general tune-up

Keep it on topic, it will make it easier to find what you need.
So Cal Mark

Re: general tune-up

Post by So Cal Mark »

sorry I wasn't able to help sooner. I've been gone all week to the SEMA show. Your whole problem is CO, not ignition timing. Set timing to the spec on the underhood tag, probably 0. Make sure your air pump is working. The air output should increase from the pump when you rev it. Make sure the air injection rail is not plugged with carbon. You should be able to blow air into the check valve and feel air out the tailpipe. Unless you have really long arms, this is a two person job.
Once you're sure the air pump is putting air into the exhaust, look at the carb. With those CO readings you could have carb issues such as a bad float or incorrect setting. Adjusting the idle mix won't help on the loaded mode test. If the float height is correct and the choke is opening fully, you're going to have to look at the low speed jet and air correctors. Remove the idle cutoff solenoid and make sure the idle jet on the end isn't damaged. (of course the solenoid has to tighten into the carb fully. If it fits loosely, fuel will be able to bypass the jet.
If the condition of everything looks okay, you'll need to reduce the low speed jet about two sizes and increase the air corrector one or two sizes. Sometimes the secondary air corrector is larger than the primary. If that's your case you can swap the two for the test.
Once the test is done, I'd spend some time getting that CO in the proper range. 9% is WAY too rich. Not only are you wasting fuel, you're adding wear and tear to the motor by diluting oil from the excess fuel.
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maytag
Posts: 1789
Joined: Mon Oct 19, 2009 9:22 pm
Your car is a: 1976 124 spider
Location: Rocky Mountains....UTAH! (Not Colorado)

Re: general tune-up

Post by maytag »

now THAT was an authoritative answer that made sense too!
Y'all have been great. Thanks for all your help. And Mark: as I get started on this new motor.... I think you're gonna become my new best friend! :D

thanks again everyone, for your help.
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
So Cal Mark

Re: general tune-up

Post by So Cal Mark »

be sure to post your next test results
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maytag
Posts: 1789
Joined: Mon Oct 19, 2009 9:22 pm
Your car is a: 1976 124 spider
Location: Rocky Mountains....UTAH! (Not Colorado)

Re: general tune-up

Post by maytag »

I tore the carb apart tonight while I was waiting on some paint to dry.
Here's my jetting details:

Venturis both say "3.5"
Air correctors are 185 pri. / 170 sec.
Emulsion tubes are both F74
Mains are 1.40 pri. / 1.25 sec. :!:
float needle seat says "200". (is this matched to the needle? I couldn't find any markings on it)
Idle jets are .5 pri. / .60 sec.

So I think most of this looks stock, with the exception of the mains seemed to be swapped :?: my guess is that someone may have done this in an attempt to help it pass emissions previously, since it seems it would be worse if I swapped them back

wait.... is that correct? is the secondary open at all on the 25mph test? Maybe I've identified the problem here? :shock:
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
So Cal Mark

Re: general tune-up

Post by So Cal Mark »

you're mostly running on the low speed jet til almost 3500 rpm. Don't even worry about anything with the secondary except to make sure the throttle plate set screw is not adjusted to hold the secondary plate open. Swapping the two main jets would help quite abit. Make sure the float height is correct and that the accelerator pump nozzle o-ring is tight and not allowing fuel to be pulled around the outside of the nozzle. Is the low speed jet in good shape, not worn off on the tip?
If I were you, besides swapping the two main jets, I'd look for a 195 or 200 primary air jet and a 45 low speed jet. That should get you within emission specs.
Have you checked the air pump system?
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maytag
Posts: 1789
Joined: Mon Oct 19, 2009 9:22 pm
Your car is a: 1976 124 spider
Location: Rocky Mountains....UTAH! (Not Colorado)

Re: general tune-up

Post by maytag »

I checked the air pump system the other day, but not as thoroughly as you have suggested. Tomorrow my boy should have some time for me (since I've been helping him build a half-pipe for his skateboard for a week!) and we can blow some air through, as you suggested.
I know that the pump is moving air. I know that it's getting to the diverter / check-valve. I know the valve works that direction... but I'm afraid it may not be a 'one-way' valve any longer. There seems to be a lot of exhaust coming back at me when the hose is off. how much is normal?. I took it off and I've got it soaking in some diesel fuel now. I think someone mentioned they are easy to come-by... but I haven't looked yet. I didn't check to be sure the air increases as the motor speed does. I'll need to get it back together and check that too.

I've put all my jetting info into the form that Pierce has on their site, and we'll see what they recommend as well; I'm hoping they have dealt with the high altitude and these cars before. But I trust what you're suggesting, Mark, and it makes perfect sense as well.

SO: what are the chance that my local VW speed-shop will have jets for my ADFA? :roll:

Float level: The only way I know how to set those is with the little template that comes in a carb-rebuild kit. I am assuming there's another way? Walk me through that?

Last question: "Low-speed Jet".... :?: is this another name for the primary idle jet, located behind the solenoid? Or is this another jet I'm looking for? and no; it is NOT in good shape. It is, in fact, quite worn. I noticed that while looking for an identifier on it.

How much of this stuff comes in a carb-kit?
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
So Cal Mark

Re: general tune-up

Post by So Cal Mark »

the old master kits used to come with new throttle plates, screws, jets etc but now all of the kits I see are just soft parts.
The low speed or idle jet is on the end of the solenoid, and the engine will run on that jet up to about 3500 rpm. If the jet is worn off, you may not have to reduce the size of it, just get a new jet that will seal.
The air check valve should just be a one way valve. If you have exhaust coming back through at least you know the rail isn't plugged with carbon. When you see high CO numbers like your test revealed you usually see lots of carbon deposits. That check valve is the same as GM used for many years, so they're fairly cheap and obtainable at any parts store
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maytag
Posts: 1789
Joined: Mon Oct 19, 2009 9:22 pm
Your car is a: 1976 124 spider
Location: Rocky Mountains....UTAH! (Not Colorado)

Re: general tune-up

Post by maytag »

well, the pressure's been mounting at work; and so has the frustration. So I decided after popping-off yesterday to a co-worker (he 'deserved it', but it's still not okay for me to do that) that I'd take a day off... before I get fired! :oops:

So I went out into the garage and re-assembled all the crap I had apart.
My new jets aren't here yet, but I decided to put the mains in their correct locations (the P.O. had 'em swapped) and go test it again.

Passed with flying colors. I'll post the results soon, along with everything I did between each of the various results.
So now I'm legal (went and got plates for it too)... just in time for snow this weekend! :(

I think I'll leave the tuning just where it is for now, because I've ordered everything I need to put an Air/Fuel ratio gauge on the car and dial it in where I want it. And I'd like to see just exactly what A/F ratio equates to the current level of emissions from the test!

This will be educational for me, I'm sure. I'll share what I learn as I go.

thanks for everyone's help and suggestions!
I'm no Boy-Racer..... but if I can't take every on-ramp at TWICE the posted limit.... I'm a total failure!
So Cal Mark

Re: general tune-up

Post by So Cal Mark »

I'd like to see what the test readings were
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