Hi guys, I have a HSR'd 327, but I am still using a stock dual 48mm TPI throttle body. I have had 2 of these throttle bodies in used, high mileage condition, and both of them have a lot of slop in the throttle shaft. This translates into a hanging high idle unless you blip the throttle (you can see the TPS readings will settle around 0.58-0.60 volts if the throttle is gently closed, coasting to a stop in traffic, but if you rev and snap the throttle shut it drops to around 0.54 volts and then idles at the correct speed). I have tried adding additional throttle return springs, but I still get the hanging high idle, only it takes slightly less effort to snap the throttle shut now. I would hate to spend hundreds on a BBK or similar aftermarket throttle body when the stock 48mm dual is enough for my 327. Does anyone know of a service who will drill out the throttle body and add bronze or roller bushings/bearings to solve my problem? Any idea of the cost to have this done?

 

Maybe for the price that some one would rebuild it you can buy a used one on the boards here for alot cheaped. Just my opinion. I can imagine them being that much.

 

Any competent carb rebuild shop should be able to rebush the TB's for like 30-40$

Isnt any difference doing it to a carb or a TB

later
Jeremy

 

Thanks guys, I figured a carb shop might be the route to go. There is no such thing as a good used stock throttle body, they all ovaled out the casting to some degree. Some are not far enough along to hang the idle yet but I am not willing to continue to spend $50-60 on used TB's and find all the bad ones. I have already done this twice and both units do not close that last 1% TPS to get a consistent idle reading.

 

I had similar problems, and found that an infrequent lube kept it working. Carb/EFI cleaner dries out the bushings and doesn't lube. Don't remember what I used. I also loosened the cable to the cruise control by one step on the swiss cheese connector, but you probably aren't running with cruise.

 

I had the exact same prob. so I took the TB to a local auto electric place that said they could do it. When done, it actually had MORE play than when I brought it in. The only good news is that the new bushing is apparently self-lubricating, and at least doesn't hang up on me any more. The best thing would be to put a bearing in there. There's a guy on ebay that does it, or if you had an extra TB you could do it if you had the right sized bearing.

 

It sounds like you have already checked and found the slop in the throttle shaft but I just wanted to throw something else out there.

I had the same simptoms with my car a year ago and I talked with my friend, a mechanic. He said that the TPS sensor can get worn out over time and parts in the sensor itself can bind-up not allowing the throttle to always close right. For me that was the problem, just a thought if others are having this problem and their TB is still seems like its in good shape.

Not to even metion the IAC which I always check first.