Float level and other Qs

[Macadoo]

Thanks Cliff, that's all surprising info.  But the older I get, the more I understand that reality and "sales pitches" are rarely the same.
But at the same time, there's no way I could lower a cast iron intake onto my motor by myself, especially with the motor in the car.  Even so, I may keep an eye out for a pre-EGR iron intake on Facebook.
However, I'm stuck with, at the very least, a 1/2 inch spacer because of clearance issues.  The bracket I have to use for the 200-4r TV cable interferes with the back runner and needs to be raised.
I haven't seen a semi-open spacer offered on Summit or Jegs so I may have to make my own from hardwood.  I've done it before, it's not difficult.

I've already made the timing tape so I'll go ahead and use it (until it falls off).  A fellow on the ClassicOldsmobile site made a printable template for the Olds balancer that is spot-on.


What's your take on moving the timing from the mechanical more to the initial, as I've done?  A lot of talk on the internet claims that can be beneficial for large cams.  I know it has increased my idle rpm, allowing me to back off the idle speed screw.  I was too far into the transfer slots before the change.  Right now I have a *park* idle of 1100 with no nozzle drip.  In gear it drops down to 850.

[Macadoo]

Update:
The timing tape was a big help.  My dial-back light was jumping all over the place.  My old style light and the tape was nice and steady.  I've got 19* initial and 17* at the mechanical for a 36* total.

But I'm having trouble with the tip method for the APT.  I set it at 2100 rpm and tipped in the choke.  RPMs dropped so I lifted the power piston a half turn and tipped in again.  RPMs still dropped.  I kept turning the screw counter clockwise and kept dropping RPM.  I got to about 6 turns out with no difference.  So I tuned it all the way in and back out 2 turns.  The tip in didn't drop RPMs at that setting but it didn't increase RPMs either.
It runs okay at this setting but wants to stall after a short WOT run.  As in every time.  Choke is set at 1/4 with 7 psi fuel pressure.  Float needle is installed but not through a hole in the choke.

Cliff, what would it cost me for one of your custom Q-jet builds?

[Cliff Ruggles]

1100 RPM is too fast for idle speed and you are seeing too much RPM drop when the trans is placed in gear.  I suspect some of the mechanical curve is in and falling out when the additional load is placed on the engine.

I don't like to run that much initial timing either, and you shouldn't have to with your combination of parts.  For most engines we build and/or tune here we set the initial timing around 10-14 degrees and they will idle great and not "buck" the starter on hot restarts.

We sell custom units outright, no core required, pretty long wait time for them at the moment.  Price would depend on exactly what you wanted, and they are all fully restored with plated parts and colored castings.....Cliff

[Macadoo]

I can verify the mechanical coming in at the 1100 *park* idle with a timing light, correct?  So, Put it in Drive, the mechanical advance that's also increasing the idle speed in park, drops out and lowers the idle speed in gear even more.  Kind of a viscous cycle.
But if I take the *park* idle down to, say, 800 or 850, putting it in gear, idle will drop to a point where it feels like it wants to die and the engine rocks in the bay like it wants to jump out of there.
If I wiped a lobe during break-in, it would act like a a sticking valve and show up on a vacuum gauge test, yes?

[Cliff Ruggles]

Huge drops in RPM placing the trans in gear is usually distributor related with some timing falling out.  This happens if/when aftermarket spring/weight kits are used, or if the stock springs are getting weak or stretched out.  I've also seen worn pins and weight holes cause this.

Insufficient idle fuel to the mixture screws can aggravate the scenario, so when a load is placed on the engine timing falling out and not enough fuel as the vacuum signal is reduced causes the huge drop in RPM's and idle quality getting worse.......Cliff

[Macadoo]

Man, this is like herding cats, lol.  Thank you, Cliff, for your patience as i get this ironed out.

I am running an MSD spring and weight kit, as you say; aftermarket.  One light spring and one medium.  Although I can't see my tach, it sounds to me like the curve isn't all the way in until around 3000 - 3500.  I'll see if I can get the wife to sit in the car while I test this, this weekend.

Do you think I need to open up the idle tubes and DCRs a little more?  Currently they are at:
Idle tubes are at .038
Down channels .055
Idle bypass air is at .120
Mixture screw holes; I can't remember exactly (I'm at work), but on the high side of recommendation, maybe a little over.  One coil clipped from springs.
Jets: Cliff's 73
Metering Rods: Cliff's 44

Again, I can still pull the AC can vac hose from the intake and the idle speed increases maybe 200 rpm.  This is why I took the idle bypass air to .120.  Is this to be expected?

[Cliff Ruggles]

You will get some idle speed increase from pulling a vacuum hose unless there is a serious lack of idle fuel available, then the engine will act worse and/or RPM drop off.

I use that method more to see if it needs more idle bypass air than any other reason.  Just yesterday was testing a Marine carb, they do not have idle bypass available.

To simulate a smoother idling Marine engine and to get rid of the nozzle drip we were seeing I move the vacuum advance to manifold vacuum and pulled off the vacuum supply to the choke pull-off.  This allowed me to lower the throttle angle and stop the nozzle drip we were seeing and get control with the mixture screws. 

Before you can do any idle tuning you have to verify that no timing is being added at idle speed, it has to be rock solid below about 900 rpm's.  If it falls out any at all it makes idle tuning difficult.

To this day I don't know why folks think you have to have the mechanical advance "all in" early in the RPM range.  That's more of a "crutch" fix for engines that don't have enough compression for the cam choice, really tight LSA camshafts, or just plain poor choices in general for the combination of parts.

The distributor in my engine is pretty much untouched since the mid 1980's when I first placed it in service.  It's been in 4 different engines and even dyno tested against an MSD billet with a 6AL box.  The dyno runs were nearly blueprints of each other with a very slight advantage to the HEI.  I suspect this is from how precise the tips of the pointers are on the pick-up vs the broad/wide ends on the MSD unit.

I just had it out a few weeks ago to check the status of the bronze gear and cleaned things up.  It's a Pontiac HEI with stock weights, stock springs, stock center cam, stock 990 module, and stock coil.  The only modification done to it is adding a positive stop so it can't continue to add timing at really high RPMs (common problem with factory HEI's and compounded when you put lighter springs on them).

It starts adding timing right off idle/900rpms and smooth/steady timing curve all in around 3000 rpm's.  I add another 14 degrees from the vacuum unit via ported vacuum.  Base timing set at 10 degrees, 30 total.

[Macadoo]

Excellent info, once again.  I'll report back when I get this stuff nailed down.

[Cliff Ruggles]

Sounds great. 

I will add that at least 50 percent if not more of the problems we see here with tuning is the distributor and not just the carburetor.

It's ALWAYS the same thing, some "goofy" offshore spring weight kit added to the factory distributor at some point and the excellent factory center cam, weights and springs are long gone.

Those kits not only use less spring tension they change the geometry of the parts and allow the weights additional leverage on the center cam to bring in timing early and easy.  Problem is that it is often difficult, if not impossible to keep some of the curve out at idle speed with those parts.

Nearly ALL of the aftermarket HEI's we've seen in recent years have the same problem.  I'd also add that I reject most that show up here due to low quality of the internals and lessons in humility trying to get a decent spark curve with them.

I use and prefer stock distributors and stock components.

Case in point.  Recently we had a Buick 455 Stage I car brought here for custom tuning.  Many hands had been on it, and it was NOT making the grade anyplace.  Biggest complaint lacking in power (wouldn't even spin the tires).

As soon as we removed the air cleaner the "lacking in power" was clearly evident as the carb "builder" used the wrong choke pull-off (2bbl) and it wasn't allowing the secondary flaps to open. 

We went thru the carb and it was a little "hacked" so fixed all the issues with it and recalibrated it for the application.  We installed the carb and the owner took it for a drive, came back smiling ear to ear, so power was restored.  The idle quality was a little "funky" and I noticed it "bucked" the starter slightly on a hot re-start I we put a timing light on it.  At idle timing was over 1" off the scale and hardly any advance when you revved it up.

Removed the cap/rotor and low and behold a "goofy" spring and weight set-up allowing nearly all the advance it an idle speed.

We installed factory weights and springs and took a look at the curve with the timing light and re-timed the engine.  Another quick test drive and the owner says that it's just a "touch" down on power right off idle.

I removed the factory springs, opened up the "eyes" just a tad, one more test drive and good to go.

With that simple modification we saw NO advance at idle speed, and the timing started advancing at 900rpm's and all in around 2800-3000rpm's.  No more "bucking" the starter on hot restarts and idle settled now nicely every single time you let off the throttle, just like it should be doing.......Cliff

[Macadoo]

Okay Cliff, did some checking this morning.
There is no timing difference between 800 and 1100 RPM so it's not advancing at that high idle, probably due to the stiffer springs.  However, when revving, there is a quick jump that starts at about 1300 RPM up to 28 degrees, and then slowly advances after that up to 37 degrees at about 4000 RPM (although this is still by ear. I need to find a helper to read the tach). Certainly NOT a smooth timing curve.
As far as the timing "settling nicely" when letting off the throttle; I have little experience with what is to be expected but it seemed to settle a little slowly.
I did save the stock weights, center plate, and springs.  However, this is not a stock distributor.  [Full discloser]: it's one of the eBay cheap aftermarkets.

If I look for an original GM distributor, it would need to be Oldsmobile, correct?  Since they turn counter-clockwise.  May be a little hard to find.

[Cliff Ruggles]

I've rejected every single aftermarket HEI that's been send or brought here for help.

I would obtain a stock Olds HEI and completely/correctly rebuild it.  At most it may need a lighter spring on one side or you may get what you want by opening up the "eyes" in the springs slightly.

Always weld in a positive stop for the advance for exactly how much timing you want it to add and so it doesn't keep adding timing at high RPM's.

The current timing curve you have is too slow to get things started.  The timing should start moving right off idle and smooth/steady to full advance and not slow up and some point, then take a lot more RPM's to get all the timing in.......Cliff

[Macadoo]

I'm not sure I follow.  Advance starts right off idle, then a smooth steady curve all in by 2800-3000.  And that's where I would want the lock, yes?  No more advance after 3000.  No quick jump and then slowing way down of the curve, right?  Might that be the MSD weights and center plate?  I'll play with it in the interim.

I'll start the hunt for a factory unit.  Might make a fun winter project.

[Cliff Ruggles]

No advance till 1300rpms could use a little help.  I like to see the timing start immediately with RPM's right off idle or at least by 1000rpms if not 900. 

No need to split hairs with this sort of thing but as engine speed increases timing needs to increase so it has sufficient opportunity to effectively burn the mixture and maximum efficiency of using the heat energy to push the piston down.

The vacuum advance, being a load sensing device helps us at very light engine load and light throttle openings, but when you go to heavy/full throttle the mechanical advance is adding the timing, and if there is a delay in when it starts there can also be a hesitation/stumble/bog or slight lack of power until it starts advancing the timing.

You probably wouldn't notice it at 1300rpm's but I've seen troubled distributors with rusted weights, worn/rusted pins, etc cause issues that acted like carburetor problems when it was simply a spark advance issue.......Cliff