Hi,
I putting together a 85 F250HD 4x4 with a 460 out of a 87 F250. I am going to be using the stock exhaust manifolds with a custom 2-1/2" dual into 3" single low-restriction exhaust, and a low restriction dual inlet air cleaner.
From what I can tell the stock carb is jetted way lean. 61 on the primary and 63 on the secondary. I was wondering if anybody has ever done much with "tuning" these 4180's on 460's.
With just a good rebuild and a single stage power valve, I have seen these work excellent on the 83-85 HO Mustangs. Which for reference are jetted much richer than the 460's. Thanks

 

The smaller the carb or the bigger the engine will take less jet as the signal is very strong at the boosters and they draw fuel very well. If you put a 1100 cfm Dominator on a 302 it will need jets near 99 or 100's but on my 357 I only need 88's. On my 460 the Holley 750 on it has 67 jets on the primary side. The carb came new with 72's in it and it was a bit fat so I have been cutting it down one jet at a time until the plugs came around. 61's on a small carb on a big engine sound correct. How did the plugs look?

 

Have not had it running yet. I was just going by "back in the day" when ever you put "good" exhuast on something you had to rejet to get max performance. On a 428CJ Mustang or Torino came with a 735 Holley with 66s and 79s. Once you did some exhaust work they came alive, but required like 70's and 82's to really run. My dads Mach1 ran like 13.2's with stock settings going lean, and with changing the jets until the plugs got a little black and backing them back down 2 sizes, it went 12.73.
On the 460 I thought the primary would be pretty close seens the annular booster have a stronger vacuum signal, but the secondarys is what I am worried about.