GMC carburetor fuel to air ratio

[thomas g. warner]

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
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[philip l. stewart]

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