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Original Okrasa engine stumbling, hesitation on acceleration.
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evanfrucht
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PostPosted: Fri Jul 23, 2021 7:42 pm    Post subject: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Hi I'm helping out a neighbor who just acquired a clean and recently restored '57 rag top with an original Okrasa engine. The carbs are real solex, etc. Has the original style linkage. Has a Bosch 010.

Among other smaller issues, the car is very annoying to drive to the point where its almost undrivable. It wants to stall going into first and sometimes second because it's kinda sputtering and missing for a sec. I'm able to keep it running and can drive around semi reasonably but it's not right. Once you get past 2000 or so rpms it smooths out to what I'd say is normal. Problem is very noticable during off idle acceleration.

I did a few things initially... After changing the points, condenser, setting the timing it ran better but barely. Then I started to look at the carbs. I noticed one of the accel pumps was not coming on as quick as the other one, so I adjusted those nuts a good bit tighter so that it would start to squirt right as the linkage moved, matching the other one. That seemed to make it better but the issue is still apparent.

Questions are.

I notice only one of the two carbs has what seems to be a choke, the other one doesn't. I'm assuming that is normal?

What is the accelerator pump shot spec for these carbs? I'm trying to get it in the ballpark here.

Do these carbs have any specific problems associated with them I should be aware of.

Part of me kinda suspects the linkage but it does seems to be in sync basically...

Any ideas?
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evanfrucht
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PostPosted: Sat Jul 24, 2021 11:10 am    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

After looking more carefully at his distributor and comparing it my old 010 core that I have it seems that his advance mechanism inside the distibutor is very loose and possibly broken. The distributor looks well used in general. The shaft isn't loose but the lobes on the shaft have some very minor but visible wear.

I'm not that familiar with the 010 so I didn't realize that the advance might be bad until I started fiddling with my old one and found the mechanism doesn't flop around like his does.

I'm thinking now that maybe its advancing way to early or erratically until the full advance comes on. It seems to match the symptoms of needing to really step on it off idle to be able to drive it

Anyone ever run into an issue like this. Do these distributors fail like this? I can see two non broken springs in there, but these other weight things seems to be loose. No loose parts inside. Just rotating the rotor while holding the bottom of the shaft it will easily rotate and rattle the weights, which kinda swing out if that makes sense. My old 010 is not like that, but I don't know what is normal, as mine was purchased as a core...

His engine was responding to timing changes (seemingly normally) at idle which is also weird tho?
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PostPosted: Sat Jul 24, 2021 1:04 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

sync the carbs with the linkage disconnected, then make sure the carbs open and close the same with the linkage connected. There should be a balance pipe between the two as well.

swap in a known good 009? thats my go to for a quick diagnosis. I've taken them out of my car and put in a friends - when their car starts running perfect all of a sudden, you have it figured out...
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tasb
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PostPosted: Sat Jul 24, 2021 1:45 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

see your first topic on this issue:

https://www.thesamba.com/vw/forum/viewtopic.php?t=757322&highlight=distributor
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evanfrucht
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PostPosted: Sat Jul 24, 2021 2:29 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

tasb wrote:
see your first topic on this issue:

https://www.thesamba.com/vw/forum/viewtopic.php?t=757322&highlight=distributor

Thanks for the link to that.

I started this thread as a general troubleshooting thread but didn't get any response for a while. Then the 010 became highly suspect so I made a post in the perfomance section where that specific distributor might be more relevant.
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PostPosted: Sat Jul 24, 2021 2:30 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Erik G wrote:
sync the carbs with the linkage disconnected, then make sure the carbs open and close the same with the linkage connected. There should be a balance pipe between the two as well.

swap in a known good 009? thats my go to for a quick diagnosis. I've taken them out of my car and put in a friends - when their car starts running perfect all of a sudden, you have it figured out...

Yep. That's most likely in order. The ol' swap from my car to his... see what she does.
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PostPosted: Sat Jul 24, 2021 2:40 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

The original PBIC-32 Solex's on the Porsche 356's had too large of venturi's for a 36 horse engine. If the venturi's are 26's or was it 28's then that could be part of the problem. Probably want 24mm for a Stock VW 64mm Bore X 77mm Stroke engine if that is even what is in it. If it has an auxiliary venturi that would be ok.
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PostPosted: Mon Sep 20, 2021 4:13 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Working on the carbs now. The do have 26mm venturis. They also had a lot of debris in the float bowl but I did not physically find a clogged anywhere. Fingers crossed that was the issue... wondering what else to check for.

Can't find any good info on setting/checking float level for these carbs. ( Dual Solex 32 PBIC )

Looking into the history on this car Mr. Okrasa has sent me email confirmation that he did rebuild these carbs back in 2013 for the previous owner. I'm hesitant to change jetting and stuff due to that.
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PostPosted: Sat Sep 25, 2021 10:36 am    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Ok, so I figured out the issue. IT WAS A DIRTY CARB which was possibly setup wrong (someone put a very thick stack of 4 gaskets under the float needle on one carb which was almost 1/4" thick.) I cleaned the carb and bench adjusted it, got them set up on the car, and took it for a drive. The difference was night and day. THE CAR CAN NOW ACCELERATE FROM A STOP OR CHANGE GEARS WITHOUT MISSING AND SPUTTERING, NOW I CAN FEATHER AWAY FROM A STOP BY GENTLY PUSHING THE ACCELERATOR. BEFORE IT NEEDED TO BE REVVED UP HIGH JUST TO TAKE OFF WITHOUT STALLING. It has good torque off idle now.

So, it's basically fixed BUT I feel like the engine could use a little more fine tuning as a very slight "flat spot" remains at around 2000 RPM, maybe just under. It's not really noticeable unless you accelerate hard. The torque/power is good up to then and then after but it kinda hesitates or something before the main kicks in (I'm thinking.)

I'm used to driving a later bigger hotter engine with dual DRLA 45's... so maybe I'm expecting too much or comparing apples to oranges? But part of thinks it could just be a hair better. Please enlighten me.

Where do you guys like to set the throttle plates and stops in relation to the progression holes?
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PostPosted: Sat Sep 25, 2021 11:52 am    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Are the accelerator pumps squirting through out the whole stroke to WOT? A flat spot usually means it wants more gas. I use the drinking straw method to sinc. the linkage, Hold a straw on each carbs butterfly lightly and have a helper slowly press the gas peddle, adjust linkage until both carbs open at the same moment.
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PostPosted: Sat Sep 25, 2021 12:07 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Starbucket wrote:
Are the accelerator pumps squirting through out the whole stroke to WOT? A flat spot usually means it wants more gas. I use the drinking straw method to sinc. the linkage, Hold a straw on each carbs butterfly lightly and have a helper slowly press the gas peddle, adjust linkage until both carbs open at the same moment.


Yes both ACC pumps are putting out a long duration shot throughout most of the travel. I've done the basic carb setup. I have the linkage setup so carbs open at the same moment and equally, but I need an adapter for my snail tool so I haven't been able to properly sync them, but they are close. I set the throttle plate stop screws so that the butterfly just completely covered the first progression hole. I don't know if they should be more covered or if I should expose half the first progression hole (these are the kind of things I'm wondering, for example) I feel like the transition into the main circuit is not happening fast enough... that is my hunch.

All I have to go on is a couple outdated Solex manuals from the 60's which are not detailed. I am fairly experienced working on and rebuilding carbs, but have never worked on this specific type... so I'm basically just trial and error tuning at this point.
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PostPosted: Sat Sep 25, 2021 1:18 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

You can make an adaptor out of stiff cardboard (like a shoe box) to fit over the top of carb. Dual carbs don't need a choke because they are so close to the heads so I wonder whats up with that. Check the throttle shafts for looseness, if they leak air there tuning will be next to impossable.
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PostPosted: Sat Sep 25, 2021 1:33 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

I have an old manual and it says the accelerator pump stream should hit the venturi wall at the point the buttery fly opens, it's says CRITICAL. What's the model# of the carbs this manual has all the specs for old Porsche Solex carbs.
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PostPosted: Sat Sep 25, 2021 1:52 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

When cleaning and rebuilding the carbs I found the choke was blocked off by a gasket so I just remade that block off gasket. Basically the choke is there for show but it doesn't do anything. Not sure why but it's an original Okrasa kit so I'm not trying to change stuff like that. The kit seems to use the choke as a mount for a linkage return spring also.

The ACC pump seems to be working well. I'm not sure if the stream of fuel literally hits the venturi. I recall the stream of fuel is directed more downwards, down the carb throat/ intake manifold. BUT yes it happens instantly when you crack the throttle. The acceleration is actually good.

The only real minor nitpicky "issue" currently is that the power curve isn't very even. There seems to be an extremely slight dip in power around 2000 rpms but then it picks right back up. Also right up to that point the acceleration is good with nice off idle torque and response.
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PostPosted: Sat Sep 25, 2021 2:35 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

PBIC-32/ main jet=112.5/ air corrector=200/ idle piolet jet=50/ idle air bleed=1.5/ float Gr=5.7/ fuel level=25/32"/ accelerator pump jet=Gp60/ nozzle high=0.8/ injection quantity Cc=0.5-0.7 (adjust by adding washers if needed). You can make a catch bottle with a eye dropper glass tube, just melt the small opening with a torch or plug with epoxy then wrap it with soft copper wire around the neck flange leaving a "tail" to hold it under accelerator jet tube to catch the stream and pore it in a graduated vial. The gas streem should hit the opening where the butterfly opens downward.
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PostPosted: Tue Nov 22, 2022 2:06 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

on the okrasa kit carbs 32pbic, the accelerator pump adjustment, does turning the nut in increase or decrease the squirt?
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PostPosted: Tue Nov 22, 2022 4:09 pm    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

Turn the nut in to increase and add washers if more is needed.
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PostPosted: Fri Nov 25, 2022 8:13 am    Post subject: Re: Original Okrasa engine stumbling, hesitation on acceleration. Reply with quote

As for the hesitation. give it 2-3 degrees more advance and see if that cures it. If it does you can change the curve afterwards. Remeber, these engines like relatively much advance
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