Found why the Closed Chamber heads did not work - Chevelle Tech
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post #1 of 26 (permalink) Old Nov 19th, 19, 2:56 PM Thread Starter
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Found why the Closed Chamber heads did not work

My good friend who is a cyl head guy figured out why my CC 215's did not work this year. He spotted it in the pictures I sent him before and after the work I did, here is what happened. The first picture was the way I got them and I did know the valve job was horrible but I did not realize that I should have opened up the bowl area more according to him. He said, cramming in a large valve without opening up the port/bowl is not going to help and most likely hurt power mainly torque. He went on to say that my valve job looked great but if I were to open the intake bowls more and do some chamber work those heads will pick up a lot. Since I have not worked over too many of these in the past I was unaware of most of this. I really though a bowl clean would work, I was wrong. As you can see in the before and after pictures he was right. Good news is he really liked my L-29 heads so that will be the next test on this 461.
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post #2 of 26 (permalink) Old Nov 19th, 19, 3:42 PM
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We need flowbench 😎 i have my ported peanuts laying on my table, every time i look at those it is very hard for me to not do any more grinding, but it is Irritating to do modifications without knowing the impact.
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post #3 of 26 (permalink) Old Nov 19th, 19, 3:45 PM
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Re: Found why the Closed Chamber heads did not work

Closed chamber ovals have always worked well for me and others over the years.
Now you know why yours did not.
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post #4 of 26 (permalink) Old Nov 19th, 19, 4:01 PM
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Re: Found why the Closed Chamber heads did not work

Follow Mark Jones / VortecPro Recommendations from his videos..hell of a good starting point, might be hard to improve over his results, assuming you have the proper machinery to implement his recommendations. Good luck.
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post #5 of 26 (permalink) Old Nov 19th, 19, 5:08 PM
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Re: Found why the Closed Chamber heads did not work

Ever hear of an early Buick NAIL HEAD engine? Those engines had what is referred to as a "tulip shaped head" valve set.

Now, I am fully aware the cylinder head gurus will bo bonkers over this,m but, it is not ll porting to make a head work.

Almost every head guru does it dead wrong, they "flow" a port DRY, air only, and there lies the rub. Does your engine run on air only? I doubt it, they run on a WET fuel/air mixture, not dry air.

Ever see a fog mist change direction in a fog bank? Same thing occurs in a port, even though the mixture is under vacuum.

The Buick people knew this, and developed one other facet of their Nail Head port/valve development, PUTTING THE WET MIXTURE IN THE RIGHT PLACE IN THE CHAMBER.

The tulip directed mixture flow to where it needed to be in the chamber to be most efficient. And, helped to make transition mixture flow in the port go where it should go.

The biggest problem with dry flow head work is, do the ports actually do what they should, get the mixture to everywhere in the chamber, or, does it literally force dry, dead fill areas in that chamber.

The closed chamber big block heads had a few very bad flow paths, and created lean spots with the wrong flow fill patterns.

Think about this the next time you decide to go insane portng nuts, and hog that port bowl out, cut that valve, etc.
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post #6 of 26 (permalink) Old Nov 19th, 19, 6:57 PM
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Re: Found why the Closed Chamber heads did not work

Clarification, the name "Nail Head" didn't refer to any specific engine design, only the tulip shape of the valve heads, as used to direct fuel mix to the chambers correctly. The chambers were a basic wedge, equidistant for each part of the wedge, pistons had a slight dome, and the valves ran straight up and down into one face of the wedge in the heads.

Just wanted to make that fact clear. thanks.
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post #7 of 26 (permalink) Old Nov 19th, 19, 9:23 PM Thread Starter
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Re: Found why the Closed Chamber heads did not work

Funny thing is, I did not even do a ton of porting to my peanut port heads, they have been one of the best heads I have tried in a long time. Guess I will need to try them on a short block with some more compression and it will really come alive.
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post #8 of 26 (permalink) Old Nov 19th, 19, 10:52 PM
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Re: Found why the Closed Chamber heads did not work

Dave Ray, do you know who Lloyd Creek is?
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Machined GM production heads
Oil pan modifications
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post #9 of 26 (permalink) Old Nov 19th, 19, 11:42 PM
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Re: Found why the Closed Chamber heads did not work

Quote:
Originally Posted by 68Chevele View Post
My good friend who is a cyl head guy figured out why my CC 215's did not work this year. He spotted it in the pictures I sent him before and after the work I did, here is what happened. The first picture was the way I got them and I did know the valve job was horrible but I did not realize that I should have opened up the bowl area more according to him. He said, cramming in a large valve without opening up the port/bowl is not going to help and most likely hurt power mainly torque. He went on to say that my valve job looked great but if I were to open the intake bowls more and do some chamber work those heads will pick up a lot. Since I have not worked over too many of these in the past I was unaware of most of this. I really though a bowl clean would work, I was wrong. As you can see in the before and after pictures he was right. Good news is he really liked my L-29 heads so that will be the next test on this 461.
Would love to know for sure. Would be a good test to see these with the suggested changes from your friend and back on the engine. What does he suggest for throat diameters with the valves you used?

As always, I dig the experimentation you're doing, keep it up.
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post #10 of 26 (permalink) Old Nov 20th, 19, 6:37 AM
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Mark you should make videos of porting peanut port heads. Really liked those 781 oval port videos.
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post #11 of 26 (permalink) Old Nov 20th, 19, 6:39 AM
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Quote:
Originally Posted by vortec710 View Post
Follow Mark Jones / VortecPro Recommendations from his videos..hell of a good starting point, might be hard to improve over his results, assuming you have the proper machinery to implement his recommendations. Good luck.
Mark should make videos of porting peanut port heads. Really liked those 781 oval port videos.
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post #12 of 26 (permalink) Old Nov 20th, 19, 11:17 AM Thread Starter
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Re: Found why the Closed Chamber heads did not work

Quote:
Originally Posted by Rmchevelle View Post
Would love to know for sure. Would be a good test to see these with the suggested changes from your friend and back on the engine. What does he suggest for throat diameters with the valves you used?

As always, I dig the experimentation you're doing, keep it up.
He suggested opening the the area to 90% of the intake valve, redo the valve job and blend from there. Will have to see what areas work best for unshrouding the valves as I know that will need to be done for sure. All in all the test was not a total loss this year as it did pick up on a bottom end in the ET area just not up top where I though the bigger valves might help. I do know that my 781's would have put the 215's to shame though but I did not have the right piston in the engine to do it and my 12 to 1's are not of a street friendly variety.
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post #13 of 26 (permalink) Old Nov 21st, 19, 6:42 AM
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Quote:
Originally Posted by 68Chevele View Post
My good friend who is a cyl head guy figured out why my CC 215's did not work this year. He spotted it in the pictures I sent him before and after the work I did, here is what happened. The first picture was the way I got them and I did know the valve job was horrible but I did not realize that I should have opened up the bowl area more according to him. He said, cramming in a large valve without opening up the port/bowl is not going to help and most likely hurt power mainly torque. He went on to say that my valve job looked great but if I were to open the intake bowls more and do some chamber work those heads will pick up a lot. Since I have not worked over too many of these in the past I was unaware of most of this. I really though a bowl clean would work, I was wrong. As you can see in the before and after pictures he was right. Good news is he really liked my L-29 heads so that will be the next test on this 461.
Excellent feedback, it will be interesting to see the improvement on the flow bench, but also in the ETs and mph.

Proving every day hindsight is 20/20.
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post #14 of 26 (permalink) Old Nov 21st, 19, 6:52 AM
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Quote:
Originally Posted by Dave Ray View Post
Ever hear of an early Buick NAIL HEAD engine? Those engines had what is referred to as a "tulip shaped head" valve set.

Now, I am fully aware the cylinder head gurus will bo bonkers over this,m but, it is not ll porting to make a head work.

Almost every head guru does it dead wrong, they "flow" a port DRY, air only, and there lies the rub. Does your engine run on air only? I doubt it, they run on a WET fuel/air mixture, not dry air.

Ever see a fog mist change direction in a fog bank? Same thing occurs in a port, even though the mixture is under vacuum.

The Buick people knew this, and developed one other facet of their Nail Head port/valve development, PUTTING THE WET MIXTURE IN THE RIGHT PLACE IN THE CHAMBER.

The tulip directed mixture flow to where it needed to be in the chamber to be most efficient. And, helped to make transition mixture flow in the port go where it should go.

The biggest problem with dry flow head work is, do the ports actually do what they should, get the mixture to everywhere in the chamber, or, does it literally force dry, dead fill areas in that chamber.

The closed chamber big block heads had a few very bad flow paths, and created lean spots with the wrong flow fill patterns.

Think about this the next time you decide to go insane portng nuts, and hog that port bowl out, cut that valve, etc.
Very interesting comment. In Mark’s video, when porting the roof, he said it’s important the one side stays higher than the other. I wonder if this is for straight flow or helping direct the mixture in. I suppose it’s a was either way, and the shape is a “must have” for that port. .

Proving every day hindsight is 20/20.
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post #15 of 26 (permalink) Old Nov 21st, 19, 9:33 AM
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Re: Found why the Closed Chamber heads did not work

Many years ago, I had a stock pair of 215 castings on a 10.2:1 compression 454 with a 223/[email protected] 112 LSA flat tappet Ultradyne cam.
The same engine picked up a solid and consistent 2.5-3 MPH increase swapping over to mildly ported 063 castings that had 2.19/1.88 valves. They flowed around 268 [email protected] .550 lift on the intake and 200 on the exhaust.
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