SBC combination critique

[Sumtingwong]

What would the perceived benefit of valve seat angles greater than conventionally used?

Not sure Im getting the jist of that.

High rpm or higher rpm usage I presume? Seems like it would be a negative to overlap exchange and therefore VE

[GARY C]

What would the perceived benefit of valve seat angles greater than conventionally used?

Not sure Im getting the jist of that.

High rpm or higher rpm usage I presume? Seems like it would be a negative to overlap exchange and therefore VE

In simple terms, super high lift, high rpm engines use steeper seats to prevent valve bounce, from a power prospective the reduced overlap effect allows a bigger cam than normal which allows you to take advantage of more lift earlier in the intake stroke.

[ClassAct]

What would the perceived benefit of valve seat angles greater than conventionally used?

Not sure Im getting the jist of that.

High rpm or higher rpm usage I presume? Seems like it would be a negative to overlap exchange and therefore VE

In simple terms, super high lift, high rpm engines use steeper seats to prevent valve bounce, from a power prospective the reduced overlap effect allows a bigger cam than normal which allows you to take advantage of more lift earlier in the intake stroke.

Lift is NOT a factor. Wasn't this covered in the other threads? It was. As for durability...there is no reason why a 50 degree seat is any less reliable than a 45. Just like a 45 is no less reliable than a 30.

You can stay stuck in the past or move forward. If it's a performance deal, you should at least look at a 50. IIRC, one guy used a 50 on his tow rig. Had under .500 lift. I forget his name. Look it up.

[GARY C]

What would the perceived benefit of valve seat angles greater than conventionally used?

Not sure Im getting the jist of that.

High rpm or higher rpm usage I presume? Seems like it would be a negative to overlap exchange and therefore VE

In simple terms, super high lift, high rpm engines use steeper seats to prevent valve bounce, from a power prospective the reduced overlap effect allows a bigger cam than normal which allows you to take advantage of more lift earlier in the intake stroke.

Lift is NOT a factor. Wasn't this covered in the other threads? It was. As for durability...there is no reason why a 50 degree seat is any less reliable than a 45. Just like a 45 is no less reliable than a 30.

You can stay stuck in the past or move forward. If it's a performance deal, you should at least look at a 50. IIRC, one guy used a 50 on his tow rig. Had under .500 lift. I forget his name. Look it up.

Then I guess it's settled.

[Sumtingwong]

How could there not be an increase in pressure concentration as that inclination angle increases????????

[ClassAct]

In simple terms, super high lift, high rpm engines use steeper seats to prevent valve bounce, from a power prospective the reduced overlap effect allows a bigger cam than normal which allows you to take advantage of more lift earlier in the intake stroke.

Lift is NOT a factor. Wasn't this covered in the other threads? It was. As for durability...there is no reason why a 50 degree seat is any less reliable than a 45. Just like a 45 is no less reliable than a 30.

You can stay stuck in the past or move forward. If it's a performance deal, you should at least look at a 50. IIRC, one guy used a 50 on his tow rig. Had under .500 lift. I forget his name. Look it up.

Then I guess it's settled.

So how many 50 degree valve jobs have you done? I had them in street cars (including my own) drag stuff and circle junk. I have NEVER seen the seats look any worse than any other valve job. Sure, beat on it and they look at bit worse but I've never had one fail.

Again, it's about the shape.

I suggest the OP do his 30 degree seat and be happy. It's what he wanted. I should have never said anything because moving forward for some is just too damn hard.

[midnightbluS10]

How could there not be an increase in pressure concentration as that inclination angle increases????????

So you know enough to use big words like that but can't build a run-of-the-mill 350 in any of 500 magazines without help?

Something doesn't add up.

[Sumtingwong]

How could there not be an increase in pressure concentration as that inclination angle increases????????

So you know enough to use big words like that but can't build a run-of-the-mill 350 in any of 500 magazines without help?

Something doesn't add up.

Can you provide a link to a 500 horse pump 350?

[fdicrasto]

A 4.00" bore with 2.080" intake valve and stock valve guide placement is a waste of time because of little to no bore edge to intake valve clearance. You need to pop a head on the bare block, flip it over and see what you have for clearance, if any. No problem with a bigger bore.

[GARY C]

Lift is NOT a factor. Wasn't this covered in the other threads? It was. As for durability...there is no reason why a 50 degree seat is any less reliable than a 45. Just like a 45 is no less reliable than a 30.

You can stay stuck in the past or move forward. If it's a performance deal, you should at least look at a 50. IIRC, one guy used a 50 on his tow rig. Had under .500 lift. I forget his name. Look it up.

Then I guess it's settled.

So how many 50 degree valve jobs have you done? I had them in street cars (including my own) drag stuff and circle junk. I have NEVER seen the seats look any worse than any other valve job. Sure, beat on it and they look at bit worse but I've never had one fail.

Again, it's about the shape.

I suggest the OP do his 30 degree seat and be happy. It's what he wanted. I should have never said anything because moving forward for some is just too damn hard.

Who said anything about one failing?

[GARY C]

Food for thought from the valve mnf and some pro engine builders on this subject.
https://www.enginelabs.com/features/val ... rk-engine/

EDIT
I found this interesting.
"There certainly isn’t a downside to 45-degree valve-seat angles. There are plenty of winners using a standard 60-45-30 valve job. And in a recent report by Race Engine Technology, there was an in-depth retrospect on the Cosworth CA Formula 1 V8 engine from 2006. Revving to 20,000 rpm, this 2.4-liter engine featured 41.3mm (1.63-inch) solid titanium intake valves with a 1mm (.039-inch) wide 45-degree seat. On top, there were four progressive shallow angles before blending into the stem. The intake also featured four different coatings to improve durability. On the exhaust side, there was 35.0mm (1.38-inch) sodium-cooled titanium valve with a 2mm wide 42-degree seat. So, the fastest-spinning V8 in racing used a 45-degree angle on the intake and even shallower on the exhaust."

And this!
“The seat angle is not always the magic,” reminds Boggs. “The magic is in the angles above and below it and how that shapes the venturi. People tend to fixate on the seat angle. It’s only one piece of a multi-angle puzzle. The whole thing is about creating the shape of the venturi.”

[Warp Speed]

Some things never change! Lol

[GARY C]

Some things never change! Lol

You said it!

[MELWAY]

How could there not be an increase in pressure concentration as that inclination angle increases????????

So you know enough to use big words like that but can't build a run-of-the-mill 350 in any of 500 magazines without help?

Something doesn't add up.

Can you provide a link to a 500 horse pump 350?

A 2.02 valve with 45 seat is more than capable of 500hp at
355 cu in

[NewbVetteGuy]

So perhaps I will keep it simple with a three angle 45 degree 2.02 valve seat job and hope it comes close to meeting my goals....

I could be wrong, but I think the Dart Platinum heads already come with a 45 degree valve seat angle-based 5 angle valve job. -You planning on intentionally "downgrading" your heads with a new 3 angle valve job over the stock 5 angle valve job???

https://static.summitracing.com/global/ ... 20head.pdf
Stock intake valve job: 32, 45, 60, 70, 80
Exhaust: 37, 45, radius

Adam