Good Cam Choice?

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Killer6 said:
If that was the Dulcich exercise, He's abandoned that altogether. It's not the lift that's key there, it's the duration seat-to-seat that's the limitation on a 30°vj, like Newbomb said...it's a flowbench "lie". Anything significant over a mild stock cam, say the avg. Factory HP, will experience reversion & lose more Hp than the "flow" will gain...
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He’s going to dig out his comic books and show us how they did it back in the day. I lived through it, and DV was leading the charge of 30 degree seats and radius valve jobs on the intake seat.

He was wrong on both.
 
I rebuilt a head for a Mack semi once, it had 20 degree intake seats (Yes, twenty). I had to buy a cutter just for that head. Never used it again.
I'd sell it cheap if somebody wants to REALLY step up their low lift flow.....
 
Below is the substantial flow testing done by Steve Dulcich, published in MM Feb 1999. Dulcich worked with D. Vizard, which could be where the idea to use a 30* seat came from.
Note:
- Column 7. Hard to read but the 30*, seat fully ported, flowed more at every lift from 0.025" to the max lift of 0.650". 346 head.
- Column 8. 30* seat, template ported, flowed more up to 400 lift. Serious flow loss started after 500 lift. 452 head
- 30* seats were tested with 2.14" valves because you cannot convert a 2.08" seat from 45 to 30.

Comments by SD on the 30* seat:
- 'Why throw away 25% better flow?
- The already excellent midrange flow reached astoundingly fat numbers, with strong double digit gains all the way to .500 inch lift. The top end flow showed moderate improvement.
In this form, this IS A KILLER STREET HEAD for STREET or RACE applications, with moderate cam lifts.

On the early 915/906 heads, the 30* seat provided substantial gains up to 0.250'lift

img343.jpg
 
Just to add to the Pontiac comment.....
All Pontiac V8 heads had fully machined combustion chambers. The flat chamber floor worked well with the 30* seat, & they used a valve with a flat head because the tulip shape does NOT work with the 30* seat. For the Ram Air 4 engine, they used the 45* seat, 1.65 rockers [ instead of 1.5 ] which added about 0.045" more valve lift.....& made about 4 hp more.
 
Bewy said:
Below is the substantial flow testing done by Steve Dulcich, published in MM Feb 1999. Dulcich worked with D. Vizard, which could be where the idea to use a 30* seat came from.
Note:
- Column 7. Hard to read but the 30*, seat fully ported, flowed more at every lift from 0.025" to the max lift of 0.650". 346 head.
- Column 8. 30* seat, template ported, flowed more up to 400 lift. Serious flow loss started after 500 lift. 452 head
- 30* seats were tested with 2.14" valves because you cannot convert a 2.08" seat from 45 to 30.

Comments by SD on the 30* seat:
- 'Why throw away 25% better flow?
- The already excellent midrange flow reached astoundingly fat numbers, with strong double digit gains all the way to .500 inch lift. The top end flow showed moderate improvement.
In this form, this IS A KILLER STREET HEAD for STREET or RACE applications, with moderate cam lifts.

On the early 915/906 heads, the 30* seat provided substantial gains up to 0.250'lift

View attachment 1716199510
Click to expand...

Right on cue with the nonsense numbers.

What you fail to grasp is you have to get the air around the valve.

I guess we all should stop and cut 30’s on everything we have because Dulcich says it’s the way to go.

Again, the flow bench will fib to you IF you let it. This is one of those cases where it’s fibbing.
 
Bewy said:
Just to add to the Pontiac comment.....
All Pontiac V8 heads had fully machined combustion chambers. The flat chamber floor worked well with the 30* seat, & they used a valve with a flat head because the tulip shape does NOT work with the 30* seat. For the Ram Air 4 engine, they used the 45* seat, 1.65 rockers [ instead of 1.5 ] which added about 0.045" more valve lift.....& made about 4 hp more.
Click to expand...
Yes they did and I've always liked that. A lot of the Ford FE engines were the same.
 
NBT,
Your BS post #157. So they took the valves out to get the good #s??
You must have a real comprehension problem. Myself, nor anybody else said to use 30* seats on everything.
Myself & others pointed out that the 30* benefit is up to about 400-500" lift. It is good for an engine that is valve lift limited, for whatever reason.
 
Bewy said:
NBT,
Your BS post #157. So they took the valves out to get the good #s??
You must have a real comprehension problem. Myself, nor anybody else said to use 30* seats on everything.
Myself & others pointed out that the 30* benefit is up to about 400-500" lift. It is good for an engine that is valve lift limited, for whatever reason.
Click to expand...


Lift has nothing to do with what valve job you chose.
 
Newbomb Turk said:
Bewy said under some arbitrary lift number a 30 degree seat is better.

It’s not. It’s never been a good option. The amount of lift you are using does not dictate what the valve job should be.
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That is a more reasonable statement, although it would be more accurate to say that lift ALONE does not dictate the valve job.

The previous statement that lift has NOTHING to do with the valve job is not accurate.
 
Earlie A said:
That is a more reasonable statement, although it would be more accurate to say that lift ALONE does not dictate the valve job.

The previous statement that lift has NOTHING to do with the valve job is not accurate.
Click to expand...


Sure it is. Do you base your valve job on lift? I don’t. No one I know of does it either.

Using lift to determine what valve job to use is nuts.

So lift has nothing to do with a valve job. Not even steeper than 45 degree seats.
 
Newbomb Turk said:
Sure it is. Do you base your valve job on lift? I don’t. No one I know of does it either.

Using lift to determine what valve job to use is nuts.

So lift has nothing to do with a valve job. Not even steeper than 45 degree seats.
Click to expand...
I stand by the accuracy of my statements.
 
Right. Valve lift has little to nothing to do with the valve job. They need to seal when closed for a stock cam just like they have to seal with a wild cam
 
volaredon said:
Right. Valve lift has little to nothing to do with the valve job. They need to seal when closed for a stock cam just like they have to seal with a wild cam
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a stock cam build do fine with a basic 3 angle valve job, most "wild" builds gonna gain more with a good 5 angle valve job, but thats apples to oranges!
 
AND NBT just keeps digging a deeper hole......to fill in with BS.
 
RustyRatRod said:
I think you've got that kinda wrong. On every single dyno simulation I've ever run, the tighter LSA gives up low RPM torque and power for a higher RPM peak torque and power. Every single time. The wider LSA also broadens and flattens the torque curve. Every single time. I think guys get hung up on peak this and peak that and forget about everything else sometimes. For the street, I'd choose a 110 or possibly even wider LSA. .....now here come the Vizard rule guys to tell me how wrong I am. Chrysler factory engineers used 113, 114 and 115 lobe seperations, so they can call them stupid, too. lol
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The famous 327/350 SBC hydraulic cam was ground on 114
IIRC one of the 340 cams was 113 or 114
 
Last edited:
Brook,

It is probably safe to say that most factory cams for American engines were ground on wide LSAs.
More knowledge gained over the years has shown that that thinking was a mistake if more hp/tq is the goal.
 
Bewy said:
Brook,

It is probably safe to say that most factory cams for American engines were ground on wide LSAs.
More knowledge gained over the years has shown that that thinking was a mistake if more hp/tq is the goal.
Click to expand...
Thats why my warmed over 360 Magnum has a 113.5 lsa
You can't argue with thousands of hrs of actual Dyno time
I don't give a damn what the computer says
 
Cause factory goes with wider lsa doesn't make it optimal. Manufacturers have more to worry about then best power.
 
Newbomb Turk said:
Not to hijack your thread but are those pistons an off the shelf part number or are they custom?

TIA

EDIT: is that .550 lift with the 1.6 rockers?
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exactly, can you provide a part/job# for the pistons please. JE, Ross ect. don't seems to comprehend 3.79 stroke!
 
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