1968 C4 Vacuum Modulator

[dalorzo_f]

As the engine had to come out for repair took the opportunity to rebuild the C4. A pretty easy weekend job, once you find all the parts!

I have two vacuum modulators. One with a green stripe marked K-12-4 and one with a white stripe marked K-12-14. Other than that they appear identical. Anyone know if there is a difference and if so which would be best to use in a stock C4 behind a fairly stock C code? Assuming there may be some set point difference.

I have installed a TransGo SK 4SL basic shift improvement kit if that matters...(there's a money maker, $80 for 4 springs and a drill bit...!)

 

[dalorzo_f]

... and I'll add that the Bad Shoe productions transmission rebuild videos are a fantastic reference. Really helped on both the C6 and C4.

 

[Mosesatm]

According to this site the one with the white stripe is for 1964-1972 and the one with the green stripe is for 1973-1986.

 

[dalorzo_f]

Yep, have seen the dates but as a green was on the car and it seememd to work fine curious if anyone knows the specific differences. Ken from Bad Shoe Productions said "either will work".

I've seen slightly differnt years noted for the changeover too. The white seems to be "early" C4/C6 then a green for late (71-74 changeover noted on some sites) C4 and purple for late C6.

Was interested as an engineer in the impact using one or the other may have as I've seen both used in similar transmissions but have never done a "swap them out" test to see if any noticeable differnce is a result... as they can swap would not seem very significant, more curiosity than anything else...