RMC List - Picnic

Mon Aug 15 17:31:53 EDT 2022

Amazing information here!

So what I'm hearing as far as action items would be:
-adjust ignition timing
-larger jets in the carbs
-ensure all rubber fuel hoses are ethanol compliant (replace if not)

Forgive me if I missed anything.  Are all of these jobs that can be
accomplished by a layman in the garage, or would they require special
attention from more professional hands?

Thanks again,
Mikey

On Mon, Aug 15, 2022 at 12:53 PM Kenneth Schifftner <scrubbr at ix.netcom.com>
wrote:

> Mike:
>
> What I was told about carburetors and air/fuel ratios is that an IC engine
> depends upon both the VOLUME of air being passed through the engine and the
> MASS (weight of air). It is the kinetic energy of the air passing through
> the jet that primarily creates the needed atomization, not just the
> volumetric  (air) flow.The kinetic energy is the gas (air) velocity times
> the mass of the air. Thus, as the altitude increases and the air density
> decreases, kinetic energy required for fuel atomization decreases.
> Compensation is needed.
>
> But there is more. What about the fuel? The fuel needs to pass through the
> orifice in the jet. The jet (orifice) in a carburetor resists the flow of
> the fuel thus a slightly larger jet reduces the fuel flow resistance.
> Therefore, the bigger jet adjusts for the altitude's reduced kinetic energy
> as dictated by the lighter, lower density air. Less air kinetic energy is
> compensated by lowering the fuel flow resistance imparted to the fuel by
> the jet.
>
> Modern FI systems have MASS FLOW sensors for this reason. The atmospheric
> pressure sensor determines the altitude variable and the ambient
> temperature sensor provides the temperature variable, the computer
> determines the available atomization kinetic energy. The signal then is
> used to set the air/fuel mixture under various throttle position (and
> exhaust oxygen) settings.
>
> Hope that helps!
>
> Ken Scifttner
>
> On Aug 15, 2022, at 12:13 PM, MICHAEL PIPER via RMC-List <
> rmc-list at corvair.org> wrote:
>
> My $0.02-
>
> The high alcohol fuel will boil if you look at it cross-eyed.  It also has
> more oxygen on it so to compensate you can make the fuel/air mix richer to
> cut down on detonation.  I have two 140 engines and they tend to detonate
> easily.  I don't know what jets I have but they are bigger than stock.
>
> In the mists of time, using leaded fuel, the old rule was to advance the
> timing 1/2 degree per 1000 feet of elevation, or 2 1/2 degrees at 5000
> feet.  That did not work well in my 140 engines.  I've had detonation
> issues so I'm pretty close to the book timing advance.
>
> Be very careful when putting rubber hoses in the engine bay.  If you loose
> a belt and cut a line, you have the makings of a fire if the pump keeps
> running.
>
> I've put electric fuel pumps in the front near the right front wheel or
> back by the left rear wheel.  If the pump is low in the system it does not
> need to suck fuel to speak of.  If it is the engine bay where Mikey's is it
> will need to lift fuel to the carbs.  If it's hot due to the engine plus
> you are sucking on the fuel, that could enhance vapor lock chances due to
> reduced atmospheric pressure.
>
> Regards,
>
> Mike
>
> On 08/15/2022 11:34 AM Paul Jarrett Sr <pjarrettsr at yahoo.com> wrote:
>
>
>
> Why would you increase jet size at higher altitude?
>
> On Monday, August 15, 2022 at 11:18:34 AM MDT, JOHN DAWSON via RMC-List <
> rmc-list at corvair.org> wrote:
>
>
> Mikey:
> all of the issues you mention could contribute to the surging, but it was
> a hot day and having the electric fuel pump inside the engine compartment
> could be a major contributing factor.
>
> Sounds like a vapor lock or a heat-related fuel issue, as what happened to
> me just two miles from home and my electric fuel pump is located up front
> near the tank; but is subject to all the heat radiating up from the hot
> asphalt pavement. The 10% ethanol in the fuels we have in the metro area
> does not help one bit either.
>
> Most important in setting the car up for 5280' elevation is to advance the
> ignition timing by about 3 - 5 degrees and maybe having larger jets in the
> carbs (go from 49 to 51). I've been able to get by with just advancing the
> ignition. And always spend the extra money on the 91 octane "Premium"
> fuel...even if it has ethanol in it.
>
> Make sure that you've replaced all the rubber fuel hoses with an
> ethanol-compliant hose (Gates 4219BG for instance) This is available at
> most auto parts stores (I've purchased it from O'Reilly's recently)
>
> The PowerGlide in of itself is probably not the main culprit other than
> it's just a two-speed transmission, and therefore does not allow for
> keeping the engine rpm up a bit when going uphill (unless it's in "L" and
> then the rpms may be a bit too high...)
>
> Hope this helps
>
> Be safe out there
> John Dawson
>
> On 08/15/2022 10:46 AM Mikey Spaulding <mspaulding166 at gmail.com> wrote:
>
>
> Interestingly, twice on my drive home while heading uphill, I had a sort
> of surging in the vehicle and seeming loss of power, almost like it was
> stalling out.  The last time it happened on Federal, I slowed down to about
> 30mph (not intentionally) before making it to the top of the hill.  Once
> past the crest, I had no more problems.  Any ideas as to what gremlin could
> cause this?  Would it be related to not having the carbs tuned to this
> elevation since bringing it from Minnesota, where my elevation was 912'
> asl?  Or is this more a transmission issue with the PowerGlide?
>
> Thanks for any help and ideas!
>
> Mikey
>
> On Sun, Aug 14, 2022 at 9:08 PM MICHAEL PIPER via RMC-List <
> rmc-list at corvair.org> wrote:
>
> My red Corsa has an Airtex solenoid style pump, the white car has a Carter
> vane style pump.  Both are low pressure pumps.  I think the problem with
> the red Corsa is the wiring in the engine bay vs the pump.  I wiggle the
> wires by the bulkhead connector and off it goes.  The problem has been very
> hard to duplicate sitting in the garage.
>
> Maybe I failed to pay my dues to the gremlin union.
>
> Hope this is a little helpful.
>
> Mike
>
> On 08/14/2022 8:54 PM JOHN DAWSON via RMC-List <rmc-list at corvair.org>
> wrote:
>
>
> That darn gremlin may have been passed over from Mike's car to my sedan...
> the electric fuel pump decided to take a coffee break as I was waiting at
> the light at Orchard and Broadway on the way home. was able to get the car
> to a safe place and 30 minutes later, the pump was back to work...and of
> course that was after calling AAA for a tow and letting Karen know that I'd
> be a little late getting home.
>
> BTW: what type of electric pump have you used on your daily drivers?
>
> Great to see you and Linea today.
>
> Be safe out there
> JD
>
> On 08/14/2022 5:04 PM Eric Schakel via RMC-List <rmc-list at corvair.org>
> wrote:
>
>
> Good time, good people, enjoyed the cars and company. Special thanks to
> Mike Piper, who once again did “Corvair gremlin” duty so the rest could
> drive trouble-free! And thank you, Dale, for getting this up so quickly!
>
>
> Eric S.
>
>
>
> *From:* RMC-List <rmc-list-bounces at corvair.org> *On Behalf Of *Dale N.
> via RMC-List
> *Sent:* Sunday, August 14, 2022 3:57 PM
> *To:* Corvair - RMC Email List <rmc-list at corvair.org>
> *Subject:* RMC List - Picnic
>
>
> Hello RMCrs,
>
> We got together for the Wilshire Memorial Picnic today.
> As usual, it was a combination of pleasant weather, almost too much food,
> and not enough conversation.
> Never seems to be enough time to catch up with everyone.
>
> If you were unable to attend, you missed a good time and we missed you.
>
> Check this link for a few photos from the gathering.
>
> https://www.rockymountaincorsa.org/2022-08-14-picnic/
>
> Dale
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>
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>
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