6066 (1960-1966) GMC Truck Club

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-   -   I Beam Exhaust on 305C (https://6066gmcclub.com/showthread.php?t=50333)

vanhow10 April 22nd, 2018 02:49 PM

I Beam Exhaust on 305C
 
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 April 23rd, 2018 05:02 AM

Re: I Beam Exhaust on 305C
 
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, :pullinghairout: well just because they're not I beam shaped and are a smooth casting.:lolsmack2: 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 April 23rd, 2018 05:15 AM

Re: I Beam Exhaust on 305C
 
Quote:

Originally Posted by bigblockv6 (Post 69074)
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, :pullinghairout: well just because they're not I beam shaped and are a smooth casting.:lolsmack2: 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.:upyes:

vanhow10 April 25th, 2018 12:04 AM

Re: I Beam Exhaust on 305C
 
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.


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