Overdrive shifts early 700R4

[86suburbanNJ609]

When I got the the truck I noticed in overdrive when downshifting it stays in high gear until about 25mph and she'll shift herself. I started down shifting manually into drive and then putting it back into overdrive when over 50.I recently replaced the manual fuel pump on the truck and noticed that now going through the gears it wants to shift from 3rd to OD very rapidly around 35mph. My gut is telling me that it's a vacuum problem but I'm not sure. Any help would be appreciated thanks.

 

[CSFJ]

Have you checked the adjustment of the throttle valve (TV) cable?

 

[86suburbanNJ609]

How do I know if it's at the right adjustment? When I bought the truck I did notice that a few things were put back in half ass and I figured I would go through them as I go along.

 

[86suburbanNJ609]

This is what I'm looking at. The cable is loose not tight at all

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[74 Shortbed]

First, get rid of that spring on the cable, then have someone stand on the throttle and make sure the carb is at WOT, if it is cable should be tight if not pull it tight then try it, at idle cable will be loose,

 

[CSFJ]

First, you'll need to verify that you have the correct bracketry for your carb application. The correct geometry is critical for that to work right. after you track that down, any of these videos should be able to walk you through it.

https://www.youtube.com/results?search_query=700r4+tv+cable+adjustment

 

[86suburbanNJ609]

Well I got the TV cable tight it goes into passing gear fine but the transmission still shifts into OD almost right after it goes into third.

 

[86suburbanNJ609]

Now to add insult to injury I noticed a rattling noise by the transfer case or the back of transmission

 

[HotRodPC]

You've got to get that TV cable right ASAP. If you're not 100% certain what you're doing or not mechanical, and don't take it as an insult, we don't know your mechanical ability from the man on the moon, but that is critical as in RIGHT NOW to be correct or you'll trash that transmission, so it might just be worth it to pay a trans shop to adjust that for you and make sure it's correct, and that you have the correct linkage correction on the carb conversion. I've seen it 100 times where a guy swaps to an Eddy or Holly carb and the transmission is trash in less than 500 miles.

 

[86suburbanNJ609]

I have a guy to look at it something definitely isn't right. Nothing is slamming into gear or anything like that but the overdrive is off. Ill be the first to tell you I'm in over my head with this truck but I ain't going to quit I'll figure it out.