#3
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	Just built my first 400sb last year. Went pretty much the opposite direction. Did the 350 rod deal though, little longer stroke I believe. Bored it out .60, 2.02/1.60 stainless valves with the stock heads opened up to accomodate such large valves. Stock crank just ground down .10 and polished. Really large cam 292comp cam, like around .510 lift I believe. Hydrolic lifters and roller tipped rockers. Make sure you get hardened EVERYTHING you can if you plan on running it hard, ARP bolts and such. Very very choppy idle but if tuned right with enough spark and fuel, it will move quick! I recomend HEI of course with a hot hot coil, high output with large wires. I'm running a Holley 750 double pumper with a little larger jets to pour it in. Single plane intake for sure, try Victor Jr. or Torker II. Not a really really high compretion ratio though, to keep it cool, and still run on pump gas. Make sure that the steam holes are drilled properly in the heads. And get a 4 core rad for sure with a good shroud and large enough and properly placed rigid fan. AT LEAST 2 1/2 inch exhaust with a good flowing muffler and no cats. Gas mileage will suck hard, but it will be quick so who cares? Have Fun! Douglas. And if running a huge cam ask the machine shop about the cam/piston rod clearance. They might have to grind on the rods a little. __________________ -1968 Chevy SWB = Frame Off/383/Muncie Car 4 speed -1968 Chevy SWB = numbers matching 307/Truck 4 speed. -1966 Chevy II = 2 door No Post/130,000 Orig miles/230 6cyl/powerglide/Vintage AC -1972 Chevy Nova = 2 door/412 Small Block -1927 Ford Roadster = Homebuilt/widened 8"/350/ Custom Everything.

08-02-2003, 07:21 PM	#4
Low69CST Registered User Join Date: May 2000 Location: Frankfort, Kentucky, USA Posts: 2,163	I just built my first 400. haven't got it on the road yet, but breakin the motor in, it sounds more wicked then I thought it would. I'm no expert, but what i've learned is most performance stuff is guaged on 350's and when thats put on a 400, it doesn't let it breathe as much as it needs. So, I put a Victor Jr. intake. I also went to Dart Iron Eagle heads with 200cc chambers. Again, when i researched it, i learned stock GM heads choked the motors down too much and most magazine build ups used 215 or 220 cc intakes, but due to cost reasons i had to stay with 200's. Also, if y ou gonna be running dailly on pump gas, u need to get 76 cc heads and then your compression will still be on the high side. You may even want to go to a slight dish piston. Another thing you may want to go to is a 5.7 or 6.0 rod. Stock 400's have 5.565's (?) and it creates a poor rod-stroke ratio. So if you buy pistons, u may want to go with one for a longer rod. I'm using a 284XE Comps Cam along with a 3000 holeshot coverter. Cam gives it a good lope and when you open the barrels it revs very quick. The carb i'm using now is a 650 double pumper which is way undersized for this motor. But it was free and i'm in college. Later on I'm planning to go to a 850 dp. I'm extremely happy with the results I'm getting from my motor, hope my input helps. __________________ '69 CST Short fleetside Lowered, 400 small block, 700R4, 4 wheel disc brakes, front sway bar & rear camaro sway bar (in progress) '87 V10 4x4 Short Fleetside Quad Suspension and Dual Tanks

08-02-2003, 10:34 PM	#6
brad20653 Senior Member Join Date: Jul 2003 Location: So. MD Posts: 218	ill drive everyday, what do you have in mind __________________ Soon to have 68 SWB 350 with Turbo350

08-03-2003, 07:53 AM	#7
brad20653 Senior Member Join Date: Jul 2003 Location: So. MD Posts: 218	ttt __________________ Soon to have 68 SWB 350 with Turbo350

08-02-2003, 01:49 PM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,487	I've built quite a few 400sb's and what works for me is NOT boring the block as large as you can the first time, have the machine shop see if they can do a minimum cut. What I mean by this is have them actually measure and see if they can go 10 or 20 before just making a 30 or 40 cut right off the bat. If you want longevity of the engine keep compression to a reasonable level such as 8.5 to 9.5. I have found out that 400's on the street seem to like a large combustion cyl head such as 72 or 76 cc. A do not I have also encountered is using a 2.02 head you loose some bottom end and use lots of fuel. What has worked for me has been just a 1.94 with a 1.6 exhaust. Use the 350 connecting rods for a few more rpms. Balancing is very important make sure your machine shop knows what they are doing. Crane and comp make some nice cams for all kinds of applications I personally like crane cams. For a long rod 400 I have used their 268 Not a lot of lope, still has good vacuum and a lot of pull, use quality parts and have fun. A good open exhaust is also important 3'' single flows well. The last 400 long rod I built took about $2200. to put together. Strong puller and I get about 12mpg when driving with a light foot.

08-03-2003, 10:14 PM	#8
Stroker Registered User Join Date: Mar 2001 Location: Moore, Ok Posts: 1,149	As already mentioned cylinder heads are one of the most important engine componets if HP is the goal. This is the basic combo I would recommend for a strong streetable 400 sbc. AFR 190cc heads, Comp extreme energy 274 cam, performer RPM intake and a 750 carb of your choice. Compression ratio of 9.5-10.0 and 1 3/4 full length headers in front of a performace exhaust system using an H or X cossover. Longer rods would be a nice addition not so much as a HP maker but should help the bores last a little longer, a properly prepped stock crank and rods (ARP bolts) should hold up without any problem, but I think something like the SCAT cast steel crank and the SCAT or Eagle sportsman rods are a worthwhile upgrade and considering the machining cost of the rods and crank are not really that much more $$. With a 2400 rpm stall and 3.73 gears you'll need some sticky meats to plant the power for sure. Here's a link to with a simular combo in a 350 installed in a little lighter car. Your truck being a little heavier will make good use of the additional stroke and bore. http://www.prestage.com/Product+Reviews/159.aspx Check out some of AFR's dynoed combos here. http://airflowresearch.com Good Luck........Stroker __________________ 72 SWB parts and pieces Oklahoma



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