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Bodyperson

Bodyperson

Pedal to the metal
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I did not stumble on to him, I was eluded to him through this site. I listened to some of his video on YouTube.
He likes David Vizard’s formula for calculating camshaft lobe separation angle.
I found it interesting that he changed the formula for Cleveland heads and big block Chevy heads.
This lets me wonder how accurate the formula can be when head flow is not just across the board.
You move the initial number of “ 126” to “127” and that’s a big change.
Change the CID a little, no big deal. Same with valve size.

So ya, Cleveland’s and BBC flow pretty good so let’s use 127 or 128. I get it. Should a SBC or SBM be calculated at say 127 when running aftermarket ported heads according to this formula?
 
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Must be another CDG. The one that I watched [ 33 min ] said 128 rule for parallel valve heads, & for canted valve heads [ Cleveland, BB Chev, etc ] needs to be bigger 131 or 132 [ from memory ].
This would widen the LSA, gives less overlap, & makes sense with canted valve heads that flow better.
 
Bewy said:
Must be another CDG. The one that I watched [ 33 min ] said 128 rule for parallel valve heads, & for canted valve heads [ Cleveland, BB Chev, etc ] needs to be bigger 131 or 132 [ from memory ].
This would widen the LSA, gives less overlap, & makes sense with canted valve heads that flow better.
Click to expand...
Oh ya, it was that much for the Cleveland and BB Chevy. Just wondering how it can be so blunt with 128 for so many different heads out there.
 
Bodyperson said:
I did not stumble on to him, I was eluded to him through this site. I listened to some of his video on YouTube.
He likes David Vizard’s formula for calculating camshaft lobe separation angle.
I found it interesting that he changed the formula for Cleveland heads and big block Chevy heads.
This lets me wonder how accurate the formula can be when head flow is not just across the board.
You move the initial number of “ 126” to “127” and that’s a big change.
Change the CID a little, no big deal. Same with valve size.

So ya, Cleveland’s and BBC flow pretty good so let’s use 127 or 128. I get it. Should a SBC or SBM be calculated at say 127 when running aftermarket ported heads according to this formula?
Click to expand...
Oh my, I got that all wrong. 128 is the “rule” sorry for the confusion. Comes natural for me.
 
128 is variable for SMALL BLOCK CHEVY ONLY. The variable changes engine to engine.
 
ch1ll said:
128 is variable for SMALL BLOCK CHEVY ONLY. The variable changes engine to engine.
Click to expand...
He said it works for sbm too. I agree the formula changes but not so much for engines but for head and head design. Hence the different parameter for different head design. IE, Cleavland and rat engines.
 
Hemi has the most efficient in and out of intake and exhaust and wedge least and canted in-between.
 
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Bodyperson said:
This lets me wonder how accurate the formula can be when head flow is not just across the board.
Click to expand...
Head flow is vaguely represented by valve size, eg.. 2.02 could be under 200 cfm and over 300 cfm and a bunch of overlap in flow between valve sizes.
 
The 128 variable was developed from 10’s of 1000’s of small block Chevy dyno pulls. In his video’s he alluded to other engines variables were estimated, at least that is what I got out of it. He said in the 318 mission impossible intake head porting video the SBM was close so another estimate.

I believe the only true way to spec a cam (his method) is from his and Stan Weiss IOP program which requires a thorough amount of engine data.

So the 128 SBC formula is a shortcut to use instead of the IOP program. For SBC only.

This is my take away on all of this.
 
ch1ll said:
The 128 variable was developed from 10’s of 1000’s of small block Chevy dyno pulls.
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Yes he got it from testing chevs
ch1ll said:
In his video’s he alluded to other engines variables were estimated, at least that is what I got out of it. He said in the 318 mission impossible intake head porting video the SBM was close so another estimate.
Click to expand...
He says you can use 128 for all wedge engines.
ch1ll said:
I believe the only true way to spec a cam (his method) is from his and Stan Weiss IOP program which requires a thorough amount of engine data.

So the 128 SBC formula is a shortcut to use instead of the IOP program. For SBC only.

This is my take away on all of this.
Click to expand...
I doubt there would be huge lsa differences from the formula or other wise what's the point of it but bet the program spits out all the other cam spec his formula don't.
 
Bodyperson said:
He said it works for sbm too. I agree the formula changes but not so much for engines but for head and head design. Hence the different parameter for different head design. IE, Cleavland and rat engines.
Click to expand...

273 said:
Yes he got it from testing chevs

He says you can use 128 for all wedge engines.

I doubt there would be huge lsa differences from the formula or other wise what's the point of it but bet the program spits out all the other cam spec his formula don't.
Click to expand...
You haven’t watched all DV’s videos or not close enough.

So once again, **** it.

I’m out.
 
Basically most streetable cams we use are cut on 108 110 112 114, 110 seems to been accepted as best compromise can you get a bit more going 108 probably, would you be better off going 108 with a little less duration than the average 110 cam idk like to see some dynos and e.t.s and people driving experiences, probably would if running less cr and maybe even tighter if running mid 8s cr or less as long valves don't hit.
 
ch1ll said:
You haven’t watched all DV’s videos or not close enough.

So once again, **** it.

I’m out.
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His videos are terrible, post some links to the ones making your point if can/will.
 
This video wasn't too bad to watch, he said the cam specs for the 318 should be accurate within a degree or so, sounds like it's should pretty accurate to me.

 
In this Video he does state 128 is for sbc and 127 is for sbf windsor, but for the 318 he choose to select it under chev and said It should accurate within a few degrees.

Does anyone no why it's 127 for ford wedge ?

 
273 said:
This video wasn't too bad to watch, he said the cam specs for the 318 should be accurate within a degree or so, sounds like it's should pretty accurate to me.

Click to expand...

i don't care to watch the vidya, can you just post what the cam spec is?
 
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If it is '127' for a Ferd Windsor, that means more overlap & suggests that the intake valve size is small-ish for the cubic inches it has to feed....
 
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