I am soooooo happy...., Niggling problem found and fixed Options

[porsche735]

So, after 7 years of blowing up pistons and mis-diagnosis, we have finally figured out what our problem was. (IMG:style_emoticons/default/mueba.gif) We found that even though our distributor was rebuilt and the curve tested, all that was tested was the mechanical advance. Our vacuum advance/retard canister turned out to have a leak on the retard side. This caused us to have about 40 degrees advance at points. Seems we should see about 33-35 total advance maximum (duh 27 adv with disconnect plus the 8 degrees of vacuum advance..http://www.dgi.net/914/tech/distrib.html). We are getting the new part this morning to cure this once and for all.
It has been very expensive over the years with the multiple rebuilds we have gone through (a few thousand). All for a $95 part.
One question I still have is about these A1 cardone remanufactured distributors. I got mine rebuilt by a shop and am buying a new vacuum canister. It seems like you could use this:
http://www.partsamerica.com/PartDetails.as...ype=218&PTSet=A

All I have found is the one for a 1.7L, but it seem sto come with the vacuum canister AND trigger points (same as 2.0L) for $51.99 plus $1 core at my local Kragen. This sounds too good to be true as the trigger points and canister are each about $100. Obviously, the canister is probably used, but tested to spec... but gosh...

Has anyone gone this route? You would have to throw away the distributor on the 2 liter cars, but seems worth it if you need either of the other parts. Are the trigger points new?

Anyone with first hand knowledge of this?

Chris

[Brad Roberts]

I'm betting its all used.

This has to be an all time favorite on our BBS. I *thought* I had heard/seen just about everything. I have NEVER heard of this type of failure. Of course... one dyno pull would have pointed out the excessive advance.. but damn that is CRAZY stuff.

Cool.. when is the next PCA TT ?? I would like to attend and watch..


B

[porsche735]

We are in Laguna Seca this weekend at Cherry's Jubilee. So, anyone out there that has not been on the track in a prepared Porsche (914 or otherwise) and $25 to spare can get 3 hot laps! It's for charity, so you can actually even write it off...
The next TT is October 18-19 at Thunderhill...

I really can't wait to just drive the car and not have to worry about it or fix it all the time.... It will be a pleasure.....

This time, EVERYTHING was done right. Also, not even one drop of oil after breaking it in for 2 hours.... I now swear by the Permatex Teflon Threadsealer....

Chris

[Demick]

I don't understand how a leak in the advance/retard canister can cause excessive advance. A leak on the advance side will cause less than expected advance. A leak on the retard side will cause less than expected retard. But as far as I understand, vacuum on the retard line only happens when the throttle is closed (when there is no vacuum on the advance side anyway), so usually a leak on the retard side simply causes high idle (and possible high emissions problems). Can you explain how you get double the vacuum advance when there is a leak in the advance/retard diaphram?

Demick

[Rockaria]

Okay time to give everyone my Stats since I have the EXCACT same problem and seem to not be geting a good answer. I have a stock 1975 1.8 with L-Jet FI. I am at 4,000 feet above sea level. Car runs hot with vac advance hooked up. It runs 15 degrees cooler with avance unhooked and plugged. I also get more manifold vacuum of the plemum at idle if I take off and plug the vac retard source (retard Leak? I think so...).

In the driveway I find these reading from the Vacuum source plugs:
----------------------------------------------------------------------
Manifold side: ( I am going to recheck these numbers)
RPM --vac inHg
850 -- 10
1500 -- 0
2500 -- 0
over 3 -- 0
----------------------------------------------------------------------
----------------------------------------------------------------------
Ported side:
RPM -- vac Hgin
850 -- 0
1500 -- 3
2500 -- 8
3000 --12
4000 -- 19
----------------------------------------------------------------------

Right now with the Vacuum disconected and plugged Here are my findings:
----------------------------------------------------------------------
Without Vac advace or retard hooked up
RPM --Timing
850 --Adv 7.5
1500 --Adv 17.4
2500 --Adv 29.0
over 3g --Adv never more than 32
----------------------------------------------------------------------
----------------------------------------------------------------------
With Vac Advance and retard hoked up
RPM --Timing
850 --Adv 3.0
1500 --Adv 22.1
2500 --Adv 37.8
over 3g --Adv gets near/over 42
----------------------------------------------------------------------

So I say What the F__K. I am having the canisters tested this afternoon and will reply. For now I have just disconected the advace and plugged it. The car seems a bit less spunky!

Any thoughts, Does this help, Anyone else have these numbers?

[porsche735]

Actually what you need to do is put the car under load. You can test this by jacking your rear end (the car's) in the air. Start teh car up and apply the emergency brake. Then put it in 4th gear, rev the engine to 4krpm and slowly let the clutch out this will cause the load and should cause retard to occur. Use a timing light to see what happens as you let out the clutch and keep the revs up. If you get no retard, you have a problem.
The vacuum changes as you have the car under load. It is not quite as you have listed here. It is a combination of load on the engine and rpm.

Looking at your readings, it seems you have the same problem as me. Your retard is messed up. Our's was difficult to find because we would check it by sucking on the hoses and the arm would move on both advance and retard sides. The thing we never checked until 2 nights ago was how long it would hold the vacuum......

Good luck.

BTW, I still haven't got a response on the A1 Cardone rebuilt distributor. If what seems to be true is, that is the way to go to get a tested canister. Plus, you get the added benefit of spare trigger points..

Chris

[Bleyseng]

All the A1 Cardone units I have installed/used (4) had new trigger points. A new/rebuild dizzy is soo much better on these cars.

Geoff

[McMark]

I don't know whow rebuilts the units for NAPA, but the one I bought had used trigger points that were media blasted and actually didn't work and I had to put my old ones in to get the engine to run.

[Rockaria]

Because of this post I looked into this furthur. I just got back from my friends garage. The first thing I did was to put a vacuum tester on the advance port of my dizzy. It held just find. Then I did the Retard. It moved the lever just fine. At first glance it looked and worked great but what would you know... It did not hold a vacuum at all for more than 3 seconds.

I happend to have a spare dizzy and Vaccum canister (Hey when a part like that comes up for a good deal you buy it if you think you need it or not). I quickly tested both ports and they held a vacuum just fine. I swapped the vacuum canister in my car that did not work with the working one and "I'll Be Darned" Everything started to work just like everyone has been explaining.

My curve is now spot on to the factory manuals and my advance and retard are perfect. It drives better, has better responce, runs 20 degrees cooler, and I have a feeling my gas mialage will increase. All due to my Retard canister now holding a vacuum.

Too cool,

Thanks Chris "porsche735" Your situation was my ticket to fixing my 15 month problem I have been constantly trying to figure out. (IMG:style_emoticons/default/beerchug.gif)

[porsche735]

I'm glad my 7 years of pain have come to someone else's help! (IMG:style_emoticons/default/clap56.gif)

We ran at Laguna Seca this weekend and it was the first time ever that we did not have to do anything with the car (repairwise). It's amazing how it changes your whole attitude about an event when you are not under your car.... (IMG:style_emoticons/default/mueba.gif)
We were still breaking in the engine, so we didn't go over 5k. In the past, going from turn 5 to 6 (uphill) we used to just be able to maintain rpms. Now, with the car FIXED, we can actually pull up the hill. (IMG:style_emoticons/default/smilie_pokal.gif)

Speaking of pulling up the hill, I rode in Hank Watt's car for a few laps. He has a custom 911 with a turbo installed built on a '73 tub. At low boost he is at about 550 HP on a car that weights about 2400 lbs. He cranked up the boost for me a bit and was putting out about 675 HP. He has more horsepower in 1 cylinder that we have in our whole car..... (IMG:style_emoticons/default/pray.gif) . My gosh what a violent ride that is. Quite a handful. He goes so fast on the straight that he has to lift for turn 1 because the car gets too light. In my 914, turn 1 isn't even a turn.....

chris