PDonovan Posted August 29, 2010 Share Posted August 29, 2010 Major rebuild over last 14 months. Ex Witham J60 fitted - which appeared to run fine before it was fitted into vehicle. Most engine ancillaries are new... HT Leads, Coil, distributor etc. Had new carb... which i have replaced with another new carb... to eliminate fuel issues. New fuel pump, lines and filter. See video on youtube taken today. Goes quite well considering its probably running on 5 cyls. http://www.youtube.com/watch?v=95w0ka97dnw I'm thinking sticking/dropped valve... so compression test next. Any ideas guys....:nut: Quote Link to comment Share on other sites More sharing options...
sirhc Posted August 29, 2010 Share Posted August 29, 2010 Paul, I'd get another engine, check it before fitting and then deal with this one later. It's only a couple of hours work to take the head off and put a new head gasket in/check the valves before fitting. It does sound like it has dropped a valve though! Chris Quote Link to comment Share on other sites More sharing options...
timbo Posted August 30, 2010 Share Posted August 30, 2010 Before doing anything too radical I'd check the fuel filter again. If you've not got much fuel in and it's picking up all the crap in the tank you might end up going through 3 or 4 of them before it gets clean... Quote Link to comment Share on other sites More sharing options...
PDonovan Posted August 31, 2010 Author Share Posted August 31, 2010 Before doing anything too radical I'd check the fuel filter again. If you've not got much fuel in and it's picking up all the crap in the tank you might end up going through 3 or 4 of them before it gets clean... Thanks for that.... I have previously removed the commanders seat mount.... which is basically a 12inch access cover in the lower fuel tank. There was very little sediment etc in there. All the 13 year old fuel was removed and fresh fuel put in. The fuel pressure at the carb is fine. Anyhow events have moved on... compresion test yesterday revealled No3 Cyl at 45psi... with all the others around 150psi... so stuck valve. Frustrating as the engine seemed to run fine when starting prior to any road use... see following two short videos. Both of these runs were with fresh fuel gravity fed from a small tank. However.... I initially, for some stupid reason, left the old (13yrs) fuel in the tank for the first proper short road runs. This certainly seemed to leave a very lacquer like deposit inside the new carb. I then replaced the carb and removed all the old fuel. Could this fuel have gummed up a valve in the few short runs.. I think it is possible. Will try a fuel additive before anything alse.... worth a shot. Chris ... thanks for your response also. Quote Link to comment Share on other sites More sharing options...
sirhc Posted August 31, 2010 Share Posted August 31, 2010 Paul, Andy had a similar problem on his Striker when he first got it going. It turned out one of the valves had stuck open and then been knocked by the piston. The engine was repairable, but he had to fit a new piston, valve and give the bore a good hone. Hopefully yours is not quite as damaged, I have bought new pistons (in the military box) from XK Engineering in Coventry if you need some bits. Chris Quote Link to comment Share on other sites More sharing options...
tankdiver Posted September 4, 2010 Share Posted September 4, 2010 Sometimes pouring neat Readex down the carb when the engine is running realeases the valves I have used this trick many times in the motor trade.Tons of smoke little at a time laurence Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted September 4, 2010 Share Posted September 4, 2010 I would check compession pressures first to narrow the problem down to a cylinder. Also, if it was a valve not seating, it may have "kissed" the piston and be slightly out of line, ie. bent....... Of course, it may be too obvious, but are you sure it is not a duff spark plug? Even if new they can fail under pressure, hence why it might sound OK on starting. Quote Link to comment Share on other sites More sharing options...
PDonovan Posted September 4, 2010 Author Share Posted September 4, 2010 Sometimes pouring neat Readex down the carb when the engine is running realeases the valvesI have used this trick many times in the motor trade.Tons of smoke little at a time laurence Thanks for that I'll give it a go ! Quote Link to comment Share on other sites More sharing options...
PDonovan Posted September 4, 2010 Author Share Posted September 4, 2010 I would check compession pressures first to narrow the problem down to a cylinder. Also, if it was a valve not seating, it may have "kissed" the piston and be slightly out of line, ie. bent....... Of course, it may be too obvious, but are you sure it is not a duff spark plug? Even if new they can fail under pressure, hence why it might sound OK on starting. Richard.... Compresion test shows No 3 Cyl well down (45psi) all the others are around 150psi -- so definate valve issue !! Regards Paul Quote Link to comment Share on other sites More sharing options...
marmon Posted September 5, 2010 Share Posted September 5, 2010 I watched your video on the first start up and it was running on six, I think one of two things has happened either the valve stuck slightly due to slight corrosion, lack of lube or possibly insuffiecent reaming of guide on rebuild and is now bent from a tap from piston or the valve seat has dropped out of head, due to overheat or two much clearance, I guess it is a bit late to suggest not to run it... I would think you would have no more than a slight dent in the top of the piston and just need to fix the valve. Quote Link to comment Share on other sites More sharing options...
PDonovan Posted September 7, 2010 Author Share Posted September 7, 2010 I watched your video on the first start up and it was running on six, I think one of two things has happened either the valve stuck slightly due to slight corrosion, lack of lube or possibly insuffiecent reaming of guide on rebuild and is now bent from a tap from piston or the valve seat has dropped out of head, due to overheat or two much clearance, I guess it is a bit late to suggest not to run it... I would think you would have no more than a slight dent in the top of the piston and just need to fix the valve. Many Thanks for that. I'll let you know what I find..... will be a couple of weeks before I get chance to remove the head. Quote Link to comment Share on other sites More sharing options...
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