Gear Slippage?

[jgf100]

I've got a '70 F100 with 302 and C4 transmission. I recently did a top end rebuild- rebuilt heads, edelbrock performer intake, head gaskets, and I also changed the trans fluid. I've noticed after that it seems like the trans is skipping 2nd gear. Its almost like it goes to 2nd gear for a split second then right away to 3rd gear. It also feels like rpms are running pretty high. I just installed a tach and at 70 mph its close to 3k rpm. Is that normal? To the best of my knowledge, have stock gears.
How can I confirm if transmission is having issues? Could the work I did be culprit? The transmission vacuum line connects to intake.
Thanks

[cep62]

C4s have a ball and spring under the filter that can get lost when you replace the filter .
Ask me how I know.
(I'm pretty sure it was a C4)

[Ohiotinkerer]

Check for the ball and spring....

Got my ass chewed at the transmission shop I worked at for a short time for not making sure it was in.....

[jgf100]

Dang it, I did notice the spring that fell and I did put it back on where I thought it went, but I cant recall on the ball. Is there a diagram somewhere that I can view and are those parts replaceable? As in I can order them?
Thanks!

UPDATE:
Did a quick google search and found the following pic. I figured i'd put it in here in case it helps someone else.

[huskerrush]

So my C4, which is not original to my '71, was showing the same symptom of slip/quick 2nd to 3rd shift. Was excited to hear of the possible solution of the missing spring and check valve. Found the check valve and spring kit on O'Reilly's website and ordered. Pulled the pan and filter off the tranny only to find two things:
1. that my filter looks a little different than the ones in diagrams I've seen. It does not have the "ear" that keeps the spring in place.
2. I don't find a hole underneath the area where the "ear" would be that the check valve and spring would go into.

Is it possible that some PO put some aftermarket shift kit on the valve body that would delete the need for the check valve and spring?

Any ideas?

[Ohiotinkerer]

I've tried to remember if there were any differences in the filters over the years but it's been so long since I've worked at the transmission shop that I can't recall. I did remember these charts on here though that might be of some help to identify what you have since it's not original to your truck. At the bottom of the chart it has listings for cars also which may help since we're not sure what it is - hope this helps!

https://www.fordification.com/tech/tran ... trucks.htm

[Raiver]

C4s have a ball and spring under the filter that can get lost when you replace the filter .
Ask me how I know.
(I'm pretty sure it was a C4)

We'll check the ball and spring when we work on C4. The previous owner changed the filter before my friend acquired it and it started slipping.
Gonna confirm that when it returns from the shop for the toyo tires installation and alignment.

[basketcase0302]

=Ohiotinkerer
I've tried to remember if there were any differences in the filters over the years but it's been so long since I've worked at the transmission shop that I can't recall. I did remember these charts on here though that might be of some help to identify what you have since it's not original to your truck. At the bottom of the chart it has listings for cars also which may help since we're not sure what it is - hope this helps!

https://www.fordification.com/tech/tran ... trucks.htm

I know of at least one difference in the C-4 variants. My 76' Early Bronco C-4 filter had a hole in it with a short piece of steel tube that ran down into the bottom of the pan. Can't remember if my other C-4's I owned were diff or not-as I did own 3 more in Mavericks and 2WD trucks.

[cep62]

C6's in 4WD trucks had a deep pan and needed the filter extension .
C4's could have too. especially the Bronco.