Retune 1100 after rearend gear change

I have a pretty fresh 1966 200 with a 252 cam, raised compression, 1100 carb and a c4. I got the carb tuned to perfection(well as close as I could). Then I swapped a ford 8" in with 3.25 gears instead of the 2.83 it was born with. All new V8 drums all around along with wider 21570r14 tigerpaws. I don't really notice a difference with the new gears. Now when I stomp it she stalls. Before with the old tires they would squeal a bit. Retune the carb necessary after a rear gear change? More accelerator pump shot?

With the tire change you may have lost the advantage of the 8" 3.25 gear as compared to the 2.89 with much smaller tires.
Make sure you have the accelerator pump to the maximum stroke. You may have to richen to the next larger main jet size.
The best performance would be to upgrade to the 68 distributor & upgrade to a 69 250 carb. You need to get rid of the loadamatic distributor. You can retain your present carb. if you delete the spark control valve. This requires major vacuum passage mods.
I can do the carb mod for you.
However if you have the money is fully upgrade to the DS11 distributor. This requires a module, Ford Duraspark, Mopar or the MSD-6al box & with a MSD harness which will hook directly into the dist. & the MSD box.
Another option is purchase one of my HEI distributors, which is a one wire hookup.
See my for sale section of the small six for sale part of the forum.
If you want to fool around with your present distributor advance the initial 4-6 degrees. Bill

The tires are only .33" taller. According to the online calcs that should bring the 3.25 down to an effective 3.2 ratio. I got the bog out of a mashed accelerator in the previous setup just need to do it again I suppose. I want to get that taken care of then see if I want to do dist changes.

Howdy Eric and All:

First some questions; Have you verified that the accelerator pump in the carb is functioning? How long since a carb rebuild, cleaning and kit? The rear gear change by itself should not require a carb or ignition change- if the carb and ignition was zeroed in previously. So, first step, check the condition of the carb. It's likely time for a rebuild and kit, which will include new pump parts. IIWIYS, I wouldn't change anything until I could verify that the accelerator pump was working correctly.

What is your initial advance setting on the LoM distributor? What do your spark plugs look like? What is you elevation?

I like the sound of your engine. Who did you get the new cam from. Will you share the lift and other specs? Should be a good match for your C4.

Sorry for all the questions. I'll be anxiously waiting for the rest of the story.

Adios, David

Carb and engine rebuilt five months ago. Accelerator pump was good still shoots gas down bore. Now the gas has been aging for three months during the winter. Timing advanced to I think 15 with vacuum removed. Advance works also. Something changed in the three months it was resting in the garage. The rear gears or three month old gas? The cam is a comp 252.

3 month old gas shouldn't cause that. That being said, I put seafoam in mine before I jerked the motor.

Hi, X2 the gear change should not cause a stumble when you floor it. I am curious how it performs on gentle and moderate acceleration, as well as flooring it on a roll. What about a vacuum leak? Good luck

It does fine in all other areas.

Howdy Back Eric:

I'm still thinking accelerator pump. Sitting can cause the pump diaphragm to deteriorate and/or take a warp or set. Some rebuild kits don't use the best materials. Do you remember what brand of rebuild kit you used? Have you looked down the carb lately to verify a strong squirt?

I've looked at that cam several times thinking it may be the ideal cam for a mild street engine with a C4 trans. .425" lift, lobe spread of 110 with a fat profile. Duration isn't a lot more than a stock cam which should compliment a street engine with an auto. I'd sure like to hear your impression of that cam in your package.

Keep it coming.

Adios, David

All I know about the cam is my best vacuum reading is about 12. The car runs as good as can be expected more power than ever with the original intake and carb setup.

"3 month old gas shouldn't cause that.…"
I'd respectfully disagree, this new gas goes bad so awfully quickly, wid all the ETHO in it (least here in NE).

Can't comment on it's contribution 2 yer prob tho.

12" seems kind of low. I have 15" of vac with the cam that I'm running (264/274 110*). I'm at roughly 1000' altitude here in IA. That's down from 21" I measured with the stock setup prior to new head/cam/carb.

What did it require to get rid of the bog in the previous setup?
If your new tires are wider there is more tire contact area and they may also just have better traction/grip than your old tires.
Hope you get it just right soon.

The accel pump discharge nozzle had a piece of dirt in it. I wasn't getting the full shot. I took the top of the carb off and cleaned it out. Now it runs fine. Can only squeal the tires around a turn now the new ones are too sticky!

and dats a Good Thing!
U Go Eric!
(nother proof of the 'car is a system' concept - change in 1 thing can effect the rest).