Re: 65 American 232 (I-6 rough idle/stumble)

[Matt Haas <mhaas@xxxxxxx>]

Besides checking for vacuum leaks at both the manifold and PCV hose, power 
brake systems (if so equipped) can also cause vacuum leaks.

On my 68 American, the loose manifold was caused by failed hardware (some 
had fallen out, most of what was left wouldn't hold torque) and it was only 
a problem when hot (you had to take it out and drive it around to get it 
hot enough to do this). When it was hot, I had something around a 1/4" gap 
between the engine and manifolds in the middle (near the carb) and none 
when cold. This problem is compounded by the fact that the TSM (at least 
the 66-68 ones I've seen) doesn't have a torque pattern to it and the 
pattern AMC came up with is both non-obvious and a slight pain in the 
keester with the engine in the car.

They way I fixed my car was to separate the manifolds, clean up all the old 
gasket material, replace all the hardware (bolts, nuts, and studs), and 
re-assemble. Make sure that Grade 8 hardware is used and a cleaning tap is 
run through all threaded holes and the holes are cleaned up afterwards. 
Also, this is a good time to check the heat riser valve since this can also 
cause driveability problems if it isn't working properly. In my 68, it was 
rusted half shut so it was cut out and the holes plugged.

Once the manifold is squared away, give the car a good tune-up (I'd replace 
the points and condenser while doing this). If the problem is still there, 
check that the vacuum and mechanical advance are working properly. A bad 
coil can also cause roughness and it's not uncommon for them to fail when 
hot. If it's still rough and this is a recently rebuilt engine, it's 
possible that the wrong push rods were installed and the valves aren't 
seating (or they were not machined properly). A leak down test will show this.

Matt

At 11:22 AM 2/9/2006 -0500, you wrote:
> also tell Gary to check the PCV hose where it connects onto the base of 
> the carb. mine wasn't even threaded into the base more than  one thread 
> and it leaked like heck.
>
> Jay
> ----- Original Message ----- From: <mail@xxxxxxxxxxxx>
> To: <mail@xxxxxxxxxxxx>
> Sent: Thursday, February 09, 2006 8:10 AM
> Subject: re: 65 American 232 (I-6 rough idle/stumble)
>
>
> Send Gary over to
> http://www.mattsoldcars.com/RestoreAmerican/loose_intake.shtml. It's
> most likely a leaking intake after the rebuild. Wouldn't hurt to have
> the intake checked for flatness -- and the exhaust manifold.
>
> On February 9, 2006 eddiestakes wrote:
>
> > Gary below is having some problems with his American. I mentioned to
> him that I would forward his dilemma to the amc-list and see if anyone
> here can help him out. Should you reply, please copy your reply to Gary
> also who is not a member at this time but may join. Thanks in advance to
> all who might reply. Oh, the birthday was for Jacob, who turned 3 on Feb
> 4th, we had a party at Peter Piper Pizza, better pizza than Chuck E
> Chunk, and they won't rush you out like Chucky place does either!
> > Eddie Stakes'
> > Planet Houston AMX
> > 713.464.8825
> > eddiestakes@xxxxxxxxxxxxxxxxxxxx
> > www.planethoustonamx.com
> >
> > ----- Original Message ----- From: Gary L. Kirk
> > To: Eddie Stakes
> > Sent: Sunday, February 05, 2006 6:26 PM
> > Subject: 65 American 232
> >
> >
> > Hi Eddie,
> > Thanks for calling me back the other day! How was your sons birthday?
> > I've decided that my question is not that urgent that I can't try to
> put it into text. My 65 american stumbles and stalls sometimes. I have
> rebuilt the carb and the base/throttle plate is all tight. It still
> stumbles. The previous owner tells me and gives me proof that the engine
> was rebuilt by "Jasper Engines"
> > There is a guy on ebay who claims that with the fomoco carb kit he
> sells for around 300 bucks, that he can solve the problem. I have read
> that this stumbling might be a common problem.
> > All the ignition system is original- points ect. I was thinking of
> upgrading it to maybe an expensive electronic system. But now, I am
> wondering if you have had or heard of remidies for this engine?
> > I hope you can make out what I am saying, And thanks again for all
> your recent and help over the years!
> > Gary Kirk Va.
>
> Frank Swygert

mhaas@xxxxxxx
Cincinnati, OH
http://www.mattsoldcars.com
1967 Rambler American wagon
1968 Rambler American sedan
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