Need help putting a DUI dizzy back together (1 Viewer)

[jestlurnin]

Summit Racing SUM-G5212 Summit Racing™ HEI Advance Curve Kits | Summit Racing

Free Shipping - Summit Racing™ HEI Advance Curve Kits with qualifying orders of $109. Shop Distributor Advance Kits at Summit Racing.

www.summitracing.com

Hopefully this works. Not sure how to post a link even though I should as I’ve been on mud for over a decade…this kit from summit looks like it has everything but the “studs” are different. Might work and for $10 it might be worth a shot.

 

[pb4ugo]

The E clips retain the center plate I have circled. The studs are pressed/tack welded into the plate below. You already have the weights and springs. The other parts in the kit are bushings that go over the studs, because the holes in the aftermarket weights are larger. A lot of folks who purchase the kit, swap the springs and use the original weights. I did this on my sbc, so I could get my mechanical advance to come in earlier.

 

[jestlurnin]

Ahhh so the studs are permanently attached to the center plate and the E clip just holds it down. Makes sense now. I guess best case I secure a new center plate from Davis and the 2 studs that go through the weights. Then I could theoretically put this thing back together.

How are the studs held in the weights normally? Just by the tension of the spring coming off the center plate? The reference photo I posted doesn’t look like there are any E clips holding the studs into the weights.

Thanks @pb4ugo

 

[pb4ugo]

The E clips retain this piece(pic below) to the plate below which the studs are attached to. At low rpm the weights are held against this piece by spring tension. As rpms increase these weights fly away from this plate and advances the timing(mechanical/centrifugal advance). The springs control how and when the advanced timing comes in. Usually around 2500 to 3000 rpms the centrifugal advance is all in. The springs keep the fly weights in place. In the 2nd pic is where the studs you found were attached.

 

[jestlurnin]

@pb4ugo now I have a complete understanding of what happened. How in the world did those studs just shear off?! Crazy.

Spoke to Davis this morning also and it sounds like they are suggesting replacing the center shaft which I assume includes where the studs sheared off where pb4ugo circled in the above photo. What they are saying makes way more sense now.

Guess I know how to fix it. Now need to decide if I want to fix or drop in a city racer replacement.

If I go with a city racer replacement I’ll have to figure out if my coil is good. I could see the PO dropping in the Davis dizzy because the coil in the rig gave up the ghost. This picture is of my coil/ignitor correct?

 

[pb4ugo]

Yes, what dui said would be the repair. You would have to remove the drive gear at the bottom of the distributor and pull the shaft up out of the housing and replace it.

 

[jestlurnin]

Man….decisions decisions. Either way I’d have to pull the dizzy. So I guess I’d learn a new skill which is cool.

If I replace ls the center shaft on the current set up I wouldn’t have to worry about my ignitor/coil potentially not working as I would if I go back to a Toyota dizzy. Plus upon inspection the wiring to the ignitor/coil looks like it’s been kinda hacked up so I’d have to figure that out as well…

 

[charliemeyer007]

Seems to me you could weld/silver solder the studs in place, and they don't need to be their studs either.
Never heard of a Davis dizzy before, I would find something else. I like straight mechanical advance, vacuum anything sucks.

 

[pb4ugo]

Vacuum advance is typically used in cars and trucks because throttle input is variable and it should increase your fuel mileage. It adjusts and advances or retards the timing according to throttle input, like when no or minimal load is present, like coasting with light or minimal throttle input, or hard acceleration and it pulls back timing. Engines without vacuum advance are usually service engines, boats or drag racing. These engines are typically on constant load, or during drag racing when the throttle is wide open and has no appreciable vacuum.

 

[jestlurnin]

Appreciate everyone’s input and help so far.

Still looking at all my options.

Got ahold of city racer and they are under the impression that the 2F 3F dizzy he sells is for semi electronic ignition system and would not work with my November 77’ FJ55

I googled semi electronic ignition systems and got nowhere. Anyone care to explain what that means?

I’ve included a picture of igniter/coil combo that’s still in the piggie (or was until I removed it). The connections look like they would plug right into the city racer dizzy but who the heck knows if that’s even relevant.

Thanks again everyone.

 

[Grayscale]

I'm running with an semi-electronic coil. Probably from a 4/75 FJ40, in my 2/75 USA-spec. FJ40. I have the early F distributor installed. The igniter was introduced to create the low-voltage signal that runs thru the coil, triggered by a circuit that runs thru the points in the distributor. In the points-only-type-ignitions, the low-voltage side of the coil is running across the distributor points. The two types of distributors can mostly work for both types of ignition systems, just not the fully electronic types - they have a signal generator in the distributor.

So, in '78 (11/77), they transitioned to the fully electronic coil / igniter. You'll need a used distributor to run that coil, pictured, I think.

I'd buy the Racer 2F/ 3F distributor, and run it with a new OEM '74 coil, condenser, resistor(?) and the points they come with. Or, the same distributor, and then install Pertronix, and have fully electronic ignition. Personally, it is more than a preference for new distributors, they have new mechanical parts that can't be replaced easily when rebuilt.

 

[jestlurnin]

Wanted to wrap up the final fix here.

I was able to get ahold of Davis Unified Ignitions (DUI) in Memphis last Monday. Their customer service was awesome and they knew exactly what happened and what I needed. Package arrived yesterday.

Set the timing to TDC compression stroke. Used both BB/Line on fly wheel but also had the valve cover off so confirmed both exhaust and intake valves were “up” on the #1 cylinder. Put the broken rotor back on and marked the head with a sharpie. It was basically pointing at the #4 plug which corresponds to the #1 wire on the cap.Then I loosened the clamp and pulled the dizzy.

The dizzy came out super easy. DUI sent a new center shaft with weights/springs, a new gear, a shim, and a new rotor. There is a roll pin that holds the center shaft/gear on at the end of the dizzy that punches out pretty easy. Installation is the reverse. The shim that was on the unit measured at about 3000th and the 3 shims they sent were all around 14000th so I just reused the original as it was in perfect condition and there were no instructions as to the # you are looking for.

Also checked the vacuum advance with a vacuum gauge/tester when I had everything back together. Worked perfectly.

 

[jestlurnin]

The dizzy popped right back in EXCEPT there was about a 1/4 in gap that it needed to drop in fully. I used my hand crank/starter rod to rotate the engine around back to TDC compression on cylinder 1 and the dizzy dropped in the last little bit. Rotor was pointing at the mark I made on the head/#1 wire on the cap so I figured all good.

Took this opportunity to adjust the valves cold, set the timing to 14 deg BTDC which is where this dizzy seems to run really well. Adjusted idle to 650 even though it shows 660 in the picture. It was bouncing between 640 and 670 but mostly staying on 650 so I called it good. With the valves adjusted, timing set at 14 BTDC these are the numbers I was getting. Pretty happy with the vacuum. Ran outa time yesterday so shake down run will happen today. Pulling installing a dizzy was something I’d never done before and a bit intimidating but glad I did it. Now have a new skill I can continue to hone on my cruisers.

 

[jestlurnin]

I do want to eventually go back to a Toyota dizzy/coil set up but this fix was $170 all in instead of over $400 so it’s good enough for now. Glad there are multiple options.

 

[charliemeyer007]

Awesome they fixed you right up.