hesitating beauty - 1966 912

[badamack]

I pulled my 66 912 out of long term storage recently cleaned her up a bit. checked oil and changed battery. cleaned up points, cap, and rotor and she started up and ran pretty good.

But...

on the shakedown cruise i noticed significant hesitation on partial throttle but good running and acceleration when it is more open.

sounds like a carb / jetting issue right?
but, i remember having this problem before with different carburators.
could it be distributor / timing?

i'm running dual weber 40s (previous were dellorto 45s.
1750 big bore kit.
050 distributor
bursch exhaust.

where would you go next?
can you point me to any good writeups here on carb tuning and timing?

Thanks in advance for the help!

Why did you replace the Dellorto's for the Webers. Jetting could certainly play a role in the bad performance - current jetting? - also a 050 VW-distributor is not the best choice for a 912 engine. You will need a 022 or 031 providing the correct advance curve - 32 degr. at 3500 rpm. Did the engine run fine before you pulled/stored it?

I hope you also changed oil, replaced the oil filter and did a valve job. Did you?

Tell us some more and we might be able to help you further.

BTW The search function here on the board is very helpfull...

Otto

[Jaems]

As Otto has said you will need to change the Distributor to a 022, 031 or the Benton RS0012. They will have the correct curve for your engine.

The Webers, unless you have already change them must have the 32 vent. The Webers are generally sold as for VW bug engines. They will have the 28 vent. Which will choke the engine too much. Also depending where you live in altitude (seashore, mountains). The jetting, corrections and etc. will most likely need to be changed. Once the Webers are properly sorted out with the right distributor there will be no hesitation.

[badamack]

i bought the webers from a seller in italy. supposedly set up for the 912. i dont know the jetting. how do i check.

it ran about like this when i put it away.

can the 050 be made to work or is a distributor change a must?
among the distributor choices: which is preferred and why?

thanks!
Adam.

[Jaems]

For the best performance the Distributor change is a most. One of the three mention is your only option.

The 050 was used as a cheap replacement, back in the 80's, when the 022 was getting too old and needed rebuilding. The advance curve is not right for a 912 or Porsche engine. The best ones were made in Germany. Then Bosh out sourced it South American and then to China. The 050 will get you by. However, you will notice the difference with one of the recommended distributors.

I doubt that the Webers, originally, were setup for the 912. Just check the venturi's and see if they are 32's or 28's. 28's will mean that they are setup for VW bug engines not 912. If they are 32's then someone may have set them up for the 912/356 engine. Then it is just the air correction, emulsion tubes, main jets ant etc. The Weber setups have been gone over here and at the 912BBS extensively. You will just have to do a search for the setups.

[apriliaguy]

Webers are a bit finicky to sync. I would try that first. Make sure you unhook your linkage. Or you'll never get it right. And turn screws slowly and pause for a few seconds. Hope this helps you. 912 bbs has some good posts on this

I don't want to be unkind, but it is impossible to get the engine running properly without knowing what the condition of the enige is (compression, leak down), without using the right components, like a suitable ignition in good condition. Then do a valve job, give her some fresh juice and and filter. Run the engine, adjust the ignition and last but not least, adjust the carbs. With the engine stored for some years, drive it a 100 miles after the first adjustments and check/readjust all the settings.

If you do not work in this sequence, you will never get the engine run as it should/could - unless you are one of these guys who always win the jackpot when gambling.

Yes, there are some people who are able to rebuild a 050 to a usable advance curve for your engine, but what you will pay for such a "transformation" is better spent on a maintanance free electronic version or a professionally rebuild 022/031.

Sorry, but this is what I think the only way it should be done.

Otto

[badamack]

no apology necessary Otto. thanks!
that's about what i was thinking.

so, i started with the valve adjustment. Everything was good except #4 was a bit tight so i adjusted.

then, i pulled the plugs. cleaned and gapped the 3 i could get out. They looked pretty good. i worked and worked at #3 but could not get it out! any recommendations there? i think the sheetmetal and the weber intake manifold make it near impossible. do i need to remove the intake manifold to get the darn spark plug out?!

meanwhile, i'll obtain a compression tester and test the compression.

after i do the 4th plug i plan to check and adjust the timing with a timing light.

then, i'll go after the carbs starting with making sure there are no leaks at either of the intake manifold gaskets...

any help with the plug would be appreciated.
it i can't get the plug out to service/replace it i surely cannot get the compression tester in there...

thanks again!
Adam.

Hi Adam,

That's the way to do it!

There are (at least) two types of manifolds sold for the Weber IDF carbs. One is a bit wider than the other. For the wider type the engine tin around the manifold has to be adapted - read cut - to fit around it. This setup makes makes it very hard to take the plugs out. I know, because one of my 912's has this handicap.

For the plugs I use a socket with a thin extension bar. The socket should be just long enough to fit over the plug. The thin bar enables me to guide the socket correctly on the plug. Then just loosen the plug. To turn it out of the thread and take it out the "cavity" I push a piece of tight fitting rubber hose (appr. 10") over the ceramic neck of the plug. The plug can be turned out - and in - quite easily, without the risk that is disappears somewhere under the engine tin. If you don't have the proper socket, try to get one or modify one for this purpose.

Try to get a leak down tester. It will give you some quite reliable basic information regarding valve leakage and/or possible leaking/worn piston rings.

And don't forget to look for one of the reccommended distributors...

Keep posting the results and don't hesitate to ask for more info.

Otto

[apriliaguy]

I'm sorry Otto. I was assuming his valves and timing were in check. I know my webers were a pain to get in sync correctly.

[Jaems]

Some folks like the 944 spark plug tool for removal of the plugs. I know that the original 66 912 spark plug tool work fine with my Weber manifold. However, I may have the smaller Weber manifolds. My Webers have been on the engine for over 40 years.

If the Webers are in good shape. They are just as easy to tune as any other of the carburetors. You will need Webers Sync tool. The Unisync will work but the Webers is more actuate.

I start with cylinder #1 With the engine warm and running and the linkage disconnected. Turn the idle mixture screw gently all the way in and then turn it out for two turns. Set the weber sync (WS) and read the meter. Then go to number #2 Cylinder and turn the idle mixture screw all the way in and then turn it out 2 compete turns and read the WS meter if different than #1 then adjust the Idle mixture screw in or out until the meter read the same as number #1. Then do the same for #3 and number #4 rev the engine a little to reset the carbs and then check # 1 again and then the other cylinder and if they still read the same on the WS meter then the sync it done. If not, then readjust which cylinder that may be out rev the engine again and check them again. Then all you need to do is adjust the idle and adjust the linkage to fit and reconnect. Again this is the way that I do it and it works for me.

Remember the more worn the carburetors are the harder they are to get to sync. If the carburetors are new or rebuilt with new parts. It will take less that 5 minutes to sync. Also once adjusted they will last for thousands of mile. In the last 10 years I have only adjusted my idle once. This was because my State went to 10% alcohol and my idle dropped.

@apriliaguy

Please don't apologize. It was just that I wanted to create some logical order in the discussion and our help for Adam. Sometimes I'm just a bit too quickly too much to the point. With 5000 air miles between us there will be some culturaI difference causing my reaction.

Back to the 912 engine. I agree with you that adjusting Webers and other multiple carbs on an engine in general, are a PITA. As I wrote before, sometimes you are a lucky winner and you are done within half an hour.

Basic setting, like Jaems described, is done in minutes and can give a good basic performance on a rebuild engine or an engine with not too many miles. But to really fine tune it, temperature, altitude, engine condition (1800 cc p/c, Adam's), ignition timing and many other parameters have to be considered with. For me, after 15 years experience with these engines - honestly, I realize I still have to learn a lot - even my ears are used to fine tune the engines. And each time I know it could have been done a bit better. I think it's part of the basic fun of these unique Porsche engines. Only driving it gives a bigger smile...

Otto

[badamack]

sincere thanks.
this is all very helpful.
i'll keep you posted.

for now:
the carbs are in very good rebuilt condition.
it is possible that they got dirty while parked and failed, but, i doubt that is the problem.

i'm shopping for a good dizzy.

i'm fairly confident in the head rebuild i had done though this could be bad too.

i used, well, not the best pistons and cylinders. I can certainly imagine a case where a piston ring stuck and is causing a problem. if the compression and leakdown tests bear this out i'll pull the engine and invest better this time in pistons and cylinders. i think i have some original 912 cylinders. i've heard they are good to bore out and use with good quality oversized (forged?) pistons. but i don't want to go there unless i have to...

thanks again!
Adam.

[badamack]

I unpacked a bunch of old parts today and found some good stuff.
Including a BR18 distributor.
How can I tell if it is in good usable condition without sending it to one of those high buck rebuilder/restorer types?

[badamack]

here are a few pics.

https://mail.google.com/mail/ca/u/0/?ui=2&ik=5c9f5934c5&view=att&th=13ef8751db858cf9&attid=0.1&disp=thd&realattid=1436514553762414592-local0&zw

https://mail.google.com/mail/ca/u/0/?ui=2&ik=5c9f5934c5&view=att&th=13ef874fbefe985b&attid=0.1&disp=thd&realattid=1436514540656263168-local0&zw

Hi Adam,

Please post your pics here, so everyone can see them.

The BR18 is a very nice - and wanted - early 912/356 distributor and should fit perfectly to your engine.

Well, the best way to test is a Bosch testing box for these distributors, but you could put it in the engine and run it. With few degr. advance at idle and around 32 degr. at 3500 rpm it should be fine. Of course these are just two points of the curve, but enough for a basic indication of good/bad.

If it fails at its first test, take it apart, clean it and reassemble it with some fresh grease. After many years of storage the old grease gets dry and hard. I'm not sure about the availability of parts or complete rebuild kits for it.

I hope the BR18 is in good condition. It would be a giant improvement for your engine!

Otto

[badamack]

if you could not open the other links, maybe this will work.

Hi Adam,

I think that pictures should be integrated in the post and not on an external link. For linking to specific galleries with many pics it can be done, but for reading threads where readers need the viasual info immediately it's not reccommended. So, next step in posting pictures is resizing them to something like 800x600 pixels and with sufficient compression to make the file uploadable.

It looks like you have a great find with this original BR18 which perhaps only needs some cleaning. I would spend the energy on this one to get it in good shape for your 912.

I hope you can make some progress this weekend.

Otto

[badamack]

me too! thanks again for the input.

couple more questions:

1.) how would you go about cleaning this distributor?
i've found a local guy who can rebuild it, but, if it's not necessary i'll save the $200+

2.) is there any way to 'measure' the cam grind with the cam in the car?
i really wish i knew what i had. something tells me this 'hot' cam grind could be contributing to my low end drive-ability issues as well...

adam.

[Jaems]

The BR18 was used on the 356A- early 1963 356C/SC then replaced later with the 022. When in good shape the BR18 should have a very close curve to the 022 or 031.

This place (not recommending) you might it check out. If you live in the states. They sale rebuilt and also rebuild Bosch carburetors:

VINTAGE WERKS
521 North 1200 West,
Salt Lake City, Utah 84116