Cheap carburetor / HEI Ignition Timing

[King951]

Hey there,

My 71 C20 307 / 3-speed I purchased last month as a daily driver / work truck had a "rebuilt" Rochester 2G from the previous owner. It ran alright but every vacuum port on the carburetor had been plugged by what appeared to be a lead plug of some sort. I wasn't confident in my ability to drill it out without destroying the carburetor so I did some searching around. The current state I was in: I was driving my truck with no vacuum advance, it was just plugged off. A local carburetor shop had a 2G Rochester but they wanted $200 plus my core carburetor despite mine running already. Fast forward about a week and my truck leaves me stranded, the filter in the carburetor itself was completely clogged to where no fuel would flow through it. (It was black instead of orange.) I put a new one in but by that point I guess it had already sucked dirt into the carb itself. Now it is 9 PM and I am rebuilding this carburetor after being towed home because I need to get this truck to work tomorrow. All said and done it now runs but the accelerator pump breaks in the process and now I am having issues taking off, especially when the truck is cold and my vacuum advance doesn't work. Despite all this I find something online. A remake of a Rochester 2GV on Amazon for $86. I am pretty certain this is one of those Chinese remakes but it has perfect reviews everywhere I look online and free 2-day shipping. I go for it. Receive the carburetor the next day. Come with base plate, gaskets, and more than enough vacuum ports. Everything is brand new and it looks clean inside and out. I hook it up to my truck and use vacuum plugs for the ports I am not going to use. (I believe this is based off of a newer design, mine was a 2GC this is a 2GV). Despite all this I hook the carburetor up, move the air/fuel setting to 1.5 turns out, and the truck fires rite up. I set the idle to ~650 RPM. Extremely responsive, running great. I take a drive to Auto Zone to buy some vacuum line and the truck is now running better than it ever has, very impressed so far. I get the correct vacuum line and hook it up in the parking lot for the first time. I can't believe this is the same truck I was driving to work everyday. I don't know if it was my old carburetor, or the fact that I now have a vacuum advance, or just the combination of both, but it feels like I am driving a totally different truck. It went from a truck that pretty much lugged along (the bed is fully loaded) to now the thing will throw you back if you step on it, before you had to be careful not to step on it to quick or it would hesitate and now it has near instant throttle response. The truck doesn't even sound the same when it idles, it quieter and smoother. I am not saying Chinese carburetors (assuming that is what this is) are better, but I do not think they are a horrible option like I have seen some people make them out to be. I am sure if you broke everything down or did a side by side test / comparison the Rochester or name brand carburetors are probably a much better option, but for $86 so far I am extremely pleased. I will update about this carburetor as I go along.

Now on to my main question. I now have a vacuum advance on my 307. I am running an HEI distributor. Is that going to change where I set my timing? I have seen mixed reviews on how I should set my timing on a 307 online. Some say 10 BTDC, some say 2 BTDC, some say 12-18. I am confused as to what is true or if HEI distributor makes a difference.

Any input is much appreciated.

Thanks in advance.