Re: [FWDLK] Exhaust Manifold Heat Riser

["Ron Waters" <Ronbo97@xxxxxxxx>]

Dave  (and others) -

        Thanks for your responses.  I think it would be worthwhile to post them to
the group, since a lot of people may have the same question.  I've included
Dave's response below.  BTW, I wouldn't bet the rent that the exhaust
manifold is clogged with carbon.  I had the engine rebuilt 8000 miles ago.
Also had hardened valve seats installed.  I paid an extra $125 for this
service. Very worthwhile.

Ron

----------
> From: David Grove Grove Automotive <groveautomotive@xxxxxx>
> To: ronbo97@xxxxxxxx
> Subject: Re: [FWDLK] Exhaust Manifold Heat Riser
> Date: Sunday, November 08, 1998 3:15 PM
>
> Ron - in your case, your mechanic is right - you might notice some
> driveability problems in cold weather with the heat riser open - but I
> doubt it.  On cars built in the mid 70's up until fuel injection it's a
> different story.  They hesitate, backfire, stall, etc, due to the leaner
> mixtures calibrated into the carburetor, where heat is needed to vaporize
> the fuel.  I would not hesitate to say that undoubtedly the passages in
> your intake manifold that allow the exhaust heat to travel from one bank
to
> the other are plugged up solid with carbon anyway!  Unless you have a big
> block engine - I would almost guarantee it.  Therefore - you must keep
the
> valve in the open position (all the way), or you may end up with some
> burned valves on the right bank.  While it is true that your fuel milage
> would be better with a "hot" intake - I don't think the driveability will
> suffer, the only thing you might notice is improper choke operation (if
you
> have a "divorced" choke - I can't remember), it may take a long time for
> the choke to open all the way.  DaveG.
>
> ----------
> > From: Ron Waters <Ronbo97@xxxxxxxx>
> > To: L-FORWARDLOOK@xxxxxxxxxxxxx
> > Subject: [FWDLK] Exhaust Manifold Heat Riser
> > Date: Sunday, November 08, 1998 5:06 PM
> >
> > There is a manifold heat riser on the right exhaust manifold of my 58
> > Plymouth.  Like most of these things, mine is frozen up.  A mechanic I
> > spoke to told me that they're not really necessary unless you plan to
> drive
> > your car in icy cold weather.  Since I only drive the Plymouth on warm
> > days, is this a good solution ?  What I actually did was open it up 2/3
> of
> > the way, so a little heat will go up while most will go out the
tailpipe.
> > Any thoughts on this ?
> >
> > Ron