<VV> Carb Heat-Related Issue
wrokit at hotmail.com
Tue Mar 8 22:34:35 EST 2016
Date: Mon, 07 Mar 2016 21:12:33 -0800
From: Bernie Livengood <bernielivengood2001 at yahoo.com>
To: Grant <gyoungwolf at earthlink.net>, Dennis
<virtualvairs at corvair.org>, virtualvairs <virtualvairs at corvair.org>
Subject: Re: <VV> Carb Heat-Related Issue
Message-ID: <53ycs0u1c7pj6dse6m5vnoh0.1457413953321 at email.android.com>
Content-Type: text/plain; charset=utf-8
Your throttle plate is not centered in the throttle shaft, either far left or right,? works ok cold, but under heat soak , can intermittenly bind. recheck that area!?? Bernie
On Mar 7, 2016 4:46 PM, Dennis Pleau via VirtualVairs <virtualvairs at corvair.org> wrote:
> There is no lock in the linkage or the carb on a '65. They should always open. That was what the tried to fix with the Rube Goldberg later linkage.
> Sent from my MetroPCS 4G LTE Android device-------- Original message --------From: Grant Young via VirtualVairs <virtualvairs at corvair.org> Date: 3/7/2016? 11:57 AM? (GMT-08:00) To: virtualvairs at corvair.org Subject:? Carb Heat-Related Issue
> After having rebuilt thousands and thousands of Rochesters, I thought I had seen everything as well as screwing up everything at least once. But I have come across an issue with some '65 secondary carbs that I hope someone else has encountered. The carbs seem to fit and seal properly. They have the requisite new throttle shafts and good run out. They do not leak air at idle. The car starts up and runs fine for the first 10-15 minutes or 30 miles or so, but when the driver attempts to use them after that they are "locked" in place and can not be opened with the gas pedal and linkage. They work fine on the engine prior to that place in time. All the linkage is installed correctly with no excessive play anywhere. It appears to me to be heat related, but I don't know how to correct it since the throttle body areas have already been re-polished in an attempt to correct it. (The plates are installed correctly so the angle matches the bores). Any ideas?
Is it possible to identify what is actually binding when hot? I wonder if it might be the linkage itself. It might make some sense to get the engine hot enough to cause the secondary's to stick, then disconnect the linkage and then
try to move the plates. If they are still stuck, then spray some oil on the shafts to see if that improves it or not. If there
is no change, then the bores have to have something wrong with them such that the throttle plates are getting stuck.
Some of the kooky things that I've seen that have caused throttle plate to bore binding are angles not cut correctly
on the plates (sometimes this can be corrected by slightly thinning the sides of the plate that have to meet the bore)
Burrs on the id of the bore where the throttle shaft holes intersect the bores, burrs on the edges of the plates where
they meet the bore and throttle shaft hole intersection. One other thing, sometimes the linkage itself can apply a slight
lateral push to the throttle shaft, tending to push the plate to one side of the bore on opening, then when closing
the linkage causes it to tug back the other way. I've dealt with that particular one by adding some shims to both sides
of the throttle shaft to prevent binding caused by lateral slop.
63 Turbo, EFI Daily driver
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