Was wondering if anyone has had the 58mm holley tb before and what were the quirks with it, it looks pretty good and seems to be a good piece

 

pics

 

this pic is a little better

 

I am sorry to be the bearer of bad news but I have used that exact TB before and it was a nightmare. There's a few things you will definitely want to check to make sure you don't have the same problems I did.

Primary problems:

1. No positive stop of the throttle shaft. You could easily open the throttle plates WAY beyond 90*. I built my own throttle stop to solve the problem.

2. Stock early-style adjustable TPS sensor (like used on an 87 TPI) had bigtime interferece problems that required a few hours of checking and grinding and rechecking to get it to fit, give appropriate voltages and operate smoothly.

3. The bolts supplied had the wrong thread to attach to my plenum. Literally, they were metric thread bolts where the plenum took standard SAE threads (or vice-versa- I don't recall any more- it's been a few years). Stripped 1 of the threads out of the plenum before I realized what was going on. Had to drill and heli-coil it to repair. Blood pressure was near the boiling point.

Maybe I got a bad one or I just wasn't doing things right but I never had problems like that with my SLP throttle bodies. I came away from the experience wondering if Holley ever actually tried to insall one of these damend things before they put it on the market for sale.

 

were you installing it on a stealthram? i was talking to holley and they said that their tb's are best with the stealthram, but i dont know, i really appreciate the input, it will save me time and a big headache. the main reason i was drawn to the holley was because i have the stealthram , plus i like the look.

 

On a Miniram. Can't imagine how the intake choice could affect most of the issues I ran into, but.....

 

Had all the same problems, but I didn't have to worry about going past WOT. The TPS, I had to do some grinding on, which is very uncomfortable when you have to do that to a new one, but it didn't take but about an hour of so. The big PISSOFF were that the bolt holes for the TPS weren't the same. I had to cut new threads into it. And the TPI snorkel was a little bit of a fight. But with the 2 1/2....3 hours it took, I still think it's worth it....

 

sounds like the biggest prob was the tps, i guess ill have my work cut out for me , i checked and the tb bolts they sent with the tb are the same thread as the holley stealthram so atleast i wont have probs with that. now i just got to get this tps issue fixed and be ready to go

 

I have the 52mm unit, which has all of the same issues, but I felt they were all very minor and very easy to overcome.

Mine doesn't have throttle stops, but the linkage hits the body at exactly 90*. Maybe the newer style throttle cable linkages don't do that, I don't know.

Trimming the TPS took 2 minutes with a metal file. It was seriously a non-issue. That trimmed TPS still works fine on a stock TB too, so it's not going to need to be changed if you swap back to a stock TB later on.

The only thing that pissed me off was that Holley decided to use a non-stock thread pitch in the tps mounting holes, and the bolts they supplied were too short. A trip to a hardware store fixed that for me.

I can't comment on the TB mounting bolts, because I had a complete set of stainless hardware. There's no reason you couldn't use the stock bolts anyway. In fact, I didn't even realize that the holley came with new mounting bolts. I would just expect to reuse what you have.

 

well i was gonna use their bolts, i guess if you put it back on the tpi you could reuse the stock bolts with no prob

 

Hey Jgifford. Are those custom intake runners on your setup? I at first thought they were SLP then in the other picture they look to be custom. Allen

 

I FOUND ANOTHER PROBLEM WITH HOLLEY TB'S.

Once you've got it on, check the voltages at the TPS sensor. Mine was reading about right for idle, but were too low for the ECM to realize when it hit WOT. And I couldn't adjust it out with the slots in the TPS. Put my 58mm BBK back on, and adjusted it so that it reads just fine (100% in data logs). So the TPS sensor wasn't the problem.

Just something to check. Looks like the geometry on mine was all wrong. I'm using it on a 91, I suppose there's a possibility it's for a pre-89 motor and TPS for those is different, but I doubt it. My BBK is definitely for the 89-92 and it works just fine. Except now I've got to play with my tune again.... but that never ends anyway!

 

You had it right the first time. They are SLP runners. I spent countless hours sanding and polishing them, but during the last rebuild I had the powder coated, aloong with the plenum, plenum extension, and all accessory brackets.

 

Use washers to poke the TPS out farther.

All my bolts came from my TPI and worked on the GM TB, new TB, and the Stealthram.

The boot was a PITA, just lube it and it goes right on.

Took me 20min to do the swap and get the idle air dialed in.

 

2.