AA Type 4 Heads and exhaust port question.

[MuzzcoVW]

I'm at the initial planning stage of rebuilding my 77 Westy 2.0 engine. Even though my current heads have low miles, about 40K I'm considering replacing them with new AA heads as a fresh start. Not sure it's worth sending the originals out seeing as some won't touch them anymore. Once I tear it down I'll inspect and decide. If they're not worth doing, my question is would you stick with oval port replacements or change to square ports? I have to replace my whole exhaust system anyway and planned on a 72-74 heater box swap. I could always go the Federal 1979 style. Was there any advantage to flow etc, or was it strictly a better sealing surface at the head?

[Vanapplebomb]

In case you didn’t know, the AA casting is a replica of the early 2.0 heads, found on the Porsche 914. They have different spark plug locations than the later 2.0 heads used on the bus.

The AA head castings are real nice, but they are pretty much a carbon copy of the 914 head, which means it has the same weakness. They have thin tops to the chambers and thin exhaust ports. The 914 2.0 heads are notorious for cracking around the spark plug and in the exhaust ports.

Also, you 100% MUST ditch the 2.0 bus pistons!!! Those engines had too low of compression from the factory. Using the Aa 2.0 head castings will make that already bad situation much worse because the combustion chambers are bigger than all other type 4 heads. If you use those heads, you need flat top pistons. If you don’t, you will really struggle to get the engine to run well. Low compression and T4 engines do not go hand and hand. You will roast that engine in short order unless you get that compression back up.

Some people do use the 914 2.0 heads on busses, but I personally wouldn’t. Save it for a higher performance street car.

I would suggest the 1.8 heads. Much more durable. A little secret, the intake and exhaust ports have (as far as I can tell) the same internal profile. The camber is smaller and slightly more shrouded than the 2.0 914, but the flow difference is only minor until you are near max lift. The spark plugs are in the same location as your bus engine, so you won’t need to modify the cooling tin or find 914 upper tins.

If you want the 914 chamber and spark plug angle, AMC has 1.8 heads which are welded and profiled to match the 914 2.0. More expensive, but the benefit is thicker chambers and less likely to crack.

As far as flow difference between the oval port and rectangle port 2.0 bus heads, they flow so close it makes no difference. The later ones are easier to assemble, but I prefer the earlier ones. The rectangular port heads have a full length port, and all that heat stays in the head. The earlier heads are basically just an opening into the exhaust bowl, and the exhaust makes up the majority of what normally would be the port. They run cooler that way.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[Alstrup]

What have you been drinking?
Look at their site again.
There are the 914 2,0 heads AND the "VW" style heads.

Muzzo, if you are going to replace the entire exh system anyway, I would definitely go with the square port heads as they do flow a little better out of the box and are easy to improve further. Also, the exh gasket is easier to work with compared to the copper one.
I kinda agree on the dished pistons, as I like more static too in almost any case.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[MuzzcoVW]

[Alstrup]

No. Flat tops give more CR. Like 8,5ish i think.
The 73/86 solution is a widely used solution for a "cheap" cam. IMHO it is too much exh. duration. It costs power and especially torque. The RAT 7550 (I think its called) has less exh. duration and is better suited for a bus with a good exhaust sytem. Also, the 86 grind doesnt like high static compression, so the properties go against each other (IMO)
I know what is recommended for CR with that and similar cams. We have slightly colder climate here, and a hair better fuel. That said, when I do engines like that I never go below 8,5 with the 7550, still on 91 octane. In fact the engine really wakes up at 9-1 with 93 octane, and the "fun" part is that the heads stay nice and cool, - if you know how to set your ignition timing up.
As I use to say for you US based guys, Set the CR up for premium fuel at sea level and use the octane needed at the altitude you are driving in.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[MuzzcoVW]

[Alstrup]

Then the 7550 is the way to go.
The 142 is "just" a 412E/914 2,0 cam.
The ´77 bus is L jet, right?
That can easily be modified to work significantly better, - and handle the extra power.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[MuzzcoVW]

[Wreck]

A little trivial and not relevant in this case . AA used the VW head to cast their square port heads , it is a shame they didn't copy the AMC casting . The AMC square port head has more material to work with on the long side of the exhaust port .

Even though mine are opened up , I can still use the stock gasket . just have to carefully open it up with a die grinder , then put the 3 seperated parts together with a little maniseal .

[raygreenwood]

Just a few corrections here....just cleaning up and not poking at anyone!

The. cam Alstrup was speaking about is the "9550". Yes....it's been discontinued.

It was a variation of the web #73 with a couple of degrees difference in overlap or timing. I can post the specs later when I get home.
Both the #73 and the 9550 cams are based around the valve timing (within a few degrees) as the original 1.7L 411 cam which continued perhaps into the very first few 412 with 1.7L....Both with D-jet injection. That is listed as the "V" series factory cam. The later 412 and 914 cams were "Z" series.

I will post specs for each that I have. The critical difference between the factory V and Z series was considerably different valve timing for intake and exhaust opening and closing points.
Both cams worked "well" with factory D-jet injection but the early V series I think tuned a little better. It also was the cam used on the carbed 411 in 1968 -1971.
The later Z grind works a little better with the first L-jet used in 1974 412 and 914. That's just my personal opinion. I am not 100% sure off the top of my head which cam the 1.8 used.

The current replacement cam for the 9550 is the 9590 available from the Type 4 store.

It is essentially the same cam as 9550 with about 2.5° extra exhaust duration or overlap. Cannot remember which one. I will see if I have the specs on all of them.

Ray

[MuzzcoVW]

Thanks Ray. It hit me earlier thinking about the web 73 being very close to the 9550. The straight 73 is the one I was originally going to use in my L-Jet 2 liter. Some had recommended the 9590 but then others have said the it has too much exhaust duration, and will kill torque. I don't want this as I don't like running higher RPM than needed. I feel I'm honing in on what I want, and appreciate everyone input here as always.

[Wreck]

[Vanapplebomb]

[MuzzcoVW]

I know I've seen them listed the last couple years, not sure when they started. I haven't been able to find much about real world longevity results... because they are fairly new to the market

[raygreenwood]

[Vanapplebomb]

[MuzzcoVW]

Looking forward to it Ray, thanks. As for the setup I plan to run, stock gears for a 1977 bus and I MAY run 215-75r15 tires. Not sure on that yet, but I always felt these rigs were under tired ( if thats a thing) for their size. I have them on my Vanagon now and love the look and handling. So if I do that my RPM will be close to a couple hundred lower. I don't drive aggressively but do occasionally take the highways. Here in New England I'm not dealing with the Rockies haha. Thanks again and looking forward to more. Craig

[MuzzcoVW]

[Vanapplebomb]

Yeah, AMC have gotten a little nasty with casting flash. They didn’t used to be so bad, but it has definitely gotten worse. Takes a lot of work to clean up the flashing in the air cooling passages.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[MuzzcoVW]