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When do secondaries kick in on 351 |
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nobrainsd 
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Joined: August-13-2015 Location: San Diego Status: Offline Points: 157 |
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 Topic: When do secondaries kick in on 351Posted: October-01-2021 at 12:36pm |
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I have been having a fuel starvation issue. Checked the vent and the anti siphon valve. The fuel filter water separator is almost new, but I will change it today. The mechanical fuel pump isn't leaking. One of my associates was all about it being my secondaries not opening on the 4160 Holley carb on my 351 PCM Ford Ski Nautique. I am having issues initiate at around 20 mph. I think I should still be running on the primaries at that speed, but I changed the diaphragm anyways. Checked the vacuum passage too. Really going to be surprised if my relatively new filter is clogged. Tank had some debris from the deteriorated rubber ring (anti slosh) at the tank bottom, but not much. Alas. Hope a new filter is all it takes. But I really would like to know when do those secondaries come into play?
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3750 |
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Posted: October-01-2021 at 1:19pm |
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An internal circuit pulls vacuum on the diaphragm opening the secondaries. I can’t say exactly when the secondaries open but pulling out a skier, if they were big and strong I would sometimes hear the 4bbl open up while pulling them out. You could always open the engine cover and have your observer watch to see them open. It is really obvious, you see the throttle plate rotate as the vacuum pulls up on it. You can even manually open it while driving as a test. Care has to be taken to stay out of all the moving parts of course but it is a quick test to see if your secondaries open and if they function once open.
What you are describing sounds more like a fuel supply issue.
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75 Tique
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Joined: August-12-2004 Location: Seven Lakes, NC Status: Offline Points: 6130 |
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Posted: October-01-2021 at 6:10pm |
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Sound advice.  |
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_____________
“So, how was your weekend?” “Well, let me see…sun burn, stiff neck, screwed up back, assorted aches and pains….yup, my weekend was great, thanks for asking.” |
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gun-driver
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Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Posted: October-01-2021 at 8:38pm |
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Pull it together with a couple butterflies and some super glue and your back in business.
 Just remember “chicks dig scars” just make the story good
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Gary S
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Posted: October-01-2021 at 9:55pm |
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Is that when the Foot was cutting up the horse?
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KENO
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Posted: October-02-2021 at 6:04am |
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There's a little orifice in the right side primary and secondary venturis that internally connects to the secondary diaphragm housing and as air flow through the primary venturi increases, it creates a vacuum in that line that has to overcome the spring pressure holding the secondaries shut and then they'll gradually open. There's a little assist from the secondary airflow after they are open some also.
So..............you're thinking right, 20 mph lightly loaded, just cruising, they're closed and will be till probably somewhere in the 3500 ish range depending on boat weight and loading and the strength of the spring in the chamber.
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KENO
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Posted: October-02-2021 at 6:07am |
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Looks like the story of Larry and the alternator
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nobrainsd
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Joined: August-13-2015 Location: San Diego Status: Offline Points: 157 |
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Posted: October-02-2021 at 10:34am |
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Thank you all for the comments. I rechecked my vent and anti siphon. I changed my fuel filter/water separator and emptied it into a fuel filter/water separator funnel (a necessary item when fueling in Mexico). No water and no debris. Re tightened all fittings and replaced the secondary diaphragm (which looked good but was definitely getting old). Still had issues, so I pulled the fuel bowls.
I blew air into the intake lines on the fuel bowls and operated the needle with the float. The primary seemed good, but the secondary had restricted flow even with the float all of the way down touching the bottom of the fuel bowl. Ah ha! My carb was a rebuilt purchase. One of the needles had a really hard rubber tip and was not sealing well. So I had rebuilt the carb. I used the gaskets that came with my rebuild kit that perfectly fit on the needle seat to fuel bowl body. That was my mistake. The added depth on the needle seat kept the needle/fuel float assembly from fully opening. Thus restricted flow. When I got up to speed I was draining the fuel bowl faster than it was filling. The fuel bowl levels were right and I never thought to check that they were fully opening. I removed the gaskets and re installed the needle seats without a gasket. Blew into the assembly and didn't have any leaks. Engine has full power now. Not sure what the gaskets were actually for. But the kit had some other parts that weren't applicable to my carb. I had tested the carb in the driveway and the no load results fooled me into thinking everything was good to go. Only had this boat in the water in no wake zones recently. It ran fine for that! So I thought the stumbling and lack of power had to be something else. Oh well. I guess examining whatever I did last should have been the first thing on my list. The replies here and other posts I have read on CCF got me squared away. Thank you. |
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KENO
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Posted: October-02-2021 at 9:00pm |
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I'll boldly venture forth with a guess as to what those gaskets were for..............they go between the seat and the body
Feel free to verify my guess Like any other gasket they're there to form a leak tight seal. I suppose that if you cram the brass seat into the pot metal body hard enough it won't leak..........maybe. I'm a little confused about your description of issues at 20 mph on the primaries being resolved by playing with the secondaries which won't be open at that speed/load But.........you were there, you fixed it, hope it stays "fixed" Did you take out the front gasket too? I can't decide from what's written. It sounds like a case of some mismatched parts.
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MrMcD
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Posted: October-02-2021 at 11:45pm |
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That is a Nasty Open wound. Was someone less than careful? Hope it healed OK.
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nobrainsd
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Posted: October-03-2021 at 1:00am |
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Yep, Keno, pulled out both washers. Hmmm, maybe a thinner washer? But not really seeing any issues. No leaking or dripping on either primary or secondary. Could not see how it would be possible to alter the float arm or float needle seat to change the dynamics of the situation. Maybe I'm missing something. The Holley parts diagrams I find are not for the older needle marine configuration. Do they have a washer/gasket originally? Not like I can't make a thin washer. Either the bowl is overfull or the needle isn't opening sufficiently with the washers supplied. Gasket loss changed that. Could be that I just had the wrong gaskets and a thinner gasket would be the solution. Gasket or no gasket. that is the question :)
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KENO
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Posted: October-03-2021 at 5:36am |
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i could measure the thickness of the gasket for you .I'll post it later
Meanwhile, it's working, so why mess with success
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KENO
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Posted: October-03-2021 at 5:43am |
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Alternator vs Larry, see link below The meat eating alternator on Larry's engine  |
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KENO
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Posted: October-03-2021 at 6:15am |
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Meanwhile back at the carburetor.............here'a a picture courtesy of wayoutthere of some Holley needle and seat assemblies in unopened packages.
The bottom ones are like yours and the gasket is packaged with the needle and seat.  |
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KENO
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Posted: October-03-2021 at 9:09am |
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The gasket is 0.031 inches thick. I have some extras and could send you a couple, but you'd probably be better off buying a couple of Holley needle and seat assemblies with the gaskets if you run into issues with your setup you have right now. Send a PM with your address if you want them
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nobrainsd
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Posted: October-03-2021 at 5:45pm |
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Well, I figured I should go with gaskets. Cut an unused gasket from my carb to manifold. Tried all sorts of positions with the float. Raised the tab on the float, tried lowering the the arm. No matter what I'm getting overflow out the j tube. I have no idea what's up. Been at it all day. Tired of breathing gas fumes as I break open the carb again. Blowing into the bowl/needle seat assembly it sure seems it is sealing. But maybe I need a new needle and seat. Sure doesn't seem like it. I find it hard to believe it is a gasket leak, because the bowl fills up fast. Checked the primary diaphragm again. Made sure the linkage had a bit of play. Damn, there just aren't that many moving parts! May I ask, Keno, what material the gasket for the needle seat is made of? I was hoping to roll to a Fly In out of my area, but it looks like I'm waiting on Holley parts :) Oh the joy of boating!
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8122pbrainard
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Posted: October-03-2021 at 7:01pm |
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Kelson,
It would be interesting to know what the fuel pressure is going to the carb. I've had to use a pressure regulator once since the pressure was high enough to push past the needle.
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KENO
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Posted: October-03-2021 at 8:03pm |
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They're metal with a pretty hard black coating on both sides Do you still have just the secondary side having an issue?
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nobrainsd
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Posted: October-03-2021 at 8:50pm |
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Well, at least I don't have a wound like Larry!
Should have probably been happy with the gasket less set up that did run, but it might have been a bad idea. Of course, I am trying to leave and go someplace! Don't all boat flails involve imminent departures? A lack of immediately available parts? I spent all day sucking gas fumes. Hmmm, just a little crabby? Tried every variation of float tab and arm position. With a non adjustable set up it is a pain in the ass every time you want to make an adjustment. When I blow through the needle valve it does shut off. But who knows. I may be exerting more pressure by hand than the float is when floating in gas. It is an older needle/seat. I have another needle seat set arriving tomorrow. So maybe that will be the obvious/normal solution. Might be too smart for my own good thinking the needle tip is good because I can operate it manually. I did replace the other one. I could only get one locally. The boat starts great, runs awesome and then the j tube pukes on my day (and kills the stoke). It is now clearly a primary issue I'm chasing. Killed a couple of transfer tube o rings while I was having fun with the carb. No more at Ace locally. Will have to road trip. I did not whip out a lighter and flambe my boat... but thought about it. I know it will all be good. This Ski Nautique has led me down the Protec conversion, it lost the TBI, this rebuilt carb lasted 8 years before acting up and after replacing my shaft, strut, rear engine mounts and prop it is super smooth... when it runs, which is most of the time until now. Hope everyone is having a great evening. I am fortunate to live in San Diego, so I will get the boat running and I will ride all year. I am being optimistic right at the moment :)
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nobrainsd
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Posted: October-03-2021 at 8:56pm |
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Yo Keno! I wouldn't expect a fuel pressure issue from a mechanical fuel pump, but I have read that it does happen. May have to check it out. I will give it a go with a new needle/seat and float tomorrow. If it takes longer I will get back to it. I do appreciate your feed back. The overflow in the primary bowl is a simple problem of too much gas! Can't be that bad, if I have time for parts :)
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8122pbrainard
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Posted: October-04-2021 at 5:42am |
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The fuel pressure problem I referenced was with a mechanical pump.
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KENO
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Posted: October-04-2021 at 6:48am |
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Yo right back at ya............if you're confusing me with Pete, you've obviously been inhaling too many gas fumes and need a break. Since you're only overflowing one bowl right now,I think your new needle and seat for that bowl is a good approach |
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KENO
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Posted: October-04-2021 at 7:12am |
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Maybe Pete will explain how he rebuilt his fuel pump and then it had too much pressure for some reason and he had to put a "non original part" on his boat.............then again, maybe he won't.
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8122pbrainard
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Posted: October-04-2021 at 7:50am |
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Did I say it was my boat? NO! Did I say I rebuilt the pump? NO!
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KENO
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Posted: October-04-2021 at 8:10am |
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Here's a little trip down memory lane for you Pete. Your 312, your pump rebuild, your fuel pressure regulator. I won't bother yelling in CAPS
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KENO
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Posted: October-04-2021 at 8:30am |
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And if you stop and think about it, if nobrainsd's fuel pump just started mysteriously putting out more pressure for some unknown reason, to cause his problem, would you maybe fix or replace the pump or go and put a band aid (fuel pressure regulator) on it ?
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MrMcD
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Posted: October-04-2021 at 1:19pm |
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It is well known that Carb Needle and Seat set ups work well at 4-7 PSI and fail when more than that is used regardless of mechanical or electric pump supply. That is why pressure regulators are so available.
I do agree in this boat, the pump was not changed and had worked for years so the pressure that worked a month ago should still work and a new needle and seat should solve the issue. No reason to beat on Pete, he only tried to help. He is a continuous source of help on this forum.
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KENO
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Posted: October-04-2021 at 5:46pm |
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I guess you could say that we have a difference of opinion about some of that "help"
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nobrainsd
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Posted: October-04-2021 at 8:25pm |
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My "by 11 am tomorrow" parts didn't arrive. I think my problem will just be the needle/seat. I had the float and needle assembly set so tight that it was restricting flow. It needed that pressure up on the low position float to actually control the bowl level at all. Now it just won't seal enough at any setting. Except for totally closed. How I hit a sweet spot with no gasket on the seat I don't know. Looking forward to getting the parts. Also, I now have the time, since I'm not going anywhere, to pick up a Quickfuel M-600 if I want. Which I do, because I needed to drill, tap and use inserts on my metering plate 4 times on this round of fun. The threaded holes for the plate are wearing out. Only two more to go. #8 inserts were a pain to source too. I think maybe this rebuilt Holley has given me my moneys worth. But I will throw the needle and seat in and confirm. Always good to have a spare :)
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8122pbrainard
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Posted: October-05-2021 at 5:45am |
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Thank you
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MrMcD wrote: