sbc 350 or 400
05-17-2008, 03:13 PM
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sbc 350 or 400 I recently blew my motor and was looking to buy a sbc 350 4bolt main and rebuilt it for nitrous but I am having trouble finding one for a good price in my area but I was able to find a sb 400
I never really looked into these motor's but did here that they are know to crack, overheat and I will need to get the steam holes drilled, any opinions or suggestions
this is the setup I was planning to run on the 350: 750holley, weiland stealth or edelbrock rpm air gap intake, brodix IK 200 heads 64cc, 274 xtreme energy comp cam, forge flat top pistons, stock crank and rods with arp head and rod bolts, 9.4-9.8-1 CR depending on the headgaskets I go with and a 150 to 200shot of nitrous
I never really looked into these motor's but did here that they are know to crack, overheat and I will need to get the steam holes drilled, any opinions or suggestions
this is the setup I was planning to run on the 350: 750holley, weiland stealth or edelbrock rpm air gap intake, brodix IK 200 heads 64cc, 274 xtreme energy comp cam, forge flat top pistons, stock crank and rods with arp head and rod bolts, 9.4-9.8-1 CR depending on the headgaskets I go with and a 150 to 200shot of nitrous
05-17-2008, 06:10 PM
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I have been asking around and reading and it look like a 350 is more nitrous friendly than a 400 due to the thickness of the cylinder walls
05-18-2008, 03:18 AM
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do you know what kind of times they run, I would consider lowering the shot to 150 if I could make around 450-500hp on the motor with the setup stated above
05-18-2008, 10:09 AM
#7
I ran a 377 (destroked 400) 4.145 bore x 3.50 stroke and sprayed it for more than a 200 shot like you want for over 2 years and street drove it. I only went .020 bore and then put some splayed caps on a 2 bolt block.
9.8-1 with the parts you have will make a good torque motor in a 400 it won't be a revving motor. I ran a griffin 31x19 1 1/4 dual core radiator, Moroso 63539 street water pump with a black magic fan and it would never go over 180*
If you're running a plate system I would run a victor jr. intake, it will distribute a wet system better. You could also consider a 210cc head, 400 is 50 cid bigger than a 350 but a 200 would work fine also.
Run at minimum a 1 3/4 header. Also consider a slightly larger cc, a 400 with a flat top with a 64cc head will have a good deal of compression, maybe consider a 72cc head or slightly dished piston to get the compression you want.
On the motor on pump gas keep the timing about 34* then when you spray it of course take out the appropriate timing. I ran 2 separate fuel systems in mine on for the motor with c-12 gas, one with a 1 gallon front mounted cell with it's own pump and regulator and a return with c-16 gas.
If you can I would get an annular 750 if someone makes one, they work pretty good with nitrous, at least I like them better for nitrous than the downleg boosters. Last you might consider a nitrous HP cam it'll make a little more power on the nitrous, and since it isn't a high level N/A setup it's not going to run a big number N/A anyways so you might as well set up up to get the most off the bottle. As long as you keep the rpm down and don't run it lean a 200 shot with a forged piston will be fine, also make sure to gap the rings for a street nitrous level.
As long as you run a good cooling system and don't bore it too much you should be ok. I ran my 400 block for years without cracks or over heating.
9.8-1 with the parts you have will make a good torque motor in a 400 it won't be a revving motor. I ran a griffin 31x19 1 1/4 dual core radiator, Moroso 63539 street water pump with a black magic fan and it would never go over 180*
If you're running a plate system I would run a victor jr. intake, it will distribute a wet system better. You could also consider a 210cc head, 400 is 50 cid bigger than a 350 but a 200 would work fine also.
Run at minimum a 1 3/4 header. Also consider a slightly larger cc, a 400 with a flat top with a 64cc head will have a good deal of compression, maybe consider a 72cc head or slightly dished piston to get the compression you want.
On the motor on pump gas keep the timing about 34* then when you spray it of course take out the appropriate timing. I ran 2 separate fuel systems in mine on for the motor with c-12 gas, one with a 1 gallon front mounted cell with it's own pump and regulator and a return with c-16 gas.
If you can I would get an annular 750 if someone makes one, they work pretty good with nitrous, at least I like them better for nitrous than the downleg boosters. Last you might consider a nitrous HP cam it'll make a little more power on the nitrous, and since it isn't a high level N/A setup it's not going to run a big number N/A anyways so you might as well set up up to get the most off the bottle. As long as you keep the rpm down and don't run it lean a 200 shot with a forged piston will be fine, also make sure to gap the rings for a street nitrous level.
As long as you run a good cooling system and don't bore it too much you should be ok. I ran my 400 block for years without cracks or over heating.
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05-18-2008, 03:43 PM
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I ran a 377 (destroked 400) 4.145 bore x 3.50 stroke and sprayed it for more than a 200 shot like you want for over 2 years and street drove it. I only went .020 bore and then put some splayed caps on a 2 bolt block.
9.8-1 with the parts you have will make a good torque motor in a 400 it won't be a revving motor. I ran a griffin 31x19 1 1/4 dual core radiator, Moroso 63539 street water pump with a black magic fan and it would never go over 180*
If you're running a plate system I would run a victor jr. intake, it will distribute a wet system better. You could also consider a 210cc head, 400 is 50 cid bigger than a 350 but a 200 would work fine also.
Run at minimum a 1 3/4 header. Also consider a slightly larger cc, a 400 with a flat top with a 64cc head will have a good deal of compression, maybe consider a 72cc head or slightly dished piston to get the compression you want.
On the motor on pump gas keep the timing about 34* then when you spray it of course take out the appropriate timing. I ran 2 separate fuel systems in mine on for the motor with c-12 gas, one with a 1 gallon front mounted cell with it's own pump and regulator and a return with c-16 gas.
If you can I would get an annular 750 if someone makes one, they work pretty good with nitrous, at least I like them better for nitrous than the downleg boosters. Last you might consider a nitrous HP cam it'll make a little more power on the nitrous, and since it isn't a high level N/A setup it's not going to run a big number N/A anyways so you might as well set up up to get the most off the bottle. As long as you keep the rpm down and don't run it lean a 200 shot with a forged piston will be fine, also make sure to gap the rings for a street nitrous level.
As long as you run a good cooling system and don't bore it too much you should be ok. I ran my 400 block for years without cracks or over heating.
9.8-1 with the parts you have will make a good torque motor in a 400 it won't be a revving motor. I ran a griffin 31x19 1 1/4 dual core radiator, Moroso 63539 street water pump with a black magic fan and it would never go over 180*
If you're running a plate system I would run a victor jr. intake, it will distribute a wet system better. You could also consider a 210cc head, 400 is 50 cid bigger than a 350 but a 200 would work fine also.
Run at minimum a 1 3/4 header. Also consider a slightly larger cc, a 400 with a flat top with a 64cc head will have a good deal of compression, maybe consider a 72cc head or slightly dished piston to get the compression you want.
On the motor on pump gas keep the timing about 34* then when you spray it of course take out the appropriate timing. I ran 2 separate fuel systems in mine on for the motor with c-12 gas, one with a 1 gallon front mounted cell with it's own pump and regulator and a return with c-16 gas.
If you can I would get an annular 750 if someone makes one, they work pretty good with nitrous, at least I like them better for nitrous than the downleg boosters. Last you might consider a nitrous HP cam it'll make a little more power on the nitrous, and since it isn't a high level N/A setup it's not going to run a big number N/A anyways so you might as well set up up to get the most off the bottle. As long as you keep the rpm down and don't run it lean a 200 shot with a forged piston will be fine, also make sure to gap the rings for a street nitrous level.
As long as you run a good cooling system and don't bore it too much you should be ok. I ran my 400 block for years without cracks or over heating.
thanks for the input, I am going to research alittle more to see what it will take to push around 450-500hp and rev to 6500-7000k on a 400sbc. if I can get these #'s for around the same price it was cost me to build a 350 I'll just spray alittle less nitrous
I never thought it would be this hard to find a decent sb 4bolt 350 
05-18-2008, 08:19 PM
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the guy with the 400 want 500.00 for the complete motor but he said it's been sitting for a few years and he will have to check his yard to see about the 350.
all and all if I can not find a 350 I'll just build the 400 and run less nitrous. I was planning to spray out the hole with the 350 so maybe with the extra torque of the 400 I won't have too. One good thing is with the extra 50cube's I'll get some idle and vac back
05-18-2008, 09:56 PM
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05-19-2008, 11:42 AM
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if you are serious about a 400 block. i live about an hour east of philly. i have a 2 bolt. if you are interested, i will get it magged and do all the machine work for you. i'll put main studs or bolts in it, align hone it, square deck it, bore and hone it .020 or .030 over, depending on what you want. i'll never use this block, i just got a dart iron eagle block so i'll never use it. let me know if interested.
05-19-2008, 01:53 PM
#16
so what kind of #'s were you pushing, weight, 1/4 times on and off the juice hp, tq and rpms. from what I have been reading the a 377 will be alittle out of my budget since I they like to rev and I would have to mostly likely go with a better valve train and better flowing heads or some machine work and get the heads drilled for the steam holes
thanks for the input, I am going to research alittle more to see what it will take to push around 450-500hp and rev to 6500-7000k on a 400sbc. if I can get these #'s for around the same price it was cost me to build a 350 I'll just spray alittle less nitrous
I never thought it would be this hard to find a decent sb 4bolt 350
thanks for the input, I am going to research alittle more to see what it will take to push around 450-500hp and rev to 6500-7000k on a 400sbc. if I can get these #'s for around the same price it was cost me to build a 350 I'll just spray alittle less nitrous
I never thought it would be this hard to find a decent sb 4bolt 350I drove and raced this motor for almost 3 years and drove it on the street, all I ever did as change the valve springs once right before I sold it.
05-19-2008, 02:22 PM
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if you are serious about a 400 block. i live about an hour east of philly. i have a 2 bolt. if you are interested, i will get it magged and do all the machine work for you. i'll put main studs or bolts in it, align hone it, square deck it, bore and hone it .020 or .030 over, depending on what you want. i'll never use this block, i just got a dart iron eagle block so i'll never use it. let me know if interested.
05-19-2008, 09:00 PM
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Well I called the machine shop said he has a 3 4bolt 350 blocks, 2 with a 2 peice rear seal and 1 with a 1 peice and he also has a 400block. He basicly said the samething you guys were saying but after talking to him about how I drive the truck, nitrous and etc he suggest the 350 due to the thick walls and cooling issue's. But he did add either block will work and the 400 is a great motor but he said the 350 will live longer when it comes to dealing with traffic. So I am going with the 350 due to the better cooling and it fits better in my budget and the 400 will cause more to build correctly, ie better cooling system.
thanks for your help guys but I am going with the 350 now I just need to makeup my mind if I want to go roller or not
thanks for your help guys but I am going with the 350 now I just need to makeup my mind if I want to go roller or not
05-19-2008, 09:58 PM
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