moved.. Dennis's thread regarding his open chamber heads..

moved.. Dennis's thread regarding his open chamber heads..

Joined: January 1st, 1970, 12:00 am

September 6th, 2011, 4:05 pm #1

Sept 6 2011 9:30am Brent wrote: "did you get your heads CC"d?.."

Sept 6 2011 9:51am Dennis Responded...
I'm hopping to have them cc'd today, I had to move my son away to collage yesterday, didn't get back home till close to midnight.
I forgot to ask, At the machine shop the owner said they had a tool for de-shrouding the valves. Once done I would imagine that there is some blending to do as well. How will this effect CR and if the de-shrouding is done, is there any need for the, I know, controversial V groove technology?
How much will de-shrouding decrees CR?



Sept 6 2011 9:30am Brent wrote: SCR should go down..
If he was just talking about opening the chambers up a little bit to help the flow around the outside sides of the valves, then SCR should go down because you're making the combustion chamber bigger. The amount it goes down is just based on how much bigger the chambers are.

I've never used the grooves, so I have no first-hand information on it. But then again, I've never had to.


Never Pet a burning dog, and don't fry bacon naked... Gary Busey on Celeb Apprentice.
Last edited by blizzardND on September 6th, 2011, 4:09 pm, edited 1 time in total.
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Joined: November 18th, 2005, 12:44 am

September 8th, 2011, 10:28 pm #2

OK, I checked one combustion chamber on each Aussie head and one was 57CC and the other 56CC. I also checked the CC's of the piston @ tdc and it was 12CC's
The top of the deck was machined and I talked to the Machine shop and he said that it was machined to the mains. Not sure if he used the mains or off of the oil pan rails. The factory machines the oil pan rails from off of the mains, is what he said. He said that it was measured from corner to corner and from the pan rails up, the block was checked for core shift.

So Now there is one other thing. The heads need to be machined as well. I have about .004 clearance in the center of one head and .005 on the other. This was done with a accurate straight edge from corner to corner and I used feeler gauges to check the center. Now that I need to machine the heads, and also un-shroud the exhaust valves, Am I at a stand still till this is done and then check what I have from there?
the way it is now what do you think the CC is now for this motor.

Again here is the info on the cam and pistons and the balance sheet.

The cam is the XE262 ADV DUR: .262 intake, .275 Exh
DUR@ .050: .218 Intake and .224 Exh
Lobe Separation, 110.0
Valve Lift: .513 intake and .519 Exh
[/IMG]
[/IMG]

The exhaust will be 2.5 all the way, with an X pipe and headers.
As for headers, I do have access to a set of Dyno Max 4V headers, Not sure how good this brand is, Maybe someone can give some insight on how good they are compared to Hedman lets say.
Thanks
Dennis
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Joined: May 20th, 2005, 4:48 pm

September 8th, 2011, 10:38 pm #3

Those are flat tops with valve reliefs, right?

Brent Lykins
B2 Motorsports, LLC






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Joined: November 18th, 2005, 12:44 am

September 9th, 2011, 1:05 am #4

Yes they are Brent.
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Joined: November 18th, 2005, 12:44 am

September 9th, 2011, 1:16 am #5

Those are flat tops with valve reliefs, right?

Brent Lykins
B2 Motorsports, LLC





I checked the Piston to deck CC volume the same way as I did the heads. I petroleum jelly on the face of the heads with plexy glass on top with a hole in it. I then used a 60cc syringe filled with mineral oil and filled the chambers with that. I then subtracted the amount left in the syringe from 60 and that is how I check to see how many cc's were used to fill the chamber. I did the exact thing for the piston to deck cc amount. I was thinking that since there is a volume that is not accounted for from the top of the piston to the ring lands. If I did this wrong let me know. By the way, the piston was at TDC, I checked with a dial indicator.
The pistons are flat tops with reliefs.
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Joined: October 1st, 2004, 8:05 pm

September 9th, 2011, 1:48 am #6

Dennis

at the moment your motor has about 77cc to 78cc total clearance volume (volume above the top piston ring at top dead center). I assumed a 0.040" head gasket in that calculation.

A 0.030" over size motor has 731cc swept volume per cylinder.

731cc + 78cc / 78cc = 10.37:1 static compression ratio

you need 86cc total clearance volume to achieve a 9.5:1 static compression ratio.

To gain 8cc with a head gasket it would have to double in thickness, i.e. 0.080" head gaskets. That's bad news.

If you installed an old school camshaft like the D1ZZ-BX cam (290/290 duration, 0.505"/0.505" lift, 62 degrees overlap) it closes the intake valve much later than the cam you were intending to use, and you could get away with higher static compression because closing the intake valve later reduces the dynamic compression. I calculated your dynamic compression using the full 10.37:1 static compression you currently have, and the 74 degrees ABDC intake valve closing spec for the D1ZZ-BX camshaft. The dynamic compression ratio calculator at Wallace Racing says your dynamic compression would be 7.67:1, which is perfectly fine with high octane pump gas.

Wallace Racing

If you still want to lower the static compression ... every 0.005" you add to the clearance increases the volume by 1cc. Cometic makes 0.045", 0.051" and 0.056" head gaskets for the 351C.

You don't want to take any more material off the block!



-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
Last edited by gpence on September 9th, 2011, 2:03 am, edited 1 time in total.
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Joined: November 18th, 2005, 12:44 am

September 9th, 2011, 3:05 am #7

George,
The old school cam that you showed looks a lot like what I had in the motor many years ago, I just know it was a .505 lift on both intake and exhaust. Having a CR of 7.67:1 is really low, I don't think I want to go there.
1) To clean up the heads, I will probably have to take off .020, If I do this, do you have an idea how many cc's I will lose and if I un-shroud the exhaust could I gain back those cc's?
2) Just as a thought that I had, how many cc's are the newer style aluminum AFD heads? Are the combustion chambers not as deep allowing them to have the shape of the combustion chamber they do? The reason I ask is, since I have to un-shroud the chambers, can this shape of the newer style heads be applied to the Aussie heads? I know not interlay but mostly around the exhaust. I only asked this question, because It's one that has been on my mind for a long time and just thought it was a good time to ask.
3) I know you are trying to steer me in the right direction with the size of cam that I have. From what I am getting is with this cam, I really need to get down to 9.5:1, What would happen if I was to get it to 10:1 would this mean the cam then would be too small? This is just to help me rap my head around all this info.
4) I know we don't want to be adding gasket thickness, we have already gone over that and I now understand that opening up the cc's of the combustion chamber is defeating the quench effect and possibly loosing the gain in torque. As for question number 2 I know that I have already answered my own question and the chamber of the Aussie head passed the point of un-shrouding would be unwise.
5) In the event of cleaning up the heads, I know that in reality I will be taking off more material from the outsides of the head than the center, since that is the low area anyway. This means I will have to CC all the chambers to the same. Can I CC them all back to 58cc's after all the machining has been done or would that mean taking out a huge amount to gain back what I had. "This is looking like the best thing to do is get the KB 13cc dished pistons and be done with it.
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Joined: December 16th, 2003, 1:59 am

September 9th, 2011, 6:17 am #8

is not Static Compression Ratio

it's Dynamic Compression Ratio

Static CR only takes into consideration the swept volume and the unswept volume, the cylinder and the chamber

Dynamic CR figures in when the chamber is actually sealed, the intake valve doesn't close until the piston is well on it's way up in the cylinder. from the point when the intake valve closes is the amount of crankshaft stroke that actually counts toward squeezing the jam. connecting rod length is a factor in DCR

that's why i asked what cam you'll be using earlier, the closing point of the intake valve and where the piston is in the cylinder at that point makes a big difference in octane requirement

there'll be phantoms, there'll be fires on the road... and the white man dancing
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Joined: October 1st, 2004, 8:05 pm

September 9th, 2011, 6:38 am #9

George,
The old school cam that you showed looks a lot like what I had in the motor many years ago, I just know it was a .505 lift on both intake and exhaust. Having a CR of 7.67:1 is really low, I don't think I want to go there.
1) To clean up the heads, I will probably have to take off .020, If I do this, do you have an idea how many cc's I will lose and if I un-shroud the exhaust could I gain back those cc's?
2) Just as a thought that I had, how many cc's are the newer style aluminum AFD heads? Are the combustion chambers not as deep allowing them to have the shape of the combustion chamber they do? The reason I ask is, since I have to un-shroud the chambers, can this shape of the newer style heads be applied to the Aussie heads? I know not interlay but mostly around the exhaust. I only asked this question, because It's one that has been on my mind for a long time and just thought it was a good time to ask.
3) I know you are trying to steer me in the right direction with the size of cam that I have. From what I am getting is with this cam, I really need to get down to 9.5:1, What would happen if I was to get it to 10:1 would this mean the cam then would be too small? This is just to help me rap my head around all this info.
4) I know we don't want to be adding gasket thickness, we have already gone over that and I now understand that opening up the cc's of the combustion chamber is defeating the quench effect and possibly loosing the gain in torque. As for question number 2 I know that I have already answered my own question and the chamber of the Aussie head passed the point of un-shrouding would be unwise.
5) In the event of cleaning up the heads, I know that in reality I will be taking off more material from the outsides of the head than the center, since that is the low area anyway. This means I will have to CC all the chambers to the same. Can I CC them all back to 58cc's after all the machining has been done or would that mean taking out a huge amount to gain back what I had. "This is looking like the best thing to do is get the KB 13cc dished pistons and be done with it.
you loose 1cc in the combustion chambers for every 0.006" milled off a quench chamber head. This is Ford's number, not mine.

You juggle static compression ratio and camshaft timing (specifically the intake valve closing point) in order to attain the proper dynamic compression ratio. Dynamic compression is the more important number. For premium pump gas you want the dynamic compression ratio in the range of 7.5:1 to 8.0:1 with iron 351C heads. 8.0:1 is pushing it.

The camshaft with 0.505" valve lift is a grind originating from Ford, but copied by everyone. The original spec closed the intake valve at 74 degrees ABDC. It is a hydraulic version of the Boss 351 cam. It has a burbling idle and a very wide power band. It will make peak horsepower around 6000 rpm, depending upon the combination. Its a nice strong daily driver street cam, and I know guys who used for road racing too.

-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
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Joined: May 20th, 2005, 4:48 pm

September 9th, 2011, 1:12 pm #10

George,
The old school cam that you showed looks a lot like what I had in the motor many years ago, I just know it was a .505 lift on both intake and exhaust. Having a CR of 7.67:1 is really low, I don't think I want to go there.
1) To clean up the heads, I will probably have to take off .020, If I do this, do you have an idea how many cc's I will lose and if I un-shroud the exhaust could I gain back those cc's?
2) Just as a thought that I had, how many cc's are the newer style aluminum AFD heads? Are the combustion chambers not as deep allowing them to have the shape of the combustion chamber they do? The reason I ask is, since I have to un-shroud the chambers, can this shape of the newer style heads be applied to the Aussie heads? I know not interlay but mostly around the exhaust. I only asked this question, because It's one that has been on my mind for a long time and just thought it was a good time to ask.
3) I know you are trying to steer me in the right direction with the size of cam that I have. From what I am getting is with this cam, I really need to get down to 9.5:1, What would happen if I was to get it to 10:1 would this mean the cam then would be too small? This is just to help me rap my head around all this info.
4) I know we don't want to be adding gasket thickness, we have already gone over that and I now understand that opening up the cc's of the combustion chamber is defeating the quench effect and possibly loosing the gain in torque. As for question number 2 I know that I have already answered my own question and the chamber of the Aussie head passed the point of un-shrouding would be unwise.
5) In the event of cleaning up the heads, I know that in reality I will be taking off more material from the outsides of the head than the center, since that is the low area anyway. This means I will have to CC all the chambers to the same. Can I CC them all back to 58cc's after all the machining has been done or would that mean taking out a huge amount to gain back what I had. "This is looking like the best thing to do is get the KB 13cc dished pistons and be done with it.
Having to juggle several variables just to crutch another is not the best plan of action.

You are taking the time to measure everything accurately and that is good....that's more than what 99% of home builders do.

My vote is to get the KB pistons. However, if the heads need milled and you're looking at taking that much material off, then we're really starting back at square one, with not knowing exactly where we will be. All machining needs to be done first.

Do you have any other heads laying around? I don't know what kind of budget you're trying to stay under, so we're all trying to recommend things that will be easiest on the wallet.

Brent Lykins
B2 Motorsports, LLC






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