Camming a 10.3 to 1 350

[paulzig]

Head A flows 265cfm/ Head B flows 250 cfm.
How is the cam selection differed based on this?

Thats 15 CFM difference but do all the other parameters stay the same CSA, seat angles, shape?

If so I cant see running the same cam for both changing much.

[paulzig]

Assuming the same exhaust "flowz" on both heads. Head A needs less intake duration to maintain "ratio" or wait... I mean the exhaust needs more duration to maintain "ratio" oh wait.... I mean B needs more intake duration, or less exhaust duration to maintain "ratio" I'm so confused.
I'm out!

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

The George Costanza cam selection method, 'get general consensus do opposite'.

[randy331]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

[CGT]

What are the realistic chances of the intake and exhaust wanting the same exact duration? Seems like an extremely unlikely scenario to me.

[groberts101]

What are the realistic chances of the intake and exhaust wanting the same exact duration? Seems like an extremely unlikely scenario to me.

Right.. it's not a VVT setup. And what a powerband prefer's at one rpm may not be so good at another. Just a law of averages and we're forced to pick what matters most

[GARY C]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

I don't think you can go off of ex/in ratio but seat angle would have an effect on the opening point and duration.

[77cruiser]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

You make too much you better tame it down.

[CamKing]

What are the realistic chances of the intake and exhaust wanting the same exact duration? Seems like an extremely unlikely scenario to me.

exactly the same chance, as the engine wanting 13 degrees more exhaust.
There is a correct duration required to evacuate the cylinder, for every engine application, and how it compares to the intake duration is irrelevant.

[Scotthatch]

What are the realistic chances of the intake and exhaust wanting the same exact duration? Seems like an extremely unlikely scenario to me.

exactly the same chance, as the engine wanting 13 degrees more exhaust.

I like that answer....spot on

[CGT]

What are the realistic chances of the intake and exhaust wanting the same exact duration? Seems like an extremely unlikely scenario to me.

exactly the same chance, as the engine wanting 13 degrees more exhaust.
There is a correct duration required to evacuate the cylinder, for every engine application, and how it compares to the intake duration is irrelevant.

You see a lot of 2 valve competitive, unrestricted stuff with single pattern cams? I guess it depends on the flowz right?

[CGT]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

Yes if going by the flowz. And dont you know an engine needs the same exhaust duration at 5000 and 9000? The
same duration to "evacuate" that cylinder will be ideal at both of those rpm's.

[Warp Speed]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

Yes if going by the flowz. And dont you know an engine needs the same exhaust duration at 5000 and 9000? The
same duration to "evacuate" that cylinder will be ideal at both of those rpm's.

LOL

[GARY C]

If you see 75-80% intake to exhaust ratio, some people will say perfect candidate for a single or reverse pattern, so you do the opposite, you smash 15-20° split in the bastard just out of spite...

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

Yes if going by the flowz. And dont you know an engine needs the same exhaust duration at 5000 and 9000? The
same duration to "evacuate" that cylinder will be ideal at both of those rpm's.

If you started with a single pattern cam and the engine was making 1.4 ft lbs per cube how much would it gain with 10 degrees more exhaust duration?

[groberts101]

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

Yes if going by the flowz. And dont you know an engine needs the same exhaust duration at 5000 and 9000? The
same duration to "evacuate" that cylinder will be ideal at both of those rpm's.

If you started with a single pattern cam and the engine was making 1.4 ft lbs per cube how much would it gain with 10 degrees more exhaust duration?

ooh ooh.. I might know this one! 200-300 rpm more power past peak?

[Warp Speed]

So I have the wrong cam in my 421 ?
It has 78% ex/in ratio, but has 13* more ex duration.

Would it make more power and a better power curve with a single pattern cam ?

Randy

Yes if going by the flowz. And dont you know an engine needs the same exhaust duration at 5000 and 9000? The
same duration to "evacuate" that cylinder will be ideal at both of those rpm's.

If you started with a single pattern cam and the engine was making 1.4 ft lbs per cube how much would it gain with 10 degrees more exhaust duration?

Depends on what rpm it was making the "1.4 ft lbs per cube".