SBC combination critique

[Sumtingwong]

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?

[BOOT]

I'd like to hear what others have to says bout that intake valve for NA with that comp.

[RevTheory]

I'd like to hear what others have to says bout that intake valve for NA with that comp.

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.

[Sumtingwong]

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?

[Newold1]

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.

[RevTheory]

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.

[BOOT]

I'd like to hear what others have to says bout that intake valve for NA with that comp.

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.

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.

[Sumtingwong]

I don't think you get there with those specs. Maybe 475HP. Build it as a 383 and use the extra torque.

So a 2.05 valve will do 500 in your opinion?

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.

Wouldn't all that early efficiency promote filling at IVC? Whats the solution smaller valve or seat configuration?

[ClassAct]

I don't think you get there with those specs. Maybe 475HP. Build it as a 383 and use the extra torque.

So a 2.05 valve will do 500 in your opinion?

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.

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.

[Newold1]

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?

[Sumtingwong]

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.

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.?

[RevTheory]

I was hoping the OP had made a typo, BOOT. My bad on a poor quote/post effort.

[pdq67]

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

[Sumtingwong]

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?

£4000.00 rough, I have cylinder head blanks only.

[Sumtingwong]

Thanks to all