so i was working on the granada today the tranny has been acting up not wanting to stay in high gear i figured id check the vacuum at the modulator, so i decided to set the timing to stock since i didn know where it was at but i knew it wasnt right. it was off of the indicator id say 16-18 degrees (stock is 12) so i set it right checked my vacuum 21 inches on the manifold at idle and 18 at idle at the tranny took it out for a short ride(it started raining and i found out i need wiper blades bad) and it shifted smother into all gears and stayed in high anyone out there that can explain how this works?
can ignition timing effect shifting?
- Thread starter 79granada
- Start date
You raised manifold Vacuum , by increasing the timing , Ford transmissions C-4 and C-6 use a modulator valve to control shift timing and line pressure , the higher the vacuum the lower the pressure and the earlier the shift , it also tell the trans to stay in high longer as a high vacuum is indicative of a light or no load condition , so no need to drop a gear. that help ?
Some modulators can be adjusted to speed up the shift or slow it down too. Also if your kick down linkage can be set to down shift into 2nd sooner or later adjustment is at the carb 
falcon that did help that did help i was thinking the same thing but i thought id check thank you. bubba i dont have the ford transmission i have the jatco 3n71b it has a likage on the carb that pushes a switch and the wires from that switch run to the tranny i would guess that would be my kickdown? and i would like to find an adjustable modulator for it but i dont know if they are out there parts and info on that tranny are kinda tough to find if you know where i can find one let me know
GeeZeeEmm (see http://www.gzm.com.au/gallery.htm) in Australia use Nissan 3n71b cores. That 450 kw Commodore with Nissan RB30 is actually 600 horspower.
As noted, it was the standard auto option for Datsun 240/260/280/Maxima's untill 1984, definately not impossible to find in a junkyard paradise in Asia, Australia, New Zealand. If you can find an LD24 or L28 powered rear drive rust bucket 1981-1983 Maxima, or a rusted out 1978-1982 280ZX without a turbo engine will have it, so will a 1977 to 1982 Auto 1.8 liter Ford Courier, or Mazda 929, RX-7 auto, Datsun Bluebird or whatever you called the 180b/200b based 1.8, 2 and 2.2 and 2.4 Naps-Z engined Dato's. Cause they rust, they are good sources.
Over here, the Datsun L24/26/28 diesel LD 28 and Holden and Datsun/Nissan RB20/24/26/30 got versions of that box standard, so its not hard to find. The Kiwis and Aussie tend to network with Asian relatives in Australasia,and so finding the original while box supplies from Japan or copies from Korea, Malasia, Tiwan ROC or China isn't too hard.
As noted, it was the standard auto option for Datsun 240/260/280/Maxima's untill 1984, definately not impossible to find in a junkyard paradise in Asia, Australia, New Zealand. If you can find an LD24 or L28 powered rear drive rust bucket 1981-1983 Maxima, or a rusted out 1978-1982 280ZX without a turbo engine will have it, so will a 1977 to 1982 Auto 1.8 liter Ford Courier, or Mazda 929, RX-7 auto, Datsun Bluebird or whatever you called the 180b/200b based 1.8, 2 and 2.2 and 2.4 Naps-Z engined Dato's. Cause they rust, they are good sources.
Over here, the Datsun L24/26/28 diesel LD 28 and Holden and Datsun/Nissan RB20/24/26/30 got versions of that box standard, so its not hard to find. The Kiwis and Aussie tend to network with Asian relatives in Australasia,and so finding the original while box supplies from Japan or copies from Korea, Malasia, Tiwan ROC or China isn't too hard.
My service truck back in the 1980's was a 77 Datsun KingCab with L20B and had that type auto trans. It was still in good working condition when I started driving it, had about 60,000 miles on it. First thing I did was change the oil and filter and add a trans cooler (the single best thing you can do for any auto trans). At that time there were no shift kits made for them so added an adjustable modulator (NAPA) to get it to shift quicker. That truck was worked very hard and the trans lasted well over 185,000 miles.
Pull the vacuum line and look into the end of mod. if you can. It will use a small Allen wrench so you can try the wrench's don't remember the size but should be an 1/8 or smaller it may also be metric depending on who made it. 
Yeah some of the NAPA stores are not so good as they once where (its a shame) if can find the main distributor for your area they would be better.
Yeah some of the NAPA stores are not so good as they once where (its a shame) if can find the main distributor for your area they would be better.thanks bubba, yeah i remember at one time napa was the only store aroundif i have to i can go to ky is only a half hour drive to one over there that ive had pretty good experience with need to find a good carb rebuild kit first before i mess with the tranny any more.
Yeah I probably was spoiled had such a good NAPA dealer with 3 stores, the owners and counter guys knew their stuff. I took care of a small fleet of trucks and Equipment back than they gave me some of their parts books and when I needed something give them a part number they would have it ready or even bring parts to me. They used to have good carb kits and tune up parts I just pick up some parts to tune my truck for a smog test will see if they are still good or not. Good luck on your Granada
Sounds Good
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