Autolite 4100 power valve size

I have a rebuilt 4100 1.12 and I would like to know if a 6.5 will be work or the 7.5 that came with the rebuild. Who knows if the carb was put together properly. I recently ran this carb on my 289 and it had a hesitation from just off idle to 1500 rpm. Same problem I recently had with a Holley 600 which works now. Not sure how these carbs are set up but I believe it has #54 primary jets. Will a 7.5 give me more fuel when it goes from idle to drive. Thanks once again.

The jetting is somewhere around 52 on the primary and 63 on the secondary. It varies for altitude and also varies slightly by vehicle application. The jets on the pre-64 units were Holley style and on
the later one they used the Autolite design jet.
I've fooled around with the power valves in those a few times and
I seem to recall 6.5 being the right number.
If you can't tune a hesitation out with the pump shot, I used to
unbolt the booster and drill the emulsion tube holes larger.....
definitely a trial and error process.
Check to make sure there isn't a red / brown plastic gizmo inside
the accelerator pump - it serves to massively cut down on the
interior volume of the pump, so the pump shot is really small,
regardless of how you set the actuating arm. (I think only the
earlier carbs had the bigger pump housing, so it might not apply)

Thanks for the info, I am really interested on how good these carbs can be . I had a rebuild kit a while back and it had everything you needed for a complete overhaul but no power valve. I guess the power valve selection would be like a Holley, 1/2 the idle vacuum in drive gives you the powervalve size. Funny how my 570 street avenger has a 8.5 pv and my Holley600 runs on a 6.5 on the same test engine[289].I'll try a 6.5, 7.5, 8.5 and see how they work, or I might have to call Pony Carbs.

Good Luck getting any info out of Pony Carbs! If you didn't buy the carb from them, they probably won't tell you anything.

I guess Ford won't carry power valves anymore since this carb is obsolete. I took a good look at a 1958 artical with a break down from the Carb Doctor and this is a very simple carb. They have the [plain 8.5] power valve for 0-5000ft, [green 7.5] 5000-10000 ft, [yellow 6.5] 10000-15000].

Good info on the power valves.....which I didn't know obviously.
There's two articles you should know about as well on hot-rodding the
4100. The first one is real PITA to find and the other isn't too hard.
1) Petersen's Complete Ford Book #3, page 124-129.
2) Hot Rod Magazine, Dec '68, "More Go 4 FoMoCo Four Barrels."

I found the first one but the second is AWOL from my collection.
(It may be in my storage facility)
Both articles are excellent and there is similar information in both.

I've never tried to photocopy the Petersen Book, so I don't know
how it would read, but send me a PM if you'd like me to try. I
can probably get it done next week.

Thanks for the offer on the magazine articles. I lucked out today at a Ford parts dept and they had an Autolite tune up kit. The part # C2SZ-9A586-D or the new # CT-191-A and when I looked at the kit it had a power valve that looks like a holley valve, but has a different style spring on it. It is also a bit shorter than a Holley with no threads to unscrew the little brass end of the PV. I have a Motorcraft kit not some generic brand so I am going to take the carb apart and see if anything is missing. Not too many parts in the kit to replace which is a good thing. Thanks for all your assistance.