whistle while at work

here some pics plugs seem to be getting a burn down electroyde in different places

No dripless. using gortex.
Mike

Eddie,
Good to hear from you. Hope all is well. You know how us lefties are. For some reason in my mind I kept thinking they were coming in late. Going to get rid of hose going to breather on manifold from carb. Then turn the screw the other way and see what happens. I was pretty conservative on set up for new motor I think that is contributing to richness. Do you think I should try going up on heat range in plugs?
Thanks
Mike

I concur with Eddie on many points
Those plugs indicate a very rich condition and missing power somewhere in the range.

Alternative secanrio
The rich condition could be rich primaries, but engine leans up to normal when the secondaries open early with big air, hence the abrupt surge when the a/f ratio finally improves

Consider disconnecting the secondaries, , throw in fresh plugs and do some wot runs, shut down and read the plugs. They should look white with a 2.-2.5 mm soot ring around the bottom base of the insulator., else rejet

Then add in the secondaries and rinse/repeat.to get them optimal too

then lastly, adjust where the secondaries open and how fast
you really don't want to be in them at or below 36mph slalom compensation, else throttle response gets a bit dull.and delayed

10 4
As usual you guys are on top of it.
By the way those valve covers suck.
Mike

Eddie,
764's on plugs and yes to the hose from carb to breather. Or does that affect vacum?

Eddie,
It has a hose attached on rear of intake manifold to the pcv valve on opposite valve cover. Wont harldly run without it
This hose not sure what it does if anything.Maybe I should look into another solution for it. The old arrestor was done same way from factory.

Plug gaps are at 45 maybe I should go a little more?

Backfoot:

You are correct. I have high praise for the QF carbs. I had one little glitch with a needle and seat, but other than that, the QF is a nice piece of engineering. The QF M-600 is the "equivalent" of the standard Holley 4160, but the QF has many features not available on the Holley:

- Sight window in float bowl for float adjustment
- Exterior float adjustment hardware
- Screw-in air bleeds
- Screw in jets in the secondary metering block
- Adjustable secondary housing unit

I realize that "feel" is a very subjective issue, but my engine with the QF carb and DUI distributor FEELS equal to when the TBI / Pro-Tech was working. I was expecting a perfomance downgrade when I make the switch-out, but I've been very pleased with the results.

Living in Utah means boating at altitude. I typically frequent Utah Lake (4,400 feet), There are other "alpine" lakes that range from 5,400 to 6,200 feet in elevation.

My QF carb came from the factory with the following configuration:

6.5 power valve
67 main jets and 76 secondary jets
.073/.039 idle air bleeds
.028/.028 high speed air bleeds

I started out by dropping the size of the main and secondary jets by 2 down to 65/74. When I pulled my plugs after 50 hours, it was obvious that I was running rich. Black, sooty plugs. Not oily, just soot.

My question on the spark plug heat range is based on the carbon/soot issue. If someone wanted to purpously run a bit rich, would a one-level hotter plug be OK or would it cause any problems? The reason for my question, is that I take the boat down to Lake Powell every year, and the elevation there is 3,600 feet. That could be the reason for the soot build-up on the plugs. The great thing about Fuel Injection is the automatic adjustment for elevation. My automatic elevation adjustment includes a new gasket and carburetor jet changes. Not that this is a huge problem, but I would rather not have to open up the carburetor before heading down to Lake Powell. If the 765 plugs solve the soot issue without causing unwanted side effects, then I MAY consider. If not, I'll just stick with the tried-and-true 764 plugs.

At the end-of-season lay-up, I changed the jets to the next smaller size. Now it is 64/73. I did also buy the next 2 sizes of air bleeds. I haven't yet experimented with the air bleeds, as I first want to see how the new jets perform.

Additionally, at my altitude, I don't swing a standard wheel (ACME 422). Instead, I run an ACME 654. The 2 wheels are very similar, with the 654 being 1/2" less in pitch.

This combo of carb configuration and prop seems to work well at my altitude. With 3 people in the boat, I can turn 5,000 RPMs and run 43 MPH.

JQ

Thanks Rob,
That's some good info. What timing are you running? What is your engine vacuum at your primary elevation which sounds like 4400'?

You're getting some pretty impressive performance numbers for that elevation already. I'm no expert and I've never tuned an engine for altitude but the research I've done tells me that spark plugs aren't the answer. Seems most try do go that route but in the end, jet and timing changes are the ticket and the reason I asked about your timing.

Most here are running 6.5PV on engines that are pulling 15-17" vacuum at sea level. The vacuum will be lower at your altitude so the 6.5PV may too high. You might have that PV open at anything much above an idle!!!! Get out the vacuum gauge and see where you're at. I think you may need to go down to at least a 5.5 or 4.5.

If it were mine, I would get it dialed in for 4400' and on the occasional jaunt to 6200' I would advance the timing a few degrees and put a little less pitch prop on it to keep the RPM's a touch higher and see how it does. It'll be a little rich but not the end of the world.
The general rule of thumb is don't worry about any changes for up to 2000' changes in altitude (some say every 1000' but nothing is carved in granite it seems). You're right at that 2000' ceiling in this scenario.

Then your trip to Lake Powell is less then 1000' downhill from your base settings. Run a little higher octane (if available) and If that' isn't available, retard the timing a degree or two and go skiing. Don't even mess with anything else.

Now, I might be completely wrong on everything. I really have no idea. I'm just a carb junkie looking for new fix. You need to get your ride tuned first at your elevation, The rest should take care of itself with a little common sense.

Eddie,
So whats the deal you trying to keep the skier out in front of the nautique. Got to be some reason your not running a pcv. I know that wouldnt be hard with a bow tie. These fords seem to be so fickle to make clean HP.

Foot:

Timing is at 10 degrees BTDC at 700 RPM. If memory serves, total advance at 4,800 - 5,000 RPM is about 32 degrees BTDC.

Interesting comment about the Power Valve and high elevation. Hmmmm....

When I tuned the QF carb, I used a vacuum gauge to set the idle air/fuel screw and I believe that I was only pulling 12 - 13 inches. Again, high elevation.

Well, it seems like I'm getting darn close to "dialed-in". I'm curious to see how the new jets perform.

(Don't think I'll mess around with the hotter plugs. Just stay with the 764)

JQ

Hi,
Adjusted the secondarys coming in right at 4k. Can still feel it but not nearly as bad. Leaned out carb some. Got rid of breather to carb and installed a filter type breather. Other set up was sucking oil into air filter. Put in a new pcv. Boat ran good. Very quick out of hole. Have not had chance to look at plugs. I had already ran it with old set up.
Did seem like it was not quite as smooth at cruising speed.
Got some work to do. Top speed on speedos had me right around 45 with about 5k on the tach

lakedog55 wrote: Leaned out carb some.

Could you expand on that?

no idea what you guys are talking about...but I sure love the sound of it.

I know why Eddie usually won't let me under the motor box.


john

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