Help! High Throttle hesitation |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Posted: May-30-2017 at 2:04pm |
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So I put hour number 2 and 3 on the new motor this weekend... Motor starts like a Swiss watch, half a revolution on the starter and it just purrs. We spent lots of time varying the RPM in the low range (1500-2500 RPM) as I am still seating rings and just overall watching things to make sure it's right.
Everything felt good, until we made a reasonably hard run and I gave ~ almost full throttle. We ran hard up to about 42 on the air guide for about 30 seconds, and then the engine started to feel like it loaded up, and bogged down. I pulled it back to idle speed, and ran up to about 2000 RPM with normal response, 2500 or so, the engine sputtered like it was flooding out. hammer the throttle and it bogged, and then felt like it started to come out. We have a Wake the World event that I am trying to be ready for in June, so I need to solve this issue quickly. Where do I start? |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Need a little refresher here, this is what a pro tec to distributor and Holley carb conversion.?
What's the condition of the carburetor? |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Hi Ken, thanks for the response. My original engine was a Protec, with TBI, all of it was junk after being left out in the weather with the engine cover up for a couple of rainy seasons. I replaced everything last year with a 351w standard rotation, roller cam, with Edelbrock RPM intake. Carb is 4160 Holley, and the distributor is a DUI.
Carb was from another member here, but it was supposed to have been rebuilt not long before I bought it. I suspect the carb may be the problem, but I am guessing at this point. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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I'd suspect the same and make a guess that when the secondaries are open that's when your problems start.
I think I'd take it apart for a clean/rebuild as a starting point |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Thanks Ken,
I have a rebuild kit at home just in case... I guess I will pull it and try to rebuild it this week. is there anything I should be looking for? |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Hey, at least you're prepared
I'd just have a good manual/set of instructions but look closely at secondary related items especially, just as a hunch. Cleanliness is your friend. Plenty of people here with Holley experience to help out with any questions Don't know if you have a clutch headed screwdriver for the secondary metering plate, they're not real easy to find but you can "hack" your way through the job with a flat blade of the right size. You made it this far, you're almost there |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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yep, I have a clutch blade, I did the Holley carb on my 82, and it ran afterwards, Just have never experienced a high end stumble like this one. Thanks for the help and encouragement I am definitely ready for a trouble free day on the water, getting to the water seems to take an act of God... it's definitely frustrating to have problems once we're there. I keep having to remind myself that it can all be fixed, and I'll eventually get there.
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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New cam or reused? Not sure this sounds like proper engine break in procedure.
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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Sure does sound like carb issues.
First thought is that the secondaries are not opening correctly. Second thought is that the power valve could be bad. Per Holley: "Holley carburetors have a power enrichment system that provides fuel to the main power circuit during heavy loads or under full throttle situations. The vacuum operated power enrichment system is controlled by a Power Valve that times the operation to your engine's specific needs." JQ |
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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New, Roller cam. I was told by the engine builder that the first 20 minutes of run time were the important part, I followed their instructions for that break in period. I know there are several schools of thought on engine break in, but I would be interested in hearing where you feel I am going wrong, and what to do differently. I only want to do this engine replacement task once. I am running Joe Gibbs break in oil, and have ~2-3 hours on the engine. Update on the carb situation: I pulled it apart last night, and began the cleaning process. I soaked all the parts in carb dip, and everything looked pretty clean. I blew the orifices of the main body out with air, and a chunk of black goo came out of one of the secondary orifices, so good possibility that was the problem. I did notice that many of the fasteners were barely finger tight, and that the main jets(?) on the primary side were loose. Unfortunately one for the alignment pins on the primary metering block fell on the workbench when I took the plate off, so I am going to see if I can find a new metering block as a replacement. I also read up on power valves, there is a 2.5 in the carb kit, but from the way I understand it, I want to move to a 4 or 6.5 with my upgraded intake manifold? I do not intend to go further with upgrades, but with the free'er intake I need a higher number valve, correct? I appreciate fuel economy, so I am thinking the 4 is probably a good compromise with correct mixture at the higher throttle positions, but not changing the fuel mixture too early. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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I'd always been a 5.0 or a 6.5 PV guy myself, but there are plenty of 351's running around with 2.5 PV's too. Things change
Most Holley's for marine 351's had 65 or 66 mains and the secondary metering plate was stamped with a number like maybe for example a 3 or a 6 or a 36 that when you look up the info will tell you the main hole and idle hole sizes. What's the list number on the air horn? I could tell you quite a bit about what it should have for jets etc from that. I've put a carb primary metering block on with only one of those pesky little pins and if you line things up carefully it works. They're usually really tight in the metering block edit, they're cast in when the metering block is cast Loose main jets would screw things up and that glob of junk couldn't help things any. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Roller cam, good. Post cam break in (not needed for roller- flat tappet only), you want to set the rings. You want to load/unload the engine pretty good right off the bat. Don't stay at any rpm for very long- avoid idle (once warm) and no prolonged wot. Constantly varying the throttle is good, but don't be trying to keep the rpm way low.
Fuel/cooling/timing needs basic sorting before you begin, of course. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Can't let this slide by |
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1980nautique
Senior Member Joined: December-25-2012 Location: W.Massachusetts Status: Offline Points: 146 |
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Kris,
I would use the proven method of Holley power Valve selection!!! The starting point is to check manifold vacuum at idle on a warmed up engine. Divide this number in half. ex. 13 hg.'s at idle divided by 2= 6.5. A 4.0 hg. power valve will slam shut at 4.1 hg.'s and begin to lean out the fuel mix as the engine recovers vacuum and RPMs at WOT. Recommend putting in the 6.0 or 6.5 hg. Power valve that comes in the 4160 Holley marine Kit. I don't believe you will find a marine based Carb Kit for a 4160 Holley that comes with a 2.5 hg. power valve Compared to the street version the Power valve, Main Jet sizes and the J Tubes are the main difference in the Marine Carburetor,.Keep us informed!!!! |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Ken - I don't have the list number here at work, but I can post it later good to know on the pins... Is their only function to align the gasket? the rest of the metering block looks good... it's not got further damage anyway.
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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I don't believe you're right It's hard to find a later model 600 cfm marine Holley 4160 with something other than a 2.5 PV as the original PV. Earlier ones a 6.5 was common You should clean your !!!!! key too by the way |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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It keeps the idle passages lined up too but being careful you can get it right. |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Tim - thanks for advice. I did set timing etc, and will check it again once I reinstall the carb, and will also dial in the carb with a vacuum guage once it is re-set. Cooling is working well, all systems were normal during my lake run on Monday.
I have followed the school of thought that rings need seating at all ranges of RPM, when new, so I'll adjust my speed expectations and run a little faster to make sure we set the rings correctly, but will not baby it so to speak. 1980 - sounds like good advice... no Idea where my vacuum numbers are right now, so I guess that you are suggesting I install the 2.5 that came in my kit and replace once I have accurate vacuum numbers? |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Post your list number later and I can probably tell you what it originally came with.assuming your list number is in my Holley manual.
You'll probably notice that me and 80SN and probably a whole bunch of others like a 6.5. Your idle vacuum should be over 13. Sometime back the Holley engineering department decided to build 600 cfm 4160 marine carbs with a 2.5 PV and I've had genuine Holley marine kits come with a 2.5 that I've replaced with a 6.5. I figure their engineering dept is pretty smart and they had their reasons My guess is slightly better fuel economy And by the way vacuum never recovers till you back off the throttle 1980 nautique Your boat isn't a car cruising on the highway |
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1980nautique
Senior Member Joined: December-25-2012 Location: W.Massachusetts Status: Offline Points: 146 |
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Kris, cut and paste this address: "http://documents.holley.com/techlibrary_carb_numerical_listing.pd" into your browser. and use your LIST # and verify required Power Valve.
Does the Carb have "J" tubes on the bowl vents? |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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A good hardware store should have one of those boxes of assorted dowel pins. Probably back at the service desk. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Hey thanks for the chart I've got 7 marine 600 cfm 4160's either on boats or on the shelf You might call me a hoarder or maybe somebody who likes spare parts First one is a 6576 list number not on the Holley chart, it's old (from 1976) it's always had a 6.5 PV since it was new Continuing on list number 50419-1 (have 2 of them) 2.5PV List 9392 2.5 PV List 7163 2.5 PV List 80319-1 2.5 PV and last but not least a list 75009 with a 6.5 PV And all those PV numbers are from the Holley chart |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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The one I had to assemble with one pin was because the pin broke off and after looking at a metering block today, it's pretty safe to say that the "pin" is part of the casting and somebody did some "creative engineering" to drill a hole and put a new pin in Dreaming's metering block. Seems like it wasn't a very good fit since it fell out. |
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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When I talked to Holley's tech line a few years ago they told me they purged alot of the older carb info when they computerized
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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As another point of reference -- my QuickFuel M-600 is based on the Holley 4160 design. It came from the factory with a 6.5 power-valve.
JQ |
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3359 |
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The whole 2.5 pv never made sense to me when they made that switch, especially to old list rebuild kits that used to come with a 5.5 or 6.5.
To have to wait til the vacuum is less than 2.5" before the carb switches from lean cruise to high load, only induces a distinct dull flat spot when you mash it. |
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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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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Hmmm. lots to think about. We had a bit of a crazy night last night, so I wasn't able to get to the garage to pull the list number. I will pull it today and repost. On the metering block pin, it was once molded into the carburetor, but must have been either cracked/weakened, or I broke it getting the metering block off. I did talk with my local machine shop/speed shop on the way home from work last night, and he said he would reuse the metering block with only one of the alignment pins as Ken stated.
On the PV discussion, I hope to read a bit more, but for the moment, it sounds like I should install the 2.5 and then take some vacuum readings. Seems like the vacuum at idle seems funny because that is not when the PV is used, but I can take the reading and report for sure... then you smart guys can help me to size it correctly. |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Alright,
There 3 sets of numbers on the horn of the carb, they are: FIJL-CA 50469-1 3492 I believe the list # is the 3492, but not too sure at this point. I may try and start assembling tonight, likely going to be tomorrow evening. |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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50469-1 is the list number.
The link a handful of posts ago only lists a 50469 but I have a paper list that does have the 50469-1 It's a 600 cfm with 65 main jets, and a 2.5 power valve. If you have the number from the secondary metering plate, I should be able to tell you some info on that. It's just a number cast into the plate like a 5 or 6 or 34 just for example. There are a lot of different numbers. I'd put it together with what you have (2.5) and get a 5.0 or a 6.5 to try later if you feel like it You did find issues so with those corrected maybe your problem will be resolved You could also get a couple of 66 main jets to try if you're buying parts |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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So I re-assembled the carb last night and just spent a couple of hours putting everything back together. I reset the timing at 11°BTDC at 600 RPM. then adjusted the carb idle needles for 16.5-17" vacuum (600 rpm). I'll have to wait until tomorrow to throw the boat in the water, but it is running on the hose. I hope all is well on the top end now, it does start good, and seems to idle nicely. I did check the idle mixture screws, and they will make the engine die if I get them too far in, so we're running on the idle circuit at idle.
One more fun fact for Ken The secondary plate seems to have a 59 stamped on it. the five is pretty lightly stamped, but I think that was the correct number. |
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