Thanks for the tips again. I have already set in my mind that as I start with the valve cover there should be a story that unfolds. I have found in the past that if there is a problem some place there will be tell tale signs along the way. First thing to check will be the Valve train as the cover comes off. As for the hiss in the cover, there will be some leak past the rings depending on the pressure in the cylinder. If the PSI is low then the ring will not seat all that good to the land nor force out to the cylinder wall. So a little leak is okay i am guessing. I did get the air up high enough to start the piston on the down stroke, with this as soon as the intake valve opened I could here the air hiss in the carb throat. I did not go to the exhaust to listen , however, based on the plug condition for that hole together with the fact the prev. owner ran a very long time with an extremly rich setting on the carb and the fact that #6 compression is 25psi, I can assume the problem should be in the exhaust valve. I didnt realy like the way the exhaust valve rocker for #1 was set. I didnt have the cover off cause I am tight with time and work the swing shift, but I am not in too much of a hurry to get this thing running. I can waite a while, plus I like this kind of stuff, I did it for 25 years in the Navy. So, tomorrow the valve cover comes off and the investigation begins, failure analysis is always fun. Well I too have learned some things in regards to the "Big Block L6", well I will keep things updated as they unfold.
Joe

 

Well, finally got the head removed today. There is nothing jumping out at me as far as valves go. I will still bring it in for work as I might not have this opportunity again. I did notice that whoever put it toghether last time set the intakes loose. When a piston is at TDC the exhaust valve is snug and the intakes are way loose, according to the material I have it says to set them untill the push rod cannot be twirled. Havign sadi that I did notice all the intake valve stems look a little more worn then I would expect to see with this many miles. I filled the piston holes with oil and rolled it over and all holes do not drain out, and all cylinder walls look clean and there is a good cross hatch pattern. I think I will now focus on the lifters, I just finished reading a thread that was recently posted about lifter travle and a collapsed lifter test, I will research new lifters. The valve cover was coated with sludge, I believe from running real rich and maybe lack of frequent oil changes. the engine only has 3-5K miles. I will do the lifters later. One other question? looking at the front of the truck at the back left corner of the block right below the head there is a screw in device with a little spring sticking out, I think I broke whatever it was when I lifted the head, does anybody know what it is?? well thanks for the help, its off to the machine shop.
Joe

 

Joe, it sounds as if you clobbered the coolant temperature gage sending unit. It is threaded into the block with a pipe thread. The best way to remove it is with a six-point socket, although a 12-point will also do. Its body is brass and an open end wrench may strip the flats. The part you broke off is probably still on the end of the wire that you will need to reconnect to your replacement sender.

If any rockers were loose, it is likely that they were sitting with their valve open and slowly collapsed and are stuck in the collapsed position. This usually is not a problem as long as the lifter pumps back up when the engine is started, although an engine with this problem may make a lot of clattering for the first moments being started.

I would do the lifters while you have the engine apart. Lifters are pretty cheap - I just bought a set of new lifters for a 300 on eBay for around $30. Be sure to re-read that other thread - you need to lube the lifter bases and do a proper break-in or you could end up with a bad cam lobe. Also make certain that the holes through the pushrods are open and allow oil to flow to the top end of the engine. Inspect all your rockers for strange wear patterns.

I still would be most suspicious of exhaust valve #6 - have your shop confirm that it was (or was not) bad. It is always best to actually be certain you have found the problem, although sometimes it does seem that nothing was obvious and upon re-assembly, the symptoms are gone. If you know you found the problem, there is less of a gamble to engine repair.

 

Well, as the disassembly goes I am 99% sure I have found the problem. While pulling out the lifters the lifter for the #6 Exhaust valve is concave!! all other lifters check out fine. So, I will replace the lifters as a set and put everything back together. I will pass on the head job, as everything looks good. From what I can see of the CAM lobe there is no damage. The lifter is designed to fail before the cam, and I can say it did just that, I will get the exhaust manifold trued up and will attempt to put it together as ford reccomends. No exhaust gasket, intake gasket only, unless it is reccomended from the pro's here to go with the combo gasket. so, I am glad to have found the problem, just wish it didnt involve so much disassebly. But, its good to keep the proficiency level up there. Thanks for all the help ACHEDA, I will let you know how assembly and the first run goes. Pleae feel free to give any tips in the assebly phase.
Joe

 

If you just replace the lifters you will likely have the same failure in the very near future.

 

Silver Streak is right - a concave bottom on a lifter is an indication that there has been a lot of wear. If you put that lifter back on the lobe that fits its concave bottom, it might last a while or it might not. (I would NOT agree with the lifter being designed to wear out before the cam - if anything the hard case on the cam lobes is thinner than the lifter bottom.) A new lifter has to do some wearing in and if that is enough to wear through the hard surface of the cam lobe, the whole lobe will get worn off in only a few minutes, leaving you with a five-cylinder engine.

The best thing to do is to put in a new cam with the new lifters. If you are not able to do this, putting in new lifters is probably a waste of money. You could put every lifter back where it was (exactly where it was) and start saving $$$ for the complete cam & lifter set (AND a new timing gear set to replace the plastic one which is preparing to fail - see numerous other threads on 300 timing gears).

I recommend you measure the amount of lift of that lifter and compare it to another of the same (intake/exhaust) kind to see if you are already have a worn lobe - this may help you feel better about buying a new cam.

P.S.: You are not the first to have the experience of getting into an engine and finding out that there is one thing after another. This is why many of us just plan on doing the whole engine at once. If you have the $$$ it is better to do it all and be done with it.

 

You are correct, I was just glad to see the problem and was not thinking things through. I have all the tool at home to measure lift. Before I go with the cam replacement I will measure the lift on several good lobes first then compare it to the one with the bad lifter. Looking towards the worst case scenario, cna the cam be taken out in frame? I did a cam swap in frame on an old Dart and it was doable but it took some tough engineering, I would think that with all the room in the truck engine compartment, I could just pull the timing cover the radiator and several other items and then bring it out the front. Do any of you have any links or pointers in doing such a job? and I just want to say thanks again for being the voice of reason this forumn has saved me several times already. Well I'll let you know how it goes
Joe

 

The cam is almost as long as the block & it has to come straight out. (You probably already know this from your Dodge cam swap. Measure how much distance you have to the inside of your grill - as you know, the radiator has to come out. You might have to pull the grill or you could just break out part of the plastic (JUST KIDDING!).

Do searches in this forum for both "300 timing gears" and "300 cam change". If there are any gaps or things you don't understand, just ask a question in this thread.

P.S.: Are you doing a valve job while you have the head off?

 

I was considering that. The head looks real clean, like I said the engine has only 3-5k since rebuild. Since all the intake valve rockers were loose when I brought them to TDC I think the last builder set them wrong, everything I read says to set them tight other then that I cant see anything wrong with it right now. I am gonna go with the cam swap, it looks doable. I am gonna get ahold of either crane or comp cams and get a mild RV cam with a good set of lifters, this should give me a little more pep in the step yet still run the stock carb. This will give me some thing to keep me busy for a while. Once its all together I am sure it will give me many hours of happy motoring.

Joe

 

Well, thought I would give an update. The machine shop magnafluxed the head and was amazed that the vehicle was still running! The last engine builder (out of business now) had plugged the head in three different places, and they were all leaking. The head even though it looks clean is beyond repair. I found a place in San Antonio that had a stock Re-man for believe it or not $175.00 with an $85.00 core charge. Best price i found anyplace, and this was reccomended to me by a reputable machine shop. Got a good cam reccomendation from a thread back in Dec. so I did the research and purchased the Crane cam 503905 and a set of crane Hyd lifters. All in all, I wasnt happy with what I found but some things are just that way. At least I know and will be able to trust the upper end of this thing now. Well I hope to give better reports as the world turns or as the engine assembles

Joe