| DHunt | -- 10-23-2015 @ 9:40 AM |
|
I just had my 1935 Flathead engine rebuilt by a reputable local builder. The engine starts and idles fine but has no power. No issues with back firing. Top speed is only ~ 20 mph. Engine compression is ~ 105 psi on each cylinder. We tried two different carburetors. I believe my distributor (original design) timing adjustments are correct. Any idea what I’m missing? Thanks for your ideas. David Hunt Kingwood TX
|
|
| 37 Coupe | -- 10-23-2015 @ 11:14 AM |
|
Mayby check air going in and exhaust out. Resticted air filter or plugged exhaust.Are you sure mechanically your accelerator to carb linkage is free not binding. Try another condensor This message was edited by 37 Coupe on 10-23-15 @ 11:15 AM
|
|
| CharlieStephens | -- 10-23-2015 @ 12:12 PM |
|
Check to be sure you have full travel on your carburetor linkage. Are you opening the butterflies all the way? Maybe the linkage was bent when putting the engine into the car. Please let us know the final result. Charlie Stephens
|
|
| 1932BB | -- 10-23-2015 @ 12:42 PM |
|
Check gas supply to the carb. Sometimes filters can dry out during the engine rebuilding process and not pass enough fuel.
|
|
| MG | -- 10-23-2015 @ 5:06 PM |
|
Sounds like your engine running on only four cylinders - gas is getting to just four cylinders. Change the carburetor.
|
|
| 37 Coupe | -- 10-23-2015 @ 5:50 PM |
|
Somewhere he mentioned trying two carburetors but you brought something interesting up,fuel not reaching all 8 cylinders. He could check the plugs to see if some have not fired,mayby be the plugs,spark to certain plugs or fuel not reaching a cylinder because of obstruction in manifold or the block,mayby something was left in a hole, that is plugged.
|
|
| timcolr | -- 10-23-2015 @ 7:29 PM |
|
Just a thought, is the vacuum advance on the distributor OK? May have a crack or hole in the diaphram. Tim 1950 Fordor Deluxe 6
|
|
| trjford8 | -- 10-24-2015 @ 7:18 AM |
|
I think Tim may have the answer. Lack of proper vacuum to the stock distributor is the likely problem. I believe that distributor depends totally on vacuum to operate correctly. It is not advancing as you try to accelerate.
|
|
| TomO | -- 10-24-2015 @ 8:31 AM |
|
Check your spark at all cylinders. You should have a 1/2" blue spark when the engine is idling. A weak coil, a weak condenser or point gap can cause a weak spark limiting your power. If the spark is OK, check your vacuum at idle and at speed. Here is a link on how to interpret the readings. http://www.secondchancegarage.com/public/186.cfm If the readings are normal or near normal, I would check fuel delivery next. You could have a plugged fuel line, vacuum leak in the supply side or a flex line that is collapsing under vacuum. To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas. The vacuum brake on the distributor prevents too much advance under load. I doubt that it would affect power as much as you are seeing. It would more likely cause overheating under loaded conditions. Tom
|
|
| DHunt | -- 10-24-2015 @ 9:17 AM |
|
Thanks for all the great insight. I appreciate it. I will get to work on them David Hunt
|
|
| trjford8 | -- 10-25-2015 @ 10:01 AM |
|
TomO, I will correct my answer. I was thinking of the distributor on an 8 BA motor.
|
|
| supereal | -- 11-13-2015 @ 12:20 PM |
|
Substitute a new or known good condenser. Lack of power is a symptom of an open or weak condenser. The condenser, in addition to helping preserve the points, controls the coil by allowing a full charge after draining the previous cycle.
|
|
| carcrazy | -- 11-13-2015 @ 1:23 PM |
|
Have you checked the valve timing? Camshaft could be indexed incorrectly throwing the valve timing off.
|
|
| drkbp | -- 11-13-2015 @ 2:42 PM |
|
David, Be sure the vacuum port for the windshield wiper is connected properly or plugged. Ken in Houston Texas
|
|
| DHunt | -- 12-26-2015 @ 8:01 AM |
|
I hope this note finds you enjoying Christmas with you loved ones. I thought I would give an update and seek your further advice. (Other issues have kept me away from working on my car until recently.) I have looked into issues you all raised. I have found that I lose all vacuum during engine acceleration. I have ~ 14 inches of Vacuum at idle. I have checked for leaks on the carburetor (I have swapped carb with no success). I have a good seal between the manifold and carb. No leaks around the intake manifold or on the fuel pump riser. I don't believe I have a restricted exhaust pipe but can't say I have dropped it to confirm. I have swapped coils and condenser. I have good fuel flow from the fuel pump. I have good compression and my engine builder assures me the camshaft was installed correctly. At this point I have run out of ideas and would appreciate any further advice. Thanks David Hunt Kingwood TX
|
|
| TomO | -- 12-26-2015 @ 8:19 AM |
|
If you have good compression, and do not have a modified camshaft, you should have closer to 20 inches of vacuum at idle. A clogged exhaust system is can cause these symptoms. Here is a link to interpreting the vacuum gauge readings. http://www.secondchancegarage.com/public/186.cfm Scenario 14 shows the effect of a plugged exhaust system on engine vacuum. Tom
|
|
| DHunt | -- 12-26-2015 @ 8:38 AM |
|
Thanks Tom, Your link you shared earlier was very useful. For an exhaust leak Scenario 14 says its a relatively slow drop in vacuum upon acceleration. My drop is immediate upon acceleration. I'm happy to drop the exhaust to confirm. I have a Smitty Muffler I got from Mac's which is been on the car for about 5 years. I had asked my shop who installed the engine about this earlier and they said he had checked the exhaust manifold for debris before they installed the motor. Thanks David
|
|
| MG | -- 12-26-2015 @ 9:32 AM |
|
I'm still of the opinion your engine is running on just 4 cylinders. Do you have spark at all plugs? If you do, I'd check the intake manifold for restrictions...
|
|
| TomO | -- 12-26-2015 @ 10:20 AM |
|
Dave, Just a few more ideas about your problem. The vacuum gauge reading of 14 inches at idle, confirms your driving experience that the engine is very inefficient. You have good even compression, so now you have to determine what else could be causing this inefficiency. Normal indications on the vacuum gauge is that the vacuum will drop immediately when the throttle is opened, then the vacuum will increase as the engine develops power. If you continue to keep the throttle at the same opening, and the exhaust is plugged, the vacuum will decrease as the back pressure increases. You say that your distributor timing is correct, how did you come to this conclusion? Is the gap between the rotor and the cap terminals OK? Is the spark strong at all of the cylinders? Have you checked the rotor for excess play? Jake Fleming in Dallas has a lot of experience in setting the points on these distributors. He has a distributor machine and his charge is reasonable. Your rebuilder says that the camshaft was installed correctly, I have found that no one wants to admit that he may have made a mistake, until you show him different. To check, you would have to remove the timing gear cover, get no 1 (the front cylinder on the right bank) cylinder on the compression stroke and then line up the timing marks on the crank and cam gears. What spark plugs are you using and what did you gap them at? Tom
|
|
| trjford8 | -- 12-26-2015 @ 10:45 AM |
|
I know this may sound a little strange, but if your car sat for awhile when doing the repairs perhaps a mouse or a rat entered the tailpipe and built a nest in there. Maybe even got trapped in there somehow and plugged the exhaust. It has been known to happen, especially with "barn" cars.
|
|
| len47merc | -- 12-26-2015 @ 12:46 PM |
|
Happened to my '47 just as as you described trford8. Mouse hotel well established in the muffler after 35 or so years of being idled in a dry fully enclosed pole barn. Had to cut open one end of the original miffler to remove the Hilton. Almost had the exhaust fully blocked. Steve
|
|
| DHunt | -- 12-27-2015 @ 5:52 PM |
|
Thanks all for the continued interest in my issue. When accelerating the vacuum quickly falls to zero then builds back to a steady 15 inches. So that should rule out a restricted exhaust. My car only sat for 2 months this summer while the engine was being rebuilt. I would say that Scenario 11 describes my situation. It suggest retarded timing or bad points or Spark plug gap as the cause. I have new Motorcraft spark plugs TT 10 gapped at 0.025" inches. I have 1932 Cast Iron heads so these are the big plugs like a Model A. I had my distributor reconditioned recently (last month) by a professional shop in Indiana. I know he installed a new rotor as part of the reconditioning. How to I check the tolerance between the rotor and cap? I had a new set of caps from Mac's but I couldn't get them to sit true on my distributor so I put my old distributor caps back on. Those caps are the only thing I haven't replaced in my ignition system. I have spark to all my spark plugs. Engine also slows if a remove the wire from each of the spark plugs. Early in the troubleshooting we removed the intake manifold and checked it for debris and found none. Thanks for your continued help. David Hunt
|
|
| pauls39coupe | -- 12-27-2015 @ 10:14 PM |
|
I still believe you may have an exhaust restriction, have you removed the pipes or muffler to check this out? Check all the plug wires from cap to plug, to make sure they are in the correct order. Try a different distributor to be sure the timing is not retarded. Even the best rebuilders make mistakes now and then. Are the 32 heads a new addition? The chamber size may be large, causing a loss in compression. Check the brakes. You may have one or more locked up from sitting. Dragging brakes may seem like lost engine power. Let us know how this turns out.
|
|
| len47merc | -- 12-28-2015 @ 5:33 AM |
|
David - still trying to think of the most simple solutions to your problem. Just to be sure check the heat riser valve (if your vehicle's exhaust still has one) on the driver's side exhaust manifold to see both if it has free travel (meaning it is not stuck closed) and the butterfly is still attached to the shaft and rotating with the shaft when it turns. Steve
|
|
| TomO | -- 12-28-2015 @ 9:33 AM |
|
David, To check the gap between the rotor and cap, just remove the coil and turn over the engine until the rotor point is aligned with the contact on the distributor cap. The gap should be around .010". It is probably a good thing that you did not replace the inner caps as the new ones are of such poor quality that they should only be used on engine that don't need to be run. If you have a dwell meter, while you have the coil off, add a short wire to screw that holds the condenser to the coil. Make it long enough that you can connect your dwell meter lead to it. When you have the coil mounted on the distributor, connect your dwell meter to the wire and ground. Start the engine and check for 34-36 degrees of dwell. You also need to check the rotor for rotational and lateral play. Just because it is new doesn't mean that there isn't a problem with it. You could also try a different brand of spark plug and a larger plug gap (may be .028 - .030). Tom
|
|
| 40 Coupe | -- 12-29-2015 @ 6:03 AM |
|
14" of vacuum at idle is too low, with one Carb and a stock cam your looking for approx. 18" with a fresh rebuild maybe higher. The vacuum should drop suddenly as you accelerate RPM. Look on the web for a description of engine vacuum readings and problems associated, compare your vacuum reading to those. Have you adjusted the carburetor idle mixture screws? Ford tolerance gap rotor to inner distributor terminal for 35 Ford is .0035 min to .0105" This message was edited by 40 Coupe on 12-29-15 @ 6:16 AM
|
|
| shogun1940 | -- 01-01-2016 @ 10:18 AM |
|
I think your compression is to low,,the throttle plate must be wide open,,all spark plugs out. When all cylinders are low it indicates wrong cam/crank timing. Vacuum should be 18" at idle and go up to 19-20 at 1500 rpm, snap open the throttle and it should drop to near zero and then go 5" over what you had at 1500 rpm. If the exhaust is not the problem which it could be. Put the timing mark on tdc and put compressed air into # 1 cylinder if air comes out of the carb or exhaust you are probably one tooth off on the cam/crank gears
|
|
| DHunt | -- 01-01-2016 @ 5:55 PM |
|
Thanks for all your advice. I have learned a lot in the process. A quick update.. I don't have an orginal exhaust heat riser valve that could be restricting the exhaust. Also confirmed I'm not dragging my brakes. I agree its sometimes the simple things that are the source of the problems. The 1932 Cast Iron Heads have been on the car since I purchased it and I kept them on during the rebuilt. I replaced my new Motorcraft plugs with my old Champions that I had in the car before the rebuild. Gapped them for 0.025 inch. Noted the Champion plugs have the electrodes fully exposed compared to the Motorcraft plugs which have the electrode recessed into the plug body so I felt good about the change. After I did that the engine performance improved slightly. Engine Vacuum increased to ~ 16 inches. The mild back fire improved but was still there and still low on power. Without anymore "easy" ideas I advanced my Timing as much as it would go in my stock Distributor. I now have 18 inches of Vacuum and the Car has full power. Its also running cooler. So what does this mean? Is it possible to be a tooth out still on my cam? (Recall I have good compression on all my cylinders (100 psig). Thanks the comments. David Hunt Kingwood TX
|
|
| TomO | -- 01-01-2016 @ 8:20 PM |
|
It is more likely that your points are not set correctly. The opening of the break set of points determines the spark timing. Your timing could be off due to the way the points were set or due to wear. Jake Fleming's contact information can be found here http://www.lzoc.org/Sources/sources.htm He is in Dallas and is the closest reference that I can give for quality distributor work. Tom
|
|
| EFV-8 Club Forum : | https://www.earlyfordv8.org/forum |
| Topic: | https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=9095 |