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Piledriver wrote:I still can't figure out how it runs 30 degrees retarded at all.
Perhaps it's something that is out of the troubleshooting loop...
Plugged exhaust?

Wait....memory jogging here.
something is odd. The guy who built this says its a 1.8L....and set at 8.3:1. Thats pretty hard to do with stock guts.
A 1.7L sure. They started at 8.2:1 with a shim. But the 1.8L piston and cylinder sets generally produce lower compression unless you do some work.

Q: is the timing of 30* retarded seen with vaccum hoses off or on?
If its with hoses on...having the wrong hose to the wrong port will pullfar too much vacuum when it should be pulling advance

Also...its possible in some odd cases thtaq maybe the fan is on wrong. Did the ub still have its locating pin? Gotta think about this one. Ray

I've been processing on this for days and I'm still coming up stupid, so it's gotta be something weird or stupid.

8.3 is not hard, no shims or gaskets (~.040ish) puts you right there or higher with cleaned up heads and a 6cc dish.

Take off the vac hose? What then?
(NEVER set the timing with vac connected)

Piledriver wrote:I still can't figure out how it runs 30 degrees retarded at all.
Perhaps it's something that is out of the troubleshooting loop...
Plugged exhaust?

It's very very quizzy, I know.

Exhaust is good.

Ray & PD: tuning procedure is by the book, no bonehead moves here. I've been through this 3 dozen times on this car within the last three days, so there's no goofy "oh, I forgot to..." stuff going on.

All the hoses go to the right places.

If the fan were on wrong the TDC mark wouldn't be in the window at TDC.

TDC on the fan is TDC. Period. Dot. Exclamation mark.

No one really understands why the car runs, so we're not alone on that one. Tram don't know. Russ don't know. The builder and the builder's mechanic don't know. Me don't know. We don't know.

The builder said he did do the work to bring the CR up. This time around he's going to bring it up to 8.7:1 to compensate for the increase in swept volume with the 1.8's.

It seems like it could be any one or any combination of 3 things:
1)cam's in off a tooth
2)mystery cam
3)dizzy drive gear on the crank is not oriented correctly

Or,
1)any two of those things
2)all three of those things

If it doesn't run right after this time around the builder's going to have to resolve things in a money way. He's got a 411 core, he can give me that and my money and I'll go to the SFBay T4 guru Ken Jensen and he can build a good one.

In any case I agree, very very quizzy.

Ray, sorry, should have answered your question directly: the 30 or so degrees paint mark is seen through the window, hoses off and plugged at 3500 RPM.

Just ordered a new WebCam stock grind, new 0 gear and new lifters for the builder to install. Could have a + or - gear at present, I don't know, the builder never said.

I've asked him to raise the CR to 8.7:1 to compensate for the increased swept volume with the 1.8L jugs. I think my math's about right on that.

If he can manage to get the rocker arm geometry right all should be fine when he's done. Car goes in next Thursday, supposed to be done Saturday.

Light candles, murmur fervent prayers. I'll post an update when it's done, no more noggin' scratchin' required.

Know what?....bus timing marks are some distance in degrees to the left side as seen against the plastic scale that is bolted to the fan housing....right?
Could it be that you have a bus fan (purely an idiot guess)....or even a bus cam (never was really sure what difference there might be other than intake valve timing).
Either way...lets say that is the case.....that your timing would be close to correct....if viewed against a 1.8 bus timing scale mounted on the fan housing. The other issues with running could be the normal changes in tuning thta would need to be done to MPS after doing significant work on an engine.
Let us know what you find inside of the case with the cam and gearing. Ray

I'm having the guy replace the torque converter ( to eliminate that possible cause of poor drivability) and the vacuum modulator. The modulator is the last possible vacuum leak on the car.

Except for leaky valves, that is. 3/4 developed a tick pretty quick.

AMC heads. He doesn't remember if he installed new seats the last time.

The thing with this guy is it's an endless fog of bullshit. No one besides himself knows if he's truth telling or not. Since the state consumer enforcement bureau is involved it has to go back to him so he can make a good faith effort to make the motor right.

After that it gets resolved in a different way. So here's hoping he comes to his senses and does the right thing.

Ray pm'd you.

Any update yet?

david58 wrote:Any update yet?

Waiting for a torque converter to arrive from G.A., car hasn't gone in yet, it's docked.

Since it's probably a few bad things at once, fiddled, replaced a weak injector, pulled rocker arm shafts & put a steel straight edge on the valve stem ends: look's like a stretchy exhaust valve or a sunk seat on #4.

Dropped seat in 3K miles, that's a pretty crappy batting average.

Compression's not what it ought to be for new jugs and pistons.

Mystery motor.

The builder used to be one of the aircooled go-to guys in San Francisco. No longer.

Bump...update? Hope things went OK...

Still workin' on it but the timing's not an issue anymore. Idle is surging, not an f.i.issue, not a vacuum leak issue, at least not on top of the engine. Maybe an air leak, could be a leaky jug or something, need a leak down test. The guy pulled the motor and went thru it again, AMC heads got new seats, new valves, new guides. Springs, rockers rocker shafts, all unknown to me. Stock length pushrods for sure, the machinist never did rocker geometry, just threw stock pushpods back in after taking 1.8 heads and dished pistons to 8.5:1. Shoemaker stuff.

The mechanic's such a dingaling a judge may need to help sort things out $$$ way, we'll see. New fellow will do the compression/leak down.

Stick a timing light on it and make sure the advance mechanism isn't moving until a couple of hundred RPM OVER idle speed. Most distributors are sloppy to some extent.

If the advance is working (EDIT---at idle speed), snug up the springs a tad by bending the outer spring mounts (in most cases---should be obvious)

This will cause the idle to hunt.

Well, sorry to hear of your mechanic troubles.

It's hard to find a good old-fashioned MECHANIC any more. All the kids get trained in computer diagnosis, very few learn how to really work on the blasted thing instead. If the computer does your thinking for you, there's less opportunity to learn HOW THINGS WORK as opposed to how the computer presents data.

btectonic wrote:Still workin' on it but the timing's not an issue anymore. Idle is surging, not an f.i.issue, not a vacuum leak issue, at least not on top of the engine. Maybe an air leak, could be a leaky jug or something, need a leak down test. The guy pulled the motor and went thru it again, AMC heads got new seats, new valves, new guides. Springs, rockers rocker shafts, all unknown to me. Stock length pushrods for sure, the machinist never did rocker geometry, just threw stock pushpods back in after taking 1.8 heads and dished pistons to 8.5:1. Shoemaker stuff.

The mechanic's such a dingaling a judge may need to help sort things out $$$ way, we'll see. New fellow will do the compression/leak down.

Yes...it is an airleak issue...but maybe not in the manner you think.

If you truely have found and fixed all vacuum leak sources...every tube, every hose, the gaskets between runners and heads and the runner boots, the TB o-ring, the proper closed position of the TB...meaning throttle cable adjustment, injector seals, valve cover gaskets, AAR, decel valve and its hoses if you have one, automatic tranny vacuum midulator and hoses, throttle dashpot, vacuum advance hoses and dashpot, MPS........everything verified....and you still get this problem then.....it is still an air leak. Or....more factually...and air to fuel imbalance.

When the idle is surging....check your fuel pressure with an accurate gauge. If all vacuum issues have been fixed, the problem is usually a gross excess of fuel. Occasionally it can be a gross lean situation but that is usually quick to see in poor drivability.
What many people do not get the feel for until they work on D-jet for a while is that it is really all vacuum based.

Here is the problem: since two injectors in this paired system fire way out of time....you tend to run with two ports wet at idle. If your fuel pressure is high or the adjustment is off on the MPS....the rich running always keeps an excess of fuel in the ports at idle and some very low rpm running like in bumper to bumper traffic.

Know this:....even small excesses or losses of fuel mixture at idle change the pumping efficiency of the engine as combustion efficiency rises and falls. That directly affect the vacuum signature......which directly and sometimes disproportionatly affects fuel mixture. If you are running say...10% to rich at the MPs.....the off an on surge of excess fuel being scavenged at the ports.....causes an overly rich situation from moment to moment. Idle falls. As the ports are scavenged clean idle rises again and spikes the MPS....which is adjusted to rich....and gives excess fuel mixture again....starting the process over.
In very excessively rich situations...usually an MPS maladjustment paired with variable or too high fuel mixture....a double whammy....the idle will submarine up and down for from 1-3 minutes before eventually stalling because it just cannot keep up with the excess scavenge fuel in the ports.

If all of your leaks are fixed, set fuel pressure to standard...and timing....and make a couple of tweeks to the MPS starting with the outer full load stop. Ray