Won't Idle below 1000 |
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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Posted: April-23-2010 at 10:54am |
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I'm betting someone installed an automotive intake on 91's motor and that is why it has a different setup. Don't see why they would suddenly start to use a heat riser passage on the intake when they never did in the 70's and 80's.
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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91, I dont think anyone's following you yet, cant you get a picture of what you are describing?
The carb gets no warm up from exhaust gases, it uses an electric choke wich is a round device attached to it's side. The port on the carb spacer connects to the PCV valve on the passenger's side valve cover for gas fumes recovery. The intake manifold has a port for this too but it's blocked off on most marine applications. Exhaust fumes are generated in the combustion chambers and leave the engine through the exhaust manifolds, they dont come back into the engine as far as I know... |
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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have you checked the secondaries are fully closed?
spray some w40 on the secondaries shaft and move the mechanism, you could also press it to see if they didnt stuck a bit open. They have a metal piece that needs to be custom bended for them to top closed, check they are getting fully closed. |
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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The gaskets used were standard holley 4 barrel gaskets, cut to match the old ones by the way.
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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Alright, tonight I got the other gasket on. The idle actually increased a little. So changing the gasket did nothing. I am at a loss as what to do now. The mixture screws change nothing in my idle, and I have the curb adjuster screw completely taken out and cable disconnected from lever. The timing is set correctly and I sprayed starter fluid all around the manifold and carb to see if there were any leaks. No leaks.
I also turned the mixture screws in all the way, It cut out when I did this. I still have the original gaskets although I don't think I could reuse them. Where can I find a reproduction of the originals? I don't have a clue as to what to try next guys! |
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91nautique
Senior Member Joined: May-26-2005 Status: Offline Points: 104 |
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Luchog Said..I think what you are refering to is the PCV port.
No -way, the manifold had an exhaust port under the plate, thick gasket with shim over the port,and appeared to have never been pulled apart,the gasket had blown,and leaking exhaust gas into the motor under the spacer. The gasket had a Ford part no,and was clearly marked "Top" and 'Right" and was made out a thick heat resistant material,the only gasket available to me was a thin paper material, could be fitted either way or either up or down (hope that made sense) - that would never have worked. The gasket between the carb and spacer was also very thick, and had a Ford part no, made from a typical paper type material. When I read....
It would appear he is chasing a vacuum leak, the only thing's he has disturbed are the intake to head's/intake to spacer and spacer to carb, you guys have talked him through the obvious scenario's. and I wondered if WLS had used a standard automotive/aftermarket gasket, but was unsure if the manifold was the same as mine. At the time (it was around 2002) the gasket was available in the US (I tracked it down via the part no - (saw a picture of it)- from memory it was on marinengines.com or Skidim. I was told at the time the manifold used was from a 1980's Ford truck. (can't confirm) To solve the problem at the time I used a steel aftermarket adaptor plate and high temp sealant on the manifold to spacer and a standard aftermarket gasket between the carb and spacer. Lewy, Standard ignition system |
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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swap the gaskets locations only if the plate has four holes in it and isn't one large open area, if the plate is one large open area get two matching gaskets that are open like the plate is.
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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It used to run perfect, until I took it apart! I am thinking it must be the gaskets. The old gaskets were identical top and bottom. The front barrels of the carb were open to eachother, and the rear was two individual barrels. The gaskets now on there are different. Bottom is like original, however the top has the front barrels open to eachother, as well as the rear open to eachother.
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lewy2001
Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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That is different 91. Were they Protec ignition engines? They may have some differences in the intake manifold as well. Very unusual
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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I think what you are refering to is the PCV port, wich connects the carb wedge plate to the valve cover.
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91nautique
Senior Member Joined: May-26-2005 Status: Offline Points: 104 |
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Luchog,
Iv'e since changed the manifolds to Elderbrock performer's and thrown out the old manifolds. The original gasket on both engine's looked like this one off a 351Clevland. It was very thick material and had a steel plate embedded into the gasket that covered the port. Skidim used to sell them, and when I emailed them about it years ago they knew exactly what I was enquiring about. |
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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91nautique, why dont you post a pic of your "port that supplies exhaust gas to the base plate to warm up the carb"
I dont think anyone has one of those in their boats. |
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91nautique
Senior Member Joined: May-26-2005 Status: Offline Points: 104 |
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No there not, they are way different on the '91 and '95 351 Pcm's I have, and you can not use a standard base gasket between the spacer and manifold. Mine has leaked through the port that supplies exhaust gas to the base plate to warm up the carb, and the engine behaved exactly like White lake skier's. Skidim used to sell the correct gasket, but it is now unavailable. Iv'e not seen a manifold on a '84 302 PCM like WL skier's, that's why I asked if they have the same setup as mine, and considering he has just pulled the manifold and baseplate off, this may well be the issue. WL skier, How was the motor running prior to pulling it apart? |
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82wake2001
Senior Member Joined: February-14-2008 Location: United States Status: Offline Points: 240 |
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I had this exact issue with my 82...351...last weekend i changed the cap rotor all the plugs(autolite 24 gapped at .35) and 7mm plug wires from skidim...
side note the sales associates at skidim are amazing!!!!! fired up the boat, by the way on the first crank without and throttle and adjusted the carb after it came up to temp..... now i have it idling at 650 and can start the boat without using the throttle... and the pipes sound mean when she is all tuned up.... |
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Joe
1982 ski nautique 2001 "Lady of the Wake" |
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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this is not a car with an old fashoined choke coil mounted on the intake it has an electric choke so there is no exhaust port to worry about the gasket on top of the spacer is the same as the gasket on the botom of the spacer. |
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91nautique
Senior Member Joined: May-26-2005 Status: Offline Points: 104 |
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Guy's Is there an exhaust crossover port on this model engine under the carb spacer? If so what gasket did you use between the spacer and the manifold? (You can't use the standard gasket that you use between the carb and manifold) It will burn through and leak exhaust gases into the engine under the spacer. |
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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The curb adjustment. I call it a screw that adjusts the lever to change idle. it is unscrewed and sitting on my dash. With that out, it will run at 650/700. Sure that is where I want to be, but shouldn't an engine stall with the screw taken all the way out?
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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ok maybe some games are being played. But what's on the dash? and Why is it now idling below 1000 and set about where it needs to be, I'm confused and about finished with any future help. |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5778 |
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I think 79 has tried to communicate this to you but give this a try.
Back your curb idle all the way out which I think you have already done. Now turn your idle mixture screws in(closed) all the way(both sides). If the motor does not stall then you're not running on the idle circuit so we have to figure out why. Is there any possible way your linkage is binding preventing the throttle from completely closing? Is there gasket material binding on the butterflies? Something is keeping the throttle part open. Guys is there any way for the secondaries to be partly opening or how about a float level too high on the secondaries dumping fuel down? What about the secondary linkage, any possibilty of binding or bent linkage. |
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You can’t change the wind but you can adjust your sails
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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If you were at 10ATDC, it might start ok, but wouldnt like any sort of load. Probably not your problem though, as you could still dial in your idle with wacked out timing.
If the curb adjustment has no effect, then something may be hung up- are the butterflies all closed? |
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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It runs well where it is. I doubt it would run this well if it was 20 degrees below where it should be?
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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Well It must be RH then. I shall readjust timing then
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vondy
Platinum Member Joined: November-29-2007 Location: Dallas, Texas Status: Offline Points: 1116 |
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I'm sure it is. Just trying to think of anything.
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Vondy, Ive only seen/heard about the backwards timing marks on a handful of engines, and all were of the 60's to early 70's vintage. The marinizers must have gotten their act together soon after that, as every RR engine Ive dealt with (78 and newer) has had the marks going in the right direction. I suspect his mid-80's PCM to fall into that category. |
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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Ohhh I see! Sorry about that. Yes I have adjusted that. In fact it is sitting on my dash now! Still idles at 650/700!
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vondy
Platinum Member Joined: November-29-2007 Location: Dallas, Texas Status: Offline Points: 1116 |
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If you sitting in the back of the boat looking forward is your engine turning clockwise or counterclockwise?
Clockwise would be right hand, reverse, rotation. Counterclockwise would left hand rotation. If you look at your timing marks, from the front of the engine, is the BTDC side on the right of 0, TDC, or left? My BTDC is on the right of TDC. And I have a reverse rotation engine so that means my timing marks are backwards. When this is the case you buy some timing tape, like I just did, and put it on upside down. I went to ACE hardware and got some fittings to plug my vacuum gauge in on the manifold right behind the carb. I removed the brass plug you see in this pic. Here it is in my new manifold. The brass fitting to the right with the red cap. Sorry it's the only pic of it I have here at work. You should be able to plug it into your PVC port on your spacer as well. I'm no expert here so if anyone sees anything wrong please correct me. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Clearly we have a communication issue! I'm not asking about the timing, Im asking if you adjusted the curb idle adjustment screw (presumably a Holley on that PCM):
If there is a piece of advice that confuses you, ask! |
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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Yes, set at 10 degrees
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21169 |
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Have you adjusted your curb, as mentioned (several times) above?
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WhiteLakeSkier
Senior Member Joined: July-03-2009 Location: White Lake, NY Status: Offline Points: 197 |
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Hmmm, How can I tell if it is reverse rotation? The motor spins counterclockwise when looking at the flywheel. I still need to get a vacuum gauge, do I just hook into the PCV line? It just troubles me that I cannot adjust the idle to stall. Something is not right and I don't know what else to adjust!
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