afc rack travel help!
 

OK I ground the end of rack 1/8. Replaced cup washer w a flat one. But when I put compressed air to it the rack will not travel all the way forward. Bout 1/4" from touching case. I pulled the diaphram back apart the problem is the washer is hitting the backside of starwheel. Am I doing something wrong? I played with different air pressure and I'm at 35ish to "almost full"travel. But to get "full" travel I need to loosen star more but then the spring has no tension. Should I stretch the spring some? On test drive it has same boost numbers at top end. And I've been toying w smoke screw which def helped it build boost sooner. But shouldn't I have gained some top end boost? Thanks for any help.

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Mods are htt62/71/13. 370s. Shimmed gov. 100 plate ff. Afc ff.

If you still have the fuel plate in and haven't moved it, then no you will not gain top end boost because the AFC foot generally moves beyond the fuel plate (assuming not full forward or a radical grind) and the fuel plate becomes the ultimate stop for rack travel.

Now, if you have removed the fuel plate for some reason and have the modded AFC full forward, then you may be bumping the rack plug or simply at the peak of your fueling setup... The AFC itself does NOT dictate total fueling (unless fuel plate is removed), it simply prevents gross overfueling until the boost signal catches up and suggests that ample air exists for more fuel.

So should I take plate out? I did this to gain fuel when I want it. But also wanted to tune it for better MPG and not watch my fuel dump out my exhaust so much

I'd leave the plate in, personally, and look into 3k or 4k gov springs to help fight gov-induced defueling a little better than just shims. Just remember that the 4k's will need stiffer valve springs to prevent valve float.

stretch your afc spring or use a longer one it will help

Is there a special way to stretch it? Heat? Thanks

Heat removes the temper and will make a spring go limp or softer, so don't heat it.

Rather than stretching the spring, I would look more toward removing the interference if you are concerned with full travel, such as maybe disassembling the star wheel mechanism and shaving a slight bit off the actual star wheel collar to allow for that extra movement without completely removing tension. I still don't think the extra AFC foot travel will matter without an exotic or absent fuel plate and a rack plug...but I'm not entirely sure on your setup.