Stock heads flow in the neighborhood of 140cfm intake and 110 exhaust at 28" depression.

Lou

_________________
Home of Slant6-powered fun machines since 1988

I see a few issues not mentioned here...this type of subject has been beaten to death on the Pontiac web boards before various companies released products, whether it be heads or blocks...but here is my two cents.

A raised port should not be an issue with current aftermarket or stock intakes or headers, they would simply sit higher in the engine compartment...that said, the exhaust system currently in that location probably won't fit anymore because it was designed to fit obstacles in the frame and linkage areas.

The idea of using V8 rockers is worthy of research because of the inexpensive(relative) availability of different ratio rockers...but this isn't critical in my opinion because of the big lifter allowing much lift with custom camshafts anyway.

Water flow thru the head is the critical factor for cooling, not thickness...and most aluminum heads not cast initially by Edelbrock have horrendously bad coolant passages and known issues with cooling in high horsepower applications. Ive seen brodix heads with chunks of casting and wire sand support sticking into the coolant passages...

The slant six runs so cool with minimal radiator( mine runs 155 degrees) that warping should not be a huge issue with the thick deck anyway. And if your not running your engine that cool...you should seriously reconsider why you don't...but thats a different thread.

The sparkplug needs to be moved to the exhaust valve side of the chamber if other combustion chamber mods are made or you won't see as much improvement. In other words, most modern heads with good flame kernal creation tend have the spark plug biased to the exhaust valve, and not centrally located.

High squish chamber would be great but a custom piston would be needed if you don't raise the valve somewhat as well as raise the port. I would want the ability to run 10.5:1 (aluminum can run at least 1 point more compression) with a flat top piston at zero to +.005" deck to take advantage of any squish. So the chamber volume must be taken into account for flat top zero deck apps or the whole issue of building the head is pointless in my opinion. That said, if you raise the valve somewhat as well...say raise the port 1 inch, but the valves and chamber 1/4"(math needs doing) then you gain a lighter valve, increased chamber volume, and the ability to plan for better springs. Else the added expense of a custom reverse dome piston would negate the value of the head and I would put the money into a highly modified iron head instead.

Springs(valve)...a larger diameter seat should be planned for and a taller pocket after mild research on available spring packages for typical camshaft choices. No point in designing the head and then going thru the hassle of trying to find springs to support good cams to fit in the puny stock location and size.

After reading about Lou's escapades in the southern hemisphere and the Aussie guys finding that reduced exhaust cam timing helps HP...I believe it would be prudent to consider not increasing the exhaust valve size much, but instead concentrating on the available inexpensive high flow valves, and an increase in port flow rather than valve size...this allows concentrating on intake port configuration, valve size, and most important, shrouding.

There is of course more...and I could write this better, but I have my doubts as to any of this coming to fruition due to the years of writing about this stuff on Pontiac boards and seeing nothing come of it....

But good luck if you try...I would certainly be interested if the cost benefit of any aluminum head you create is better than the money spent on an iron head if you plan ahead with the same types of mods and appropriate pistons and rod length.

But thats the ultimate question...can I buy longer rods, light custom dished pistons, and modify the head for less than the conversion to aluminum and have any more power with the aluminum.

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

Sorry...had to run off real quick and drive someone somewhere...

What I was getting at is that there is yet another issue that needs confronting. You can't just put a high squish head on a block that isn't zero deck or close to it. I have seen time and again a closed chamber head having the compression lowered by cutting the piston top and creating an inefficient, detonating turd of an engine, independent of port flow.

If you offer this head to the slant six community, then you had better plan on a stock style combustion chamber, or a package of rods and pistons that solves the deck clearance issue, or you will have dissapointed customers and a reputation issue to deal with...

If you do not understand this aspect, then you should not be designing cylinder heads in the first place. It does not take much research to understand the issues related to squish and quench, deck heights, and unexposed, non turbulated combustion mixtures in a closed chamber head design.

I believe you do understand the benefit of squish or would not be talking about it in one of the first posts...but...what about those who would buy the head and stick it on an otherwise stock short block. And a custom piston with a raised deck and ring package may or may not be a solution due to weight and other factors I have not had time to think about...but it is an issue worthy of considerable research before creating an expensive aftermarket product from which only quantity will produce profit.

Quantity will be hard to achieve without including general enthusiasts in your marketing plans rather than people like myself, Lou, you, and other engine nerds who understand these issues to some extent.

I have already been surprised over and over on this board by how much money people spend to do things to heads and then leave out some of the most important considerations for making power and efficiency. It is no wonder that so many people are disappointed in the performance of the slants they build after spending so much money and going no faster(quicker) than my 350k old engine. It doesn't surprise me when I read what they have tried to do...but I can see why it surprises them.

If you don't plan for peole such as these buying your product and being disappointed, you will be the recipient of many a flame on discussion boards...I've seen it over and over on V8 boards by people who throw money rather than knowledge and time at going quick. I think the problem would be exsasparated(sp?) on the slant engine.

I don't mean to be a downer, since I would love to see a good head available, but it would be doing a disservice if you don't consider the entire package needed in your head design, and the slant suffers from a short rod relative to deck height that cannot be overcome easily.

I guess that was four or five cents worth.

Still...good luck if you pursue it, and I would be more than happy to help if you think my skills would be of value in the design and planning stages.

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

I believe the 24-valve Jaguar AJ6 head also has a 4.0" bore spacing. I overlaid a slant six head gasket over a 12-valve Jag block and other than slight variances in the head bolt pattern, it fit. The older Jag sixes I've seen had flat top pistons. Some Jag blocks are close to 3.6" bore which might cause the valves to hit the slant block. This would be a one-off oddball swap which requires skilled machinist work, but no new castings.

Same here. Many have discussed it in the past.
Interesting, but how would you overcome the head bolt pattern differences?

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

I find the Aj6 head interesting as well, since my older sister has a non running Jag I could get my hands on...but isn't the 24 valve overhead cam...much more than just a head bolt issue. I'm not afraid of machining for this...but to create an overhead cam drivetrain might be a bit of a project.

That said, I don't really know anything about this swap, since even though my sister has one, I've never looked under the hood of it...

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

The classic Jaguar timing chain setup is pretty complicated. I have never seen the final 24-valve AJ6 version, the classic Jaguar setup has a chain on the front of the motor, and another chain to the two camshafts. The front of the Jaguar head has a case for the chain. There is probably enough beef on the front of the slant six block to mount a chain cover. Yet, its a whole lot of expensive work.

Clamping the Jaguar head might be tricky, maybe not? The head bolt pattern on the slant six is 4" square, the Jaguar pattern allows for the wide spacing of the camshafts and is therefore more of a rectangle. I have no idea what the 24-valve AJ6 looks like. I figure the deck of the slant six could accept some welding, maybe studs could be run through the bottom of the slant six crankcase. The classic Jag heads I've seen had small head studs. My experience with Jaguars is limited to the junk yard. The water passages appear to be in the right places, don't know about oil flow, you could probably plumb the oil lines. Again, this is junkyard 101.

Jaguar pushed the cylinder bores to more than 2.60", then, cut a steam channel at the top of what would have been siamezed cylinder walls, as a workaround to the casting technology of the day. Jaguar engineers didn't have a big budget, they improvised. The AJ6 couldn't compete with BMW, Jaguar went with a new V8.

If someone did this 32 years ago on his own, an alu head could not be that difficult.
http://dansby.net/slant/ohc.jpg

_________________
Lasse

Signet -66 225
Holley 600 Offy-5270 Dutra Dual,regrind. cam 272 0,420 110, head shaved 0.100 slight.ported
MSD6A
A904
7 1/4 3.23

How bout this?

So.....use your imagination a little....3.6litre....EFI....4 valve,,, 4" bolt circle ,,,aluminum.

Is it not difficult to put standard components in that head?

_________________
Lasse

Signet -66 225
Holley 600 Offy-5270 Dutra Dual,regrind. cam 272 0,420 110, head shaved 0.100 slight.ported
MSD6A
A904
7 1/4 3.23

So what came out of this? There's more than enough interest to show that this would be a very popular (and therefore profitable) venture for any cylinder head manufacturer. Off-topic, does anyone know what happened to Clifford Performance? Their website has been taken over by some search engine clown...

http://www.cliffordperformance.net/

_________________
David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

There are a few major issues with the aluminum head project that have prevented it from ever coming to fruition:
1. Startup cost
2. Final cost of a bolt-on head
3. Deciding what features the head needs
4. There are less than 12 cars in the country that would see any benefit from an aluminum head, and they all run different combinations anyway
5. Slant owners are notoriously tight-asses and won't spend money

The aluminum head has been the holy grail of Slantdom forever. Unfortunately it is such a small market piece that it is econamically unfeasible for anyone to produce one. A stock head can be reworked to perform very well, and an aluminum head will not be a "magic bullet" that will fix any of our performance problems.

On the other hand, a block with 4" bores would do wonders...................

_________________
Official Cookie and Mater Tormentor.

Bagel is right the holy grail would be a slant with 4 inch bores. A alluninum head to save say 35 pounds doint warrent racers to have one. On a street car what differance does it make. To have one less just say for a thousand dollars who would buy one. Thanks Ron Parker










New Year New Gear