[rebel-builders] Anyone wanna buy an almost finished Super Rebel?
Posted: Sun Feb 19, 2012 11:03 am
I was going to use my aviation differential compression tester until I saw
the automotive one that my friend had. It seemed to be much better quality.
It took numerous attempts to get a good test because the engine would turn a
bit when getting about 40-50 psi in the cylinder if I didn't have it exactly
at TDC. I recognized the possibility of low compression due to an engine
not completely broken in early on. The clincher for deciding to replace the
gaskets was the oil seepage around the head bolts that I was never able to
explain.
Once the old gaskets were off, looking at the Felpro catalogue confirmed
that I had the wrong gaskets. (So much for having a so called engine expert
friend order all the parts for me.) I had a Felpro 1010 gasket installed
which the catalogue says should not be used on sleeved aluminum blocks. I
have now installed 1034 gaskets which the catalogue says is for sleeved
aluminum blocks with aluminum heads. They pretty much look identical but
the 1034 has a steel core on the metal rings and the 1010 has a copper core.
I still find it hard to believe such a small thing could make a difference
but here's hoping my problems go away. Heads are on and final torqued.
Dave Ricker talked about sealing the head studs with something but I
confirmed again that my studs are in blank holes in the block. No coolant
galleries, no oil galleries there. The head gasket is the seal to those
bolts.
Tomorrow is for assembling the rest. Intake manifold, carb, etc. Set the
valve lash, re-test compression, run the engine. Wish me luck.
Mike
044SR
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: Thursday, August 03, 2006 12:02 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Anyone wanna buy an almost finished Super
Rebel?
Mike
FWIW I've found that automotive leakage testors may not be all that
precise. Nor particularly indicative of anything on some new engines
that aren't broken in a bit. You also must make sure that you haven't
gone even a little bit past TDC or the rings unseat from the bottom of
the piston lands and leakage increases. Personally I wouldn't get overly
upset about your readings as long as all cylinders are in the same
ballpark. I'd expect some ring leakage and I'd put my ear to the
crankcase vent and confirm that you can hear leakage past the rings and
not past the valves and that there are no bubbles in the coolant. By
all means check the gasket part number but I wouldn't expect the wrong
gasket to be responsible for the leakage readings that you have
reported. Maybe if one or two cylinders were out in left field but not
with uniform numbers, even if they do seem low to you. Don't know about
the oil on the bolts though and I have no experience with your specific
engine. Despite keeping the soob internals totally stock, I had
moments when I wondered why I hadn't just used a Lycosaur during ground
runs, but I'm quite pleased with it now ;)
The Rebel is different of course but it also has lots of flaperon slop
such as you described on the ground but it all goes away in flight and
it also flies just fine with no control issues.
Ken
Mike Kimball wrote:
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the automotive one that my friend had. It seemed to be much better quality.
It took numerous attempts to get a good test because the engine would turn a
bit when getting about 40-50 psi in the cylinder if I didn't have it exactly
at TDC. I recognized the possibility of low compression due to an engine
not completely broken in early on. The clincher for deciding to replace the
gaskets was the oil seepage around the head bolts that I was never able to
explain.
Once the old gaskets were off, looking at the Felpro catalogue confirmed
that I had the wrong gaskets. (So much for having a so called engine expert
friend order all the parts for me.) I had a Felpro 1010 gasket installed
which the catalogue says should not be used on sleeved aluminum blocks. I
have now installed 1034 gaskets which the catalogue says is for sleeved
aluminum blocks with aluminum heads. They pretty much look identical but
the 1034 has a steel core on the metal rings and the 1010 has a copper core.
I still find it hard to believe such a small thing could make a difference
but here's hoping my problems go away. Heads are on and final torqued.
Dave Ricker talked about sealing the head studs with something but I
confirmed again that my studs are in blank holes in the block. No coolant
galleries, no oil galleries there. The head gasket is the seal to those
bolts.
Tomorrow is for assembling the rest. Intake manifold, carb, etc. Set the
valve lash, re-test compression, run the engine. Wish me luck.
Mike
044SR
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: Thursday, August 03, 2006 12:02 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Anyone wanna buy an almost finished Super
Rebel?
Mike
FWIW I've found that automotive leakage testors may not be all that
precise. Nor particularly indicative of anything on some new engines
that aren't broken in a bit. You also must make sure that you haven't
gone even a little bit past TDC or the rings unseat from the bottom of
the piston lands and leakage increases. Personally I wouldn't get overly
upset about your readings as long as all cylinders are in the same
ballpark. I'd expect some ring leakage and I'd put my ear to the
crankcase vent and confirm that you can hear leakage past the rings and
not past the valves and that there are no bubbles in the coolant. By
all means check the gasket part number but I wouldn't expect the wrong
gasket to be responsible for the leakage readings that you have
reported. Maybe if one or two cylinders were out in left field but not
with uniform numbers, even if they do seem low to you. Don't know about
the oil on the bolts though and I have no experience with your specific
engine. Despite keeping the soob internals totally stock, I had
moments when I wondered why I hadn't just used a Lycosaur during ground
runs, but I'm quite pleased with it now ;)
The Rebel is different of course but it also has lots of flaperon slop
such as you described on the ground but it all goes away in flight and
it also flies just fine with no control issues.
Ken
Mike Kimball wrote:
80Everything is completely final riveted, and bolted in place. Not to worry
though. I have received responses from two other builders who are both
flying and they have similar slop and report no in flight problems other
than a little control harmony issue and a bit of wandering on heading when
letting go long enough to glance at charts or tune radios. To me, this is
great news. I had considered this problem to be the worst of the obstacles
I am facing but now I am simply moving on to my other troubles.
I did a differential compression test on two cylinders today. One on each
side of my V8. 62/75 on one side and 65/75 on the other. (75 instead of
blown,because my automotive tool has a chart for percentage leakage based on 75)
That's not good. I didn't even bother checking other cylinders at that
point. Low compression along with the oil that collects on the head bolts
when running the engines, I now believe, not that my head gaskets are
but rather my head gaskets are not the right ones. I'm going to make some
phone calls, make sure I use the correct gaskets, and install new ones
tomorrow. I'm hoping that my cooling problems will either go away or
improve significantly once that's done.
Mike
044SR
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