shift points C-4

[Anonymous]

hi, any one have any advice on getting the shifts points back up to higher rpm after install of a higher lift cam. i havent meqasured vacuum yet but assume it has dropped.

the tranny wont hold in gear very long at all on the up shifts. even at full throttle. at full throttle it just starts to pull then at a very low rpm i would guess under 2000rpm it shift thru into 2nd.

i read up on all the ford and tranny manuals that i have but it is not clear to me what need to be done. does the 68 falcon C-4 have an adjustment that can be made to the shift modulator ?

I have read about and see they sell vaccum canisters in the cam section of Jegs and the like. will these hold enough vacuum to cover for normal shift points?

We went to the knotts-berry-farm fabulous fords show yesterday which was a great show with lots of variety and nice weather...except not too many hotrod sixes.

any help on the auto tranny info...or where i can read about it would be greatly appreciated thanks
frankie

 

[Anonymous]

I just finished my C4 install, and am tweaking to avoid the same situation. I have read that by adjusting the vac modulator you can alter the shift points and feel (hard or softer). Not all modulators have the adjustable fitting though. If it does, you should be able to turn the fitting in (clockwise) to raise the shift points and create a firmer shift BUT this will also raise the internal pressures. I turned mine in a turn and haven't seen any differnece yet. You are supposed to go one turn at a time.

What is your stall raiting on the TC?

of course, I'm so green when it comes to transmissions, everything above could be completely wrong, so you'd better wait for someone with a bit more know-how to chime in! Maybe this should be part of my signature! LOL!

 

[wsa111]

Frankie, & Bryce,
The vacuum modulator will raise the line pressure, which will up the part throttle & full throttle shift points. Turn the adjuster several turns & road test.
To get the full throttle upshifts higher you have to pull the tailshaft housing off to expose the governor. you had better take it to a good trans shop because they have to modify the primary piston on the governor.William

 

[Anonymous]

appreciate your replies . i will consider playing with the modulator setting then. but will keep track so i can set it back to original.

anyone familiar with the vacuum cannister idea? i would think this might also work. although my logic says this could hold the shifts too high if the tank retains idle vacuum level. maybe a solenoid valve could be used to switch the vaccum line off when a shift is desired.

i have kept my stock converter which has a very low stall. with the cam i have 264-12 it is cranky when cold. have to add a little throttle to keepit from stalling when drop in reverse. it seems to work slightly better dropping in drive( doesnt stall as easy). it is something i can drive OK since 95% of my driving is at freeway cruise in drive. I have a few different cam/converter mismatches in the past and this isnt that bad. but the low shift points arent useful and make it a dog to get her going.

i am working on the tach install this afternoon which will help guide my adjustments. any tales or experience in these areas i would like to hear.

thanks frankie

 

[Anonymous]

i readjusted the downshift cable several ways. too far and it limits your throttle travel. but since i had bent my accelerator pedal linkage to work with the edelbrock setup, the cable adjustment was off. I adjusted the cable so it full bottoms when the throttle is wide open; this setting does improve the ability to hold the wide open throttle shiftpoint much higher, and allows downshift to the limit of the governor. however part throttle upshift is real early.

i havent looked at the modulator valve yet. plan to do that this weekend. but i did order and received the vacuum canister from summit.
it is a real nice piece. comes with a check valve, connection barbs and a mounting bracket. and i ordered their chrome vacuum guage which is a neat sturdy little 1" guage that goes right on top the cannister.

I think i will install the cannister into the vacuum modulator line first and then adjust the modulator. see what i can learn. i expect the can might hold the shift too high or i might get lucky.

with the stock converter it is very cranky and wants to stall at idle and when engaging drive or reverse, esp when it is cold, but once it warms up
this is not a problem. i am reluctant to idle it up any higher. it idles at 1200, due to the cam profile it is a softer engage than you would expect.
this is a little higher idle than ideal as it wants to creep. i could idle it down closer to 1000 when its warm but then it wont stay lit when cold when i drop into drive. later once i get further into the carb thing I hope to have a fully functional center carb with automatic choke and fast idle. this will help in that area.

also read the string on "vacuum leaks o-rings". i will check into that as well in case leaks might be causing extra idle roughness.

still would like to hear from anyone with cam/ c-4 experience. what did you do?

thanks frankie