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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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Posted: March-13-2016 at 2:11pm |
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Here goes
351hic, gt40p cc'd with no exhaust seals, cam, intake, dui dist, quick fuel carb, k&n Arrestor. 80 hours on rebuild 20 over. 540 prop Problem, secondaries? Applying throttle wether smooth or jumping in it around 3300k It gets a kick in the arse and a whistling noise like a turbo which i think is coming from valve cover breater. (pretty cool feeling) Cant remeber how to upload pics from phone ] |
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Lakedog55
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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here some pics plugs seem to be getting a burn down electroyde in different places |
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Lakedog55
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Drip less shaft system installed?
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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No dripless. using gortex.
Mike |
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Lakedog55
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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Damn Mike, that looks to be awfully rich.
The kick in the ass that you're feeling are the secondaries coming in too soon and too fast. They're are letting much more air in before the additional fuel comes along with it. Makes it feel like the kick in the ass that you're experiencing as well as the sound of two more barrels opening all of a sudden. Everyone mistakenly assumes when the secondaries open this is what it's supposed to feel like.. In reality you're experiencing a very quick lean condition (which is actually stopping your acceleration) followed by the kick in the ass (when the extra fuel gets there). Old school hot rodders call it driving by the seat of your pants. If you were on a track being timed, you'd find that you actually lose time over a properly tuned carb. You shouldn't feel the secondaries come in like that and 3300 RPM is way too soon anyway. The secondaries should be coming in someplace around 3700-3900 RPM in our boats. I haven't actually worked on a QF carb yet but they are supposed to be externally adjustable for this. Very cool feature!!!! It looks to me like the screw on the right side of the vacuum secondary housing should be turned in to slow down the opening rate (in accordance with the S and F on the housing cover). I would try turning it in just enough to stop driving driving by the seat of your pants. Then put a new set of plugs in. I have a feeling that the secondaries opening so soon is causing you to run so rich. . |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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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 |
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Lakedog55
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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I'm not understanding what hose you're talking a Mike. Are you talking about the hose from the breather to the carb? That one should stay there.
What plugs you running? Pretty sure that GT40P heads should be running 764's. No reason to change them. Get the carb dialed in first.. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3357 |
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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 |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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Dogg:
That looks just like my set-up (excluding the valve covers). After 50 hours on my QF carb, my plugs came out looking just like yours. I called QF and they recommended that I lean-out by 1 jet size. They also said that I could try bigger air bleeds instead. I bought both jets and air bleeds, so we'll see how things perform (once the lake warms up a bit). Some of you motor-heads chime-in here: what would happen with a 765 plug instead of the 764? The 765 is one level "hotter". I agree with the other suggestions that your "kick-in" is probably an out-of-adjustment secondary actuator. The QF design should make the adjustment fairly simple. JQ |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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10 4
As usual you guys are on top of it. By the way those valve covers suck. Mike |
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Lakedog55
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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JQ,
I did change squirter sizes to a larger size. At first had a stumble, turns out front float was low. May have to change that back. One other thing when I first installed carb I used the ground that it came with. Not good. When throttle linkage passed by it made a definite spark. Luckily it was getting late when I installed it so i could see the blue flame So if you used the stock one with aluminum intake you might give it a look. |
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Lakedog55
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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Eddie,
764's on plugs and yes to the hose from carb to breather. Or does that affect vacum? |
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Lakedog55
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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Yes, you don't want to disconnect that hose. That's providing a positive suction in the crankcase aka...PCV. That hose is usually run to a vacuum port on the base of the carb or the carb adapter if so equipped. That's where you're getting the greatest vacuum signal from the engine. Some have tapped into a single runner on the intake but debates have been plenty about how effective that is. Either option would have to be better than being on the flame arrestor but I have seen them that way more than a few times too. Maybe someone else might confirm/deny that to be sure.
Interesting to hear this Rob. Every person that has installed a QF carb has had nothing but praise for it, yourself included. Pretty much bolt it on and go. What altitude are you running at? Higher elevations could certainly explain a rich condition that needs attention. Heat ranges of plugs takes a lot of things into consideration. Compression ratios, gas quality, elevation, A/F ratios, timing advance, overall engine use (excessive idling or under heavy loads),etc. The list goes on and on. Getting the carb tuned properly is much more important first IMHO. However, I firmly believe that using the recommended manufacturer and heat range plug is vitally important before you start tuning that carb. Our classic, old school, OHV, pushrod, Detroit iron have ignition systems designed to run plain old cheap, copper core plugs that you can buy 8 for the price of one Platinum, Iridium, Plutonium or any other plug that ends in "ium". You're wasting your money and loosing performance. Even new DUI and MSD ignitions recommend using those same cheap copper core plugs with the only difference being the gaps.. At least mine does. Don't mess with that. Make sure that when you start playing with the jets and/or air bleeds, change just one at a time. then test on the primaries like Tom recommended before doing anything else. It's time consuming and uses a lot of plugs but can be well worth the effort. If you're running as rich as Mike is, you're losing quite a bit of performance potential |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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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? |
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Lakedog55
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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OK, I think I got it now. We may have been using different terminology for the same thing. The pic you posted at the start of the thread is for the PCV then or the breather? I was using that as a reference and thinking that is what you were calling the breather. I was thinking it was the PCV. Here is a pic of my setup. PCV on the left attached to the base of the carb. Breather on the right that looks like a mini air filter. Think of it like one side is intake (Breather) and the other exhaust (PCV) for the crankcase. As long as your breather isn't restricting the PCV airflow it'll be fine. Your setup is using the flame arrestor as the air filter (for lack of a better term). If that's the case, it probably does look like the PCV. You could certainly replace it with something similar to my setup but it isn't necessary. .45" plug gap is fine. I'm not sure what others with DUI are running. Where there any recommendations with the DUI? From what I found online, if you have the high voltage coil, .55" isn't a problem. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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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 |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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Eddie,
I see where it is confusing, your breather looks just like mine, I still have a pcv valve on other side, if i get rid of pcv valve will I see any gains? |
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Lakedog55
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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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. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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Leave the PCV alone and get it leaned out a little bit. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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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. |
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Lakedog55
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Hollywood
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He is running a PCV
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Jonny Quest
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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 |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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backfoot100
Platinum Member Joined: January-03-2007 Location: United States Status: Offline Points: 1897 |
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Vacuum numbers are significantly affected at altitude. That 6.5PV is way too much if you're truly pulling 12-13". I would experiment with a 4.5 or even possibly a 2.5 and see how it performs. You can also increase your base timing a little bit at altitude. I would think that you can advance the timing by at least 4 or 5 degrees from where you're at now. I think you can figure 1 degree advance/every 1000' elevation from sea level. It really boils down to trial and error. Bump it up and see how it performs. If it increases performance, keep increasing timing. If it starts to ping, back it off till it doesn't. |
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When people run down to the lake to see what's making that noise, you've succeeded.
Eddie |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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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 |
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Lakedog55
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Mike, Hopefully you meant the flame arrester that I see pictured and you didn't put a filter on? |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3357 |
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Could you expand on that? |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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No way Pete. I am dangerous enough dont need any help
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Lakedog55
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jbear
Grand Poobah Joined: January-21-2005 Location: Lake Wales FL. Status: Offline Points: 8193 |
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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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"Loud pipes save lives"
AdamT sez "I'm Canadian and a beaver lover myself"... |
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lakedog55
Gold Member Joined: November-11-2010 Location: Lake Weir Fl Status: Offline Points: 835 |
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That is one clean plug |
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Lakedog55
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lakedog55
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