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71hornet6 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/01/2016 at 4:11pm
An interesting thing happened...
I kept boosting my initial timing to try and figure out how much the car can take so I can figure out how much mechanical I would need to get up to about 38
I had it up to 18 and it ran like a scalded cat! Idle was a bit rough and much smoother if the speed is set to 700.
I haven't heard knocking but maybe I just don't have the ear for it yet. (I'm using 91 gas.)
So as I was adjusting things on the engine, I noticed that the idle timing was up in the '20s and the max advance was not changed
I realized the single gold spring (lightest) had been putting all the tension on the stock black spring (2nd lightest) and it finally got a little stretched out so it was advancing at idle.
I put BACK in the other stock black spring and now it's at 18 initial and 40 total - good!
I don't know what my advice would be...
One option is you could leave the stock springs in there and just drive around with a retarded engine until they loosen up - that extra 6 degrees of top end power would be a shame to live without.
I guess I would still recommend putting the gold spring in there until the black one gets stretched out?

'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401harry Quote  Post ReplyReply Direct Link To This Post Posted: Jun/01/2016 at 6:13pm
Cant comment on the cheap HEIs out there but I will say that the DUI I bought in 2002 is the best distributor/ignition I have ever had. It ran perfect out of the box and been in several cars/engines combos (all 401s) without fail. Its semi retired now as a back up distributor/ignition in case my MSD/Crane system quits at the track. I will buy another if it dies 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Jun/01/2016 at 6:26pm
Originally posted by 401harry 401harry wrote:

Cant comment on the cheap HEIs out there but I will say that the DUI I bought in 2002 is the best distributor/ignition I have ever had. It ran perfect out of the box and been in several cars/engines combos (all 401s) without fail. Its semi retired now as a back up distributor/ignition in case my MSD/Crane system quits at the track. I will buy another if it dies 



I think the OP is doing this as a tutorial as well as an install.

To me any ignition system will work fine as long as the components are good. Also there are good points and bad points to various ignitions. I gave a good artical to show what to look for with such an install. It covered both street and performance use, though the primary was on performance.

I chose a custom HEI for my 390 build, because of ease of maintenance and for its cost effectiveness. Though mine was picked as an untouched Cad distributor and machined to exact tollerances from a good factory unit. Which I cannot say all custom HEI distributors are machined, from who knows where, are done in such a way.

You can make a cost effective upgrade hand picking components, as long as you don't mind doing some experimenting.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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71hornet6 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/02/2016 at 4:17pm

I didn't like that the stock black springs stretched out so fast through normal advance curve experimentation so I looked for another lighter tension spring that was better quality.
The springs that came in the advance kit look to be the same 3 sets that are in every kit.
2 very light springs, a heavy set and a crazy heavy set of springs.
I was looking for more variety in the medium area.

The goal is 38 degrees as it seems like the most people recommend for a warm street car.
Greyhounds_AMX has had the most success at the drag strip at this level. I did a couple tests and it seemed like the engine could take low 40s in advance degrees but it's a street car so it's best to dial back a few degrees. I'm starting to think that 22 mech advance is kinda about right because it puts initial timing in the 12-16 range (for 34-38 total) which is peppy! EDIT: It seems like 10-14 would be better initial as the idle RPM could be lower and starting the engine would be easier
I have initial at 16, mech advance is max 22 for a total of 38 -
I need springs that are heavy enough to not advance at idle (because I need all 16 initial to be on the distributor to hit my target) but light enough to allow mech advance to max out around 3000
I went to the hardware store and got some springs that are heavier than
the gold springs and decided to try those as a set. Upon firing it up,
it was advancing at idle, so I needed heavier springs.
This is the next thing I tried:
16 initial timing at 700rpm
One hardware store spring and one black spring from the advance kit
Here's what I got

I only took three data points because I didn't have a helper.



I think this is looking pretty good. It is a steep curve. What do y'all think? I still have a very heavy spring in the advance kit that would probably bring all-in advance at well over 3000 and have a more gradual curve.



Edited by 71hornet6 - Jun/03/2016 at 12:50pm
'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
Back to Top
71hornet6 View Drop Down
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Joined: Nov/18/2012
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/03/2016 at 3:18pm
I dremeled out the slots under the weights for more max advance.
I took off material to allow about 1/32" more travel and got about 3 more max degrees.
I now have
13 initial
25 mechanical
38 degrees somewhere that sounds like about 3000.
Using the spring combo from above.

I also hooked up the vac advance "blindly" by recommendations on the web
Manifold vac
2nd to most extreme lockout notch
9 turns out on the can. (2.5mm hex wrench)
This should give me a minimum of vac advance
I need to reregister my car before I can do more extensive testing like part throttle highway cruising.

I have a feeling the module in the dist is crap. Sometimes the engine sounds like it has old spark plugs. I don't know if they put any heat sink under it either.
I have a Saginaw D1906 module (made in America) coming in the mail. Everyone says the older Delco D1906 or other quality stock replacement modules work well.


Edited by 71hornet6 - Jun/03/2016 at 3:51pm
'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
Back to Top
71hornet6 View Drop Down
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Joined: Nov/18/2012
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/06/2016 at 12:54pm
I'm starting the think the mechanical advance slots for this distributor should have been set to 26 or 28 for use on the AMC258 so the initial timing could be set from 6-18. The range of timing for this engine, from what I can tell, is 32-42 I&M.
The full 28 mech advance wont be needed by everyone but it's easy to put in stiffer springs. It's hard to drill out the slots like I had to do.
Without enough mechanical advance, to reach your peak timing goal you have to boost your initial timing which means you have to increase idle speed to smooth it out. Most people don't want a  high idle to get their distributor to perform well.
As you would expect from a "Chinese Performance" distributor, it's not engineered quite right.

Update:

I found a chart on "classicinlines.com" that is interesting
It said:
cam duration 260, idle speed 600-800, advance 10-12
cam duration 270, idle speed 700-900, advance 10-12
cam duration 280, idle speed 900-1000, advance 12-14
I think this must be wrong for my engine because it seems to want more and more idle timing. It's really a dog if I turn initial timing down to 12.
When I try to do the "set idle timing to highest engine vacuum" thing it goes as follows -
I check the manifold vacuum reading. I advance the timing by turning the distributor. The idle speed goes up. I turn the idle speed back down to where it was on the carb idle speed screw. The manifold vacuum has increased. Repeat. The idle gets rougher, but it seems to always take more timing.
I've also heard people say "keep turning up the timing to max manifold vacuum and then back it down until the reading 1.75-2 inches vacuum less than max". I did the test for timing sweet spot again and got 42 at just over 21 inches vacuum. The best idle timing settings seem to be around 20 inches vacuum, which is higher than that formula would suggest. It will take 18 degrees advance at 750RPM with 20 inches vacuum.

Edited by 71hornet6 - Jun/07/2016 at 3:57pm
'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
Back to Top
71hornet6 View Drop Down
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Joined: Nov/18/2012
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/06/2016 at 1:53pm
To test the vac advance at idle, which is max, I got it idling at 15 degrees advance and I pulled the vac line to the vac advance can and timing dropped down to 4.
So I think that means I have
11 degrees vac advance, set by -
2nd to most extreme lockout notch on vac limiter
9 turns out on the can. (2.5mm hex wrench)
'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
Back to Top
71hornet6 View Drop Down
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Joined: Nov/18/2012
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 71hornet6 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/07/2016 at 4:18pm
I got a Saginaw D1906 module, made in USA for $14 on eBay. Stock GM style modules are known for their durability.
They sell a generic Chinese "HEI PERFORMANCE MODULE" for $10 but it's probably the same unit I already have in the distributor.
I hope the Saginaw one lasts for a while. Even if it's not an upgrade, it's good the to have the Chinese module in the glove box as a spare because they can get damaged by heat and leave you stranded.

I also stopped by a real old-fashioned hobby electronics store to get the thermal compound pictured above.
Some people use the silicone grease under the module but this is not technically the right product.
There are two levels of thermal compound - one is ceramic based, and the other has silver in it.
At the electronics store, they had tiny packages of both - enough to put in a module. The ceramic stuff was $1 and the silver was $3 so I got the good stuff. Cool
I stopped by radioshack because it was a block from the hobby electronic store and it was $9 for ceramic and $13 for silver in larger quantities than I needed. Support your local hobby electronics store!
'71 FrankenHornet:
'72 258 '95 4.0L Head Holley 390CFM
AX15 with R154 gears 5 speed Hurst shifter
AMC20 rear axle Detroit TrueTrac
Dual Exhaust
Concord Discs Spirit AMX sway bars
Back to Top
304-dude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Jun/07/2016 at 4:57pm
Then you have mil spec heat sink compound, which I use and does very well long term.

The key in using compound is to fill the voids between the layers. Too much is not good. To note on proper application, lift and look at the foot print left behind. You should see bare metal pocket surrounded by displaced residue with some areas with voids filled by the compound.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
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