|
Post by dubfreak1 on Jun 28, 2013 18:00:04 GMT -5
Hi David! Got your phone message. The VW vacuum advance distributors work on the vacuum created by the air speed thru the carb rather than manifold vacuum. The port above the throttle plate is probably the correct one to use. I think you need to make an e-mail message to Air-cooled.net with the exact setups you've tried and the results. I have not used Webers myself, but got a 45mm Dellorto single to run quite well on my basically stock 1600. The key to making that run well was the accelerator pump spring and some washers between the accelerator pump arm and the adjusting nut. A lighter spring increased the amount of time that the pump was active when you hit the throttle and the washers increased the stroke of the pump for more volume. I don't know how fuel effiecient this was, however. Rudy
|
|
clintonddk
1600dp
Posts: 755
Joined: Oct 7, 2008 18:16:45 GMT -5
|
Post by clintonddk on Jun 28, 2013 18:46:40 GMT -5
I havent't played with to many vacuum advance dizzys but most dizzys are set to Idle some where between 7 to 10 degrees advance. When vacuum comes on under load it should increased to 28 to 30.
|
|
MadMike
1600dp
Posts: 3,277
Joined: Oct 30, 2008 10:21:12 GMT -5
|
Post by MadMike on Jun 29, 2013 7:22:03 GMT -5
SomeBody loan Dave a 009 or better yet a 010 or 019,,LOL ,I've never tried a vac dizzy on any of my dual Weber motors,Madmike
|
|
Ruffuss
1600dp
Posts: 2,795
Joined: Jun 25, 2008 19:13:16 GMT -5
|
Post by Ruffuss on Jun 29, 2013 16:15:59 GMT -5
I have one if he wants to try. New in the box, all I have to do is find it.
|
|
thatmacguy
1500sp
Posts: 171
Joined: Sept 23, 2008 16:33:34 GMT -5
|
Post by thatmacguy on Jun 29, 2013 21:13:13 GMT -5
Hey guys, thanks for the offer. I might take somebody up on that eventually. Tomorrow I'm going to try and resolve an intake manifold leak that's gotten worse over the past few days. It's possible that might be responsible for part of my problem. Although I had so many problems with manifold leaks that I've taken to testing it every day or two just to be sure, and I don't think I had a leak just a few days ago. But hey I hope that maybe I just had a leak that I for some reason didn't notice. Keep your fingers crossed for me. I also looked up a lot on ported versus manifold vacuum, and I do think there might be room there in the VW community for significant fuel economy benefits if we were to figure out how to use manifold vacuum Properly on these motors. Here is a link to an excellent write up that I saw. This started coming back to me as I remembered building a GM small block 350 way back when I was around 18 years old. Had to move that motor from ported vacuum to manifold vacuum In order to get it to run right. And went from if I remember correctly around 11 miles to the gallon to 14. I've never actually run a purely mechanical advance distributor because they have such a reputation for flat spots, and I generally use my car as daily drivers, and need good smooth street performance not just wide-open throttle. But on my Beetle it's always work perfectly. Just set it to the proper specs and away you go. Maybe it would be worth my time trying to go with a different distributor at least on a temporary basis and see what the results are. This is about Chevy motors, but theoretically the information about the benefits of manifold vacuum, as well as why ported vacuum even exist, should apply universally I would think. www.chevytalk.org/fusionbb/showtopic.php?tid/239321/
|
|
MadMike
1600dp
Posts: 3,277
Joined: Oct 30, 2008 10:21:12 GMT -5
|
Post by MadMike on Jun 30, 2013 7:13:36 GMT -5
Hey Dave,Don't use the stock tin intake gaskets they leak!! Fiber or none (Ananrobi Spelling?) Loctite 515 gasket eliminator sealant,I was going to get into Ported Vac VS. Manifold vac. but didn't want to type it all with one finger,LOL,Madmike
|
|
thatmacguy
1500sp
Posts: 171
Joined: Sept 23, 2008 16:33:34 GMT -5
|
Post by thatmacguy on Jul 4, 2013 10:58:23 GMT -5
Thanks for the tip about the gaskets. I didn't like those things either and ended up getting a different set based on your feedback. These seem like they will work much better. I sealed them with the Loctite anaerobic gasket maker also, and currently have a good seal. It didn't fix my problem though, so for now I'm just running rich to mask the lean-hole. Going to try and figure things out better next week after this weekend's autocross.
I may have to modify my emulsion tubes to bring in the mains sooner. Anyone done this?
|
|
|
Post by 81pumagtc on Jul 5, 2013 0:57:38 GMT -5
The anaerobic gasket maker will ultimately cause a problem...it is the wrong thing to use here. The expansion rates are just too great, and over time, they will separate from the alloy, and in doing so, will foul and destroy the gaskets.
This is the very reason Hylomar was developed by Rolls Royce for aircraft engines. The stuff never actually hardens, and act as a micro gasket for the actual gasket. There is just too much expansion and contraction between the hot metal parts, and the cooling air flowing through the manifolds. This is one of the reasons you are having this problem.
MadMike is correct, and you should use a fiber gasket, which will provide better sealing, but Hylomar will provide a much better sealant. Remember, the term anaerobic sealer means that it will "harden" or cure even in the absence of air. It can still seal with intake bolts that are slightly tighter than finger tight.
Good luck with modifying the emulsion tubes. It seems that your options are getting to be fewer and fewer, but I have yet to read about anyone ever getting their cabs set up to their liking in all situations. Carburetors simply don't work that way. Changing the throttle opening increase or decreases the amount of air moving through the carbs, and these changes are exacerbated by temperature, humidity, altitude. Throw in acceleration and deceleration's effects on fuel bowl levels, and how that makes carburetors work differently. Even octane differences make a difference in how the carbs work across the range.
Modern fuel injection is the single greatest reason that cars get the mileage they do, and they get the performance they today.
If there was a simple solution to the problem, Weber would already be doing this.
If getting the best performance from the 912 is paramount, you will have to go out and find the pieces to make your fuel injection right.
If you want to use the carbs, get it set up the way that works well with your driving style and driving type.
Use your fuel/air mixture gauge as a guide to set the carbs up, but remember, the seat of your pants will be your best tool setting up the carbs. Once you have it set up to your liking, remove the the mixture sensor.
If originality is not an issue, there are modern fuel injection systems available that you can use, that are designed for cars that have engines that are more sophisticated and make more horsepower than your air-cooled Porsche flat four. Remember, however, that mapping a third-party FI system can be a nightmare to. Clinton has been working on his for a fair amount of time...
Dave
|
|
clintonddk
1600dp
Posts: 755
Joined: Oct 7, 2008 18:16:45 GMT -5
|
Post by clintonddk on Jul 5, 2013 7:57:15 GMT -5
Dave, my delay real isn't a mapping issue, they have software for that. It's more of a pocket book issue, or lack of. There are several good kits on the market right now but I am to cheap to buy one and would rather build my own so, I am a victim of my own demise. I had original started with an old CB kit from what I understood the previous own never got to run right and I don't why I was thinking I could LOL. I have since, built my own MS2 and rebuilt the intake system www.diyautotune.com. If I was to purchase a kit that was already R&D I would look into one of Mario's kits at thedubshop.net/.
|
|
|
Post by 81pumagtc on Jul 5, 2013 10:33:21 GMT -5
Clinton:
Oh, I remember the Megasquirt experiments, etc. My point is that even for people who have forgotten more about ultra-high performance VW engines (like you) than I will ever know, it's hard work, and expensive to boot.
The really nice systems are wonderful, but expensive, and unless you modify the engine extensively, pretty much overkill. Since the 912 is basically a two-liter engine, and has 98 horsepower for 2300 lbs, it is probably not money well spent.
One of the Puma guys has a Jake Raby built type IV for his Puma coupe, along with a five speed, but the package costs more than I think I might pay for a complete nice Puma. He is still trying to get it sorted out.
I hope to see your Bug making a few passes down the strip this year!
Fall Bug Run?
Dave
|
|
clintonddk
1600dp
Posts: 755
Joined: Oct 7, 2008 18:16:45 GMT -5
|
Post by clintonddk on Jul 5, 2013 22:03:06 GMT -5
I hope to make some passes this year. Ononadaga drag way is soppose to open this summer. I want to make the bug run too but it might conflick with a prior agangement.
|
|
thatmacguy
1500sp
Posts: 171
Joined: Sept 23, 2008 16:33:34 GMT -5
|
Post by thatmacguy on Jul 22, 2013 11:17:00 GMT -5
I still haven't resolved this issue, I've simply run out of time to work on it currently and am just running rich across the board to keep the lean-hole rich enough that I don't get a stumble. I will come back to it though.
I'm going to track down the "Hylomar" and give it a try. Never heard of it before... So it is essentially a gasket-maker/sealer that never fully hardens?
|
|
|
Post by 81pumagtc on Jul 22, 2013 23:54:08 GMT -5
Try Hylomar.com. Here is a link: www.hylomar.co.uk/index.php?option=com_content&view=article&id=62&Itemid=70Here is a link for Hylomar Universal Blue. I usually coat both sides of the gasket material, and assemble per instructions and torque. It has always worked well for me, and I have personally been using it under various names for more than 20 years, and I loved it for the SAAB two-stroke 3 cal, and V-4's. Cool stuff. Dave
|
|
MadMike
1600dp
Posts: 3,277
Joined: Oct 30, 2008 10:21:12 GMT -5
|
Post by MadMike on Jul 23, 2013 7:59:39 GMT -5
Back when I had a MC Dealership I could get Yamabond cheap,now days I use Locktite 'Moto seal' sold at Auto Value stores, semi harding,seals oil,gas, water and air,VW case halves,drain plates, pump gaskets,VC's ect.
|
|
dansam
1600dp
Posts: 2,434
Joined: Oct 25, 2008 7:23:39 GMT -5
|
Post by dansam on Aug 16, 2013 13:34:40 GMT -5
Fun stuff to read. My Idf's I ended up putting those "majik" fix vent tubes that cb makes and they seem to make it so I dont have to clean the jets all that much anymore. As for tuning, 3.5 psi is the best pressure Ive found. As for timing, I ended up going MSD with a locked out advance (always full advance) with an automatic 10 degree retard under 800rpm (to start the thing) then its full advance. It seems to like that.
|
|