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Twin cam head for the L6 from Derek at Datsunworks


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This is all Tony D’s fault:)   Hi everyone. Some of you know me from my  DIY EFI manifold project http://forums.hybridz.org/topic/63445-making-my-own-efi-intake-the-first-casting/ &#

Machine work finished!   I can relax a little:) Just got done with their first bath. Still need de-buring and edge finishing but the majority of the work is done.    

Ready for battle!       Getting geared up to start machining the heads. Officially the first production run.    

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That's an easy fix, too. Keep the head on the shelf, if you just wanna bolt it back on again later use Maxal 4943 TIG rod to do the repair with. Grind out at least 1/8" past the damage, grind the crack all the way out, then just layer in the 4943 till you're a little proud of what you need, and re-machine.

 

No heat treat required afterward, as long as you keep the casting temp under 300F. Localized heating will be unavoidable but the 4943 rod does not need a heat treat to maintain the strength, and if you DO heat treat it it reacts very close to A356, but untreated the initial hardness is high enough to hold a gasket and gets a little better with a few weeks aging.

 

The 4943 is what I am using to do my 300 Ford I6 heads with, each section of head has to be welded back together and then the deck face is surface-filled to bring compression down for the turbo motors. When I was using 4047 I had to hammer-peen the welds to bring the harness up enough to hold a headgasket without deforming.

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Chrome moly

I didn't specify a fit. I left that up to them. 

 

A little while back I wrote code for calculating stress and retention force for press fits. If you know the nominal outer diameter of the valve seat I could do a quick calculation to find a suitable range of interference fits, then use that to determine hole/seat sizes. Also, a quick calculation indicates that about .00065" interference is lost when the head expands. I assumed a valve seat outer diameter of 1".

 

CTE Chromoly (4130) 7.6*10^-6 in/in degree F

CTE Aluminum (6061) 13*10^-6 in/in degree F

T1 (room temperature) = 69 degrees F

T2 (High Safe Operating Temperature) = 190 degrees F

ValveSeatDiameter=1"

Change in interference=(CTE Aluminum - CTE Chromoly)*(T2-T1)*ValveSeatDiameter

 

What hole diameter tolerance are they hitting when they post machine the heads? What about on the valve seats themselves?

 

EDIT:

Also, you mentioned that any time you press something in you are shaving metal. My understanding is that unless the yield strength of one of the materials is exceeded, the press fit does not remove material or permanently deform either the seat or the head (at least not a significant amount). I would argue that using a press fit probably isn't bad practice unless there were other errors in the process as well.

Edited by pkz
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That's an easy fix, too. Keep the head on the shelf, if you just wanna bolt it back on again later use Maxal 4943 TIG rod to do the repair with. Grind out at least 1/8" past the damage, grind the crack all the way out, then just layer in the 4943 till you're a little proud of what you need, and re-machine.

 

No heat treat required afterward, as long as you keep the casting temp under 300F. Localized heating will be unavoidable but the 4943 rod does not need a heat treat to maintain the strength, and if you DO heat treat it it reacts very close to A356, but untreated the initial hardness is high enough to hold a gasket and gets a little better with a few weeks aging.

 

The 4943 is what I am using to do my 300 Ford I6 heads with, each section of head has to be welded back together and then the deck face is surface-filled to bring compression down for the turbo motors. When I was using 4047 I had to hammer-peen the welds to bring the harness up enough to hold a headgasket without deforming.

 

Thanks for the tip on the 4943 rod. Although I hope to not have to repair this head that's good to know. Just for fun I sent a part of a Honda K20 head down to the foundry. They are going to test the rockwell on the exterior vs the combustion chamber.  I was curious how the combustion process over time would change the hardness.

 

 

 

A little while back I wrote code for calculating stress and retention force for press fits. If you know the nominal outer diameter of the valve seat I could do a quick calculation to find a suitable range of interference fits, then use that to determine hole/seat sizes. Also, a quick calculation indicates that about .00065" interference is lost when the head expands. I assumed a valve seat outer diameter of 1".

 

CTE Chromoly (4130) 7.6*10^-6 in/in degree F

CTE Aluminum (6061) 13*10^-6 in/in degree F

T1 (room temperature) = 69 degrees F

T2 (High Safe Operating Temperature) = 190 degrees F

ValveSeatDiameter=1"

Change in interference=(CTE Aluminum - CTE Chromoly)*(T2-T1)*ValveSeatDiameter

 

What hole diameter tolerance are they hitting when they post machine the heads? What about on the valve seats themselves?

 

EDIT:

Also, you mentioned that any time you press something in you are shaving metal. My understanding is that unless the yield strength of one of the materials is exceeded, the press fit does not remove material or permanently deform either the seat or the head (at least not a significant amount). I would argue that using a press fit probably isn't bad practice unless there were other errors in the process as well.

 

I really don't have any data as to what sizing they did. Based on everything I see I'm really pretty sure it was operator error. This is all pretty basic stuff so if the seat bore isn't cracked then either the seat itself fractured or it was installed improperly. Well the seat bore isn't cracked so.....

Edited by Derek
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Making progress on V3. The major machining is all done. I have a few little handwork items left but other than that it's pretty close to being finished.

 

20170707031935-0a73159e-me.jpg

 

 

I had to build the front timing cover up a bit with some weld. I’ll blend it in better by hand. I’m also going to counter bore the bottom screws on the front timing cover so they will be hidden.

 

20170707031933-5d7c30fb-me.jpg

 

 

That is a lot of valve cover:)

 

20170707031938-f3f51784-me.jpg

 

 

The cams are over at Crane getting heat treated and the bearing journals ground. They said I should have them back by the end of the month.

 

20170707031930-8ba9bf85-me.jpg

Edited by Derek
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  • 4 weeks later...

Making some progress. Got the cams back from Crane. No major issues.

 

20170713164023-57ea023e-me.jpg

 

They turn nicely by hand so that's a good thing.

 

20170713164859-b5341d27-me.jpg

 

This is the only issue. I'm not sure if they screwed up or me but the rear bearing is not wide enough. I'll machine more off of the thrust area on the tower and dial it in. Not a big deal. 

 

20170713164717-13917f6f-me.jpg

 

Getting to the end of it. Hope to be shipping towards the end of next week.

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  • 2 weeks later...

Putting the finishing touches on V3 before it heads out to Rebellos. Decided since there isn't a head on my car now would be a good time the check the hood clearance with the higher valve cover.

 

20170724120706-0f935a3d-me.jpg

 

And....It fits

 

20170724120742-a641829c-me.jpg

 

Running a tall deck will probably require a low profile oil cap.

 

 

 

Sniff sniff....I wish it was mine:)

 

20170724120724-299a1be4-me.jpg

 

Kind of looks like it belongs in there.

 

 

Derek

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Since I get a ton of traffic on this thread I'm reaching out to HybridZ members. Dan is having trouble funding the site due to diminishing ad revenue. There is a funding drive going on here: http://forums.hybridz.org/topic/127731-hybridz-may-be-shutting-down/

 

I have donated 5 sets of speaker panels with 100% of the sales going to HybridZ. Two sets are gone so you better hurry:)

 

No need to comment here just follow the link and donate.

 

Thanks

Derek

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Putting the finishing touches on V3. 

 

I decided to put the head back in the mill to do more work to the face. This is no easy task because I have to hang the head off of the table and rack the mill over.  Originally I was going to put the sealing o-rings in the sub plates. I realized that this would make it really difficult for someone with a manual mill to make new plates. I also determined that the idler sub plate was going to be around 6mm thick. This wasn't going to be enough meat for the bolt so I made a pocket in the head so that the plate could be thicker in that spot.  The oval holes are oil scuppers. 

 

 

 

20170726120746-e996eea0-me.jpg

 

Oh look a pile of speaker panels on the floor:)

 

 

 

I had to offset the bolt holes on the idler to miss an oil passage. 

 

20170726120806-9b8e158a-me.jpg

 

 

I'm so happy with the sub plates that V2 will be going back in the mill for a modification.

 

 

 

Thanks

Derek

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  • 2 weeks later...

Family Portrait. 

V1 V2 V3

I snapped this before I shipped V3 to Rebello and V2 went for a visit to it's owner. Probably (hopefully) the last time they will be all together.

 

20170810141231-e9210edc-me.jpg
 
 
My feeble attempt at an art shot :)
 
20170810141258-7e818f41-me.jpg
 
 
 

 

 

Run off to the jungle to get chimps throwing crap at me through the fence, work 176 hours, and come back to find all this..

 

Things move pretty quick around these parts:)

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  • 3 weeks later...

Since I'm planning on trying out VCT on my build I figured I'd better finalize the valving. For me it's alway a balance of (not necessarily in this order)  function, manufacturing and style. On the VCT it's always function first since what's the point if it looks better than it works.  I knew what valve I wanted to use ( manufacturing) and where it needed to go (function) but not how to make it work ( manufacturing ) and not have it be butt ugly (style).

 

I picked the valve I did because of the fact it came with it's own manifold. This makes manufacturing a lot easier since I don't have to do any precision boring. Since it's an open pressure (bleed) circuit believe I need to locate the valve as close to the cam phaser as possible to try and minimize the response lag. I also have to deliver a pretty good volume of oil at times where a fast response is necessary. 

 

I mapped out the valve with the 4 circuits. Oil in, 2 drains, advanced and retard. 

 

20170826072132-a72294b9-me.jpg

 

The valve is a spring return and defaults to retarded cam position. Retarded seems to be the default for the phaser as well. Which makes sense.

 

Lets start with the fact that I'm not crazy style wise about hanging this valve off of the front of the timing cover. But it's the closest I can get it to the phaser and still be able to plumb it. Here is a shot of the final plumbing. Red is oil in. Light blue are the drains. brown is retard and purple is advance.

 

20170826065516-24719e03-me.jpg

 

Since I didn't want the valve there to begin with you can imagine how I felt when I finally gave in to the fact that I needed a .625" thick manifold block to handle all the cross drilling. I tried a bunch of scenarios but it would have added a ton of time to the machining because of doing that kind of work on a short production run casting is tough. 

 

20170826074314-267a0e06-me.jpg

 

I also had to flip the valve 180 from my original position to get the advance and retard ports to match the head.

 

It's all about compromises in life:)

 

Derek:

 

 

 

 

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