I Beam Exhaust on 305C

[vanhow10]

Bought a 305C with the I-beam exhausts and automatic transmission set-up. It came out of a long-bed stepside that the owner thought was a 3/4 ton truck. Is there any difference in the heads or anything else I should figure out considering it has the I-Beam exhausts? Thanks for any input.

[bigblockv6]

Just because your 305C has I beam manifolds doesn't mean there are differences in the head, these are still the same small port heads and exhaust manifolds. Lately I've noticed a lot of people thinking just because their V6 has I beam manifolds that they are Magnums. The fact is when GMC first introduced the V6 for 1960 there were no big port Magnum engines yet there were I beam shaped exhaust manifolds. Just a few minutes ago I got a message on youtube from someone saying I'm using 305 exhaust manifolds on my 478M, well just because they're not I beam shaped and are a smooth casting. I'm using 351E Magnum exhaust manifolds retain the proper look for a pickup truck. There were actually 5 different types of Magnum Exhaust manifolds.

[bigblockv6]

Originally Posted by bigblockv6

Just because your 305C has I beam manifolds doesn't mean there are differences in the head, these are still the same small port heads and exhaust manifolds. Lately I've noticed a lot of people thinking just because their V6 has I beam manifolds that they are Magnums. The fact is when GMC first introduced the V6 for 1960 there were no big port Magnum engines yet there were I beam shaped exhaust manifolds. Just a few minutes ago I got a message on youtube from someone saying I'm using 305 exhaust manifolds on my 478M, well just because they're not I beam shaped and are a smooth casting. I'm using 351E Magnum exhaust manifolds retain the proper look for a pickup truck. There were actually 5 different types of Magnum Exhaust manifolds.

What I would like to add is the fact that your 305C has I beam manifolds also means they do have bigger and smoother passages over the round type commonly used on light duty trucks and most 305C engines.

[vanhow10]

Thanks for the input, I thought that might be the case, but wanted to get a second opinion. I plan on keeping a 305 in the truck whether it be a C or E. It will just depend on which one seems to be in the best shape. I also got an original transmission adapter plate with the 305C so I'm hoping to change to an automatic transmission as I put things back together.