Distributor cap help! Please!
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
Distributor cap help! Please!
If this is me being stupid please feel free to give me the answer and pick on me because I don't know what to do LOL.
So I bought a 1985 c4 corvette earlier this year and am trying to do a tune up. The previous owner did like every gimmick available. I just want to put it back to stock before I decide if I want to explore upgrades.
I had a lot of difficulty removing the accel cap/coil that was present on the engine. Those side screws were stripped on top on the passenger side. I did not think much of it at the time, but when I went to install the AC Delco cap, the notch that ensures that the cap is on right ended up putting the electrical plugs on the other side.
I just thought maybe that accel one had the electrical plugs on the other side for some reason. When I actually went to plug the connector in, the wires weren't long enough to reach.
So, I took it off and reassessed the situation. There is literally only one way to put the cap on. Then I grabbed the accel one that was on before and noticed that the notch was in the same place as the new AC delco one. The notch looked like it had been squished somewhat and that are was cracked a little.
I went on the forums and Google image search and every picture shows the electrical plug side on the driver side. I thought maybe I had bought the wrong replacement cap, but every on I looked at had the notch at the same place.
I don't know know how to proceed. It seems to me that they just forced the old cap on the distributor. I don't see any way to continue. Help!
So I bought a 1985 c4 corvette earlier this year and am trying to do a tune up. The previous owner did like every gimmick available. I just want to put it back to stock before I decide if I want to explore upgrades.
I had a lot of difficulty removing the accel cap/coil that was present on the engine. Those side screws were stripped on top on the passenger side. I did not think much of it at the time, but when I went to install the AC Delco cap, the notch that ensures that the cap is on right ended up putting the electrical plugs on the other side.
I just thought maybe that accel one had the electrical plugs on the other side for some reason. When I actually went to plug the connector in, the wires weren't long enough to reach.
So, I took it off and reassessed the situation. There is literally only one way to put the cap on. Then I grabbed the accel one that was on before and noticed that the notch was in the same place as the new AC delco one. The notch looked like it had been squished somewhat and that are was cracked a little.
I went on the forums and Google image search and every picture shows the electrical plug side on the driver side. I thought maybe I had bought the wrong replacement cap, but every on I looked at had the notch at the same place.
I don't know know how to proceed. It seems to me that they just forced the old cap on the distributor. I don't see any way to continue. Help!
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
I went on the forums and Google image search and every picture shows the electrical plug side on the driver side.
Sounds like PO rotated the distributor. You're probably going to have to move it and re-time.
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
w/ confab - if things are really screwed up, you may have on recourse but to pull the distributor, re-index and re-orient everything, and reset the timing. 
Last edited by Joe C; Jun 20, 2018 at 06:16 AM.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Before you take distributor loses to re-orientate it. Rotate balancer to align timing mark. It will make easier to set distributor and car will start. You will need timing light to reset timing.
Team Owner
Joined: Dec 2012
Posts: 30,427
Likes: 1,609
From: Outside the Quick Stop N.J.
As stated before, it sounds like the PO put the distributor in 180 deg out. Pull the plugs, bring the engine up to TDC, line up the #1 plug wire with the #1 spot on the distributor. That should get you close enough to get the engine to run, then you can use a timing light to fine tune it. I am not sure about the 85, but on my 89 you have to disconnect the single brown wire by the brake booster.
This link has some good info.
https://www.corvetteforum.com/forums...make-sure.html
This link has some good info.
https://www.corvetteforum.com/forums...make-sure.html
Last edited by Patsgarage; Jun 16, 2018 at 11:19 PM.
Safety Car
Joined: Aug 2013
Posts: 4,425
Likes: 603
From: Minneapolis Mn
This may help diagnosis: did you notice where the #1 plug wire was on the previous cap along with the tab? I believe the FSM shows where it 'should' be located.
If they're on the reverse side then it's likely the distributor was swapped 180 degrees. You might want to confirm how it should be vs what it is before tearing things apart.
Just a thought.
If they're on the reverse side then it's likely the distributor was swapped 180 degrees. You might want to confirm how it should be vs what it is before tearing things apart.
Just a thought.
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Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
here's my personal method for indexing the distributor on an L98 engine. for years, I never gave any thought to properly indexing a SBC/L98 distributor - just did it, and hope for the best. usually with a little screwing around and some dumb luck, things went together. anyway, a few years ago, I took a good look at the "assembly mechanics" of how all this went together, and pretty much came up with this. not trying to say this is unique or anything, but here's my approach --
with the engine at #1TDC (compression) and the slot on the oil pump shaft at approximately the 5:30 position, and the distributor body squarely on the engine- that is, the four distributor cap mounting screws, parallel and perpendicular to the engine's centerline, and the electrical connections 90° (LH) to the CL. lower the distributor to the point where the gears are just shy of engagement. this is the key point - point the rotor to the center of the LH valve cover emblem (or the center of the aft two VC mounting bolts - either perimeter or center-bolt), and lower the distributor so the cam/distributor gears engage. as the gears mesh, the rotor will automatically turn CW and end up pointing to the #1 spark plug. it may take a little wiggle-giggle to mesh the gears. now, turn the distributor assembly a little CCW - try to eyeball about 3° (note my pic - my timing is set to 7°). if the gods are smiling, and everything falls into place, you should end up right around 6° BTDC on the timing. plug wires in the proper order, pull out your timing light and fine tune, and lock the distributor. been doing this for 5 or 6 years now - for me, it's no muss, no fuss. you will end up with a near perfect factory installation.
I've never verified this, and I may be out in left field, but i'm thinking if the distributor is squarely positioned to the engine's CL, the timing is exactly at 0°, and with the distributor slightly CCW, about 3°, you end up at 6° BTDC because of the 2:1 crank/cam ratio (3X2=6). again, never verified this.
the same approach or methodology holds true on spark plug wire routing. the general design those wire lengths to install with a specific routing. if you do things the way the general intended, you'll be surprised how nicely things go together, or fit together -
with the engine at #1TDC (compression) and the slot on the oil pump shaft at approximately the 5:30 position, and the distributor body squarely on the engine- that is, the four distributor cap mounting screws, parallel and perpendicular to the engine's centerline, and the electrical connections 90° (LH) to the CL. lower the distributor to the point where the gears are just shy of engagement. this is the key point - point the rotor to the center of the LH valve cover emblem (or the center of the aft two VC mounting bolts - either perimeter or center-bolt), and lower the distributor so the cam/distributor gears engage. as the gears mesh, the rotor will automatically turn CW and end up pointing to the #1 spark plug. it may take a little wiggle-giggle to mesh the gears. now, turn the distributor assembly a little CCW - try to eyeball about 3° (note my pic - my timing is set to 7°). if the gods are smiling, and everything falls into place, you should end up right around 6° BTDC on the timing. plug wires in the proper order, pull out your timing light and fine tune, and lock the distributor. been doing this for 5 or 6 years now - for me, it's no muss, no fuss. you will end up with a near perfect factory installation.
I've never verified this, and I may be out in left field, but i'm thinking if the distributor is squarely positioned to the engine's CL, the timing is exactly at 0°, and with the distributor slightly CCW, about 3°, you end up at 6° BTDC because of the 2:1 crank/cam ratio (3X2=6). again, never verified this.
the same approach or methodology holds true on spark plug wire routing. the general design those wire lengths to install with a specific routing. if you do things the way the general intended, you'll be surprised how nicely things go together, or fit together -
Last edited by Joe C; Jun 27, 2018 at 12:57 PM.
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
here's my personal method for indexing the distributor on an L98 engine. for years, I never gave any thought to properly indexing a SBC/L98 distributor - just did it, and hope for the best. usually with a little screwing around and some dumb luck, things went together. anyway, a few years ago, I took a good look at the "assembly mechanics" of how all this went together, and pretty much came up with this. not trying to say this is unique or anything, but here's my approach --
with the engine at #1TDC (compression) and the slot on the oil pump shaft at approximately the 5:30, position the distributor body squarely on the engine- that is, the four distributor cap mounting screws, parallel and perpendicular to the engine's centerline, and the electrical connections 90° (LH) to the CL. lower the distributor to the point where the gears are just shy of engagement. this is the key point - point the rotor to the center of the LH valve cover emblem (or the center of the aft two VC mounting bolts - either perimeter or center-bolt), and lower the distributor so the cam/distributor gears engage. as the gears mesh, the rotor will automatically turn CW and end up pointing to the #1 spark plug. it may take a little wiggle-giggle to mesh the gears. now, turn the distributor assembly a little CCW - try to eyeball about 3° (note my pic - my timing is set to 7°). if the gods are smiling, you should end up right around 6° BTDC on the timing. plug wires in the proper order, pull out your timing light, fine tune the timing, and lock the distributor. been doing this for 5 or 6 years now - for me, it's no muss, no fuss. you will end up with a near perfect factory installation.
I've never verified this, and I may be out in left field, but i'm thinking if the distributor is squarely positioned to the engine's CL, the timing is exactly at 0°, and with the distributor slightly CCW, about 3°, you end up at 6° BTDC because of the 2:1 crank/cam ratio (3X2=6). again, never verified this.
the same approach or methodology. holds true on spark plug wire routing. the general design those wire lengths to install with a specific routing. if you do things the way the general intended, you'll be surprised how nicely things go together -
you do not want to end up looking like this...
[IMG]https://i.ebayimg.com/00/s/MTAxMlgxNjAw/z/CUgAAOSwjB9a4UYA/$_57.JPG?set_id=8800005007
with the engine at #1TDC (compression) and the slot on the oil pump shaft at approximately the 5:30, position the distributor body squarely on the engine- that is, the four distributor cap mounting screws, parallel and perpendicular to the engine's centerline, and the electrical connections 90° (LH) to the CL. lower the distributor to the point where the gears are just shy of engagement. this is the key point - point the rotor to the center of the LH valve cover emblem (or the center of the aft two VC mounting bolts - either perimeter or center-bolt), and lower the distributor so the cam/distributor gears engage. as the gears mesh, the rotor will automatically turn CW and end up pointing to the #1 spark plug. it may take a little wiggle-giggle to mesh the gears. now, turn the distributor assembly a little CCW - try to eyeball about 3° (note my pic - my timing is set to 7°). if the gods are smiling, you should end up right around 6° BTDC on the timing. plug wires in the proper order, pull out your timing light, fine tune the timing, and lock the distributor. been doing this for 5 or 6 years now - for me, it's no muss, no fuss. you will end up with a near perfect factory installation.
I've never verified this, and I may be out in left field, but i'm thinking if the distributor is squarely positioned to the engine's CL, the timing is exactly at 0°, and with the distributor slightly CCW, about 3°, you end up at 6° BTDC because of the 2:1 crank/cam ratio (3X2=6). again, never verified this.
the same approach or methodology. holds true on spark plug wire routing. the general design those wire lengths to install with a specific routing. if you do things the way the general intended, you'll be surprised how nicely things go together -
you do not want to end up looking like this...
[IMG]https://i.ebayimg.com/00/s/MTAxMlgxNjAw/z/CUgAAOSwjB9a4UYA/$_57.JPG?set_id=8800005007
Oil Producer
Joined: Apr 2014
Posts: 9,363
Likes: 2,734
joes advice is perfect. as is his valve lash method.
its common to be any of these three on the first time so if u dont nail it dont fret:
- 1 tooth too early (like joes example of what not to be)
- 1 tooth too late
- 180deg off
u will get it
its common to be any of these three on the first time so if u dont nail it dont fret:
- 1 tooth too early (like joes example of what not to be)
- 1 tooth too late
- 180deg off
u will get it
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
Thanks for the all the help folks. You were right. The previous owner installed the distributor 180 degrees off and put the distributor cap on as if the distributor was not 180 degrees off. This was what was so confusing to me initially. The PO basically just rammed the cap on despite the distributor being the other way.
So after putting it back the right way, I started wondering about how/why this would happen. The PO put one of those Accel Coil Caps on, but that would not have required removing the distributor.
Is there some kind of belief or old wive's tale out there that suggests running the distributor 180 off is like a secret to more horsepower or something?
So after putting it back the right way, I started wondering about how/why this would happen. The PO put one of those Accel Coil Caps on, but that would not have required removing the distributor.
Is there some kind of belief or old wive's tale out there that suggests running the distributor 180 off is like a secret to more horsepower or something?
Burning Brakes
Joined: Oct 2017
Posts: 823
Likes: 106
From: Somewhere near Fort Wayne, Indiana
Personally I would not have removed the distributor. You should be able to just loosen the clamp and rotate the housing 180° and reinstall the cap. As long as the wires are in the same place it would run, yes? Assuming the wires are in their proper places to begin with.
Team Owner
Joined: Dec 2012
Posts: 30,427
Likes: 1,609
From: Outside the Quick Stop N.J.
IIRC there is not much room between the firewall. Good idea that would work if you had enough room to spin the distributor. Even a C4 is a long way from the old days.
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
Idk for sure, but you might be right. Regardless of the solution, it was actually an interesting task to complete. Doing all the steps really taught me more about how sbc's work.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
just thinking of all that's wrong with this "bubba" installation. personally, i'd pull that thing and start from scratch. i'm having a tough time even envisioning how the car's running since i'm thinking the distributor cap is keyed for orientation, and yet somehow, he clamped it down 180° out. then you have the electrical harness and connections going into the distributor body - how was all that put together? don't try to take shortcuts at this point. remember, ya can't make vanilla ice cream out of horseschitt - 
Thread Starter
Intermediate
Joined: Jun 2018
Posts: 39
Likes: 4
From: West Seneca NY
just thinking of all that's wrong with this "bubba" installation. personally, i'd pull that thing and start from scratch. i'm having a tough time even envisioning how the car's running since i'm thinking the distributor cap is keyed for orientation, and yet somehow, he clamped it down 180° out. then you have the electrical harness and connections going into the distributor body - how was all that put together? don't try to take shortcuts at this point. remember, ya can't make vanilla ice cream out of horseschitt -
). Despite the gap they knew enough that where the rotor was pointing was for the first cylinder even though it was 180 out. .To fix it I took off all of the wires, plugs, cap, rotor, distributor, etc and started from scratch like you said because after seeing the whole cap thing there was no way I could trust the rest of it LOL. Between Joe C's description and some YouTube I felt confident enough to figure out the TDC, distributor/rotor orientation and the firing order for the plugs. I also replaced the ICM because it looked cracked to me.
I got it going today and it seems to run ok. I think I might have the timing off like a degree because I couldn't see the marker really good. I need to get like a paint marker or something. Get this though -- on the balancer, the PO tried to mark the timing as well and used one of those glitter markers which made it nearly impossible to see.
Instructor
Joined: Jun 2014
Posts: 133
Likes: 6
From: Minnesota
Take a good close look at your balancer. It may have (probably has) slipped and that's what he was fighting. As I recall, 8 degrees advance on mine turned out to be 5 or so retarded. Only clue it was bad was a slight ring on the snout where it had walked back a little also. If I hadn't seen a lot of 'em I would have missed it.