I can't figure it out. Something is SERIOUSLY wrong with this base. When I took it off it was cleaned and everything checked out fine. Put it on the engine, still sticks, cold, warm, doesn't matter, it sticks only at low openings.
It's even crunchy sticking. Like in 3 spots just off idle. My plan is to remove it, bring it to a machine shop and give them $100 to install hardened brass bushings. If I can't find somebody to do it I'll need to replace the whole TBI base unit OR just go port injection with the vortec stealth ram. I can't afford to spend $300+ on another TBI unit when that's what it'll cost for me personally to convert to port injection.
<---- I'm really pissed about this.
I know a member here years ago rebuild his sticking/leaking TBI base with ball bearings in either end. I had thought about it before, I just think it would be overkill. Any thoughts.

 

sorry, just having a hard time picturing Mr. Prevost flipping out... Anywho, have you only limited your search to the intake itself? Check the cable coming right off the pedal. I've seen people get dirt/grime/soda all kinds of stuff down there, and that can ruin a weekend...or maybe I'm missunderstanding what kinda of blade stickage you got...

Bruce (90RS305)

 

I was having a problem with my idle coming down fully (particularly if I just barely stepped onthe throttle), and thought it might be a sticking throttle shaft. I wound up having to bend the throttle cable mount forward (towards the TBI) slightly so the spring on the throttle shaft didn't have to work as hard to close it completely.

Did you disassemble the unit completely to clean it?
When you say it sticks is that through the gas peddle or when opening it by hand on the TB? Maybe the throttle cable needs help- lube or rerouting?
S-D

 

Sounds to me like you got some dirt or metal shavings on the shaft. I didn't take out my shaft when grinding on my tbi and it did the same thing, took it apart and cleaned it and it was ok. Oh and the spring on it was getting kinda weak so I got a Mr gasket p/n 19 dual throttle return spring, or get one at your local junk yard.

 

Mine does it too. Its just the nature of things. With teh stiff springs, 60 lbs of force from vacuum, and stupid ridged shaft, it quickly wears into teh base and the butterflies hang up on the bores. One solution is to swap the holley shaft out for a stock throttle shaft and use bushings. Standard bearings wont work as tehre is alot of force and the gasoline will wash out all the grease in the bearings.

 

The holley springs are a little *too* strong. The area around the shaft wears into an egg shape due to all the force. It doesnt bother me, really, unless it hangs at 2000 rpm or something. Thats one problem with a huge tbi, is that the pressure differential at idle causes lots of loading on the shaft. Combine that with teh spring force, and teh shaft begins to eat in sideways and it gets off-center.

 

there was A guy selling 454 tbi's on ebay with new roller bearing installed, I would see if he would sell you some of the bearings. Well sounds good any way

 

I ran into the same problem, I thought the butterfly's were hitting the bores but Once I got them completely cleaned up all the way around the bores it still stuck on the car, and was as free as ever off the car. I came to the conclusion that it was the vacume loading the throttle shaft and causing the binding. I ended up just pollishing the throttle shaft bores to a high shine along with the throttle shaft itself, luckily that cured the problem. I had the bonze bushings sitting on the bench and a hand drill ready to hog out my TB if it didn't. I might end up doing that later on anyway. I'm just not too sure I'll get them in strait without some kind of jig.

 

Ohh yeah, I also have about 30 sealed bearing's I'lll donate to the cause if some one is willing to come up with a DIY way of moding the TB to make them fit. They are for roller blades, but I'm not sure if the I.D. is the right size for the throttle shaft, I'll have to check.

 

Keep in mind that the gas will wash out all the grease. Not taht it really matters.

Ive found that the frictional force is what causes the hard pedal but the blades are what causes it to hang open. The fit is super close and the edges are radiused to the arc that the blades swing through so even if their off by a hair theyll stick. Also keep in mind that teh bores for teh throttle shaft wear offcenter due to the net force from the throttle cable (TV as well if you ahve one), teh return springs, and teh vacuum not pointing straight down. As soon as vacuum hits it, the shaft moves off to the side and gets stuck. Easy way to test it is to pull/push moderatly hard toward the firewall (or front of the car, cant remember which) on the cable side of the shaft while trying to open and close the throttle.

 

Whats the OD of those bearings?

 

The throttle cable isn't even hooked up. I'm testing it all by hand. I'm going to remove EVERYTHING this time around to find out what is wrong. I have a feeling it will be the egg shapped base. Nothing like steel heavily loaded and rubbing into cast aluminum to make you want to kick some engineer for pinching pennies. I'd have gladly paid the $20 extra for the $2 bushings and $5 extra machining required!

 

are we talking about the stock rochester TBI units or the Holleys here ? or both ?

 

Holley 502-6

 

The bearings are a good 5/8 to 3/4" so I doubt they would work. I'm sure there are some bearings out ther that will work for what we want to do. I think our best bet would be some kind of bronze or brass bushing. They would be self lubricating and would allow you to reindex the throttle shaft at the same time.

 

I like the idea of ball bearings because the seals on those things are plastic but don't take any load. So what if the grease washs out, grease is good for preventing gauling only when there is heavy load AND high RPM. I'm only rocking it 90 degrees . The ball bearings would be ideal and the way you'd install them is with an epoxy. Basically make a seat for them on either end in the base that is about 50 thousandths give or take a bit and fill it with some metal to metal epoxy. Basically cold welding. The "slop" in the seat will let you align the bearings to the shaft and the butterfly's to the bores. I'm going to order bearings tomorrow if can't find a machine shop in the morning that'll do the bushings for under $100.

 

Yes.

As far as the housing wearing versus the shaft, I was suprised to find that the housing on mine had very little wear. The bulk of the wear was on the shaft itself. Steel versus aluminum? I was suprised to see which one showed the actual wear. Maybe yours will be different. Mine was the stock 100K TBI unit, though.
Best-
S-D

 

I just got the TBI back off the car, will be taking and posting a few pictures of my findings. I'm going to get the thing beed blasted and then I'm going to paint the outside a nice flat black. Will be doing some porting as well. I wish I was in Ohio right now, would have access to a machine shop .

 

I have a spare Holley TBI base just laying around, Email me e27spd@aol.com I do belive we can work some thing out with out any money involed.