250 CID questions

[ctumbler]

Guys -

A few questions. Recently picked up a 66 C10 with a 250 with a 700r4 behind it. Nothing on the truck quite lines up, and there is a ton that needed to be sorted. From the casting numbers on the block and the exhaust manifold it looks like this is an early 70's 250 - no idea on the 700r4 yet. First thing I am tackling is the rear end and tranny - the drive shaft is way short and the rear end fluid looks like river water, also the TV cable was melting to the exhaust manifold. In looking at getting the TV cable hooked up I noticed a few things I cannot explain on the engine block and exhaust manifold. It looks like there is a rail tapped into the block along the side of the manifolds - it is pinched at the firewall end, and capped at the radiator end - pictures attached. Any idea what this is all about?? Can I pull this and plug these holes? Also - some sort of vacuum end tapped into the end of the exhaust manifold that runs back to the distributor??

Any help would be amazing as I try and get this project moving in the right direction.

Thanks

C

[aerotruk63]

That pipe tapped into the head more than likely had a air pump attached to it at one time to help with emissions. My Dads 73 Suburban had a similar set up on the V8. You can remove it and put plugs in the head to block off the passages.

That manifold is not attached to the exhaust, but the intake, it's supplying vacuum to the vacuum advance on the distributor. If you don't like it you can remove it and send it to me and I'll pay for the adapter fitting to run just the vacuum line.

[gimmy 64]

from 68 on these trucks with 250 had a smog pump. the line going to the exhaust manifold is part of this just remove and plug. i have no idea what the thing is comming iff the intake is.

[ctumbler]

Thanks Aero -

Think I'll hang onto the manifold and just get it running properly for now, if I decide to swap it out I will let you know - so the line for the air pump, air was forced down that line and into the chambers? Was that to help give a leaner mix and therefore decrease emissions??

[aerotruk63]

I think it introduced air into the exhaust port to disguise emissions.

Hang onto that vacuum manifold. Those are hard to find to attach other vacuum related systems. Not saying that I wouldn't want to take it off your hands. The large tube headed for the power brake booster is where the vacuum supply to the booster is supposed to be hooked up. The fittings vary for the vacuum line for the Automatic Transmission, the Vacuum Gauge Option in the dash, Vacuum advance for the distributor and last but not least Vacuum Powered Air Pump, for the Air Horn, on Medium/Heavy Duty trucks without Air Brakes. Very cool thing to have. Ok now I just want it, give it to me or I'll tell Mom!

[Str8axle]

Didn't the factory refer to the smog pump and tubes as the A.I.R. System?

[aerotruk63]

Oh and please remove the rubber line from the Carburetor to the Fuel Pump and run it through a steel line like it's supposed to be. I had an engine compartment fire due to brittle rubber line. The drier fuels today dry out the rubber and they fail quicker. Please!

[ctumbler]

Guys -

Thanks so much for all the help - I appreciate the "how not to start an engine BBQ" tip....

[Rooster's 67]

It is part of the A.I.R ( Air Injection Reactor )System.
Part of the first exhaust emmission systems injected air very close to the engine, either in the cylinder head's exhaust ports or in the exhaust manifold. These systems provided oxygen to burn unburned and partially-burned fuel in the exhaust. There was significant unburned and partially-burned fuel in the exhaust of carburated1960s and early 1970s vehicles, and so air injection significantly reduced tailpipe emissions.

You can feel free to remove (if you can without breakin/stripping the fittings)and use pipe plugs to plug them, If I recall they are NPT threads.

[ctumbler]

hey areotruk63 - swapping out the inline 6 - any interest in the manifold?