A while back I posted up about surprisingly finding the non original/not factory Holley I had taken off of my ‘69 years back (close to 20 yrs ago). It’s aesthetically in good looking shape, but I have to concerns that maybe you guys can help me with. I’m trying to discern if I should go through it (rebuild) or not for my ‘71 LT1, which came with a Edelbrock that I do not want to use for various reasons. Here’s my 2 questions/concerns:
1. The ‘69 was a 350/350 car. With a cam and heads swap (no idea the hp as I never dynoed it) I was pulling 12.6 in the quarter. (that was prior to the stroker with nitrous). So, the carb obviously fed that engine well enough. I’ve read that a ‘71 LT1, with only 330 hp, had a 780 cfm carb. This carb is a 750. While I don’t plan to throw money after the hp/tenths of seconds chase like I did on the ‘69, I also don’t want to de-tune and leave hp on the table. From what I’ve read, it’s upper RPM hp that is generally lost, and this will be a tool/putter around town car. Should I use it? Should I get a 780 cfm? Again, it fed a higher hp engine really well.
2. When inspecting it after re-discovering it, I noticed one of the secondary blades had oxidation (surface rust) on the underside. Would just sanding it and using something like CLP on it be good? Or do I even need to be concerned. I do not know enough to know whether or not that underside oxidation would cause something like pooling or not. If not, no worries. If a problem, and rebuilding, then I can replace it.
Thanks in advance guys!
BTW, a 780 cfm original or original “service replacement” is not an option. This time around, this is a budget build. Seeing what those go for… no way it’s gonna work for me with the budget mindset.

 

What is the list number of the carburetor?
Can you post a picture of the problem area on the secondary blade?

 

​​​​@MelWff , thanks for asking. I’m about to head to the Christmas party my company is putting on. I can and certainly will get that pic and # tomorrow. Thanks again for your willingness to step in.

 

The carb will be just fine for general driving n the difference in HP vs a 780 will more depend on tuning. For the surface rust, try some WD-40 and fine steel wool or white scotch bride. Either should work.
what sort of choke does the 750 have. For everyday driving I would want a reliable unit that starts easily.

 

I mapped my Blueprint 350/341 HP engine on Desktop Dyno with a 600 CFM carburetor and did a quick comparison with a 780 CFM carburetor for you. As you can see the 180 CFM difference is minimal. I also did a 750 to 780 CFM comparison. The difference was one horsepower.

 

Thanks for that info! I have not looked at it in a bit, but will tomorrow. I’m pretty sure it is a mechanical choke. I do not remember running power to it, but could be wrong.

 

Outstanding! That’s great to know. I can certainly live with that. Thanks!!!

 

Ok, so after seeing you guys questions above, I went out and pulled it out of the box. I’m thinking I may not have kept the old one off the ‘69 after all. I think this may have came off of a ‘68 Firebird I had. Man am I getting old because this isn’t what I thought I saw when I re-found it a year or so ago.. I remember selling an Edelbrock and a Holley. I'm th8nking the Holley I sold was the 750 I had on the '69. 😔 I think this one is a no go. Air horn stamping is is 6R 8025 B1 and the reman sticker says 65-1850s. From my brief research, this is only a 600 cfm carb. Not really thinking it’s a good idea. And looks like the blades are somewhat rustier than I thought. Oh well. I can list it up for sale locally. Sorry to waste ya’lls time.