Ten BONUS POINTS awarded.....

Venturi vs. throat size

Care to take a sec and clarify? I measured both throats on my DICA...and both measured 32 on the top plate, and 30 in the body. Mic'd my other (2) DICA's and each measured the same as above. I am having trouble figuring out where the "23mm/23mm venturi (vs. 23/21 of the 30DIC)" dimensions are coming from. I figure I must be measuring the wrong area?

You're talking throat/barrel diameter (which is the "30" in 30DICA). The 23mm spec I noted is the venturi size, ie: where the barrel constricts inward about halfway down the barrel.

drawing2.gif


(NOTE: In the photo above, what they note as "Secondary Venturi" should be labeled instead as "Auxiliary Venturi". They likely have it labeled as it is because the photo depicts a single-barrel carb).

If you look on the front face of the carb, in the center between the barrels you'll see a small oval with the venturi sizes noted by cast-in numbers of "23-23" on the 30DICA & "23-21" on the 30DIC. This represents the 23mm secondary venturi & 23mm (or 21mm) primary venturi sizes.


What's your thoughts on the fuel pump pressure fighting the float shutoff valve? I have often wondered about these carbs without the bypass must prematurely age the float shutoff valve?

I won't even mention the cooling aspect of a continuous flow system.

I've never had a problem with the needle & seat wearing prematurely from this, so I can't really comment on it. Ditto on an "overheated" fuel supply.
 
Now I get it

Jeff,

Thanks. The necked down area in the throat(s). I found the stamping you speak of.

So you swapped the lid to give the appearance and functionality of the series I carb, and retained the larger venturi sized body of the DICA. Gotcha.

I am in disagreement with the naysayers of the 30DICA. I thoroughly rebuilt mine including reaming/lapping of an oversized primary shaft.

I see nothing inherit of a faulty design. Just the opposite. Simple straightforward. Is the pot metal thin in some areas ? Yes......look at a Mikuni 38 for comparison. Same same.

I do understand the LIMITED availability of the DICA and the need for a newer 'semi' direct fit carb being offered. That would be an easier approach.

MOST surviving 30DIC(A)(1)'s need an oversized throttle shaft fitted.
Fitting a new shaft is a demanding task that requires a whole bunch of patience.






More on body reaming/lapping later.....


lezesig
'72 850Sp
 
Easy answer

johnt,

Answer: Lash take up spring.

As you are probably aware of.....there is a spring between the axle driven shaft and the stub shaft. It is fitted in the counterbored end of the axle and rides on the nutface of the stub axle.

Pretty poor design feature on that interface there...but I digress.

The spring sheared on mine. You wouldn't know it unless you took the axle off to examine it. The spring was in two pieces and NOT extending past axle end.

With a sheared spring this allowed the axle to hammer on the stub end unchecked causing mushrooming of the stub axle end.

That in itself does not put the car in an undrivable condition but DOES make it impossible to remove that stub nut to inspect the rear wheel bearings for wear and repack with grease.

I want all four corners with repacked bearings and or new bearings prior to rollout : )

Greasing of the spline is a 'biggey' in that area too. That will allow the floating flange to freely ride on the splines. I suspect a dry spline also added to the mushrooming of the stub end.


Stuff you already found on 850's. correct ?


out for now
lezesig
'72 850Sp
 
The spring sheared on mine.
Stuff you already found on 850's. correct ?

I have seen many broken springs, but never seen a hammered stub axle. :hmm:
Many times I see where one spring was lost and the remaining spring is cut in two for use on both axles.:dunce:
Lubricating the splines and using a rubber boot on the coupler is probably the most important maintenance area on the car. I've sheared many 600 axles from overpowered cars and lack of grease on the splines. Once the boots dry-up and fall off, all elements came in and probably caused you all this grief along with a broken spring :sad:
I always use Amsoil hi-impact grease to reduce hammering effects on coupler/axle splines and chaffing/rusting on the spring. I also use a rubber boot to keep the grease in and dirt out of the coupler.
Yes, the springs are a bit quirky and no improvement over the 600. But if you watch this area every few years they work okay. My cars just sit around most of the time and I have to replace the boots every 5 years or so since they dry-up and crack. At the same time, this gives me a chance to re-grease the splines and spring.

Here is an example of a boot that is probably factory original and managed to stay intact for 40 years. With todays cheap rubber (made in China?) coupling boots, I'm lucky if they last 5 years :eek:mg:
18211484066_23a7da467c_z.jpg



I found a Honda ATV CV joint boot made from silicon to use on early 600 TA's and fits without modifications. The boot in this picture is the outer CV boot from a GEO Metro which was cut to fit.
Maybe you or somebody knows of an outer boot replacement for 850's (same boot fits 600's) :cry: I've tried VW tierod end boots for fit, which is rather tight, but they are still made out of cheap rubber.
8683770249_8e78074c9b_z.jpg


Since your on a greasing quest :laugh:, Wonder if you can tell us how to grease the front kingpins so grease flows to the top and bottom bushing. What normally happens is all the grease starts flowing out under the top bushing and never gets to the bottom bushing.:hmm:
 
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Weird design

johnt,

In regards to turn knuckle design......

Constant pressurized flow system using a supply reservoir ?

(Because) that is what they must have thought with a design like this.

Grease flowing out the path of least resistance. This case...Top shim washer.

Hmmmmm...."so we will gunbore the pin to lube the bottom end and as a side measure we will spiral groove the pin to allow tandeum grease flow from above." "Yeah, that'll work."

Not enough space to zerk the bottom because of spring end either.

I guess constant lube and waste about 80% to get the 20% where it needs to go, huh. What's the interval....1500 miles ?

Thanks for taking the time to share the experience you have had with axles. You raise many important points.

Nope, I haven't found an outer boot optional. Like you have shown, I have suspected this boot to fail after very little service.


lezesig
'72 850Sp
 
You really nailed it :worship: :worship: Very weird design and grease LOVES taking the easy path.

Sometimes the top shim area is tight enough that I don't waste a tube of grease getting just a little to ooze out the bottom.

Below is a list of things I've discovered related to 850 kingpin assemblies. Some of this is better to do with the knuckle clamped in a bench vise instead of still mounted on the car....

Dried Grease. Some kingpins are stubborn to take on grease to the bottom bushing due to old dried up grease in the grease path. I have heated-up assemblies (propane torch) and run the same grease over and over through the assembly to clear-out old hard grease. Doesn't work that good.

Kingpin designs vary. Some have a hole all the way through the length of the pin and some don't. My thought is the kingpin style without a hole all the way through have only one way to grease the bottom bushing. They only have a 1/16" hole aimed directly and the bushing.
If the pin has a hole the whole length of the pin, grease can travel much easier to the bottom plug area and grease might have a chance of making it's way back UP into the bushing. Maybe even up to the bushing following those stupid spiral grooves. :laugh:

Sealing the upper shim. To exert more pressure past the top shim area I've tried several wraps around the shim area. Using various sizes of rope or vinyl covered electrical wire to wrap tightly around the shim provides some benefit sometimes. Usually you end up with a big mess of grease anyway :nuts:. Sometimes putting the weight of the car down on the kingpin assembly by allowing the bottom of the leaf spring to rest on a floor jack helps seal the shim better. Even turning the steering to different positions helps a bit sometimes.

Compressed air. While using the sealing trick above, I've used a rubber tipped blow gun to push some light fluid (WD40 etc) through the grease path to clear it out. After removing the grease zerk a rubber tip fits good and tight but it's still a struggle to keep the top shim from leaking.

Install a bottom bushing grease zerk. I've been thinking about drilling some place around the bottom bushing for a new zerk. Haven't got around to doing this yet. I was thinking about using smaller, low profile or button head zerks like what I listed below, but a standard style might work if you find the right spot:hmm2:

http://www.ebay.com/itm/1-4-28-Flush-Straight-Grease-Zerk-Nipple-Fitting-10-Pcs-/171521076894

These zerks require a special needle tip like this to grease them.
[ame="http://www.amazon.com/Lincoln-Lubrication-5803-Grease-Needle/dp/B0002SR6XE"]Amazon.com: Lincoln Lubrication 5803 Grease Needle Nozzle: Automotive[/ame]


1500 mile intervals
. That would be nice if we actually kept records. I kinda do try to record a few things like that, but I would just say grease them as often as possible to keep the grease flowing and soft. Of course, frequent greasing probably improves longevity of the bushings and takes up some slop/wear.
I don't like the job since it's so messy and hard to clean up all the grease that leaks out in the process.
 
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THANK YOU

johnt,

That info you just supplied is priceless. Thanks for taking the time to post !

After use data supports original design to paint the larger picture.

Here is a real-world element that fits somewhere on the curve.

Case in point:

850Spider.....several several thousand miles and zero maintenance. KingPin assembly not lubed ONCE. Presented no perceptible problem to the driver. Turn Knuckle assembly NOT inspected for wear so its ccondition was unknown.

It would be interesting to know how widespread and common cases like above 'were'.


lezesig
'72 850Sp
 
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