Mopar Muscle Association UK

I did a warm compression test on the 340 in the Duster and I have one bad cylinder. Seven cyls are 140 ish but one is 85. I put oil down the bore but still the same so I'm guessing a valve problem. The car runs OK, no smoke or other problems. My question is could I use the car for some shows this year, maybe cover 500 miles maximum, and then strip down over the winter or is that just asking for trouble! Also, what gasket set is recommended. I have seen the Fel Pro ks2114 set for $60ish. Is this a decent set for an old engine?

All depends on what is the cause.
A slightly bent valve could go for miles but a burnt seat could really upset your day, and by the looks of that spark plug what we feared has already happened and I would go for a burnt seat, especially if it has not got lead free seats.

Pull the heads.

OK thanks. Not sure what you mean about the spark plug. The plug from that cylinder looked clean. Electrode was still white with no deposits. Looks like I'll be getting a lift to Brooklands then

If there are no running issues what led you to doing a compression test? If it's a burnt or bent valve it will show up as a misfire and lack of performance, worn guides usually show up as increased oil consumption and blue smoke on start up.

The coolant was pretty sludgy when I changed it and worried about it being a head gasket. Flushed it, ran it a while and has been OK since. Thought I'd do compression check as back up. If one cyl is bad could that be head gasket? No water In oil as far as I can tell and levels all stable. No excess pressure or bubbles in coolant. Started stripping it now so guess I'll find out soon. Any advise about which gaskets to get?

Yes it could well be the head gasket, I normally use Fel pro. If you're pulling the head anyway I guess you'll soon find out.

does it labour on the starter, when its been left?

You can't compress coolant, so that would be a sure fire indicator of a considerable gasket issue, to turn over it would need to be forced past the rings...

easy to dismiss as tired battery.

evidence of water in oil depends on the coolant water mix, water in oil evaporates if the oil gets hot enough.
Oil in coolant makes a nice mayonaise in the radiator cap spout, and if its pink thats trans fluid....!

you don't sound like you have either

wispy white smoke when idleing, gasket or cracked head.....

worth getting the straight edge out to check the head i ended up doing the gasket twice, minor head skim did the trick

i only have 1 long head to worry about, went through a lot of nylon pads cleaning the block and head up each time , PITA


Dave

Were the Coolant hoses pressurising? ("Blowing up"?)
Usually a sign of a leak between combustion areas / gasses and the Cooling system.

Is the Oil clear and uncontaminated?

Until I dropped the coolant I thought everything was great. Nice idle, no smoke, drove well, always spins well on starter but takes a while to start when cold but always has done. Put that down to the thermoquad. Should have head off next week. Fingers crossed nothing too expensive

Sometimes ignorance is bliss......