[Vckline313]

Originally Posted by PAUL K

Sorry to hear that. Keep in mind this is the Internet and that's where modern day fairy tales are created.

To have a reputable shop do my extra set of heads the way I can achieve the goals I'm looking for.
And what all do I need to be asking done?
Can a reputable machine shop do it or should I stick to pontiac gurus? There is a machine shop not far from me, I know they are good with sbc stuff, but all that doesn't correlate to pontiac

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[PAUL K]

Originally Posted by Vckline313

To have a reputable shop do my extra set of heads the way I can achieve the goals I'm looking for.
And what all do I need to be asking done?
Can a reputable machine shop do it or should I stick to pontiac gurus? There is a machine shop not far from me, I know they are good with sbc stuff, but all that doesn't correlate to pontiac

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There is a huge difference between a engine machine shop and a shop that can properly port heads. Few machine shops can port heads worth a darn but will tell you they can. I would start a thread asking for recomendation's and experiences in regards to ported Pontiac heads. I know there are good shops in Florida, Tennessee and one of the Carolinas which should all be within a days drive for you. Maybe you can find a shop that can supply cores and only have to worry about transportation one way. BTW in my previous post I meant to say UPS not USPS. USPS generally doesn't want to ship larger items and charges accordingly.

[Nacs Fab]

Newb Question. Why would you start with a set of 6x heads when a 62 Head is a better head? Is it to keep compression down?


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[Scarebird]

Far easier and more efficient to simply buy a set of KRE 72cc D ports than ship heads across the country and you still can run higher compression.

The Kauffmans made these specifically as replacements for street cars.

[Formulajones]

That's kind of where I stand when it comes to this dilemma.

By the time I have a set of factory iron heads done, new guides, seats, valves, springs, positive seals, all the machine work needed, I'm usually in for $1000 or a little more than that right off the bat.

Toss in some labor for someone that knows how to port a cylinder head and flow bench time and the price can go as far as you care to take it.

So unless it's for some sort of numbers matching deal and needs to be absolutely stock appearing, I tend to lean towards a good aluminum cylinder head when you start getting up in that price range.

I like iron heads, but to do them and do them right is just not a very cheap proposition anymore. So very few shops I even trust with machine works these days.

To add to that, I'd never run a set of aluminum heads right out of the box either until I've had a reputable place go through and at a minimum check them out for guide clearance and valve job etc.... Anymore, if it's feasible, I also like to have them flow tested just to see if they are what the manufacture claims.

[PunchT37]

Originally Posted by Formulajones

That's kind of where I stand when it comes to this dilemma.

By the time I have a set of factory iron heads done, new guides, seats, valves, springs, positive seals, all the machine work needed, I'm usually in for $1000 or a little more than that right off the bat.

Toss in some labor for someone that knows how to port a cylinder head and flow bench time and the price can go as far as you care to take it.

So unless it's for some sort of numbers matching deal and needs to be absolutely stock appearing, I tend to lean towards a good aluminum cylinder head when you start getting up in that price range.

I like iron heads, but to do them and do them right is just not a very cheap proposition anymore. So very few shops I even trust with machine works these days.

To add to that, I'd never run a set of aluminum heads right out of the box either until I've had a reputable place go through and at a minimum check them out for guide clearance and valve job etc.... Anymore, if it's feasible, I also like to have them flow tested just to see if they are what the manufacture claims.

Especially when he’s starting out with #8 heads on a 400.

[Vckline313]

Originally Posted by Nacs Fab

Newb Question. Why would you start with a set of 6x heads when a 62 Head is a better head? Is it to keep compression down?


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Where do you get the 62 head from? Car has 5c

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[Vckline313]

Originally Posted by Formulajones

That's kind of where I stand when it comes to this dilemma.

By the time I have a set of factory iron heads done, new guides, seats, valves, springs, positive seals, all the machine work needed, I'm usually in for $1000 or a little more than that right off the bat.

Toss in some labor for someone that knows how to port a cylinder head and flow bench time and the price can go as far as you care to take it.

So unless it's for some sort of numbers matching deal and needs to be absolutely stock appearing, I tend to lean towards a good aluminum cylinder head when you start getting up in that price range.

I like iron heads, but to do them and do them right is just not a very cheap proposition anymore. So very few shops I even trust with machine works these days.

To add to that, I'd never run a set of aluminum heads right out of the box either until I've had a reputable place go through and at a minimum check them out for guide clearance and valve job etc.... Anymore, if it's feasible, I also like to have them flow tested just to see if they are what the manufacture claims.

That's what I've been reading, that to get iron heads properly done the price will not be too far from a set of aluminum heads

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[PAUL K]

Don't mean to hi-jack this thread but maybe someone can explain:

If a pair of ported iron heads would out perform a pair of new aluminum heads and both were the same price why would one lean towards the aluminum heads?

[Nacs Fab]

Originally Posted by Vckline313

Where do you get the 62 head from? Car has 5c

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You said you would take the 6x heads and have them extensively ported. I am asking the forum more of a General question, why do many people use the 6X head which is typically a later less performance head than let’s say a 62 since we are on the topic of D-Ports. Why would someone use the 6x vs a 62 head if available? I’m just curious. Trying not to take this off topic.


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[Steve C.]

"why would one lean towards the aluminum heads"

Not posted as a specific answer, but offering the topic of some aluminum heads providing more modern features like a heart-shaped combustion chamber and improved spark plug placement.

That said, if the alum head and the iron head had the same flow curve would the chamber design make any difference. Other that say the timing issue. ???

Types of Combustion Chamber: Functions, Advantages & Disadvantages


.

[PAUL K]

Originally Posted by Nacs Fab

You said you would take the 6x heads and have them extensively ported. I am asking the forum more of a General question, why do many people use the 6X head which is typically a later less performance head than let’s say a 62 since we are on the topic of D-Ports. Why would someone use the 6x vs a 62 head if available? I’m just curious. Trying not to take this off topic.


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When using an iron head for a typical performance build combustion chamber size should be your first concern. You want to use the chamber that will get you to your desired compression ratio. I believe the 6X heads are more popular because they are more common and easy to get pump gas friendly compression on a 460'ish CID engine using shelf parts. In addition the 6X heads have induction hardened exhaust seats and a slightly better intake port (in stock form) compared to most earlier d-port heads. Lastly the popular 67-70 big valve heads usually command a higher price than the common 6X head and are harder to find in good condition for a performance build. JMO

[Vckline313]

Originally Posted by Nacs Fab

You said you would take the 6x heads and have them extensively ported. I am asking the forum more of a General question, why do many people use the 6X head which is typically a later less performance head than let’s say a 62 since we are on the topic of D-Ports. Why would someone use the 6x vs a 62 head if available? I’m just curious. Trying not to take this off topic.


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I have 5c on the car 6x on the ground

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[PAUL K]

Originally Posted by Steve C.

"why would one lean towards the aluminum heads"

Not posted as a specific answer, but offering the topic of some aluminum heads providing more modern features like a heart-shaped combustion chamber and improved spark plug placement.

That said, if the alum head and the iron head had the same flow curve would the chamber design make any difference. Other that say the timing issue. ???

Types of Combustion Chamber: Functions, Advantages & Disadvantages


.

Hi Steve, thanks for the response. Usually the "heart shaped" chamber helps with emissions. The better placement of the spark plug may help the power out a little. We have found no noticeable power improvement in any of the tests we've done going to a CNC heart shaped chamber compared to the old "bathtub" chamber. In some instances the bathtub chambers offered definite advantages.

[Skip Fix]

Originally Posted by PAUL K

Don't mean to hi-jack this thread but maybe someone can explain:

If a pair of ported iron heads would out perform a pair of new aluminum heads and both were the same price why would one lean towards the aluminum heads?

My back would if I have to replace head gaskets in the car

6Xs have a better basic port design.

[PAUL K]

Originally Posted by Skip Fix

My back would if I have to replace head gaskets in the car

6Xs have a better basic port design.

I am with you there young man! 💪💪👋😴

[Steve C.]

Thanks Paul.

Your testing indicated no noticeable power improvement. That somewhat follows Dave Bisschop's small 10 HP gain with the heart shaped chamber on 310 cfm CNC Edelbrock heads. He did find peak power was achieved with 2 degrees less timing.

I had a friend bring one of my original '70 d-port iron heads down from my attic for me to measure something. That was about a year ago and it's still on the garage floor and not returned to the attic. This OLD MAN even has a hard time lifting it
.

[lust4speed]

6X-8 heads will be about 98cc's after a clean up mill and be used with stock flat top piston for a street friendly compression ratio of about 9.3:1. 62's after a cleanup mill will come out about 72cc's and will require a piston with a 31cc dish to keep the same street friendly compression ratio.

[NeighborsComplaint]

Get the car running right. Worry about the other stuff down the road.

5C vs 6X w stock ports are nearly identical. If ported, the 6X is better. Both are large chamber heads (8's) so your compression is quite low on a 400 (around 7.6:1). You would need to mill them to the CR up.

As far as the sooty exhaust, if the car runs fine, is not loading up at idle and stalling, etc. I think you just need a choke adjustment since your idle vacuum is fine.

Again, don't put the cart before the horse. Optimize what you have through tuning and you may be happy with it just the way it sits. Get your carb dialed in and you'll be fine. That timing is a mystery but again, it wouldn't run if that far off. If it was BTDC, I'd wager you clipped it to the #2 cylinder which fires 45 degrees before #1.

[Vckline313]

Originally Posted by NeighborsComplaint

Get the car running right. Worry about the other stuff down the road.

5C vs 6X w stock ports are nearly identical. If ported, the 6X is better. Both are large chamber heads (8's) so your compression is quite low on a 400 (around 7.6:1). You would need to mill them to the CR up.

As far as the sooty exhaust, if the car runs fine, is not loading up at idle and stalling, etc. I think you just need a choke adjustment since your idle vacuum is fine.

Again, don't put the cart before the horse. Optimize what you have through tuning and you may be happy with it just the way it sits. Get your carb dialed in and you'll be fine. That timing is a mystery but again, it wouldn't run if that far off. If it was BTDC, I'd wager you clipped it to the #2 cylinder which fires 45 degrees before #1.

I think you have topics confused. I don't have sooty exhaust, and my timing seems to be good, 12 at idle 34 all in. I did order a recurve kit for my msd distributor and will take a stab at trying it out

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