| roymech | -- 05-11-2010 @ 5:53 PM |
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i have a 53 ford pickup with a newly rebuilt .030 over 239 in it. i have 85 pnds. comp. cranking on all cyls. spark on all cyls., its got new pistons,rings,valves,springs,heads,timing,10/10 crank, like new cam, new distributor,cap,rotor. and it still misses on #3 and #5 cyls. ive swapped out the intake and gone thru the valves twice changed plugs and wires and still no change. any advice or thoughts would be greatly appreciated. thank you.
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| ford38v8 | -- 05-11-2010 @ 8:40 PM |
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Roy, If the miss is constant, you may have swapped plug wires between 3&5. If it is intermittent, check for carbon tracking inside the distributor cap. Any backfiring through the carburetor can also indicate cross firing. Alan
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| roymech | -- 05-12-2010 @ 3:58 AM |
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i have checked and rechecked the firing order ,swapped plug wires and even put a different cap on. same results its always #3 nd #5 could the carb be the problem?
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| supereal | -- 05-12-2010 @ 8:44 AM |
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How did you determine that only #3 and #5 are misfiring? As the other cylinders fed from the carb seem to be OK, it is doubtful that the carb is at fault. Check all plug wires with an ohmmeter. They should all register within a few ohms of each other. If they are carbon filament wires, flex them as you check, particularly at the end connectors. At idle sped, pull the plug wires and test to ground at the cylinder head. The suspect cylinders should be as "hot" as the rest, with a strong, blue spark. You have covered most of the "usual suspects", but the problem you state is almost always found in the secondary (high voltage) side of the system.
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| 37RAGTOPMAN | -- 05-13-2010 @ 7:15 AM |
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this is along shot., but how are the distributer cam lobes ? does the points open and close for every cylinder? is there a wrobble in the shaft ? check your dwell, new dist does not mean it is ok, is it China or FORD U.S.A.? just for ho ho's try a leak down test in those 2 cylinders, and also check the ignition wires, like superreal said, are they running through a loom of some sort shorting out, you can spray the wire with a mist of water while running, does the spark jump ? and just swap the 2 spark plugs with 2 others, let hear how you made out, It has to be something you overlooked KEEP ON TRUCKIN 37RAGTOPMAN
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| roymech | -- 05-13-2010 @ 11:39 AM |
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i will try everything you guys suggested all good suggestions i`ll let you guys know how it goes
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| Reds34 | -- 06-01-2010 @ 6:24 PM |
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I actually have a similar problem, although it is a '34 with a 221 c.i. It only runs on 4 cylinders though. I changed wires, distributor, taken the carb apart 2 or 3 times and still have no idea. It skips on 1,4,6 and 7 if i believe correctly. Sorry to hijack the thread. Thanks in advance for your help. Red
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| tgs40ford | -- 06-01-2010 @ 7:25 PM |
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Roy, Were you able to find the solution to your problem? I had a similar problem many years ago on a newly rebuilt motor. This may not be the same problem you are having but i hope it helps. My problem was mainly at idle. Rebuild shop had left the valve guide seals off. Allowing exhaust gases to mix with the intake fuel air mixture. Everything checked out with normal mechanical testing. Its been so long ago i forget how i finally figured it out. The seals fixed it. I pulled them all in the end and found three seals missing. Its still running great 35 years later. Good luck. Let us know how you made out.
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| supereal | -- 06-02-2010 @ 9:53 AM |
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If your engine skips or doesn't run on cylinders 1-4-6-7, they are not getting fuel, as the right (passenger) side of the intake manifold feeds those, while the left (driver) side feeds 2-3-5-8. That eliminates the ignition, as the distributor caps and rotors and wires are separate for each side. Be sure that you have the missing cylinders correctly by pulling the plugs wires to see what effect it has on each. I believe something is blocking the right side of the carb, possibly the main jet, or a passage feeding that jet is clogged. If you didn't boil out the carb and check it with compressed air thru the passages, it is easy to miss a blockage. If you have access to a spare carb, try it to confirm the problem. When diagnosing a V8 problem, always remember you are really dealing with TWO four cylinder engines joined at the crankcase.
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| supereal | -- 06-02-2010 @ 10:09 AM |
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I need to clarify my post. Looking from the FRONT of the car, the driver's side carb throat feeds cylinders 1-4-6-7, while the passenger side feeds 2-3-5-8. When I read my post, I think it could have caused confusion by saying "right and left".
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| Reds34 | -- 06-02-2010 @ 7:08 PM |
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I actually did switch carburetors and got the same problem, nothing had changed. I'm really at a loss on what to do. Thanks for your help. Red
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| supereal | -- 06-03-2010 @ 8:36 AM |
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Red: The fact that all the cylinders on one side are the problem has to be related. If the switch of carbs didn't change it, I'd pull the intake manifold and see what is happening on that side. You may find a mouse or bug nest, etc, blocking that side. I've seen that more than once. The intake manifold is the common link, as is the exhaust manifold, which could also be involved for the same reason. If the exhaust is plugged, the intake can't function.
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| TomO | -- 06-03-2010 @ 10:19 AM |
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Red, Remove the coil and look at the relationship of the rotor contacts to the inner distributor caps. It is possible someone installed a 37-41 rotor in your distributor. The rotor will fit, but the contacts will not line up. Tom
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| Reds34 | -- 06-03-2010 @ 2:15 PM |
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Superreal- it's not one side of the engine that is skipping. The cylinders that skip are the outside cylinders on the drivers side and the two inside cylinders on the passenger side. Tom O- I remember looking at the distributor and seeing that the rotor contacts were lined up with the contacts on the caps. The truck used to run fine a year ago, but one day I was driving it going up a hill and it just started skipping. It was lugging a little bit so I don't know if that has to do with it skipping. Thank all you guys for your help, I really appreciate it. Red
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| supereal | -- 06-03-2010 @ 3:58 PM |
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Actually, I was referring to one side of the intake manifold, rather than the engine. Did you ever confirm that only cylinders 1-4-6-7 are all affected? Or are others missing, as well. The fact that it ran well a year ago says, obviously, something changed. Two years ago, when I took my '47 out of storage, it began missing, bucking, and stalling. I noted that it smoothed out when I turned on my electric booster pump, so I assumed the mechanical pump was dying. Replacement didn't fix it. Neither did a new flexible line at the firewall. All filters were cleaned or changed, and the tank was new. After all of that, the only thing left was the gas line from the tank to the firewall, but I couldn't recall ever having to replace a line. Well, $18 for a new line and an hour's work fixed it all! The car runs better than it has in the 15 years I've owned it. The old line was filled with dirt and rust, and delivered only enough fuel to run the engine if power demand was very low. And all because I was "sure" the line was OK.
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| Reds34 | -- 06-03-2010 @ 7:20 PM |
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At first I used a timing light first and that said they were all working fine. Then I used a screwdriver to short out the spark plugs to find out which cylinders weren't firing. Thanks for your help. Red
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| TomO | -- 06-04-2010 @ 8:02 AM |
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Red, You have been replacing parts in the hope that you could fix it. It may be time to start over and diagnose the problem further before replacing any more parts. Sometimes the new parts will be defective also. Try this: Hook a vacuum gauge up to the windshield wiper port and try to adjust the carburetor for the highest steady reading. Make sure that both idle mixture screws adjustments affect the idle. If the engine is running too rough to determine when the highest reading is attained, turn the screws in until the engine almost stalls and then back off 1/2 turn and leave the screws in that position. Check the spark at each cylinder by holding the plug wire close to a head nut. Check for a nice blue spark at least 1/4" long at each plug. If you have a coil rebuilt by Skip, your spark should be 1/2". The spark should make a cracking sound. Short out the plugs one at a time, while observing the gauge. Record which cylinders have the most effect on the reading. Examine all of the spark plugs for good color and no carbon build up, paying special attention to the plugs from the cylinders that had little effect on the vacuum gauge. Perform a compression check on all cylinders and record the readings. Come back here with the results of your tests so we can try to diagnose the problem further. Tom
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| Reds34 | -- 06-04-2010 @ 2:32 PM |
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TomO- You said to make sure that both idle mixture screws affect the idle. I can take the passenger? side out completely and nothing changes. I put a vacuum gauge on and I got about 9 inches at 600 rpm, although I didn't mess with idle screws when I had the gauge on it. Who is Skip? I have heard his name mentioned before and I'm just curious what all he does. I was looking at getting a rebuilt coil, but they are a little high priced, so for now I'm running with a conventional coil. For removing the spark plug wires use insulated pliers to do so? I have gotten zapped by it recently and it hurt for the rest of the day.I will try to do the compression test this weekend. Thank you for your help and putting up with all my questions. Red
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| TomO | -- 06-05-2010 @ 7:45 AM |
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Red, you have found the source of your problem. Either your carburetor or intake manifold is blocked on the passenger side. Remove the passenger side idle screw and squirt carburetor cleaner in the hole for about 15 seconds, then replace the screw. Seat the screw lightly and then back out 1 turn. Start the car and see if it runs OK. If the car still only runs on 4 cylinders, remove the carburetor and check for blockage in the jets on the passenger side by removing the bowl drain plugs and squirting carburetor cleaner into the main jets. If the jets are not blocked, you blockage is in the intake manifold. You will have to remove the intake manifold and using compressed air blow through an intake port for cylinder 5 (front port on the drivers side) after plugging all of the other ports. This may dislodge the obstruction. If it doesn't try forcing water through the port. Skip is a vendor that rebuilds coils and water pumps. He is located in FL. You can purchase plastic pliers at electronic stores or at some auto supply stores. They sell them as fuse pullers. These allow you to pull a plug wire without getting zapped. Tom
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| supereal | -- 06-05-2010 @ 10:20 AM |
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If it is the two end cylinders on the driver's side, and the middle two cylinders on the passenger side that are dead, it is the passenger side of the carb that feeds them. There is no physical connection between the right and left sides of the intake manifold. That is why taking out the passenger side idle needle doesn't have an effect. No fuel or vacuum on that side is the reason. Both TomO and I have been saying this almost since this thread began.
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| Reds34 | -- 06-06-2010 @ 6:49 PM |
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Well, I got to work on the '34 today. Looks like I'm going to need to get the engine rebuilt. I sprayed carb cleaner in the idle mixture screw and it didn't make a difference. I took the carb off and prepared to take another look at it, but I decided to put my hand over the barrels on the intake. I had my dad turn it over to see if it had any vacuum. The passenger side had noticeable vacuum, but the drivers side didn't. I took the intake off and found the problem. The valve guides broke on cylinders 2 and 5. Sweet. Thank all you guys that have given me advice, I REALLY appreciate it. Red
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| TomO | -- 06-07-2010 @ 7:09 AM |
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Red, I m sorry to hear that your problem turned out to be a major one. If the engine was not an oil burner, you may be able to get by with just having a valve job done. Tom
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| supereal | -- 06-07-2010 @ 11:09 AM |
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That is why the recommended compression check would have saved a lot of guesswork. Now, the question is: why did the valve guides break? One would be understandable, but unusual, while two indicate a more serious problem of some kind.
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| Reds34 | -- 06-07-2010 @ 2:25 PM |
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I did a compression check back when this whole thing first started last year, and nothing seemed to be too out of the ordinary. I may do another one just to see, but it's crazy. The keepers are still attached to the valves so I'm not really sure what exactly happened. I may try to get some pictures of the "carnage". Thanks again everyone. Red
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| supereal | -- 06-08-2010 @ 9:28 AM |
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That would help, Red. The probable reason for valve guide failure would be loss of the fork that holds the guide in place. Carbon buildup in the valve stem might do it, if it caused the valve to seize in the guide. My problem is understanding why it would involve two valves at the same time. The old style two piece guides almost never break, but a broken or weak valve spring could allow the fork to fail by releasing tension on the assembly. We check for valve problems with dry/wet test. Compression is checked dry, then oil is squirted into he cylinder, and a new test is run. If the compression stays the same, or close to it, the valves are leaky. We will be interested in what you find, such as a missing fork lying in the bottom of the valve chamber.
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| Reds34 | -- 06-18-2010 @ 7:58 PM |
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Well, I got some pictures for you guys.
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| Reds34 | -- 06-18-2010 @ 8:01 PM |
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I can't make this stuff up. This piece was in the number 5 intake runner. I thought it was a piece of the valve guide, but I ended up taking the valve guide out and it was complete. I really have no idea how it got there.
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| Reds34 | -- 06-18-2010 @ 8:03 PM |
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One more of the flywheel. A little machining will take care of this right?
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| TomO | -- 06-19-2010 @ 5:34 PM |
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It is hard to tell what that piece is. In the first photo, it looks like a piece of the block is missing in the left hand intake port, but that piece doesn't look like it is the piece. Tom
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| Reds34 | -- 06-19-2010 @ 7:33 PM |
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In the first photo, the left intake runner (#1 cylinder) is "normal", while the right one (#2 cylinder) the piece that is higher is part of the valve guide. The second picture is the piece that was in the #5 valve port, but didn't come from that valve. I hope to get more photos after I get the engine rebuilt. Red
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| 37RAGTOPMAN | -- 06-20-2010 @ 8:22 AM |
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reds 34 that flywheel looks pretty nasty, I would try finding another, ask the machine shop what they think, advertise for one here on the want ads, KEEP ON TRUCKIN 37 RAGTOPMAN
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| supereal | -- 06-20-2010 @ 3:00 PM |
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Your flywheel has a "checked" surface, likely from a slipping clutch. Usually they can be resurfaced if the flywheel itself is not cracked. If the cut is drastic, the portion holding the pressure plate bolts must also be cut a similar amount to preserve the ability of the clutch disc to be properly gripped. We have resurfaced many that look that bad. The broken chunk seems to be from the top of one side of a valve guide.
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| Reds34 | -- 06-20-2010 @ 6:26 PM |
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I actually managed to find another flywheel so I will probably throw the old one in the scr*p pile, and get the one I found resurfaced. Red
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| ford38v8 | -- 06-20-2010 @ 9:22 PM |
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Red, after resurfacing your flywheel, bolt up the clutch and have the whole assembly balanced. Alan
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