Timing Puzzle
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=3171
Printed Date: November-23-2024 at 9:09am
Topic: Timing Puzzle
Posted By: jefmar
Subject: Timing Puzzle
Date Posted: March-12-2006 at 6:16pm
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I recently bought my '89 Nautique with PCM/Ford 351. It has low hours - 380 hrs - the previous owner was adamant that the hours are original. It was running rough with a high idle when I bought it.. but that is fixed now. I have one remaining problem when the timing is set per specifications (10 degrees btc) it stumbles/coughs under heavy acceleration in the water. I played with the timing by trial and error with the boat in the water and found that if the timing is retarded to 18 degrees btc it does not stumble; however, at 18 degrees btc the starter is slow to crank the engine. The starter cranks the engine normally at 10 degrees btc. I have a new carb and no vacuum leaks and noticed that the idle is not totally consistent (it varies from 600-800RPM) between heavy acceleration attempts. I am guessing that something is causing my timing to change. Or the distributor is not advancing correctly under power. But, the spring mechanism inside the distributor seems to move okay and the springs are functional. I also guessed that my timing chain/sprockets are loose/sloppy. Or the distributer is not set correctly...
The boat is running well but I do not feel comfortable advancing the timing so far that it affects how quickly the starter cranks the engine. Here is my diagnostic results and what I have changed so far: -Fuel pressure: 4 psi -Fuel flow: did not measure it carefully but half filled a soda can with about 10 revolutions of the engine. -Vacuum: Steady 19"Hg at idle. I had some leaks but fixed them. -Compression: looks great (120-135 psi) -New Holley 4160 marine carb for 351 (Holley part number HLY-0-80319-1) -Cleaned spark arrestor -New electronic ignition conversion (GLM Part number 72540) in the original Prestolite distributor -New distributor cap, rotor, spark plugs, spark plug wires -New coil -New gas filter/oil water separator -New PCV valve Before I tear into the timing chain or buy a new distributor, does anyone have a suggestion of what the problem is?? What would you try first?? ------------- 1989 Ski Nautique 2001 |
Replies:
Posted By: JEFF KOSTIS
Date Posted: March-12-2006 at 6:34pm
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If you had to set the timing to 18 btc, then you are advancing it. Did you try putting the timing light on it and start at idle and increase rpm as see what it is?? This will either prove correct or incorrect advance.
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: jefmar
Date Posted: March-12-2006 at 7:21pm
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Thanks Jeff. You are right, I advanced rather than retarded the timing. I wish I would have thought of checking the mechanical advance when I had it in the water earlier today. I will check it later this week.. It looks like I should be at about 32 degrees btc at 3000RPM from other posts... does that sound right? ------------- 1989 Ski Nautique 2001 |
Posted By: JEFF KOSTIS
Date Posted: March-12-2006 at 7:35pm
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I would try it at different rpms and take note of it so you can see a rough curve. Im not sure on the exact degrees for the rpm, and I forgot, you might have trouble with a generic timing light as the markings on the engine usually dont go that high. You can get a rough idea to see if it advances at all.
Jeff.. ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: Rick
Date Posted: March-12-2006 at 9:10pm
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This is a long shot but make sure 2 spark plug wires aren't crossed.check that the firing order is correct. If 2 of the wires are wrong you get a rough idle hard start and depending on the order advancing the timing can make it better. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=250&yrstart=1996&yrend=2000%20" rel="nofollow - 2000 Ski |
Posted By: 64 Skier
Date Posted: March-13-2006 at 1:00am
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Couple of questions? Does she knock with that much retardation? Initial timing is "recommended" at 10-12 degrees but the only way to time the engine is in the boat running and listening to the engine as you further retard. This is also the only way to get full power. For some reason I hvae 3 timing lights...they all read different but within about 2 degrees.
Before you time her on the lake...measure full advance and make a simple plot of timing versus rpm up to 3000 RPM. Springs get old and I've seen some "jump" which causes a stumble simlar to a carb with a weak accelerator pump. Time the engine with the fuel you plan on running. The gas we purchase on the lake is somewhat less quality than what I buy at the pump. This also made a difference in my boat. When I was tuning I had a fresh tank of premium. When pulling skiers in the spring she'll have an old tank with "Stabil" so I save the timing check for later. What cured the rough high idle? ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: 79nautique
Date Posted: March-13-2006 at 6:29am
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Remember you have to set the timing first then adjust the carb's idle and idle mixture screws and not the other way around. Get the timing at 8-12 btc then adjust the idle, then fine tune the carb using the vacumm gauge to adjust the idle mixture screws and idle screw.
Make sure that the wires aren't crossed like rick suggested as well. Set the base timing then see what it is at 3000rpm and that will tell what the full advance is. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 882001
Date Posted: March-13-2006 at 7:04am
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^^^^ well said 79^^^^ ------------- kemah texas http://www.correctcraftfan.com/diaries/details.asp?ID=163&yrstart=1986&yrend=1990 - 1988 skinautique "2001" |
Posted By: jefmar
Date Posted: March-13-2006 at 9:39am
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Thank you for the input
Jeff, Rick & 79 - I will check the spark plug wiring, reset the timing to around 10 btc at idle, adjust idle mixture and idle screws using the vacuum gage, and note the timing curve... later this week. 64 skier - there is no knock when the timing is set at 10 or 18 btc at idle. The rough, high idle was mostly caused by a vacuum leak in the hose to the pcv valve.. a tune up helped too. ------------- 1989 Ski Nautique 2001 |
Posted By: 79nautique
Date Posted: March-13-2006 at 10:11am
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Be sure that the idle is at around 600-800 rpm before you set the timing, or you will get false reading because you will start to engauge the mechanical advance. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: JEFF KOSTIS
Date Posted: March-13-2006 at 8:22pm
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All are possibilities. If timing is OK, check the PCV valve. It may be sticking and causing a leak and unstable idle. If you put your finger over the end of the PCV valve at idle, you should hear it "click" and suck your finger in. When you pull off your finger, it should "click" again.
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: jefmar
Date Posted: March-14-2006 at 7:27am
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79.. Thanks for the tip.
Thanks Jeff. I forgot to mention that I have a new PCV valve. It was changed when I fixed the vacuum leak. The new one seems to function correctly. ------------- 1989 Ski Nautique 2001 |
Posted By: jefmar
Date Posted: March-26-2006 at 8:33pm
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Sorry for the slow troubleshooting. Finally had a chance this weekend..
I checked the spark plug wiring, reset the timing to around 10 btc at idle, adjust idle mixture and idle screws, and noted the following timing curve: 600 RPM 10 degrees 1000RPM 10 1500RPM 12 2000RPM 18 2500RPM 20 3000RPM 22 What do you think? I also noticed that spark plug wiring order is correct for LH rotation but based on the schematic in the repair manual the wires appeared rotated clockwise one position (i.e.; the front is no. 6 rather than no. 2). Does this mean anything? ------------- 1989 Ski Nautique 2001 |
Posted By: 64 Skier
Date Posted: March-27-2006 at 12:05am
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You got me stumped on the wiring. I'd have to see an engine in front of me to understand.
However, you should have 10 more degrees of advance. The new electronic ignition in the old Distributor is OK, but it sounds like the advance is not working properly. Take it apart and look at the springs. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: 79nautique
Date Posted: March-27-2006 at 7:01am
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It sounds like you are referancing where the wire is on the cap relative to the diagram in the manual and if so don't it's meaningless. All you have to worry about is the order and not location.
You need to check and make sure that the base plate for the mechancal advance is moving freely and not gumed up before you start changing the advance springs to get a little more top end advance on the timing. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: jefmar
Date Posted: March-27-2006 at 7:29am
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Thank you for the input
64 skier - I took it apart a couple weeks ago.. the springs are functional. 79 - the mechanical advance inside the distributor seems to move okay; however, there is very light corrosion on the metal parts.. Do you think it is worth the effort to disassemble and lubricate the mechanical advance or would you buy a new distributor? ------------- 1989 Ski Nautique 2001 |
Posted By: 79nautique
Date Posted: March-27-2006 at 8:20am
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I would clean and lube the plate and change the springs to correct the problem with the advance. Your springs seem to be to stiff and not allowing enough advance. It's an electronic ign already and not a points dist correct? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: jefmar
Date Posted: March-27-2006 at 9:10am
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Yes. It has new electronic ignition conversion (GLM Part number 72540) in the original Prestolite distributor. Where do you purchase distributor springs? ------------- 1989 Ski Nautique 2001 |
Posted By: 79nautique
Date Posted: March-27-2006 at 9:36am
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any auto parts house
------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: jefmar
Date Posted: March-27-2006 at 9:41am
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Thanks 79, I'll give it a shot ------------- 1989 Ski Nautique 2001 |
Posted By: SS-201
Date Posted: March-28-2006 at 3:45am
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Take a timing light set to 32-34 total at 2500 -3000 rpm.If this solves the problem, forget about the inital, its only a starting point. Of course too much advance will detonate or buck at start.The chain retards it self from use, the advance springs lose their tension. If its hesitates from here then you need to check the chain and dist. ------------- SS 201 |
Posted By: jefmar
Date Posted: March-28-2006 at 6:53am
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79 - I went to a couple autoparts stores and neither had springs. I lubicated the assembly and tried adjusting the advance ajusting brackets in the distributor. I bent the brackets to engage the springs harder and I had no advance at higher RPMs. I bent the brackets the other way such that the springs were loose when starting and I get the same curve as before. I'm thinking I need a new distributor or something else is wrong. Do you agree? I noticed in your other posts that you suggested a new prestolite distributor on ebay.. Do you think that my electronic ignition conversion kit would fit in those ebay Prestolite distributors? I'm also considering Mallory.
SS-201 - I have essentially done that already. I'm only getting 12 degrees max advance so when I had the timing 18 btc at 600RPM, It was around 30 btc (18+12) at 3000RPM. You mention the chain.. 79 & SS-201 - Do you think the timing chain could have something to do with this? I'm only getting 12 degrees advance max.. I possibly could pull my distributor and have a shop measure how much advance I should see in the boat. If the shop measures 25-30 degrees max advance then the distributor is okay.. and possibly the timing chain is to blame.. Does that make sense? Or should I just buck up and buy a distributor? ------------- 1989 Ski Nautique 2001 |
Posted By: 79nautique
Date Posted: March-28-2006 at 8:16am
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The timing chain isn't the issue, it will retard the timing a little, but it won't change as it runs. Don't under stand what bracket you bent but you should have bent anything, maybe a new dist wouldn't be a bad idea, mallory YLM-554-CV or a YLU-554-CV ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: jefmar
Date Posted: March-28-2006 at 9:16am
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Thanks 79, The PCM repair manual labels the posts that hold the springs as "advance adjusting brackets". I bent them a little to put more/less spring pressure at rest. ------------- 1989 Ski Nautique 2001 |
Posted By: HOLESHOT
Date Posted: March-30-2006 at 10:24am
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jeg or sumitt will have the springs
------------- IF IT HAS A SPARKPLUG I CAN FIX IT |
Posted By: jefmar
Date Posted: April-22-2006 at 11:55pm
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I bought and installed a new old stock prestolite distributor off ebay. Here is a link to the completed auction.
. http://cgi.ebay.com/ebaymotors/351-LH-Ford-Marine-Distributor-PRESTOLITE_W0QQcmdZViewItemQQcategoryZ31284QQitemZ4633218983QQrdZ1QQsspagenameZWDVW - Purchased Distributor Unfortunately it did not solve the problem. At 10 btc initial it still stumbles in the water out of the hole. At 20 btc initial it runs very strong at any RPM but starting it is a little difficult as it requires pumping the throttle to get it started. Setting it back to 10 btc, it starts perfectly. Here is the rough timing curve measured: 700RPM - 10 degrees 1500RPM - 20 degrees 2000RPM - 22 degrees 3000RPM - 22 degrees I am thinking that Mallory MAA-YLM554CV will provide the advance curve (and adjustability) that I am looking for but it seems strange that two distributors have the same problem and something else might be going on.. Any suggestions before I spend more money and buy the Mallory?? Thank you for your help. ------------- 1989 Ski Nautique 2001 |
Posted By: 79nautique
Date Posted: April-23-2006 at 12:37am
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well first your timing should be around 8 btdc and the max needs to be 30-32, so you have a mechanical advance problem of some kind, stiff/strong springs or sticky components limiting advancement of the base plate.
Your stumble out of the hole isn't the timing at all, it's the accel pump on the carb or the carb it's self. If you can't adjust the dist you have, a new one isn't going to make matters better, do your self a favor and save your money and pay someone to fix your problems that knows how to do it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: jefmar
Date Posted: April-23-2006 at 9:43am
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Thanks for your input 79 but I will not give up and take it to a mechanic yet. I just purchased and installed a new carb; nothing changed when it was installed. If the accelerator pump is to blame, then the old carb and the new carb both had accelerator pump issues.. this is doubtfull. Changing springs in the Prestolite distributor is easy but finding springs for it is not.
------------- 1989 Ski Nautique 2001 |
Posted By: Jim_In_Houston
Date Posted: April-25-2006 at 10:01am
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Jefmar,
Your initial timing needs to be around 8 to 10 degrees BTDC. Lower timing advances like this makes the engine easier to start. (I used to drive around in a Ford Model A that had a spark advance control lever (before these modern days of automatic advance) attached to the steering column. You had to retard the spark a lot just to get the engine started - then the faster you wanted to go the more you would advance the spark.) At higher RPMs the timing has to (of course) be advanced. Every engine and installation is a little different and the best timing depends on your choice of fuel and your engine. Typically, a good total advance is somewhere around 32 to 34 degrees coming in somewhere around 2500 to 3000 RPMs. 30 degrees may work well for you but it should not be less than 26 to 28 degrees. Your total full advance is presently too low and it is coming in too soon. You are going to have to struggle with getting your advance curve to these values. It sounds like money is no problem for you. My advice is to get a new Mallory distributor and sell you other distributors on Ebay. Be sure to get a marine distributor NOT an automotive distributor. (Or less thee suffer the wrath of 79). (For peace of mind be sure to accurately describe your old distributors on Ebay.) BTW, I struggled with my timing a lot until I discovered my engine was a reverse rotation engine and the previous owner had installed a standard automotive balancer. I was setting my timing at 25 to 30 degrees ATDC and couldn't figure out why my boat ran so crappy. (I bet I am not the only one to do that.) -jim ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 79nautique
Date Posted: April-25-2006 at 10:46am
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I guess I've never seen a carb that you could take out of the box, bolt on to the engine and only have to adjust the idle, very foolish thinking to me. I've always had to inspect and adjust the linkage, idle air screws, float levels, idle and the throw of the accelarator pump. So If your saying that it runs fine at 20 degrees of timing and comes out of the hole without stumbling as well then something is way off or you have a bad harmonic blancer giving you a false timing reading but I doubt it since it doesn't crank right, so I'll assume that you still have the stumble at 20 degrees of timing and the stumble coming out of the hole is caused by accel pump being out of adjustment 9 out 10 times. The pumps not bad, it's just squirting too much or too little gas, to soon or too late causing a stumble. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: David F
Date Posted: April-25-2006 at 11:26am
| FWIW: I purchased and installed a new Prestolite marine distributor and set timing to 10 degrees BTDC. Boat ran like crap under load...no power and stumbled. I then went back to what I have been doing for years...adjust timing by ear. Basically, I advanced the timing at idle until I get the smoothest AND highest idle, then back it down just a bit. On a warm engine, it must restart easily. If it cranks slowly (hard) then I retard the timing ever so slightly until it starts easily. Then I perform full throttle acceleration runs listening for detonation. If non, then I am done. If I get detonation, then I retard just a bit and retry. At the end of this excercise, I usually get a very strong running engine with no stumbling. |
Posted By: 79nautique
Date Posted: April-25-2006 at 11:41am
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so in other words your not very good at adjusting a carb either. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: David F
Date Posted: April-25-2006 at 11:59am
| huh? Not sure I follow you. |
Posted By: 79nautique
Date Posted: April-25-2006 at 12:13pm
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instead of adjusting the carb to fix your other issues when the timing is set correctly, you choose to mask or hide the effects be advancing the timing and ignoring the real problems, thus you sacrifice maximum performance and fuel ecconony for being lazy ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: David F
Date Posted: April-25-2006 at 12:31pm
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Well, 79Nautique, when you are wrong, you are very wrong. You assume too much. Do you really think that I am that stupid or lazy? Is the carb the magic bullet that will fix timing issues? Come on now...you should know me better than that by now. ------------- |
Posted By: Jim_In_Houston
Date Posted: April-25-2006 at 12:38pm
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This place is better than a bar on Friday night.
You know, he could have both problems. He needs to get his carb and his timing right. David I agree with your posts 99.9% of the time but I think this boy needs a timing light. Setting the timing with a light is easy. Once the timing is set attack the carb. In my mind, you should do it in that order. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 79nautique
Date Posted: April-25-2006 at 12:42pm
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maybe we need a three page disortation on setting timing and how to adjust a carburetor.
The first step in a tune-up after the plugs, rotor and cap are inspected and/or replaced is to set the timing, them adjust the carb's idle and idle mixture screws and sometimes if things are really messed up you have to adjust the idle and/or idle mixture screws while getting the timing dialed in, I guess you just by-pass adjusting the carb and just turn the dist untill it sounds right, to me that's a shade tree mechanic with his head up his you know what. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 79nautique
Date Posted: April-25-2006 at 12:44pm
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then again you could just hit the carb with your hammer some more and hope that fixes the problem. Stick to fixing fiberglass ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: David F
Date Posted: April-25-2006 at 1:06pm
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Ok, since you think you know my methods, maybe I will go ahead and be more specific.
I installed a new carb and new distributor at the same time in order to feel good about selling the boat. I started and adjusted each on the trailer (i.e no load). I did the following: 1. Brought the engine up to normal operating temperature. 2. Set timing to 10 degrees. 3. Set base idle to 600 rpms (low, but done to mimic in gear idle speed). 4. Checked timing again and made small adjustment. 5. Tuned carb idle mixture screws for highest smooth idle speed. 6. Adjusted idle speed back to 600 rpms. Recheck/adjusted timing. Took the boat to the lake and although it started and idle perfect (after increasing idle speed to 600 in gear), it ran like poop. Would not take the throttle and struggled to get up to speed. Now I can guarantee that fiddling with the mixture screws would not solve the problem. Adjusting the fuel level in the fuel bowls would not solve the problem. Adjusting the accelerator pump would not solve the problem. BUT, advancing the timing like I mentioned made the engine run perfect and strong. Better than it has in years. Call it what you want, but do not assume you know how I do things. I may be different from how you do things, and that is fine. My point is that people get hung up on setting timing to factory specs...works sometimes, but other times it just does not work. BTW, my engine is/was not built to factory specs. One last thing. If you were astute, you would have figured out that the hammer was used on the old corroded carb that fouled the needle valve due to the corrosion. No amount of rebuilding was going to fix that problem and I am smart enough to know that. So, until the carb was replaced, the hammer was a easy, in the middle of lake, solution. The post was meant as humor...something some of us have and some of us do not. I am done with this thread...so flame away...you can have the last word. ------------- |
Posted By: 79nautique
Date Posted: April-25-2006 at 1:30pm
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no the idle mixture screws won't effect anything off idle and the floats could have been a little off and need adjusting, but since all of that didn't effect it or solve the problem completetly, then I would went straight too the mechinical advance, well no first I would have checked the timing at 3000 rpm and verified it was in the low 30's but then again I would have done that when I set the timing the first time, so ya I would have gone sraight the the mechanical advance, but wait maybe I would have looked at the carb a little more first and verified that the secondary's where opening up correct, rthen went to the timing.
Not everyone does things the same way some stand in the wind and try not to get wet other diagnois the problem and then find the issue causing it and fix the problem instead of covering it. It's one thing to get it running long enought to get rid of it...it's a completely different story fixing right so that you don't have to worry about it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: David F
Date Posted: April-25-2006 at 1:42pm
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I lied, I am responding again...
The secondaries were not the issue, I checked. The engine would not take the throttle at all...even before the secondaries would have come into play. I mean it would not take the throttle at all. Yes, the advance curve could be off, but that does not explain the whole story. It could be that the timing marks are all wrong (very possible). I did not just cover the problem as once the timing was set to my liking, the engine ran perfect throughout the rpm range...strong and smooth and fast. If that is covering up a problem, then so be it. Just ask Bill Clinton...a good coverup is invaluable. ------------- |
Posted By: jefmar
Date Posted: April-26-2006 at 1:10am
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Thanks for writing in everyone. Anyone have success with the ebay New Old Stock (NOS) Prestolite distributors?
David Yes, same deal, glad you wrote in. And glad you checked the carb too. I also by trial and error adjusted the initial timing to find a balance between no stumble and hard starts. The boat runs t*ts other than that. I will continue to figure this out until it is perfect. I thought it could be something with the engine that is causing the timing to retard at higher RPMs. Possibly a sloppy timing chain or worn cam gear or something?? Couldn't be two bad distributors right?? I checked for slop between the crank shaft and rotor by rotating the crankshaft back and forth with a wrench and watching the rotor move it was tight with 5 degrees slop measured at the balancer. The gear on the cam shaft looks perfect. And #1 piston at TDC lines up with the timing 0 degree mark. I suspected two bad distributors but to be sure, I went to a high performance shop with a distributor machine and had the ebay New Old Stock (NOS) distributor spun. They found that the distributor goes up very fast to 12 degrees advance, stays at 12 degrees advance until about 2800RPM, from there it goes linearly to 20 degrees max at 4600RPM. Per my previous post, when I set the initial at 10 btc, I saw 22 btc at 2000 through 3000RPM (12 degrees of advance). So it looks like it matches and the distributor is to blame because there should be 22-24 degrees of advance at 3000RPM. The hipo shop agreed that the curve is not good. The hipo shop can tune it to what I want but I am concerned that I might have to pay more to have them curve it again if it is not perfect. I can buy spring kits for aftermarket and change it myself. So Im in the market for an aftermarket distributor, leaning towards the Mallory points version for $135 because spring kits are easy to find and I am cheap But that got me into trouble with the ebay purchase already! ------------- 1989 Ski Nautique 2001 |
Posted By: jimbo
Date Posted: April-26-2006 at 2:08am
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I wouldn't go with points but that's just me. I never learned how to adjust them and I'm too old to start. IF you are going to buy a new distrubor, I'd buy an electronic ignition one.
But, I'd take the original distributor to the shop and have them check it out and make the proper adjustments. I think it's a problem with the springs or gunk on the cams. I'm not an expert but if you get 20 degress advance on the bench and you put it in the boat and set it at 10 degrees advance to start with, wouldn't it be a total of 30 degrees at 4K rpms? Any help from somebody that knows what they're talking about? |
Posted By: David F
Date Posted: April-26-2006 at 9:05am
Yes, that is where I purchased my NOS Prestolite (screw down cap) distributor. It was indeed unused and in perfect condition. I did open it up and check it out for dust bunnies and surface rust. Blew it out with compressed air and re-lubricated moving parts. ------------- |
jefmar wrote:Posted By: 64 Skier
Date Posted: April-26-2006 at 10:18am
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You need maximum advance at 2500 rpm's....and definitley before 3000 due to load.
I'm not sure who made the comments about which is more important etc....but correct timing....is correct valve opening/closing....which yields the best signal for the carburetor. Checking the marks on the harmonic balancer at TDC is a must if your in question about initial advance. This is done after every re-build and then we set the carb. Without proper signal to the carb you can start chasing your tail trying to make these things run right....and end up with smooth idle and acceleration in the garage but then you place the engine under load and find out it stumbles, won't pull a skier or even get on plane. Tune again under load. I usually pull a heavy slalom skier and put the timing light on her to see how she pulls...that's when we found that full advance at 2500 rpm's pulled better. Make sure he wears gloves, cause when you get her set right the only way to compare is WOT and it can hurt a little if he's whiner! Two bad distributors. WOW that's weird. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Jim_In_Houston
Date Posted: April-26-2006 at 5:25pm
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You got guts to open your motor box and put a timing light on the engine while running AND pulling a skier no less....
Wow. I can't do it. I can't even imagine it: "Here, put these gloves on. I'm going to time my engine while I'm pulling you." ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: April-27-2006 at 2:16am
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JIH....that's the pot calling the kettle black.....you can steer your boat, hold the speedometer and drink a beer at the same time while waving at all those Chocolate Bayou Babe's in thongs and that's way better coordination than what I do with a timing light!
I sit on the floor and just hold on to the ski pole. We don't install the motor box until it runs correctly. I got so damn tired of lifting it up after a thousand mistakes that I just left the thing out of the boat. I used to drive heavy oilfield trucks back in the late 70's. We had a John Deere 450 with backhoe and in my Bosses opinion if you couldn't drive, shift gears (split) and pour tomato juice in your beer at the same time...you were no driver at all! I guess that got me trained up for this old boat. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Waterdog
Date Posted: April-27-2006 at 7:29pm
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Just for the heck of it try pulling off one plug wire at a time & see if any one wire changes the idle quality more than another.
I looked at a southwind for sale that "only needed a tune up" it ran like crap-stumbled & idled poor. The guy let me bring it home to slap a tune up on it ( plug ,wires ,rotor,cap ect.) After the plug wire trick I found the cam lobes wiped out on the #1 cyl. I payed for the tune up and he took the boat back! I hope it's something less painful than a rebuild. |
Posted By: Munday
Date Posted: April-27-2006 at 9:57pm
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Wow quite a post here.
What I would do is take one distributer to a speed shop that had dist, machine have it spun and set to propper advance curve for the motor cam I was running.give them the recommended base timming too.reinstall and try, make any adjustments to compensate for fuel.Now play with the carb till it ran to my satisfaction Good luck Munday |