I put the formula in post 243 above.
0.150" width of pin and 0.013 per degree.



A 5L(10*) slot would be .150+.130=0.280"

 

Obviously I was wrong twice - I missed the post and I blew the calculation as I forgot the width of the pin. Thanks for gently showing the error of my ways.

 

I'm a LOT of things but subtle is not one of them.

It's amazing that slot is only little more than a quarter inch wide.

 

Ok, lathe as a distributor machine workaround, novel idea, one with a variable speed drive would be great. How about a drill press or milling machine with variable speed drive?

Hardest part would be reading the timing changes, the idea of a degree wheel on the drive end and a timing light, just make an adjustable pointer so you can set it to either 0° on your degree wheel or static timing value as you desire. As for advance, most wedge combustion chamber engines (small block Chevy) used to run best at 38-42° total advance, of course, that was with real gasoline. 34-36° would probably work today. That is total mechanical advance, modern stock low compression engines like 80s F-series can actually take more than that for mechanical advance (it is based on burn time, higher compression ratios or forced induction burns faster, ergo, less total advance needed or wanted.

Vacuum, or light load advance, with a DS-II, HEI or similar, the plugs will reliably fire the mixture with as much as 60° total advance. As for the Amazon pictured distributor, point ignition Fords and DS-I used a small cap, introduction of the higher output DS-II required a larger cap and wires to prevent crossfire and arcing to ground. Ford's quick solution, a plastic bowl that is held in place by the smaller cap's clips, a taller, longer rotor and a larger diameter cap with studs instead of socets for the wires. I was running a DS-II on my 390.

Let me clear up a slight misconception on carburetors, Carter AVS and Thermoquad carbs do indeed have adjustable tension on their air valves, the TQ has the additional damper (choke pull-off diaphragm) to delay the initial opening rate to prevent bog. Quadrajets have a similar setup with one huge difference, Q-jets have secondary metering rods operated by a cam on the air valve shaft. BTW, the infamous Motorcraft 4300D (for dog?) uses a pair of tapered rods in the secondary nozzles that are attached to the air valves.

One of the best carburetors in the world is also the simplest, an SU, two moving parts! It is the absolute simplest form of a variable venturii. Jim, motorcycle carbs are similar in their operation.

 

Thanks, Bill. Sounds like you think my "novel idea" might work. And, I agree that variable speed would be good. Unfortunately I don't have a single variable speed device as the lathe, mill, and drill press are all stepped pulleys. Guess I should consider a Variac.

And what you described with the degree wheel is what I'm thinking. I'll bore a piece of aluminum to be a slip fit on the dizzy's shaft, and I hope to sandwich it between the gear and the lathe chuck so it'll be adjustable. Hopefully I can adjust it and lock it down so the pointer doesn't have to be adjustable. But I can always add/subtract from the reading to fudge.

On the actual timing, I hope Tim can give me the #'s to use, but I suspect BruteFord's suggestion of 16 initial, 20 centrifugal, and whatever vacuum will be close. The question becomes at what RPM it should start coming in and where it should be all in. Again, hopefully that's something Tim can answer.

I'm anxious to get the Amazon dizzy as I want to find out what it is. I can't believe it'll be with the old points-style cap instead of the DS-style adaptor and large cap. They show that one as being correct for an '81 400, although they also have another one for it that has a single-port vacuum advance. By the way, did the advance/retard units have a different advance range/speed? IOW, is there a reason why I can't run the one that's coming on Rusty - obviously w/o the retard?

Last, help me with the misconception re TQ's and QJ's? What did I say incorrectly? I'm just trying to learn. And, by the way, Tim did say they the carb they use most on these built 400's is an AVS - specifically the Eddy 1806, which is their 650 CFM version. However, in an email I asked him what he thought of going with a QJet, as that is my favorite. And, as you point out, it even has secondary metering rods.

 

Gary,
Both those Amazon distributors come up as fitting my '87 truck.

You can just leave the retard port unconnected.
Don't cap it, because obviously that side is sealed, and that would affect the vacuum advance function.

Bill,
Bikes now use fuel injection to meet EPA reg's, but most used to have Constant Velocity carburetors.
(of course I had to have Dellorto's which are complex )

I understand how the Zenith/Stromberg and SU carbs work.
...Dad had an MGA.

 

Jim, I figured you did from your reference to bikes in the past. We used to claim that the CD (stands for Constant Depression) on the Zenith-Strombergs was the condition the mechanic was in trying to set them up. BTW, you haven't lived till you have set up 4 Zenith-Strombergs on a V12 Jag.

Gary, I was referencing the dashpot feature on the TQ and Q-Jet, along with the metering rods on the Q-Jet, makes all the difference in the world.

My favorite "tuneable" carbs are Webers. 48 IDAs, 4 of them on a 289 or 45 DCOEs, 3 on a 300 six or 292 Chevy.

Gary, a variac will not work on an induction AC motor only on a universal motor.

 

My great uncle, Jim, who used to live near Gary (in B.A.) had a rack of 6 dual downdraft Webers on both of his Ferrari's.
The linkages were so complex.
That was a symphony, especially the 512 where they were right behind your head!

Fritz, the old mechanic who was constantly tuning and synchronizing the MG seemed to be like that.
Maybe he was drinking the damper fluid???

 

Ok, so I was close to right with my thoughts on the AFB, AVS, TQ, & QJet. Just didn't explain fully. Gotta find a QJet for a reasonable price - one with an e-choke.

So, a Variac won't run my drill press? Shucks! I guess I'll stay with running on the lathe, which in some ways is easier as I have the live center so can support both ends of the shaft, and the housing rests against the tooling. Easy peasy.

By the way, do you have spec's for the side play on a DS shaft? The factory manual has the end play but not side play, and this old dizzy has a bit. So, I'll check that on the new one, but would like to get things set up tightly.

Edit: I should have mentioned a video I recently saw on how the new Ferrari engines are made. And one of the things they said is that they actually pipe some of that symphony into the cabin.

 

Hey Gary, I watched an episode of wheeler dealers last night. They re did a Triumph.

They extracted all water out of the cooling system and replaced it with waterless coolant. Waterless coolant builds no pressure in the cooling system since there is no evaporation.

They claimed that they will never have an overheating problem. Have you ever heard of this?

 

Gary the variac works by changing the voltage up or down, AC motors are frequency controlled, that's why they will sometimes have two RPMs listed, one for 50 Hertz and one for 60 Hertz. If you lower the voltage with a variac, all it will do is increase the current draw.

I can't find anything in the information I have here on side play, the top is the critical end, I don't think there is a bushing in the lower end, it depends on the block pilot for alignment.

 

Kyle - I've never heard of waterless coolant. Guess I'll research that.

Bill - Yeah, that's what Jim said as well. And I should have remembered that about AC motors. Duh!

On the dizzy, the lower end of the shaft runs in the block pilot? Steel to cast? So a little slop at the bottom end of that bushing is reasonable, and it is the fit at the top, as well as end play, that's key? And, IIRC, the end play needs to be at the tight end of the tolerance to keep it from walking up the gear and dropping, causing spark scatter? If so, what do you shim the shaft with?

 

Kyle - Evans Waterless Coolant. How much do you want? It's $47.95/gallon.

Edit: See it on Jay Leno's Garage.

 

Post didn't go through errr

There a few threads in the diesel side of this forum. It was not well received on the one I read at least.

The cost was enough to deter me.

Since it's not to be mixed it would basically cost twice as much per gallon for comparison sake($96 per gallon)

 

Why is this, Gary? I haven't been following the two threads consistently.