If some of you remember I posted a while ago regarding a "chugging" problem
with my Revmaster 2100d ("Calling All Revmaster Owners"). I have been
hesitant to report back on here without a clear answer to what was wrong
because I didn't want to waste anybody's time posting until I had a
definite answer.
After several days of troubleshooting, yesterday I finally found my
answer: Cracked Cylinder Heads.
*Note: I made a crucial mistake in my previous post of not explaining that
this problem was "starting" to occur even before I changed my propeller,
while still running the Culver 48" (low pitched) propeller. For those of
you who suspected too high of an engine load and/or detonation with my new
higher pitched Sterba, or advancing the throttle too fast, I greatly
appreciate this insight, however this was not the case. I take 100%
responsibility for not making this clear in the original post and for that,
I do apologize. *
Up to this point, the engine would start up normally, taxi, takeoff,
cruise, and descend without incident. However after the descent, come time
for a T&G or Go Around (basically, running a high power setting), the
engine would sputter. Initially this was no more than a nuisance and I
just had to go reeeeally easy on the throttle up to full power, but
eventually it got so bad that on a legitimate go around (not a practice), I
almost didn’t have enough power to safely fly away, regardless of how slow
I moved the throttle. Half power was about all I could manage out of the
Little Engine That Could. Needless to say, I am no longer flying the bird
until I get this problem fixed.
I first checked the obvious: spark plugs and magnetos. I pulled out the
10+ year old Champion REL37Bs, and....wow......they were nasty! They were
reported at being cleaned at the last condition inspection, however I
honestly couldn't believe they were firing at all. Not only were there
carbon deposits EVERYWHERE, but the electrodes were getting the aging
"football" shape. I elected not to clean them, and instead ordered 8 brand
new plugs. As for the magneto, although old, never overhauled, and
original to the engine (per the logbook) the Bendix 3000D fired all eight
plugs flawlessly, producing a nice crisp spark.
After installing the plugs, the engine initially ran very good and I
thought all my problems had been solved. However the very next day, while
test running the engine again, the problem returned just on the ground
alone! When idling at 1500 rpm, there was no roughness, but when the power
was increased to 2000-2500 rpm, the coughing/sputtering/roughness/vibration
returned, and the engine was meeting all the symptoms of running on three
cylinders. To confirm this, with the cowling still on and the engine
idling, I took an infrared thermometer and measured the temperature of the
EGT coming out of each exhaust pipe and noticed that front left cylinder
was running much cooler than the other three. After some further
troubleshooting, it was clear the cylinder had very little compression, so
off came the head.
As all of you VW operators can imagine (or have experienced)….there was a
fairly solid crack in-between the valves, despite being the standard 65HP
heads. I have been researching the heck out of new heads, from CB
performance, Mofoco, EPI, etc. and have found that there seems to be
cooling/cracking issues with just about every single one of them. Because
of this, I am having trouble deciding on a set of heads. Revmaster no
longer makes the stock 14mm dual heads (to my knowledge), otherwise my
decision would already be made. They only offer the REV049 heads,
featuring bigger valves and dual 12mm spark plugs. I appreciate that they
are trying to create more power, however I am skeptical about running a
head with even less area between the valves. Combined with the fact that
they are $1000 a pair, and that I would have to buy eight new 12mm plugs
(after just buying brand new 14mm plugs), this makes them a turn off for
me.
So in short, I guess my question(s) are….
1) What is a good replacement cylinder head? (stock valves and 14mm
dual spark plugs if able)
2) What type of heads are you guys running?
3) Does anybody have any stock 14mm/Dual Revmaster heads laying around?
If so, I would be more than happy to pay top dollar for one to avoid having
to wait several weeks, in addition to having to change spark plug types.
One is all I need.
I was close to buying a single stock CB head, having it machined for a
90.5/92mm bore and dual plugs and buying four 12mm plugs to go with it. I
was about ready to order this afternoon but wanted to post on here first.
Mr. Langford, your thread on the various VW heads of your 2180 engine, and
their cooling properties was invaluable to me. While I am sorry that your
DRD heads did not hold up for more than 50 hours, it prevented me from
making the same mistake and ordering from them. I noticed that you were
not impressed with the CB heads in terms of cooling, however after
researching, they appear to be the least of all evils when compared with
other brand names, hence why I was considering purchasing a stock head from
them.
And to all of you, thank you for taking the time to read this post, and be
willing to help. Although fairly new to the game, I am proud to call
myself a KR owner (even in times like this), and to also be a part of this
community.
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