Topic: Delco HEI Distributor Rebuild
in Forum: C3 Electrical
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So I've been struggling with what to do with my distributor. I have been running (for the past 7 or 8 years) a cheapie aftermarket HEI. The electrical connections at the module and at the cap are junk and they are loose and causing it to miss, I believe. I was faced with multiple options, including buying a high performance aftermarket, rebuilding this one, buying a reman from a parts house, etc. This last weekend I dug out my original and was pleased to find that the shaft bearings are nice and tight, really the only thing that might be a show stopper. I also verified that it was the correct part number with my Black Book - good news there. So I'm heading down the road of rebuilding the original. I have several parts on order: 1) new Delco pole piece/magnetic pickup (I know it's bad on the original - that's why I pulled it in the first place) 2) Pertronix capacitor and harness and 3) Pertronix adjustable vacuum advance. I already have the existing parts: 1) Accel high performance module 2) decent quality cap, rotor, and coil 3) aftermarket mechanical advance kit.
|UPDATED|11/13/2013 8:34:22 PM (AZT)|/UPDATED|
Questions:
1) anything I am missing or any problems with my method? I know it might not be the cheapest or highest performance option, but I'm a big fan of using original parts, especially when I can rebuild and upgrade a little.
2) It looks like you have to remove the shaft to replace the pole piece? Drive the roll pin out of the gear, remove the gear, and the shaft will come right out or is it more involved than that?
Here's a link to a few pics. I'll add more after the rebuild. The shiny distributor is the cheapie. (But the delco seems to be cleaning up pretty good.
|UPDATED|11/13/2013 8:34:22 PM (AZT)|/UPDATED|
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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daveo76 said:
2) It looks like you have to remove the shaft to replace the pole piece? Drive the roll pin out of the gear, remove the gear, and the shaft will come right out or is it more involved than that?
Here's a link to a few pics. I'll add more after the rebuild. The shiny distributor is the cheapie. (But the delco seems to be cleaning up pretty good.
Knock the roll pin out...yes. Shaft come right out? If yer dang lucky.
Usually, there is so much old oil gunked up inside, between the bushings, that the shaft will only move 1/2" or so. Spray that puppy down a day or so before trying to disassemble it. Then you'll prolly wind up twisting back/forth on the shaft, while pulling it out at the same time.Word of caution...be sure to note the orientation of the gear. You would be surprised at how many have tried to put the gear on upside down. Also, there is a thin, steel shim between the gear and the housing. DO NOT LOOSE IT!. Once the shaft is out, it's pretty much self explanatory after that. Use some engine oil, or a light grease on the shaft, and bushings when re-assembling it.
In the pics....I see a big problem with the gear on the "new" dist. Compare it to the original gear...see the difference?
Do you have a stock, or a non-roller cam, or is it a roller?
Joel Adams
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It's a SpeedPro non-roller cam. Are you talking about the different shape of the teeth, as in the original teeth are wider at the tips? Would that screw up my cam? I think I only have 1500 miles or so on the motor so far. Any concerns about going back in with the original? I just went out to the garage and looked more closely and the original gear seems to be in good shape, a little bit of a wear pattern in some spots, but nothing too bad.
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Definitely go back with the original gear. Looks to me(from the pic) that the other gear might not be cut right....the gear may allow some sloppiness when meshing with the cam gear. Prolly won't actually damage either gear, but certainly might cause some timing issues....
Joel Adams
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My Link
(click for Texas-sized view!) NCRS
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I have one of the generic dist, and have not have any issues that I know of yet.
|UPDATED|11/14/2013 12:16:54 PM (AZT)|/UPDATED|
To set the dist. for performance this is what I have found and have some questions?
Stock 26 deg total initial and centrifugal at 2500 RPM
8 Deg initial timing.
15 to 18 Centrifugal timing.
24 deg of vacuum advance to get close to 52 at cruise.
Performance 36 deg Total initial and centrifugal in at 2500 RPM
12-16 initial adv.
would need to change weights to get 20 deg centrifugal adv.
would need to change vacuum adv to 16 deg to get the 52 deg at cruise.
If this is all correct then what does changing the ign module do?
What does the hotter spark do?
The mods Coil, ign module, weights, vacuum adv adjustable?
then you need to balance this with the cam that you have.
|UPDATED|11/14/2013 12:16:54 PM (AZT)|/UPDATED|
Adams' Apple said: Definitely go back with the original gear. Looks to me(from the pic) that the other gear might not be cut right....the gear may allow some sloppiness when meshing with the cam gear. Prolly won't actually damage either gear, but certainly might cause some timing issues....
Thanks for the helpful insights, Joel. I like to think I would have got the gear on correctly since I'll have another distributor sitting right next to it, but I've made dumber mistakes before. Info on the shim and dis-assembly will be very helpful. And I now feel like I'm definitely rebuilding the correct distributor (my original).
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
rraider1 said: I have one of the generic dist, and have not have any issues that I know of yet.
To set the dist. for performance this is what I have found and have some questions?
Stock 26 deg total initial and centrifugal at 2500 RPM
8 Deg initial timing.
15 to 18 Centrifugal timing.
24 deg of vacuum advance to get close to 52 at cruise.
Performance 36 deg Total initial and centrifugal in at 2500 RPM
12-16 initial adv.
would need to change weights to get 20 deg centrifugal adv.
would need to change vacuum adv to 16 deg to get the 52 deg at cruise.
If this is all correct then what does changing the ign module do?
What does the hotter spark do?
The mods Coil, ign module, weights, vacuum adv adjustable?
then you need to balance this with the cam that you have.
I always meant to use the method outlined there after I got my engine running last year, but I just set initial somewhere 12 to 14 and it ran pretty dang good so I decided not to mess with it. I think now I'll need to do some more detailed tuning, though, to make sure I get the advance curve right. The way I understand it, centrifugal advance is the important part for performance. Vacuum advance may be more for economy - I'm going to have to research that more before I tune it. Changing springs is how you adjust the centrifugal: lighter springs = more advance. You want the most advance you can get without detonation. High performance module is probably more important for high RPM operation - stock modules are generally good for mild street motors. My rationale with the high perf one was more an attempt to get better reliability. A hotter coil simply produces more voltage so theoretically you can increase the plug gap for a hotter bigger spark. Seems like you can definitely overkill in this area, though. Thanks for the info.
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
in Forum: C3 Electrical
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