Ford 351w stutters/lurches/catches under load
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=37113
Printed Date: October-07-2024 at 4:30pm
Topic: Ford 351w stutters/lurches/catches under load
Posted By: hayek
Subject: Ford 351w stutters/lurches/catches under load
Date Posted: August-19-2015 at 4:47pm
|
My Ford 351w starts great, idles fine, revs up fine with no load, but as soon as I get it in the water and go to get on step, past 2000 rpm everything goes to hell with it stuttering/lurching/catching up for a fraction of a second/lurching etc. This problem started after wintering, and then in the spring, I took it in to get a "tune up" which consisted of a distributor cap and rotor, and a $500 bill (Canada is insane). In the fall on the last run, we didn't have this stuttering problem. 1. I've taken the air filter off during operation, and I can't see any fuel coming out of the secondaries. 2. I've replaced the fuel pump (it works) 3. I've checked the plug wiring sequence to the distributor cap (it's correct) 4. I've cleaned the carb, checked the bowl-to-jet line, blew out all the jets in the secondaries, everything is really clean in there. 5. Checked the linkages when the engine isn't running, and the secondaries open up as they should. 6. The carb is fairly new, and I'm having a hard time believing it's some blockage in the carb because everything seems really clean. 7. The accelerator pump is operational and working fine. 8. I've replaced the water/fuel separator filter, no water in there. 9. There's a bit of corrosion on the exterior of the distributor, don't know if that's useful information. Please help. Thanks. |
Replies:
Posted By: hayek
Date Posted: August-19-2015 at 4:48pm
| Also, it seems like the stuttering might start before the secondaries would be activated, but I'm not entirely sure. |
Posted By: JoeinNY
Date Posted: August-19-2015 at 4:57pm
|
Are you sure this isn't a transmission slipping issue? Have you checked and/or topped off the fluid lately? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: hayek
Date Posted: August-19-2015 at 5:29pm
| I'm absolutely positive it's not a transmission issue just because I can replicate the issue to a smaller degree in the driveway or lake in neutral when it's hooked up to a hose at 3000 rpm. |
Posted By: hayek
Date Posted: August-19-2015 at 5:30pm
| I guess when I said "revs up fine" in the original post that's misleading. I can still notice the hesitation when not under load, it's just far less pronounced. |
Posted By: GottaSki
Date Posted: August-19-2015 at 5:35pm
|
Secondaries dont open till much later. If the last thing they fixed was the cap or points, i would look at them next, and un-fix them. My first guess is point gap and or someone omitted the spring on the points ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: hayek
Date Posted: August-19-2015 at 6:34pm
There's no gap between the points, and the spring seems pretty strong..
|
Posted By: SNobsessed
Date Posted: August-19-2015 at 6:39pm
|
There should be a .018 inch gap when the rubbing block is on the peak of cam lobe. If not, there's your problem. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: hayek
Date Posted: August-19-2015 at 6:49pm
Here's the gap just a tiny bit before the peak. Wouldn't it never fire if the points didn't break at the peak?
|
Posted By: 8122pbrainard
Date Posted: August-19-2015 at 9:22pm
Is the "tiny bit" .018"? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
hayek wrote:Posted By: 8122pbrainard
Date Posted: August-19-2015 at 9:24pm
Please post a picture. Hopefully you don't have an air filter. If so, it's potentionally a bomb you are driving. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: hayek
Date Posted: August-19-2015 at 9:59pm
| Presumably there is a spacer I can get to measure 0.018 in? |
Posted By: 8122pbrainard
Date Posted: August-19-2015 at 10:07pm
They are called feeler gauges.  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: hayek
Date Posted: August-19-2015 at 10:11pm
| I'm calling the round assembly that sits on top of the carb fixed with a wing nut an "air filter" |
Posted By: hayek
Date Posted: August-19-2015 at 10:12pm
| Thanks. I'm in town now so I'll go buy some |
Posted By: 8122pbrainard
Date Posted: August-19-2015 at 10:14pm
Flame arrestor! To be safe, please post the picture. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: SNobsessed
Date Posted: August-19-2015 at 10:30pm
|
Those points look pretty burnt to me. Maybe run some emory cloth thru them while you are in adjustment mode. Also, make sure the centrifugal weights (under the points plate) are not rusted up &boyh have springs. 1 spring is supposed to be a little loose. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: scootdogydog
Date Posted: August-19-2015 at 10:41pm
|
Test the resistance through the points when they're together. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=7183" rel="nofollow - 1999 Python 1980 Ski Tique 1968 Mustang WIP |
Posted By: hayek
Date Posted: August-19-2015 at 11:05pm
the "air filter"
|
Posted By: hayek
Date Posted: August-19-2015 at 11:37pm
| Resistance through the points is ~30 ohms on the "200" ohm setting. |
Posted By: scootdogydog
Date Posted: August-19-2015 at 11:39pm
|
Time to replace the points... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=7183" rel="nofollow - 1999 Python 1980 Ski Tique 1968 Mustang WIP |
Posted By: hayek
Date Posted: August-19-2015 at 11:45pm
Looks like I'm missing one of the two springs. The spring that is on there would not pull the weights back to the idle setting. They move freely, and you can advance and pull them back by rotating the shaft (just a little bit of play) but I don't see them returning to the idle position based on the resistance left in that spring. No way. 
|
Posted By: hayek
Date Posted: August-19-2015 at 11:47pm
The points were just replaced. Less than 1hr on the engine since they've been replaced.. but I can put new ones in there. The gap between the points at the widest is 0.017in., so a little closer than what they're supposed to be. 
|
Posted By: scootdogydog
Date Posted: August-19-2015 at 11:54pm
30 ohms is just a bit high, i think... maybe not the source of your problem, but between two pieces of metal that are touching, it should be under 2 ohms ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=7183" rel="nofollow - 1999 Python 1980 Ski Tique 1968 Mustang WIP |
Posted By: hayek
Date Posted: August-19-2015 at 11:56pm
| Fair enough, it's about time I learn to do that anyway. Thanks. |
Posted By: 8122pbrainard
Date Posted: August-20-2015 at 7:33am
|
With only 1 hour on the point set, they should not be pitted like that. The arcing that causes the pitting is quenched by the capacitor. They are known to be bad out of the box. Wa a new capacitor installed with the new point set? Do try another set along with a new capacitor. You need both springs on the advance. They control the advance curve. You auto parts store should have them or get them. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: SNobsessed
Date Posted: August-20-2015 at 11:15am
|
Ski Dim sells the springs, IIRC. After your repairs, set the timing with a timing light, to be between 8-10 deg BTDC @ 600RPM. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: hayek
Date Posted: August-20-2015 at 12:19pm
|
The capacitor was replaced with the points. I'll get a new tune-up kit. Won't hurt to have an extra distributor cap and rotor in the boat. I'd like to just replace the whole distributor with a newer one with electronic ignition, but I'm worried I'll mess up the timing. There's a white mark on the wheel that you use to indicate timing (with the needle being on the block) but it's certainly not a factory mark, and I'm not sure if it would indicate top dead centre, or idle advance. I would hope it indicates top dead centre. It is dangerous, being an amateur and trying to find TDB oneself, applying the timing tape (the "ruler"), and setting the timing oneself? Or is that something I'm just going to have to get comfortable with? Thanks. |
Posted By: Gary S
Date Posted: August-20-2015 at 1:05pm
It was a right of passage with us baby boomers to watch our dads or grandfather tune up the car in the fall. I also remember the stories of my dad watching his grandfather pour and scrape bearings. Someday my son will tell the story of him watching his dad checking the oil level by turning a knob on the driver information center  ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: 8122pbrainard
Date Posted: August-20-2015 at 8:40pm
Get the engine running on the point set. There's nothing wrong with them. They have worked for many many years. When you install the points, make sure the point contact faces are parallel. There are times when bending the arm is needed. The picture of yours, show the pitting on one edge indicating the faces aren't parallel. . ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |