SBC combination critique
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SBC combination critique
An engine I've been thinking about trying for street strip.
350 Chevy. 4.00 x 3.48
10.5:1 compression
Dart 200 Platinum 2.08 1.6 valve with custom 30° valve job /radius\
Hydraulic roller cam 240-238 105 LCA .580 lift
Strip dominator manifold
950 Carb. Pump 91 fuel
Is there 500 horsepower here?
350 Chevy. 4.00 x 3.48
10.5:1 compression
Dart 200 Platinum 2.08 1.6 valve with custom 30° valve job /radius\
Hydraulic roller cam 240-238 105 LCA .580 lift
Strip dominator manifold
950 Carb. Pump 91 fuel
Is there 500 horsepower here?
Re: SBC combination critique
I'd like to hear what others have to says bout that intake valve for NA with that comp.
Channel About My diy Projects & Reviews https://www.youtube.com/c/BOOTdiy
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
Re: SBC combination critique
I'm hoping that was a typo. A 2.08 valve with a 30* radiused seat in a 4-inch bore and a cam on a 105 doesn't sound like a very good way to start out.
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Re: SBC combination critique
No typo. My thoughts were to get ve started early and really shine. Whats your suggestion Rev? Any VE guesses mate? I am forever open to input. Any examples out there?
Re: SBC combination critique
Intake valve to big for that head and your build.
I don't think you get there with those specs. Maybe 475HP. Build it as a 383 and use the extra torque.
I don't think you get there with those specs. Maybe 475HP. Build it as a 383 and use the extra torque.
The Older I Get, The Dumber I Get
Re: SBC combination critique
In your application, I think you'll run into a situation where you'll present so much flow potential during the overlap period that you blow your exhaust-driven intake energy right out the exhaust in one, quick gasp. Then you'll likely have so much flow available on the first half of the stoke that, unless you have a really efficient, high-velocity port, you won't have the energy built up to keep filling the cylinder after BDC.
There are several ways to look at this; I'm basically spit-balling to get the ol' mental faculties something to chew on.
There are several ways to look at this; I'm basically spit-balling to get the ol' mental faculties something to chew on.
Re: SBC combination critique
Nope not a typo, no personal experience with that size in a 350 myself but the bore to valve formula I've seen used and also some stuff I've read tells me it's too big, still some say it's not. So basically not gonna say for certain since I've not tried it myself. Still the ones who said a 2.08 is fine were higher comp or boosted and my exp with engines is that your use and situation can change some basic guidelines/rules. Kinda thought it was obvious that I didn't think it was gonna work since my post was pointing it out.
Channel About My diy Projects & Reviews https://www.youtube.com/c/BOOTdiy
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
I know as much as I can learn and try to keep an open mind to anything!
If I didn't overthink stuff I wouldn't be on speedtalk!
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Re: SBC combination critique
So a 2.05 valve will do 500 in your opinion?
Wouldn't all that early efficiency promote filling at IVC? Whats the solution smaller valve or seat configuration?
Re: SBC combination critique
Sumtingwong wrote: ↑Tue Feb 12, 2019 10:44 amSo a 2.05 valve will do 500 in your opinion?
Wouldn't all that early efficiency promote filling at IVC? Whats the solution smaller valve or seat configuration?
I wouldn't use a 30 degree seat on a lawnmower. Ever. You could have used a smaller valve, a better valve job and made more power all day long. The steep/shallow seat has been thrashed out here to the point it's become boring. Do a search and read those threads.
A 30 degree seat was useless decades ago.
Re: SBC combination critique
How much and many of these parts and such have you already acquired? Hopefully none other than maybe a block.
What's you approximate budget?
What's you approximate budget?
The Older I Get, The Dumber I Get
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Re: SBC combination critique
Im stunned to hear this. But thank you for your measure of sharing. My build is in the theoretical stages currently. Can you place some input that would help meet my goal in your opinion. Maybe my mental connection between low lift flow and torque is a partial fallacy.?ClassAct wrote: ↑Tue Feb 12, 2019 10:52 am I wouldn't use a 30 degree seat on a lawnmower. Ever. You could have used a smaller valve, a better valve job and made more power all day long. The steep/shallow seat has been thrashed out here to the point it's become boring. Do a search and read those threads.
Last edited by Sumtingwong on Tue Feb 12, 2019 11:02 am, edited 1 time in total.
Re: SBC combination critique
I was hoping the OP had made a typo, BOOT. My bad on a poor quote/post effort.
Re: SBC combination critique
Might think about making a 350(?) this way??
Use a 400 block and a 327 crank to come out with a 348.
Use flat tops and long rods and go.
pdq67
Use a 400 block and a 327 crank to come out with a 348.
Use flat tops and long rods and go.
pdq67
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