new member, first post, progressive carb issue

[ringomobile]

my daughter's 71 super baja, has a holley 5200 style carb
main jet 76, primary and secondary 132, mechanical CHROMED fuel pump (lol) and elctronic ignition
it idles kinda ok, goes up and down a bit, but when you give a little throttle, it revs way up and takes its time coming down. its like a very bad vaccuum leak.
anybody come across this before?
its kinda dangerous for her the way it is
how do you post pictures here?

[Glenn]

How to make a progressive work properly on a VW engine.

How to post photos/How to post a photo in the Forums
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

עַם יִשְׂרָאֵל חַי

[mark tucker]

does it need a return spring?a vacume addvance dist?

[ringomobile]

just mechanical advance (that also raises some concerns) and yes it has a nice throttle return spring, it just acts like it does not.
and get this: when I put my hand over the carb it will gain like 1000rpm

[modok]

Welcome
If you are new to the site you may not be aware......
The 5200 on a 1600 is regarded as a total POS by some, well, the majority probably. It is a terrible setup, really.

As a representative of this group, I recommend you replace the entire induction system, and see if that fixes it.
There is nothing specific about that setup that would cause the problem, just the usual vac leaks, busted gaskets and diaphragms, distributor not advancing correctly, carb adjusted way wrong....... but if your gonna unbolt that carb I vote you leave it that way, for the sake of mankind

[ringomobile]

the more I read here i find what you are saying is true, is the set up below any better? its the one i took off a couple weeks ago

[modok]

ah, that is the mysterious dual progressive.

In theory the dual progressive could work well, but I can't claim to ever have seen it work.
They are rare enough that I don't know of where you would get any info on them

Can you replace your single carb with one of the ones from the dual set?
I think maybe the bolt pattern is the same, and the size of the carb more suited to a small cc engine

[ringomobile]

This IS my setup like 2 weeks ago, but i couldn't get it running and so i had the carbs rebuilt. While they were out, I figured one carb would be half the headache, so I put together a single holley setup and bolted ONE of the two to it and here I am.
I can be back at the above in a few hours, but is it worth it? or should I start fresh when my pocket book can float it
thanks for the help btw

[modok]

Now I'm a little confused
The dual progressive kits sold by CB used a smaller carb, not the 5200

The 5200 has numbers cast onto the outside, outside where the venturies are, should be 26, and 27, this is the size of the venturies.
What do your say?

One way or the other, it will take some amount of jet changing to switch it from running dual to single, if it was ever close to right to begin with. Either way would be some DIY stuff.

I think the ideal single progressive setup would be a carb one size smaller than the 5200, on top of a manifold that has the heat passages that go "up the back", if your gonna do it that's got some potential.
Then again you may be able to trade the dual setup for some kadrons, it would be a fair trade IMO, your call

[mark tucker]

get your timing light out and see if it is the timing that is lazy in coming back down.it might need some cleaning or some synthetic oil driped down the center of the dist shaft to lube up the addvance/camshaft thingamajiggy.the weights rarely get stuck but if somebody used a junk greezzee that may get hard & sticky too.breakleen&some other form of spray lube down in there may also help free it up.

[BFB]

i created a post about dual progressives the other day , modok replied with a link to this post and a couple others. thanks modok!
for some reason the thread was locked and i couldnt even reply to say thanks, pm'ed mod and glenn told me to reply to one of these linked posts. not sure why im supposed to resurrect an old thread??? he never gave me an answer...
really seems like some STF stuff to me.
regardless, thanks again modok, and id sure like to hear from ppl that have run this set up and how it worked, what size engine etc etc

[modok]

The moderator thought that you were asking a question that gets asked all the time, which happens a lot. That's how it looked.

Actually it does get "asked" a lot, but very few guys actually are running this old setup, i just remembered a few and found them with the search.

Yes I too would be interested to hear the specifics, of what carburetor, how it was jetted, and how it ran on a what kind of engine, but they didn't say much.

on the one hand, in basic theory, there is no logical reason to have dual progressive carburetors, HOWEVER, on the other hand there is no reason it would not work. The design is sound, float bowls forward, the position of the throttles is good for wet flow, so it may actually perform nicely.

[oprn]

The logical reason behind it in my mind is the same for the dual progressives as it is for the single progressive or progressive throttle body 2 or 4 barrel carb or FI.

Better drivability.

This is how Porsche handled it on the 944 with a single butterfly throttle body. It gives a similar a action and peddle feel. Our Subaru is a single butterfly TB without this feature and is touchy as heck on the first 1/4 of the throttle travel which is where you drive the most.


I have tossed around the idea of getting a pair of these and going to cable controls on my Webers.

[modok]

The "formula" for throttle body size is easy.
Same size as what is in front of and after it.
Think about that way and you will understand.

[oprn]

Sizing is not what I am referring to Modoc, it's flow rate linearity or the lack of it as the throttle opens. That is where drivability comes into the picture. If you are a 1/4 mile guy or drive your car like you stole it all the time on dry roads then you will have no idea what I am talking about and no need for a linear throttle response.

I just came in from driving for 2 hours on snow covered roads in freezing rain and am so glad it was in the 944. That would have been a nightmare trip in the Subaru but instead was a mild inconvenience in the Porsche.

[modok]

it is the plenum and runner volume, that requires a large throttle size, that causes the non linearity which needs to be solved, so, no big volume, no problem to solve.

The closer you put the throttle to the head, the smaller it can be, because it is the same size as the passage.
The sizes of the passages and design of the pipes is the same no matter where you put the throttle. If you take the porsche intake and put the throttles 4" from the head, how big are they now? And how does it drive

[oprn]

Yes I follow! Where I am coming from is valve flow theory. A butterfly valve flows approximately 75 - 80% of it's total capacity in the first 20% of opening. Very non linear.

A small primary with the extra flow capacity handled by the secondary is one way to linearize that imbalance in flow.

[modok]

Yes, that's true, but I'd say with the throttles close to the head it can also be done with the linkage, for air flow.
But......far as wet flow I think this might be kinda smart. Both throttles are directing the majority of the fuel towards the center.......should be good?
How the throttle plate directs fuel actually does make a difference, although rarely discussed.

Kadrons, one throttle is the right way, the other goes the wrong way, not so smart after all. Not a HUGE problem, but it does make a difference.

[oprn]

[modok]

Possibly, yes, although idle/transfer is not as critical.
Think about where the acc pump stream goes.
I bet the optimum setting for that is not the same both sides.

And it's the same deal with the main system at part throttle, most of the fuel hits the throttle and ends up going out just one side.
partly the need for an acc pump is that a lot of the fuel gets hung up on the manifold walls initially, but the more you can direct the fuel straight to the head without hitting the walls, the less need for acc pump.