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Should I replace the distributor?

89 jimmy

89 jimmy

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I have a 89 GMC Jimmy, 350 TBI. Motor was replaced with a NEW stock crate motor from GM and professionally installed a while ago. I’ve always had a little bit of a miss at idle that still persists even with the new motor. All ignition components were replaced when new motor was installed, AC Delco all parts, cap, rotor, plugs, wires, IAC, ignition coil, ICM, fuel filter, rebuilt TBI etc. The only thing that is carried over from the old motor is the distributor, and probably the harmonic balancer. The pick up coil looks really rusty and green corrosion under the cap. I figure I might as well just replace the whole distributor Incase of worn gear etc. and that is the only ignition component that hasn’t been replaced. Do you think that the distributor could be the cause of the slight miss at idle, especially when warm and in drive while stopped? Runs excellent at all other rpms, under load etc.
 
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The only thing I didn't see mentioned was the EGR and EGR solenoid. If those are new and in good working order, then the Distributor is the only thing left to try. As long as it comes fully loaded with the Pick-up coil and ICM.
 
Just an FYI, I put a new Spectra distributor in my '95 TBI truck, and the module in it started misfiring after about 20 minutes. I had heard from others that could happen. Swapped my old one in a it's been fine for over a year.
 
EGR and solenoid replaced. I have also heard of the ICM going bad very quickly on remanufactured, or cheap distributors. I plan to use my current ICM and keep a spare. I would really like to get the NEW GM performance distributor 1103952, $400+:yikes:
 
Delphi distributor? Any good? Again I do not want a cheap, aftermarket distributor
 
Delphi makes good stuff as far as I know. Lots of OEM parts for GM.
 
Ok, I’m going to get a new Delphi distributor today. What is the best wrench for getting to the distributor bolt? A regular distributor wrench or a crows foot socket and extension? 9/16 right?
 
I have used a flex head gear wrench some.
I bought a distributor wrench and it was too long, so I cut it down and welded back together.
 
I use a dizzy wrench, I have one that splits in half, so I use the 9/16ths side of it.
 
onetonbb74 said:
I use a dizzy wrench, I have one that splits in half, so I use the 9/16ths side of it.
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Ok cool, I just picked up one of those with the new distributor. Hoping to swap it out in a few hours or so. I really hope this doesn’t turn into a 2-3 day project. I’ve been there before :whistle:
 
I guess that I didn't state it correctly. I meant to say that the swing of the distributor wrench was too long. I shortened that part, so that it had a shorter arm. It still splits in half on the rod section. Now that I am home, I can just post a pic, not that it helps since you already bought one. The longer one is what both sides used to be like.

15466510585065809818146218527478.jpg
 
Back in the day my buddy was having a hell of a time with a weird miss issue. Went through about everything under the hood and no joy. He had bought new cap, rotor etc and when we went to swap that stuff on is when we noticed the inside of the distributor was mostly dust. It had just eaten itself up. We swapped in a known good used distributor from a TBI engine I had and it ran like a champ again.

I had never seen a distributor self destruct like that before...but it seems pretty common on the TBI engines.
 
Snappy on left, hf on the right...mine is the hf
20190104_214025.jpg
 
Got the new distributor in. I used a wrench like the hf one on the right in the previous post. As previously mentioned, the swing was a bit to long so it was a long process. Had to use a crows foot socket to break it loose. Quick tip to anyone changing a distributor with a bolt and clamp. Do not completely remove the bolt. Loosen it just enough to slide the clamp back. If you remove that bolt you will have a heck of a time getting it started again due to the tight area. Starts and idles good. Went to set the timing and my VERY old Sears timing light fried and started smoking :eek1: Gotta go get a new one tomorrow. Always something :dunno: Will update after I get it timed and test drive it.
 
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89 jimmy said:
Got the new distributor in. I used a wrench like the hf one on the right in the previous post. As previously mentioned, the swing was a bit to long so it was a long process. Had to use a crows foot socket to break it loose. Quick tip to anyone changing a distributor with a bolt and clamp. Do not completely remove the bolt. Loosen it just enough to slide the clamp back. If you remove that bolt you will have a heck of a time getting it started again due to the tight area. Starts and idles good. Went to set the timing and my VERY old Sears timing light fried and started smoking :eek1: Gotta go get a new one tomorrow. Always something :dunno: Will update after I get it timed and test drive it.
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Where in the bay area are you located?
 
89 jimmy said:
Got the new distributor in. I used a wrench like the hf one on the right in the previous post. As previously mentioned, the swing was a bit to long so it was a long process. Had to use a crows foot socket to break it loose. Quick tip to anyone changing a distributor with a bolt and clamp. Do not completely remove the bolt. Loosen it just enough to slide the clamp back. If you remove that bolt you will have a heck of a time getting it started again due to the tight area. Starts and idles good. Went to set the timing and my VERY old Sears timing light fried and started smoking :eek1: Gotta go get a new one tomorrow. Always something :dunno: Will update after I get it timed and test drive it.
Click to expand...
Where are you going to get your new timing light? I am in need of one but have no idea where I should get it.
 
I got the timing set after my new timing light arrived. I was setting the timing alone and after lots of back and forth I got it set to 0*. I then tightened the distributor hold down bolt and did a final check of the timing and it showed about 1* advanced. Probably moved a bit while tightening down the distributor. Will leaving it set at 1* advanced be ok? Runs great, no engine knock. I’m sure it’s fine, just thought I’d ask.
 
89 jimmy said:
I got the timing set after my new timing light arrived. I was setting the timing alone and after lots of back and forth I got it set to 0*. I then tightened the distributor hold down bolt and did a final check of the timing and it showed about 1* advanced. Probably moved a bit while tightening down the distributor. Will leaving it set at 1* advanced be ok? Runs great, no engine knock. I’m sure it’s fine, just thought I’d ask.
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Nothing to worry about being one degree advanced. Used to run a TBI 350 4 degrees advanced when I was younger, and dumber.
 
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