710K failed emissions

[mm58]

I did a 'leak down' check and it showed about 5-10 percent leakage which is supposed to be good.


Mike

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[mm58]

In case anyone was interested to know what's down that hole where the cutoff solenoid/valves go... pic attached

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[mm58]

Just checked the droplets that are spitting out the tailpipe. Not fuel!
Gotta be water. But why, and where coming from?

Mike

[Joeri]

That would probebly condens water

[rmel]

Well here's hoping that your funky fuel cutoff solenoid is your primary problem

In any case one byproduct of combusting gas is H2O. So when you start up
initially, it will be seen on the ground and dripping from the tail pipe until
the exhaust system gets hot enough to vaporize the H2O -- then it won't drip
and becomes invisible. BTW this is why it's a good idea to run your engine hot
enough to get the exaust hot and the oil as well so that H2O buildup can
boil off in the exaust system and the crank case.

[mm58]

Man you guys are smart. Didn't know about the H20 in the exhaust.

I've ordered a new cutoff valve, so we'll see if that makes any difference.


Thanks!



Mike

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[boeing7873]

Do you know what jets you are running? Assuming all cylinders are running, I would start by knowing the jets you have. There are two sets, one was usually installed in the low emissions configuration. If you have the rich set, even with all running you may not pass. Just a guess, I don't know how the Arizona standards compare to the Europeans from the 80s.
You may also want to touch a little your idle screws, the ones under the idle electro valves. That has a direct effect on idle mixture.

[pinzinator]

I checked the exhaust on my 710M and got these numbers. It is important that the engine is at operating temperature.
This engine has PinzSSI, so there are 3 sparks at the power stroke and the exhaust stroke. If the mixture is really rich there can be an exhaust backfire,
which is a carburetion problem, NOT an ignition problem.

IMG_5989.jpg (94.67 KiB) Viewed 11287 times

[Stumbler]

Why is anyone having you perform emissions testing on a 50 year old truck? Even if it was at 100% like-new, it would probably not meet today's standards because it wasn't designed and built to those standards. Am I missing something?

[mm58]

The State of Arizona is having me perform emission testing.
And I normally DO meet the required standards.

[mushmasher]

The State of Arizona is having me perform emission testing.
And I normally DO meet the required standards.

Curious if you ever got it to pass emissions. And what the issue was that fixed it?

[mm58]

I still have not been able to pass emissions. I don't know what the issue is.

Mike

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[pinzinator]

High hydrocarbons indicates a rich mixture or not enough air (plugged air filter). The float(s) or a needle valve could be sticking. Timing at TDC can cause higher HC due to less burn time. Advance the timing.

[mm58]

How many degrees past TDC would be a good starting point?

[pinzinator]

8 degrees BTDC