I have an '89 1-ton with a 454. the truck has 300,000+ miles and for the
past 70,000 miles I have been plagued with leaking exhaust manifold
gaskests. I think that the exhaust manifolds are possibly warped, but I
have never sent them to a machine shop to confirm this suspiscion.
Eitherway, I would like to upgrade to some headers to increase torque, but
I am unsure about what to do with the pesky Air Injection Pump System.
Can the entire air pump system be removed? Where can I find an idler
pulley to take the place of the pump? Will my truck pass emissions after
I remove the pump? Does any company sell headers for an 89 truck 454?
Will a sensor pick up a signal that the pump is not working and bring on
an engine light?
If you go check out summitracing.com you can find headers that have
the connections for the smog fittings. I know thorley and edelbrock
make some that have them don't remember who else. They aren't cheap.
As far as passing emissions, technically that pump is federal and
removing it will cause you to fail. If you do want to get rid of
the entire AIR system, you can get a bypass pulley for the pump and
take the whole thing off. I have the gm part number somewhere for the
pulley, it's like 30 bucks, if you want the part # let me know i'll
look it up.
Even with headers make sure and get some good aftermarket gaskets and
not what comes with them, I like copper ones personally. And follow
the retorque directions on your new headers or you will definitely get
If you decide the headers are too pricey, gm did change the design of
the exhaust manifolds a few years after our(mine is an 89) trucks were
built. They supposedly do not warp as much. Another thing you can
try is to take off the manifolds and cut a slot in them in btwn each
cylinder, not where it meets the exhaust port but in the middle btwn
the cylinders, I did this on mine a while back and it got rid of the
leaks. One more caution is that I put on thorley headers(500 bucks)
and after 3 weeks of screwing around with it finally found that the
weld was incomplete where one of the smog connectors goes in, I ended
up sending them back and going back to my manifolds(after modifying as
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