Technical Trans issues that are probably not the trans.

No EGR but came from the factory with one.

 

14 in. of vacuum and a 3.0 gear should work fine.

Just what version/year C4 is in the car now?

Does this trans have a screw in modulator or push in? If it's a screw in, it should be white stripe, if push in, yellow stripe. Rostra markets the best modulators now. There are poor versions out there. Both are adjustable.

Search modulator pin lengths and and pick a middle of the road length and compare to what's in the trans now. There may be a homemade pin in there that's completely wrong.

Bill

 

It has a mid 70s pan filled and I am almost certain the cam has been installed a little on the retarded side,it wants to idle the smoothest with the timing cranked up but will ping bad so something is wrong and I think that is having a effect on the trans. This engine has never ran as good as others I had and seems to have low low end torque.

 

If you think it's engine vacuum related, tee the vacuum gauge into the vacuum line to trans, bring it in the car and go drive it. The vacuum will drop under load and build back up as the load is removed. Should eventually get back to your 14 in. reading or even higher, depending on RPM. If it doesn't, then maybe engine issues? Or restricted exhaust system?
What modulator is on it, and push in or screw on?

Bill

 

Did you mean no low end? I thought I read earlier it doesn’t start to run well until 2500? RPMs?
Nothing to add for help, but I read posts

 

Does not have the low end I was expecting with a RV cam I specified and definately wants to wake up higher in the RPMs,I am thinking its a slightly radical 302 cam retarded some.

 

Vacumn went up some when I advanced the timing a bunch.

 

I never saw where anyone asked this including myself, it is hooked to manifold vacuum not ported vacuum correct?

 

If it is a EGR engine, you will have pinging problems without the EGR valve.

 

Yes it is hooked up correctly.

 

not all C-4's are the same. Like T-birds that have "soft" shifting. Mustangs harder. I had a C-4 in out '41 for 25 yrs and never had a kickdown connected. My vote is vac modulator or the modulator adj. also I've had Ford trans that would not shift into 3rd if vac. modulator wasn't hooked to vac.

 

I am now thinking I should have had the AOD rebuilt since I would not have to deal with vacumn if I realized before that the cam could have been installed wrong by the idiot I had build the engine.

 

The C-4's were pretty reliable and basic as auto transmissions go, you may need to look at the pin behind the modulator as (someone stated earlier)there were different lengths and the wrong one can give you problems.
I haven't worked on one since the 80's so I'm reaching into the memory bank here, Good Luck

 

Gotta ask. Same torque converter on all 4 trans?
Buddy had a 48 Ford pickup 302/c4 and 3.00 gears. The supposedly "stock" converter ended up being a high stall (3500?) one. With the high rear gears, sometimes it would not shift into 3rd...and when it did, it wouldn't fully lock up and feel like it was slipping. Just a thought.

 

I am going to change the cam before I do anything more with the trans,its not what I specified and I think its a tooth off. I am going to get the engine to run its best and go from there,its had four trans basicly doing the same thing and the only thing that has not changed is the engine so I need to look there. I did not assemble it so I do not know what was done wrong.

 

No different converters.

 

Before you tear up your engine did you see saltflats post about having pinging problems without the EGR?

 

Then you would be dealing with a throttle valve cable and if it ain’t right it’s smoke before you get back from a test drive.

 

Just a note, AODs require a TV cable connected to the throttle linkage, and they are incredibly sensitive to its adjustment. They will burn up in under a mile if it's not right.

*edit - I see I'm not the only one that commented on that.

 

After bumping the timing up I took it for a drive and the trans seems to be shifting like it should but still have the pinging issue with the vacumn advance disconnected,yes it is supposed to have a egr but has been made to go without and never had this problem before with eliminating the egr. I ordered this engine to my specifications but now think the cam I wanted was not installed or installed wrong so since I have a gasket set its coming apart to see just what cam was installed and if it was installed correctly. I am going to get a correct cam for this engine.and while its apart change the intake and maybe the heads too,something is wrong where it needs that much advance just to get a decent idle but then too much advance for it to run correctly down the road. I will never buy another engine that someone else assembles.

 

When you pull the heads off take a look at how far down the piston is when it is at TDC.
I wouldn't be to quick to change cams (if it is good) if you can figure out what is in it. To get a new flat tappet to break in now days is a crap shoot.

 

At some point verify your TDC and timing indicator as well.

 

Maybe you need to run some better gas? My stuff all runs on midgrade better than regular. They will all ping on regular except for the Lincoln with the 302, I usually run pure gas in it and it doesn't ping a bit. I don't like to put much ethanol gas in it since it sits more than the other vehicles.

 

Why not get a degree wheel and a dial indicator and find out how the cam is currently installed? Maybe consider keeping the current cam and advancing it a couple degrees, if needed. That will pick up the manifold vacuum a bit and increase low end torque.

 

The present cam has a 302 firing order and I can tell the engine starts coming alive higher in the rpm range then I like,it has a tall highway gear so I want low end torque so time to fix that problem.

 

Before you go through all the work to install a different cam because you think its installed retarded, I would do a compression test on at least 2 cylinders. If they come out to around the normal compression of lets say 140- 150lb or so, then I doubt its installed retarded.

Could be the cam profile is not what you want though.

Compression gauge,a good vacuum gauge and a timing light are a must and not very expensive.
You need to know what you are starting with before you jump in the water with your boots on.

I believe your trans issues are not due to the camshaft and after a new cam install, the trans problems will still be there.

You also talked about spark knock. If the ignition is still Ford, hope you are not using a dual diaphragm vacuum advance. I have seen those cause all kinds of problems, unless they are hooked up exactly how the factory did it.

I believe you are using the trans problem to convince yourself to change out the cam, you don't like. That may make the engine right, but won't fix the trans.

A C4 trans is a walk in the park, compared to modern automatics or the 54 Dual Range Hydramatic, I have on my workbench right now.

I will be watching this thread, as I am curious how this plays out.

Good luck.

Bill

 

Engine is apart and the cam is not off but what would make a low compression engine require a bunch of initial timing to get the most vacumn and idle smooth but ping like crazy. Since it now has a 302 firing order it must have a slightly radical 302 cam.

 

I would like to report that with a stock 351 cam trans is shifting like it should,speedo is now about 6 too fast with the last trans that got me thinking something was wrong but it's working fine.