351C where to start?

[Cleveland Crush]

+1 on an AF gauge (wideband). Pull a couple spark plugs to get a read on them. Post some good quality photos of your spark plugs and we can offer some help.

 

[boilermaster]

351mach1,
never seen a cleveland need smaller than a .031 primary squirter, get a .033' and a .035''
you want just enough and no more.
Boilermaster

 

[Stanglover]

Now that I am a Holley tuning "expert" after 30 minutes of youtube this morning, I think my choice of carb is just fine for my stockish motor with auto trans. 600 CFM may be a bit small if I ever go with more power but for now its fine. the 4160 doesn't have a secondary metering block which is apparently beneficial for a stock engine with auto trans. If I ever drop the 5 speed in and rebuild the motor, I can add the secondary metering block via a kit but I personally would probably just be purchasing a larger carb (likely a 700 CFM 4150). Drilling holes in the throttle plates is generally for motors with very large cams that have issues idling. Probably not my case. My carb is currently sitting at 15" of vacuum.

I have an awful smell of gasoline inside of the car while driving. I thought it was a major exhaust leak but now I am thinking I am just running ridiculously rich. I think its time I purchase a timing light with tach so I can dial in the dizzy recurve myself and then really dig into the carb tuning. I don't really like paying mechanics for things I can figure out myself so I still have a lot more patience on this before giving up. I also very much enjoy becoming more knowledgeable on what I am running. If it gets to the point where I need to mess with the power valves I may enlist an expert but I think I should be able to get it pretty darn close with normal tuning and possibly swapping out the accelerator pump nozzles.

I am still learning if I actually need a smaller nozzle or a larger nozzle. I may purchase a .025 and a .035 and see how they each affect driveability. I could also play with a different accelerator pump cam but that will probably be the last thing I try to do.

Edit: maybe also worth investing in an air/fuel ratio meter

Messing around and learning as we go is a big part of the fun of owning one of these beasts. I knew practically nothing when I joined this forum and now I know almost nothing.......... and that's a big improvement.
As for the drilling of holes, my "guy" told me it was because Holley carbs tend to be too rich on the idle circuit and these big valve engine need that extra air. I do have AFR bungs welded into my exhausts and I did use an AFR which shows an almost perfect ratio. The plug read confirms that.
I also tried different pump cams but ended up with the original one, which seems to be the best option. I have tried differing choke settings, but again went back to a stock setup.
Have fun.

 

[73 SGM Mach]

Just a thought since your car has amnesia, it’s possible your symptoms point to a contamination fuel tank. I know you changed the carb, but did you trace back to the pump and the tank to verify clear fuel flow? Since the PO didn’t give you the straight story, what else did they fail to mention? Just to alleviate worry, I would check that out. Good luck.

I had a lot of issues with my car also that were similar. I threw alot of parts and money at it to fix it but it all boiled down to a gas tank full of crud. Fyi there is alot of good people in here that can help you out. Just keep plugging away at it!
Jeff

 

[351mach1]

I had a lot of issues with my car also that were similar. I threw alot of parts and money at it to fix it but it all boiled down to a gas tank full of crud. Fyi there is alot of good people in here that can help you out. Just keep plugging away at it!
Jeff

I have come to the conclusion that I would be foolish to not replace the fuel tank. It's on the list now!