Thomas, I'm sorry, I should be more clear with my questions. I didn't
have a cracked manifold, but I am wondering what the fuel to air ratio
should be to avoid too lean a mixture and possible damage to the
engine.
Phil Stewart
> Date: Sun, 8 Nov 1998 21:29:18 -0500 (EST)
> From: "Thomas G. Warner"
> Subject: Re: GMC: GMC carburetor fuel to air ratio
>
> If the analyzer was correct than I don't see how you could have cracked the
> manifolds after the new carb was installed. Exception I believe was if you
> were really pulling hard or driving fast for an extended time and than
> promptly shut off the engine.
>
> >Thomas Warner wrote regarding the GMC Exhaust Mainiolds:
> >
> >> If you have cracked a manifold you are almost surely running a very lean
> >> mixture. If the original carb is on the coach than with todays gas it is to
> >> lean. You need to get your exhaust analyzed and change the jets etc as
> >> necessary to get the mixture right.
> >
> >So I'm wondering, Thomas or anyone else listening, what should the air
> >to fuel ratio (F/A) be to get the correct mixture and avoid this and any
> >other problems with the 455 running too lean ? I recently had my OEM
> >carb recalibrated with different jets and metering rods in the primaries
> >and afterwards the engine exhaust analyzer said it was running at a F/A
> >of about 14.9 at 55 to 60 mph at Michigan altitude (600 to 700 ft msl I
> >believe).
> >
> >Phil Stewart
> >'76 Transmode
have a cracked manifold, but I am wondering what the fuel to air ratio
should be to avoid too lean a mixture and possible damage to the
engine.
Phil Stewart
> Date: Sun, 8 Nov 1998 21:29:18 -0500 (EST)
> From: "Thomas G. Warner"
> Subject: Re: GMC: GMC carburetor fuel to air ratio
>
> If the analyzer was correct than I don't see how you could have cracked the
> manifolds after the new carb was installed. Exception I believe was if you
> were really pulling hard or driving fast for an extended time and than
> promptly shut off the engine.
>
> >Thomas Warner wrote regarding the GMC Exhaust Mainiolds:
> >
> >> If you have cracked a manifold you are almost surely running a very lean
> >> mixture. If the original carb is on the coach than with todays gas it is to
> >> lean. You need to get your exhaust analyzed and change the jets etc as
> >> necessary to get the mixture right.
> >
> >So I'm wondering, Thomas or anyone else listening, what should the air
> >to fuel ratio (F/A) be to get the correct mixture and avoid this and any
> >other problems with the 455 running too lean ? I recently had my OEM
> >carb recalibrated with different jets and metering rods in the primaries
> >and afterwards the engine exhaust analyzer said it was running at a F/A
> >of about 14.9 at 55 to 60 mph at Michigan altitude (600 to 700 ft msl I
> >believe).
> >
> >Phil Stewart
> >'76 Transmode
