Slant Six Forum :: Double rockerarm shaft head

Well, once again, I'm stepping out onto unknown waters and I'll probably be drowning shortly but here goes.
From what I see looking at the head, the main problems with the slant head are in the combustion chamber and in the production methods.
There's not a lot that can be done about the chamber design. Some have tried such processes as welding up and remilling or angle shaving with unproven results. The largest impediment to flow is shrouding due to the proximity of the valves to the cylinder walls, and rough finish in the valve bowls and ports. Larger valves help, but unless something is done to unshroud them, that particular part of the equation becomes worse.
My understanding is that with some careful and thoughtful work to unshroud the valves and reduce turbulence in the ports, the slant head can be very respectable. From a modern engine design point of view, the biggest problem with the slant is it's small bore and long stroke; there isn't a lot we can do about that.
All of this is the main reason I believe that there will be such a small market for alternative heads. There are only a handful of people who are getting enough out of the motor that the head is the real stumbling block. and once you put on a better head, you start having issues with the bottom end. After all, this motor was designed 50 years ago to propell small cars with conservative drivers. It was never intended or designed to be a fire breathing monster.
The remarkable thing is not what we can't do; it's what we've been able to do despite the obvious limitaions of the little power
plant we all know and love.

Author:	zedpapa [ Sat Jan 19, 2008 2:11 pm ]
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how did you get cuts straight enough to seal with epoxy? zedpapa

Author:	slantzilla [ Sat Jan 19, 2008 3:19 pm ]
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The main handicap on a Slant is bore size, not cylinder head. The cylinder walls shroud the valves too much and impede flow. That's why Slants run so much better with boost. If ya can't suck it in, blow it in. One thing that really interests me is the people who haven't posted in this thread at all. Not saying anything, I'm just sayin'.

Author:	Valiantlord [ Sat Jan 19, 2008 7:51 pm ]
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I'm very happy about the idea.I'm also jealous it's not my idea lollllllllllll. It's a piece of art Congatulation for your great work.I have too much stuff going on with my big block stuff.I can't split my budget with other more fun stuff as my slant six could be. I have all my parts to complete my first lightly tweaked /6 I got my 2.2 pistons to go with my Dutra 198 rods bought on ebay 3 years ago.My head with 318 valves is ready to go. I got a fairly good D C cam 276/490. I know I did not post and visit alot here.I see what I'm missing now.

Author:	walpolla [ Sat Jan 19, 2008 8:42 pm ]
Post subject:
Quote: The main handicap on a Slant is bore size, not cylinder head. The cylinder walls shroud the valves too much and impede flow. That's why Slants run so much better with boost. If ya can't suck it in, blow it in. One thing that really interests me is the people who haven't posted in this thread at all. Not saying anything, I'm just sayin'. well,I would say something if I had something to say that you guys had not covered. but - no you are doing fine. must be GOOD glue is about my only comment. pretty cool looking job IMO. regards,Rod

Author:	Joshie225 [ Sat Jan 19, 2008 9:07 pm ]
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Quote: I got a fairly good D C cam 276/490. I ran that cam once upon a time. It likes a lot of compression and advancing it significantly will help too.

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Double rockerarm shaft head https://slantsix.org/forum/viewtopic.php?t=26620	Page 6 of 9

Author:	NYG95GA [ Sun Jan 20, 2008 7:49 pm ]
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Whether it holds up or not, that is the coolest thing I've ever seen on top of a slant. Kudos on your Sawzall skills!

Author:	440_Magnum [ Tue Jan 22, 2008 11:05 am ]
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Quote: Actually that was pretty good info Joshie. I can completely agree with you on the Datsun page. My dad had a 240z that would run away from my uncle's 340 challenger like it was standing still. So how did your dad manage to unplug 5 of your uncle's spark plug wires without him finding out?

Author:	Rick Covalt [ Tue Jan 22, 2008 2:37 pm ]
Post subject:	Come on now.
There are still a lot of questions that have been unanswered. I think everyone wants to know how this was done. I know I have been waiting for the details. How many pieces were used? What modifications were made to make the rockers work? How did you get the bore centerlines to line up? Are the Hemi head bolt patterns close to the slant 6? And all the other questions that were asked. Can you give us the details. I'm really impressed by your work here, but surely want to here the whole story. Now cough it up. Yes I'm being impatient. Thanks, Rick

Author:	Dart270 [ Tue Jan 22, 2008 3:12 pm ]
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Here ya go, Dennis: Nice work and good luck, Heckshemi. The cool factor is way high. Hope I can hear/see your project run sometime! Kudos on the epoxy, and I bet it'll work on a non-maxed-out aluminum headed motor. I notice that every time someone comes up with a wacky head idea or project, someone insists that the stock head isn't worth spit. I also notice that most of those people have never run a powerful Slant 6. The record for a NA motor with a stock ported head is well over 350 crank HP (238 cu in). Port flows, when adjusted for cylinder size, are in the range of many modern SB and BB V8 heads. A 400 cu in V8 needs roughly 260 cfm flow to equal the HP per cu in of a 225 with 200 cfm (or 295 cfm to equal 230 cfm). Lou

Author:	runvs_826 [ Tue Jan 22, 2008 6:50 pm ]
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Well, the Datsun (correction it was a 280z, not 240) had an inline six, triple webers, and the best weight to power ratio I have ever heard of. The Challenger was a stock 340 4speed, so maybe my uncle sucked at shifting. But my dad's a cop and will never tell me any of the good stories. The slant head is still a formidible piece and for most situations it would be more than suitable. I really want the flow through design of a v8's head and bigger ports, even though the flow through has been discussed everything I have been taught leans toward it being an asset. My only request is does anyone have a cross sectional of the head of where the water jackets are in correspondence to the ports. I don't know how much is to much and don't want to test the waters on my budget.

Author:	HyperValiant [ Tue Jan 22, 2008 7:53 pm ]
Post subject:
Lou,you said what I wanted to say,while I think that Hecks cylinder head is a great feat of homebrew engineering and that it takes an extremely talented individual to step forward with a project such as this,I dont think that I will ever require more than a well worked iron head for any of my engines and that there is plenty of potential in an iron head. With that said,We need projects like this in our communty to keep our imaginations fueled and without a doubt it is one of the coolest looking setups that I have seen bolted to the top of a Slant engine and hope that it works as well as it looks. HyperValiant

Author:	dakight [ Wed Jan 23, 2008 2:58 am ]
Post subject:
Well, once again, I'm stepping out onto unknown waters and I'll probably be drowning shortly but here goes. From what I see looking at the head, the main problems with the slant head are in the combustion chamber and in the production methods. There's not a lot that can be done about the chamber design. Some have tried such processes as welding up and remilling or angle shaving with unproven results. The largest impediment to flow is shrouding due to the proximity of the valves to the cylinder walls, and rough finish in the valve bowls and ports. Larger valves help, but unless something is done to unshroud them, that particular part of the equation becomes worse. My understanding is that with some careful and thoughtful work to unshroud the valves and reduce turbulence in the ports, the slant head can be very respectable. From a modern engine design point of view, the biggest problem with the slant is it's small bore and long stroke; there isn't a lot we can do about that. All of this is the main reason I believe that there will be such a small market for alternative heads. There are only a handful of people who are getting enough out of the motor that the head is the real stumbling block. and once you put on a better head, you start having issues with the bottom end. After all, this motor was designed 50 years ago to propell small cars with conservative drivers. It was never intended or designed to be a fire breathing monster. The remarkable thing is not what we can't do; it's what we've been able to do despite the obvious limitaions of the little powerplant we all know and love.

Author:	sandy in BC [ Wed Jan 23, 2008 9:01 am ]
Post subject:
Examine the history of the MegaSquirt for a minute. Imagine a head based on an internet board supporting a homebuilt , high tech "aftermarket head" that is assembled like a MegaSquirt. Support and testing and development spread amongst many. I have been very impressed by Franks "did it with a chainsaw proach to a number of things. A set of AutoCad plans ...a sawzall ....a Harbour Freight drill press...a lil Mars Rover Epoxy.... mebbe I dont even get it to run....but have a good time playing with it.

Author:	68barracuda [ Wed Jan 23, 2008 12:08 pm ]
Post subject:
Quote: Well, once again, I'm stepping out onto unknown waters and I'll probably be drowning shortly but here goes. From what I see looking at the head, the main problems with the slant head are in the combustion chamber and in the production methods. There's not a lot that can be done about the chamber design. Some have tried such processes as welding up and remilling or angle shaving with unproven results. The largest impediment to flow is shrouding due to the proximity of the valves to the cylinder walls, and rough finish in the valve bowls and ports. Larger valves help, but unless something is done to unshroud them, that particular part of the equation becomes worse. My understanding is that with some careful and thoughtful work to unshroud the valves and reduce turbulence in the ports, the slant head can be very respectable. From a modern engine design point of view, the biggest problem with the slant is it's small bore and long stroke; there isn't a lot we can do about that. All of this is the main reason I believe that there will be such a small market for alternative heads. There are only a handful of people who are getting enough out of the motor that the head is the real stumbling block. and once you put on a better head, you start having issues with the bottom end. After all, this motor was designed 50 years ago to propell small cars with conservative drivers. It was never intended or designed to be a fire breathing monster. The remarkable thing is not what we can't do; it's what we've been able to do despite the obvious limitaions of the little power plant we all know and love. All that and then some - and it is SO nice to see the expressions on the other make's supporters faces when you pop the hood and state No it is not an eight - its is a Slant Six I am bussy with a restification on a RHD 68 Barracuda - mechanical mods to improve handling, performance etc. on looks - it is a stock 68 \6 RSA Formula S barracuda - yep over here the 175BHP slant was called a Formula S it actually scored a bit of US S handling upgrades as well! Originally wanted to fit a LA of some sort - I am SO glad I stuck with the slant - now it is a numbers matching load off fun.

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Author:	Valleyant [ Wed Jan 23, 2008 7:55 pm ]
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Hi, I just want to say it's a great looking mill and I would like to try it on one of my slants when the time is right....Heckshemi has done a great job and the valvecover makes it look like it could have been offered as a hi-po S6 by Ma Mopar.... Frank have you looked at, and I know these are rare/expensive and hard cylinder heads to find and experiment with, the Lotus 16 valve heads used on the 2.2 L turbo cars Spirits and Daytonas from '91 thru '93 and Maserati 16 valve heads used in the 2.2L turbo LeBaron based TC cars.... ??? I know i'm throwing in the over head cam can of worms....just wondering....nico