I’ve been holding off but now I need to ask. 69, 351 w/FMX It has set shift points. 1-2~30 MPH, slams it. 2-3~45 MPH still pretty harsh, shift points are like Hard coded, feather the throttle…stays in gear to the MPH is reached.
I can force the shift from 1-2 by dropping back to 2 out of Drive. She leaks a bit out the tailshaft. but I maintain the trans oil, Hot, In park.
Now Today, I top it off and make the run to the Autozone for some new type F for the trunk. cruising along, suddenly drops out of D into 2… stays there, except when stopped, then I get the normal 1-2, no 3.
On the way home, well she normals out and back to the regular game, seems a bit nicer even (not so harsh). I have a new Vacuum Modulator but haven’t swapped it out because I have stitches in my back from my Dermatologist, not condusive to rolling around under the Cougar in the garage.
So ya think that’s my problem or something worse is lurking?
Thanks for reading
Bad connection on vacuum line to the modulator.
Thank you, I thought it might be in that area.
Well, the vacuum line is tight. No leaks, and the vacuum modulator looks to have been replaced “recently” as in not covered in oil & grease. It’s gold with a white stripe. Any other ideas guys?
The modulator has some adjustment to it. Play with it and see if the harshness goes away. FSM has it covered.
Just been reading up on Vacuum Modulators. Apparently the WHITE stripe is for a C4/C6, The FMX uses a BLUE Stripe. both “fit” both are “adjustable”
But are different units internally.
The one in the car currently has a white stripe. So it looks like the parts guy sold me the wrong replacement also, it has a White Stripe. It has been returned and a Unit with the Blue stripe is on order
Thanks for reading
Visual inspection of the hose is not enough. With the engine running, you need to pull the hose off the modulator and see if it is pulling vacuum. The engine idle should change slightly when the hose is pulled off.
The blue stripe is what’s needed for the FMX. I’ve swapped between white and blue and hadn’t noticed much difference in shift timing.
Regardless of hose stripe color, it’s just plain old manifold vacuum that gets applied to the modulator. Best way I’ve found to test modulator and hose is to disconnect the hose from the vacuum tree and apply vacuum with a MityVac. Make sure it holds for a minute or so.
Checking it from the top doesn’t tell you if vacuum is making it to the modulator. A shop near me went crazy with a Pontiac that had a 350 which also has a vacuum modulator. The inside of the metal line rusted shut. It would hold vacuum when checking from the top, but none was making it to the modulator.
I removed the vacuum Hose from the Vacuum tree from the back of the Carb, I removed the hose from the Vacuum Modulator. It held Vacuum from the Mighty Vac. I did not test with the vacuum Modulator connected. The Modulator with the white stripe is the wrong one.
I will be re-testing when the correct part is installed.
BTW it’s not the Hose color, it’s the stripe on the Body of the Vacuum Modulator
https://www.google.com/aclk?sa=l&ai=DChcSEwix_PqL18ryAhV0GH0KHYaWBOIYABAHGgJwdg&sig=AOD64_0n_QzuVz22Gbd1qvTj3ZZJruw4Pg&adurl&ctype=5&ved=2ahUKEwjGne2L18ryAhUFJDQIHVNNCyMQvhd6BAgBEEA
Basic Rant.
When the Vacuum Modulator I ordered finally came in a week late it was a Filter in the box, not a modulator. P/N was correct, part wasn’t. Manager gave me a refund. I went to a different Brand parts store, They order me one, there the next day. I inspect it, no blue stripe, No stripe to be exact. parts guy swears it’s the right one. When I got home I looked it over more closely, it says C4 on it. Grumbling ensues. I had left a Very Dissatisfied review of the original place that took a week and delivered the wrong part, using all but 3 characters of the 250 allowed in the comments (all facts,no berating).
Well yesterday the Store Manager Calls me, very apologetic and asks me to come to the Store to pick up the Vacuum modulator that he ordered for me Gratis. I was floored. It is the correct model with the Blue Stripe. Gets my business going forward.
Now to get my Cougar going forward…
Did you install the blue stripe modulator? If so, did it give you any improvement?
I finally did install the blue stripe modulator
Shifts are not as harsh. The old white stripe had the adjuster backed all the way out for soft shifts. It was definitely the wrong one. I still do not like the shift points. I’m ordering a filter change kit today, I hope I don’t go thru the fiasco I had with the modulator.
Fingers crossed!
I haven’t done the filter kit yet, however the Shifting has improved greatly after sitting a while and some short trips. I’m not sure if it just needed to “loosen up” or just be driven around a bit. The other reason I haven’t done the filter change is I can’t find 11 Quarts of Type F. I’m having to buy 1 & 2 quarts at a time at the Parts stores… Napa Guy kinda freaked when I asked for Points & a condenser also, suggested a Pertronix instead… I had to giggle a little bit.
Do you have a big cam in the car which doesn’t develop sufficient vacuum?
If it shifts too late and too hard with the blue stripe modulator, turn the modulator screw out 3 full turns, you can remove the screw from the modulator to get the earliest shift. Or, put a few gaskets in between the modulator and case. This will move the modulator out which causes the effect of a shorter modulator pin----which makes for earlier and softer shifts.
I’m pretty happy where it is shifting now. Thanks for the tip on the Gaskets, I’ll pack that one into the notebook.
I’m concentrating on issues with Vapor Lock, and Heat Soak, and tuning the Edlelbrock.
Is there one brand of vacuun modulator that is better than another or at tye very least you should not touch?