455 stage 1 emission and tuning problem

OK, there's some relevant background.

Under no circumstances whatsoever, should you get exhaust fumes/engine compartment fumes in the passenger compartment, windows open or closed.
1. Fix all exhaust leaks, the exhaust system must extend behind the rear axle.
2. Assure that there's the OEM-style rubber/plastic seal at the rear of the hood, so that engine compartment fumes cannot escape and enter the HVAC plenum at the base of the windshield.
3. Repair, replace, seal all grommets or open holes in firewall.
4. In rare cases, under-car turbulence can cause exhaust gas to enter the trunk, and from the trunk into the passenger compartment. Tailpipes must expel exhaust so that it cannot enter the trunk.

Depends on how you're looking for misfire. You'd likely "see" it on a vacuum gauge, you'd "see" it on an ignition oscilloscope. You'd "see" it on O2-sensor readings as a false-lean indication. But this does depend on the RPM the misfire happens at, and how much misfire there is.

Spark plugs have a designed-in gap range. You almost certainly have the gap pried open too far. "I" would close-up the gap to .040 maximum, and more like .035 until you can get the proper plugs.

Have you ever tested the ignition coil for spark output? A spark-tester is inexpensive, although I can't vouch for availability in Germany.

My favorite style of spark testers, available for conventional (ballast-resistor) ignitions, and HEI (no ballast resistor) ignitions. The HEI style has a larger gap using a recessed center electrode.



Use a jumper wire to ground the spark tester. Leave the wires connected to the HEI cap. Crank engine--should be a series of sparks at the tester.


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I think this is a language-barrier item. You say "floating" but I think you mean "leaking".

Not if the intake gaskets, and the intake manifold are OK. But a cracked intake manifold or failed intake gaskets could cause weird problems.

The factory spec for that distributor has been provided. You said your engine was "restored" but it is not, it's "modified". "I" would use a modified advance curve because the original advance curve was compromised by GM to avoid detonation even if performance was sacrificed. In general, there's too much vacuum advance and not enough initial or centrifugal for normal driving.

I would start with initial timing at ~16 degrees. Add ~18 degrees of centrifugal advance, not active at idle + 100 rpm minimum, "all in" by 3200 rpm. Then 10--15 degrees of vacuum advance. Adjust as needed for best performance.

HOWEVER, I don't think the advance curves are responsible for your exhaust stench.

Any chance your fuel pump is leaking into the crankcase, so that the PCV system is pulling fuel vapor into the intake manifold?

And he absolutely, positively, totally refuses to verify fuel pressure. At least three people asked him to check fuel pressure, some of us multiple times.

 

Thanks Larry there are useful information,
I just remembered that I changed the original vacuum advance because it`s diaphragm was broken and installed another new different AC vacuum advanced but the original vacuum advance on my distributor had a very hard internal spring behind the diaphragm I guess for prevent it to advance on lower vacuum/RPM and its movement distance was half of what I installed I guess for stop way over advancing on middle RPM. manual said my distributor centrifugal advance will start at 1800 RPM, earlier then others!, I can make a limiter for vacuum advance rod as in your pictures on your timing thread but can do nothing about vacuum advance internal spring.

 

Buy an adjustable vacuum advance. The adjustment tightens the spring. You may ALSO have to limit the amount.

Tom T.

 

I started today with 16 degrees initial and not attached vacuum advanced at all, acceleration was good. only on traffic in middle speed around 30-40 miles\h in uphill when I wanted to give it a little bit gas to keep up with traffic I can hear a little knocking but when RPM rise up it will gone, than second test with vacuum advanced connected to ported uphill it is knocking in all RPMs, also with 16 degrees initial when you turn it off and start again you should give it open throttle to start, my centrifugal will start from 600RPM and in 4600 RPM will be around 24, I think I should turn initial down step by step from 16 to 10 and see the result, than if I want to add vacuum advance it should be limited for example to 10 degrees.

It was a mixture of technical difficulties and possibilities, I have metal fuel pipe from fuel pump to the carburetor, I never use hoses for pressurized fuel, I saw big fires before on classics and even new cars just because of fuel houses and people that think pressurized fuel and hot engine bay and high voltage electricity are friends. Installing fuel gauge in this system means making special parts to use hoses and install gauge to this hose system while I tested return line and it was clean and I installed new fuel pump again and if in this cleaned and checked system fuel pressure be higher than it should be I really don`t know what could cause it. so I appreciated your guys helps but decided that focus on other possibilities.

How can I test this?

I changed the plugs with R45TS and result was engine vibration and weird readings on my tuning gun, It was not able to detect RPM and timing, after going back to 44TS, everything comes back to normal, I guess I have weak wires or coil that cause weak spark and lead to the emission.

 

Nevermind the manual, throw it out.
You've changed so many things the factory specifications mean nothing anymore.
You've changed the intake, the heads, the carb, the cam, and the distributor is probably worn.
Are the heads compatible with that year intake?
No vacuum leaks?

 

all 67, 68 and 69 400-430 intake and heads are compatible to each other.

 

Was the cam degreed?
Restored means a lot of different things.
Did you do the work?
I’d start with a leak down test to see if you have an engine first

 

I think at 215/225 @ 0.050, the duration has probably increased enough that the camshaft would like more timing.

Even if it were the stock cam, more timing than what the manual calls for would probably improve performance. The first thing I did when I got the Riv home (and before I read Larry's extremely helpful power timing thread) was incremently increase the timing until it pinged at WOT and the backed it down to the previous setting. Maybe it was all psychological, but I believed it ran better.

Before a leak down test, you might be able to diagnose the issue with a vacuum gauge.

 

Cam was not degreed, I just install it dot to dot (because I have no degree wheel, etc...), Just checked the cam before installation by my trusted machine shop and everything seemed fine, I installed the piston ring so I know they are OK also gaps are same and correct. Just two things cross my mind now, First, In 455 system valve springs are dual but I deleted the inner springs and make it single spring and second I was not install the intake manifold myself because I just install the core of the engine than gave a go ahead to the workshop to doing the rest but it is 50 years that they work on these engines and they know what they are doing, however I guess I should be able to see on vacuum gauge if there is a not seated valve or a leaky intake manifold?

Ignition is late but I should recurve the whole distributor, also with that splash oil system it needs race oils 10w60 should be good enough, now I made a mixed oil myself that seems working good...for now.

 

How do you mean its late? What is telling you its late?
Are you going by the vacuum gauge markings that say "Late ignition timing"?
If so, ignore that, theres NO WAY a gauge manufacturer can make a broad diagnoses of engine condition, ESPECIALLY if you have a non stock cam.

What "splash oil system"? Please explain

 

I can feel it in drive also by vacuum, in idle and mid range it feels that time is late but I can not go for time that It needs because of my mechanical advance is going in very soon also the fuel octane is lower that should be for that timing. but you are correct, what I tested when you change the cam timing and numbers vacuum will be lower and with higher vacuum ignition and fuel ratio could be wrong.

Piston lubrication on Buick big blocks are splash system, means that crankshaft will splash oil for them, there is no oil spray or oil passage on connecting rods for the pistons, with this system on high load we need a very good oil for lubrication, oil will get tin and will not lubricate well also will get hot and become worse.

 

What do you feel?
You cant go by feel, thats nonsense, what is your initial timing, what is your total and at what RPM?

ALL engines are that way, not just Buick, where you getting this info from?

 

Maybe all US v8 engines but not all engines.

 

Maybe there is a language barrier or "lost in translation" between the thoughts and the keyboard, but this seems like this is going round and round.

Most likely your issue is staring you in the face and you just don't see because of how long you've been at it. It may be time to get someone local involved. Sometimes the info is hard to read and apply on a thread.

 

Yes, find someone with a 4 or 5 gas analyzer or buy your own wide band and find out what you are chasing.

 

Yes it is.

 

Today I tested the engine with different setups. Under 10 degrees initial I have no unusual emission for non emission and catalyst engine. It is just what they did on late 60`s and 70`s, retarding engines for less emission.

I bought one of those adjustable vacuum advances, completely rubbish design, They just make a delay to the time that vacuum advance start. I also inspected what I had on HEI and it was 25 degrees vacuum advance!!,

 

Listen to Larry!