The net seems fairly quiet, so I figured I would give some supplemental info on
another set of VW heads that are not covered under Mark Langfords page of VW
heads. I posted about these heads a couple weeks ago, asking about machining a
second spark plug, but never gave an update, so here we go.
These are the heads I’m currently using on my N6399U
https://aapistons.com/collections/cylinder-heads-components/products/new-vw-1600-dual-port-high-performance-cylinder-head-40x355
The Goods
1) Comes standard with stainless steel intake and exhaust valves
2) Lot of air cooling passages (I don’t have pictures, but I would say they are
on par with the DRD heads Mr. Langford has on his page, in terms of air
passages), before any de-flashing.
3) Ready to use out of the box - for better or worse, I installed these on my
KR2 about a year ago after one of my older MOFOCO heads failed, and I other
than a simple water leak down test, I didn’t do a single thing to these heads.
The heads were able to be used right out of the box. A valve job was not
necessary.
**additionally, after I eventually did have to break down one of the heads,
after about 100 hours on one (due to one of the exhaust valves leaking ever so
slightly on #3), the valve guides were still in great shape, and there was no
“gap” in between the valve guide and the cylinder head, how Mr. Langford
discussed on his set of DRD heads.
4) CHT spark plug sensor fits with ease - the pictures I posted above
incorrectly portray this (or maybe I just got lucky), however on my set of
heads, there was lots of room in the spark plug area to install a 12mm CHT plug
sensor with no machining/dremeling required. This is different than my previous
MOFOCO heads, that required me to grind down part of the circular “edge” that
usually surrounds the spark plug, in order to install a plug-style CHT
thermocouple.
5) the valve seats do not appear to “recess” like they do on older VW heads.
Usually the valve clearances between oil changes are just about where they
should be when I go to adjust them; I never have to make any drastic changes.
I’ve gone through about 4 oil changes on them so far.
6) Lastly - they got me to and from the gathering last year, all the way from
WA to IL (and back) in some pretty harsh flying conditions. Out of all the
things that went wrong with my airplane, the heads were not one of them.
Now for two “others”
1) my #3 exhaust valve began leaking ever so slightly (compression was 125 psi
vs 150-155 psi on the other three good cylinders) which required a lap job to
get it to seat again. However, after lapping, and about 5 hours of run time, it
appears to have seated nicely again.
2) now for my BIGGEST complaint, which is almost certainly a dealbreaker for
most people - Eh Hem - Dual ignition is pretty much impossible. Because of the
geometry of these heads (when compared to something like a MOFOCO 042 or a CB
044 head), there just isn’t enough “beef” in the secondary plug area to drill a
second spark plug. No way you could get anything close to a 12mm x 3/4” spark
plug in there; probably the most you could do is something in the realm of a
10mm x 1/2”. After talking to Great Plains (who recommended against that plug
size), and a very experienced local machinist and engine builder, I decided
that the juice wasn’t worth the squeeze and just decided to keep single
ignition. If nothing else, I’ll have that much more metal in the cylinder head
for support.
Now for my typical performance numbers on a fairly hot (80-90F) day at sea
level. The engine is an upgraded Revmaster 2100 (75-80HP), Sterba 56x56, single
electronic ignition. Standard baffling (no plenums).
Temperatures are all taken from a type J thermocouple, directly under the spark
plug.
Static RPM - 2800-2900
CHT climbout at full power - absolute max 430-440F on the hottest cylinders
(full power for an extended period of time), and 400F on the coolest (front)
cylinders. Usually I apply full power on takeoff, then once safely airborne
throttle back to 2600-2700 to keep the CHTs under control; I can still usually
manage a safe 600-700 FPM climb when solo, or about 350-450 FPM at gross at
this power setting.
CHT climbout at 2/3-3/4 power - 390-410F on the hottest cylinders, and 350-375
on the coolest cylinders.
Typical CHTs during cruise (all altitudes)
#1 - 350-375F
#2 - 300-325F
#3 - 350-375F
#4 - 300-325F
It appears that the hotter cylinders run about 25-50F hotter than the two most
forward cylinders.
If nothing else, this can serve as some supplemental info for somebody looking
for a new set of heads. Just don’t expect a dual ignition setup :D.
Very Respectfully
Sam
Sent from my iPhone
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