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Posted: 5/11/2024 12:05:40 PM EDT
[#1]
Quote HistoryOriginally Posted By BillythePoet: Don't look into metric motorcycle displacement Quote HistoryOriginally Posted By BillythePoet: Originally Posted By JuanPing: 6.  >>Here comes the part where someone predictably replies with the actual difference out to 87 decimal places<< No, you're absolutely correct and I feel the same. Just curious why BP calls it a 383 since it's not 0.030 over as you would expect. Probably just a marketing thing. "Ooh, ahh...a 383!". Everyone has heard of that at one time or another. Rather than, "what's a 377?". Don't look into metric motorcycle displacement I laughed |
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CO, USA
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Posted: 5/11/2024 12:10:24 PM EDT
[#2]
The folks mentioning 17 cubic inches is no big difference are missing the fundamental bore:stroke ratio topic and the fundamental rod length:stroke ratio topic.
These have as much influence on the engine's overall personality as the cam choice, both duration and lobe centers. |
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Posted: 5/11/2024 12:12:25 PM EDT
[#3]
Whatever you do OP, jump quick. Prices are only going up.
Pic for inspiration  Attached File Attached File Attached File |
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CO, USA
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Posted: 5/11/2024 12:16:47 PM EDT
[Last Edit: PLC_Expert]
[#4]
383 = 350 block w 400 crank 4×3.750
377 = 400 block w 350 crank 4.125×3.5 The bore:stroke ratio is way more influential than the displacement difference, rod ratio comes into play as well |
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CO, USA
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Posted: 5/11/2024 12:22:32 PM EDT
[#5]
OP I'd go with the 400 and never look back.
I hate flat torque curves all else being equal. |
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CO, USA
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Posted: 5/11/2024 12:29:46 PM EDT
[Last Edit: PLC_Expert]
[#6]
Yeah those are two totally different engines
The 383 is like a .22 The 400 is like... something much more exciting Price difference? Just curious. There's going to be a decent difference in fuel mileage as well ... 400 for me. Signed, former racing engine builder that's seen hundreds of dyno sheets and specialized in SB chevys |
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Posted: 5/11/2024 12:33:36 PM EDT
[#7]
Quote HistoryOriginally Posted By Into_the_Void: Whatever you do OP, jump quick. Prices are only going up. That's no joke. When I first looked at Blueprint's Bronco engine I think it was $6k complete with FI and now the long block costs more than that. |
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USA
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Posted: 5/11/2024 1:27:17 PM EDT
[Last Edit: Square66]
[#8]
Quote HistoryOriginally Posted By PLC_Expert: Yeah those are two totally different engines The 383 is like a .22 The 400 is like... something much more exciting Price difference? Just curious. There's going to be a decent difference in fuel mileage as well ... 400 for me. Signed, former racing engine builder that's seen hundreds of dyno sheets and specialized in SB chevys Interesting. I know ATK used to make a 406 but I don’t know what sort of quality they have? Other than GM who is a good crate engine builder? I just don’t trust anyone other than the factory or the last old timer at a local shop still building engines to still know what they are doing. The competency crisis is everywhere. |
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Posted: 5/11/2024 1:49:03 PM EDT
[#9]
Quote HistoryOriginally Posted By PLC_Expert: Yeah those are two totally different engines The 383 is like a .22 The 400 is like... something much more exciting Price difference? Just curious. There's going to be a decent difference in fuel mileage as well ... 400 for me. Signed, former racing engine builder that's seen hundreds of dyno sheets and specialized in SB chevys I can get a efi ready 383 for 7200, the 400 with intake and carb for 7k. |
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CO, USA
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Posted: 5/11/2024 1:53:43 PM EDT
[#10]
Quote HistoryOriginally Posted By Square66: Interesting. I know ATK used to make a 406 but I don’t know what sort of quality they have? Other than GM who is a good crate engine builder? I just don’t trust anyone other than the factory or the last old timer at a local shop still building engines to still know what they are doing. The competency crisis is everywhere. Quote HistoryOriginally Posted By Square66: Originally Posted By PLC_Expert: Yeah those are two totally different engines The 383 is like a .22 The 400 is like... something much more exciting Price difference? Just curious. There's going to be a decent difference in fuel mileage as well ... 400 for me. Signed, former racing engine builder that's seen hundreds of dyno sheets and specialized in SB chevys Interesting. I know ATK used to make a 406 but I don’t know what sort of quality they have? Other than GM who is a good crate engine builder? I just don’t trust anyone other than the factory or the last old timer at a local shop still building engines to still know what they are doing. The competency crisis is everywhere. I've been out of the business for too long now to seriously comment on this question. Summit racing was always strong. The OPs vendor looks reliable too judging from the dyno sheet and fine print but again, no first hand current recommendations. We dealt with car owner's shops back in the day and accumulated parts from all over. Carrillo, Milodon, weaver, TRW ... on and on then we assembled combinations and dyno tested. We did a ton of R&D which on those jobs we were continuously learning then racing the best results then repeat next season. Sprint cars, Indy cars, NASCAR ... all different rules and states of the art obviously changing over time, crate engines were a relatively new market. I was always impressed by Summit as a one-stop shop I bought some stuff from them here and there but never a crate engine. |
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GA, USA
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Posted: 5/11/2024 2:09:43 PM EDT
[Last Edit: giantpune]
[#11]
Quote HistoryOriginally Posted By PLC_Expert: 383 = 350 block w 400 crank 4×3.750 377 = 400 block w 350 crank 4.125×3.5 The bore:stroke ratio is way more influential than the displacement difference, rod ratio comes into play as well I agree with you on the bolted part, mainly because the displacement difference means about zero. However, I dont think the bore: stroke ratio is significantly different in this discussion. You're talking about 4 inches vs 4.125 inches in bore. Thats a whopping 1/8 of an inch difference in bore. OP is comparing a 383(actually a 377 CID, cause its not bored to 4.030) and a 400, so same stroke. So for OP's question, it ends up being 4.000/3.75 vs 4.125/3.75. Or 1.066666 vs 1.1. Those are so close its neglegible. The difference in the dyno sheets has next to zero to do with the bore:stroke ratio. It is down to the combination of parts they bolted to the block. You could slap a bigger cam and maybe some better heads in the 383 and make the dyno sheet match the one from the 400. |
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CO, USA
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Posted: 5/11/2024 2:11:08 PM EDT
[#12]
Quote HistoryOriginally Posted By TOTHEMAX: I can get a efi ready 383 for 7200, the 400 with intake and carb for 7k. Quote HistoryOriginally Posted By TOTHEMAX: Originally Posted By PLC_Expert: Yeah those are two totally different engines The 383 is like a .22 The 400 is like... something much more exciting Price difference? Just curious. There's going to be a decent difference in fuel mileage as well ... 400 for me. Signed, former racing engine builder that's seen hundreds of dyno sheets and specialized in SB chevys I can get a efi ready 383 for 7200, the 400 with intake and carb for 7k. The OG in me likes the 400 even better now because of the carb but tuning issues aren't a thing for me. I'm guessing efi has O2 sensor feedback loop (?) which simplifies tuneup with efi. Having said that I'm sure the engine builder can support you on carb specifics if you need that. Or a local shop (?) Drivability fine-tuning on a DD is everything and it's really not tough to tackle with carbs. A fun learning curve too if your inclined in that direction. Which you seem to be ... it's not like this is a Subaru discussion  |
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GA, USA
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Posted: 5/11/2024 2:19:32 PM EDT
[#13]
Quote HistoryOriginally Posted By PLC_Expert: The OG in me likes the 400 even better now because of the carb but tuning issues aren't a thing for me. I'm guessing efi has O2 sensor feedback loop (?) which simplifies tuneup with efi. I'm a carb fan, too. But I do use an O2 sensor to tune mine. Drill a hole, drop in a sensor, and hook up a gauge. It takes a lot of the guess work out. I also have a contraption called a carb cheater. You hook it up to the O2 sensor and manifold vacuum. It lets you data log so you can go back and see your afr, vacuum, vehicle speed, and rpms. It also has the ability to auto-tune if you want to enable that. It has an IAC valve and can give you a controlled vacuum leak to help even out the AFR. I tend to just use it as a tuning tool and leave the auto-tune off. |
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Posted: 5/11/2024 2:19:58 PM EDT
[#14]
Quote HistoryOriginally Posted By PLC_Expert: The OG in me likes the 400 even better now because of the carb but tuning issues aren't a thing for me. I'm guessing efi has O2 sensor feedback loop (?) which simplifies tuneup with efi. Having said that I'm sure the engine builder can support you on carb specifics if you need that. Or a local shop (?) Drivability fine-tuning on a DD is everything and it's really not tough to tackle with carbs. A fun learning curve too if your inclined in that direction. Which you seem to be ... it's not like this is a Subaru discussion Correct. The efi is the holley sniper and it does require an o2 sensor install, which isn't a bad thing. I do like to tinker and learning how to adjust a carb, change jets, etc has been interesting. |
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CO, USA
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Posted: 5/11/2024 2:27:11 PM EDT
[Last Edit: PLC_Expert]
[#15]
Quote HistoryOriginally Posted By giantpune: I agree with you on the bolted part, mainly because the displacement difference means about zero. However, I dont think the bore: stroke ratio is significantly different in this discussion. You're talking about 4 inches vs 4.125 inches in bore. Thats a whopping 1/8 of an inch difference in bore. OP is comparing a 383(actually a 377 CID, cause its not bored to 4.030) and a 400, so same stroke. So for OP's question, it ends up being 4.000/3.75 vs 4.125/3.75. Or 1.066666 vs 1.1. Those are so close its neglegible. The difference in the dyno sheets has next to zero to do with the bore:stroke ratio. It is down to the combination of parts they bolted to the block. You could slap a bigger cam and maybe some better heads in the 383 and make the dyno sheet match the one from the 400. Quote HistoryOriginally Posted By giantpune: Originally Posted By PLC_Expert: 383 = 350 block w 400 crank 4×3.750 377 = 400 block w 350 crank 4.125×3.5 The bore:stroke ratio is way more influential than the displacement difference, rod ratio comes into play as well I agree with you on the bolted part, mainly because the displacement difference means about zero. However, I dont think the bore: stroke ratio is significantly different in this discussion. You're talking about 4 inches vs 4.125 inches in bore. Thats a whopping 1/8 of an inch difference in bore. OP is comparing a 383(actually a 377 CID, cause its not bored to 4.030) and a 400, so same stroke. So for OP's question, it ends up being 4.000/3.75 vs 4.125/3.75. Or 1.066666 vs 1.1. Those are so close its neglegible. The difference in the dyno sheets has next to zero to do with the bore:stroke ratio. It is down to the combination of parts they bolted to the block. You could slap a bigger cam and maybe some better heads in the 383 and make the dyno sheet match the one from the 400. Yeah kind of. I was just bringing those ratios into the overall question beyond displacement only. Big bore:short stroke generalizes into higher performance for higher rpm range. As does longer rod:shorter stroke. Key is getting all the factors generally aligned together whether cam, intake, headers etc etc for the target RPM range, intended use. And again, personal preference comes into play. My old mentor generally hated flat torque curves where I prefer feeling the RPM level when things all wake up together and the engine is more peaky. We argued back and forth. Gearing comes into play... fun hobby! |
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CO, USA
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Posted: 5/11/2024 2:44:08 PM EDT
[Last Edit: PLC_Expert]
[#16]
Quote HistoryOriginally Posted By giantpune: I'm a carb fan, too. But I do use an O2 sensor to tune mine. Drill a hole, drop in a sensor, and hook up a gauge. It takes a lot of the guess work out. I also have a contraption called a carb cheater. You hook it up to the O2 sensor and manifold vacuum. It lets you data log so you can go back and see your afr, vacuum, vehicle speed, and rpms. It also has the ability to auto-tune if you want to enable that. It has an IAC valve and can give you a controlled vacuum leak to help even out the AFR. I tend to just use it as a tuning tool and leave the auto-tune off. Quote HistoryOriginally Posted By giantpune: Originally Posted By PLC_Expert: The OG in me likes the 400 even better now because of the carb but tuning issues aren't a thing for me. I'm guessing efi has O2 sensor feedback loop (?) which simplifies tuneup with efi. I'm a carb fan, too. But I do use an O2 sensor to tune mine. Drill a hole, drop in a sensor, and hook up a gauge. It takes a lot of the guess work out. I also have a contraption called a carb cheater. You hook it up to the O2 sensor and manifold vacuum. It lets you data log so you can go back and see your afr, vacuum, vehicle speed, and rpms. It also has the ability to auto-tune if you want to enable that. It has an IAC valve and can give you a controlled vacuum leak to help even out the AFR. I tend to just use it as a tuning tool and leave the auto-tune off. Interesting. Yeah I had a Harley 103 that I tricked out engine-wise and became a fan of O2 feedback. Had dynojet system on it with auto tune and it would change forever if I didn't shut it off. Pretty impressive the electronic systems are today. O2 sensors have replaced reading spark plugs and exhaust port color, generally. |
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Posted: 5/11/2024 3:46:26 PM EDT
[#17]
These kind of threads really make me want to get some of my projects out of the way so I can get this into my car.
 From what the rep said I'd get the 400. |
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Posted: 5/11/2024 4:13:36 PM EDT
[#18]
Quote HistoryOriginally Posted By Coffin-Nail: These kind of threads really make me want to get some of my projects out of the way so I can get this into my car. https://i.imgur.com/fdn3uNf.jpg From what the rep said I'd get the 400. Do it! |
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GA, USA
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Posted: 5/11/2024 4:21:49 PM EDT
[#19]
Quote HistoryOriginally Posted By Coffin-Nail: These kind of threads really make me want to get some of my projects out of the way so I can get this into my car. https://i.imgur.com/fdn3uNf.jpg From what the rep said I'd get the 400. Sheeeeeeeeit. That motor's only a couple hours away from being in your car if you want it there. Pic from my recent 350 rebuild thread when the motor was going back in. 
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MO, USA
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Posted: 5/11/2024 4:22:46 PM EDT
[#20]
When you think about it. It's the same engine with bigger or smaller cylinders. I see no advantage in reducing bore size from a performance perspective.
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Posted: 5/11/2024 5:18:32 PM EDT
[#21]
OP Nice truck.
I had a 3/4 version of that truck that my father bought new for many, many years. If the engine in it is the one it came with pull it and dissemble it before you make a decision. I am an old guy, been playing with SBCs for many decades... IF that is the stock engine it may have a factory forged crank, 1048 steel if memory serves. Mine did. It was also 4 bolt main block. If all the above proves true, and it will clean up at 30 over, I would build what ya got. In a early SBC the power is in the cylinder heads. The aftermarket aluminum heads available today are light years better than what we used to be forced to use. Edelbrock has sorted packages available with heads, cam and intake all matched. You need a good machine shop (which isn't easy to find) to check your block, crank, etc. There are many heads out there, stay away from the $999 no name stuff..it is all chinese, and the castings are crap...porous. Get heads before you buy pistons, you want to keep it around 10 to one static compression for pump gas. The BP engines are OK, but it it would be cool to build the original piece as well. EFI is neat, and it works well, but if this is your summer truck and you are not worried about winter driving a new carb works fine too...and would look right under a nice SBC. Just another opinion, we are all great at spending the other guys money, LOL |
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USA
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Posted: 5/11/2024 5:23:12 PM EDT
[#22]
Quote HistoryOriginally Posted By PLC_Expert: I've been out of the business for too long now to seriously comment on this question. Summit racing was always strong. The OPs vendor looks reliable too judging from the dyno sheet and fine print but again, no first hand current recommendations. We dealt with car owner's shops back in the day and accumulated parts from all over. Carrillo, Milodon, weaver, TRW ... on and on then we assembled combinations and dyno tested. We did a ton of R&D which on those jobs we were continuously learning then racing the best results then repeat next season. Sprint cars, Indy cars, NASCAR ... all different rules and states of the art obviously changing over time, crate engines were a relatively new market. I was always impressed by Summit as a one-stop shop I bought some stuff from them here and there but never a crate engine. I remember going to their storefront in summit county. It was inspiring to say the least. Just a high school hot rod guy who's father was a sprint car mechanic. 
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USA
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Posted: 5/11/2024 5:24:26 PM EDT
[#23]
Quote HistoryOriginally Posted By giantpune: Sheeeeeeeeit. That motor's only a couple hours away from being in your car if you want it there. Pic from my recent 350 rebuild thread when the motor was going back in. https://iili.io/JUPGA0v.png Look on the dog's face is priceless 
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Posted: 5/11/2024 5:41:59 PM EDT
[#24]
Quote HistoryOriginally Posted By SPBCTS: OP Nice truck. I had a 3/4 version of that truck that my father bought new for many, many years. If the engine in it is the one it came with pull it and dissemble it before you make a decision. I am an old guy, been playing with SBCs for many decades... IF that is the stock engine it may have a factory forged crank, 1048 steel if memory serves. Mine did. It was also 4 bolt main block. If all the above proves true, and it will clean up at 30 over, I would build what ya got. In a early SBC the power is in the cylinder heads. The aftermarket aluminum heads available today are light years better than what we used to be forced to use. Edelbrock has sorted packages available with heads, cam and intake all matched. You need a good machine shop (which isn't easy to find) to check your block, crank, etc. There are many heads out there, stay away from the $999 no name stuff..it is all chinese, and the castings are crap...porous. Get heads before you buy pistons, you want to keep it around 10 to one static compression for pump gas. The BP engines are OK, but it it would be cool to build the original piece as well. EFI is neat, and it works well, but if this is your summer truck and you are not worried about winter driving a new carb works fine too...and would look right under a nice SBC. Just another opinion, we are all great at spending the other guys money, LOL I am pretty sure it's a reman. It's waay to clean to be a factory block. |
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TX, USA
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Posted: 5/11/2024 6:36:39 PM EDT
[#25]
Quote HistoryOriginally Posted By Knightzone: Didn't the 400's have overheating issues from the steam ports? I remember hearing issues with them. Yes. Advise the 383. |
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TX, USA
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Posted: 5/11/2024 6:42:21 PM EDT
[#26]
Quote HistoryOriginally Posted By McGuy: 383 has same stroke as 400. Quote HistoryOriginally Posted By McGuy: Originally Posted By elmidgeto: For a DD, I'd go 383. Less clearancing on the bottom end, shorter stroke for the same piston diameter. Probably not a big deal, but just a smidge more peace of mind. Run L31 or 0400/LS2 PCM/efi and you can easily run circles around a carb'd 396/400 SBC. 383 has same stroke as 400. Isn't a 383 a 400 crank in a 350 block. |
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Posted: 5/11/2024 7:01:37 PM EDT
[#27]
Quote HistoryOriginally Posted By Knightzone: Didn't the 400's have overheating issues from the steam ports? I remember hearing issues with them. Real 400s had Siamese cylinders that believe. It’s been a while, but that may have causes cooling issues, but there can’t be many of them left. |
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Posted: 5/12/2024 8:23:10 AM EDT
[#28]
Quote HistoryOriginally Posted By HELOBRAVO: Real 400s had Siamese cylinders that believe. It’s been a while, but that may have causes cooling issues, but there can’t be many of them left. I only owned one but it did crack there between the cylinders eventually and was replaced with a 350. It was a great motor right up until then. The engine shop told me that it was a fairly common failure with them so I'm inclined to believe they earned that reputation. Some asshole broke into the shop and stole the old motor + TH400 trans (which was actually also cracked). I thought that it was kinda funny and I hope they hurt their back moving that old thing. |
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Posted: 5/12/2024 2:15:56 PM EDT
[#29]
Quote HistoryOriginally Posted By giantpune: Sheeeeeeeeit. That motor's only a couple hours away from being in your car if you want it there. Pic from my recent 350 rebuild thread when the motor was going back in. https://iili.io/JUPGA0v.png Quote HistoryOriginally Posted By giantpune: Originally Posted By Coffin-Nail: These kind of threads really make me want to get some of my projects out of the way so I can get this into my car. https://i.imgur.com/fdn3uNf.jpg From what the rep said I'd get the 400. Sheeeeeeeeit. That motor's only a couple hours away from being in your car if you want it there. Pic from my recent 350 rebuild thread when the motor was going back in. https://iili.io/JUPGA0v.png If the car was ready I'd have it in there, it sat outside for 40+ years so it needs a tiny bit of TLC. 
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Posted: 5/12/2024 2:52:04 PM EDT
[#30]
Man this thread is making me want to do something with my LS3 4L60e wrapped in plastic like a dead hooker in my garage.
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GA, USA
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Posted: 5/12/2024 9:57:21 PM EDT
[#31]
Quote HistoryOriginally Posted By Coffin-Nail: If the car was ready I'd have it in there, it sat outside for 40+ years so it needs a tiny bit of TLC. https://i.imgur.com/yCq1n9R.jpg That car's only about 5 orders from summitracing and 15hr worth of work from being drivable. You can get it working and enjoy it, or you can leave it broke and keep talking about how one day you'll fix it up.
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