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By sc63uni - 13 Years Ago
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compression readings from #1 and 2 and 5-8-were 200-202-200-195-200-197. did not check 3 and 4 as they are kind of a pain to get to and my starter sounds as if it is going out. it is usually not a problem as i only have to bump it to start the truck, but it was having trouble with the 5 or so cranks req for test and after seeing other readings i kinda assumed.... i also recalled the guy that had the motor said " it tested pretty even at around 195" seemed high at the time so i did nt really trust his test but when i got about the same thing... maybe so anyway i was trying to detemine if i should rebuild heads( i have an extra set and kinda assumed the ones on engine would not have hardened seats and condition probably questionable) i have a slight knock on upper end of driverside. you can feel it on the valve cover but not on head or block. Passenger side sounds fine. rocker assembly looks ok and after i adjusted valves, the knock went away.... til i revved it..... then came right back. i was checking compression to see if it would tell me if lower end of motor was in good enough condition to go to expense of head rebuild ( if thats possible) and i was curious anyway to what they may read. any body have any input or suggestions for other tests? do those compression readings seem normal? high? good? thank you for any feedback
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By lovefordgalaxie - 13 Years Ago
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Those numbers look good to me, my shop manual tells that you would be fine even with 130 lbs.
More important yet is that the pressure is even, with small variations from one cylinder to the other.
On the noise, it can be one of the adjusting nuts on the rockers. If one is "too loose" it can loose its seting shortly after the lash had being adjusted. Had this problem once.
Those nuts are supposed to have a "interference" tread, and if one is easy spining, that can be your trouble.
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By sc63uni - 13 Years Ago
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thanks for the speedy reply. Ill look at that this morning
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By PF Arcand - 13 Years Ago
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Uni: You didn't say what heads & so on you have. Those readings are fairly high but even. Tulio's remarks will only apply to rockers that are of the "interference fit" type. Earlier rockers have lock nuts. Re the noise, you could very likely have a rocker that has a worn spot, so you get a somewhat false reading when setting the valves. If you can determine which one is noisy, try setting it slightly tighter than the normal setting. Also is your top end oiling normal?
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By Pete 55Tbird - 13 Years Ago
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You asked "i was checking compression to see if it would tell me if lower end of motor was in good enough condition to go to expense of head rebuild ( if thats possible) and i was curious anyway to what they may read." There is no real connection between the condition of the rings/valves and what kind of shape the bearings or wrist pins are in so what kind of oil pressure you read is a much better tell. With that much compression you either have fairly high compression ratio or lots of carbon on the piston tops or a very mild cam or a combo of all three. Pete
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By lovefordgalaxie - 13 Years Ago
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My 292with no more than 10 k miles has a 190 reading +-5 on all 8 cylinders. The heads are the the factory originals with small valves, and a Isky e-4 cam.
We here only have one kind of head, and is comon to find numbers from 140 to 190 on most engines I worked on.
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By sc63uni - 13 Years Ago
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Thanks guys. I cant remember where to look to find casting numbers on heads but original motor had CITE heads and i seem to recall the ones on this motor were the same. not sure what normal oiling is but there seams to be a steady stream of oil dripping down all pushrods and a steady drip to each valve spring base. no lock nuts on valve adjustment and all adjustments firm to adjust. found three that were noisey and snugged them up abit( 1/8 - 1/4 turn) till they sounded like the rest. (with the help of a home made stethescope, ok plastic tube) again sounded nice and quiet till i drove around block then noisey again but i think its better. when you say worn rocker do you mean where it contacts valve? can that be filed/machined flat and reinstalled? no idea about what cam is in it. other than pulling head is there a way to check for cabon build up? is it something i should be conscerned about?
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By sc63uni - 13 Years Ago
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a little more background, This motor was an ebay $500 find that i put in my 63 250 unibody daily driver about 14 mo.s ago. came from a guy that sold mostly big equipment engines and my mechanic thinks it came out of a big truck becuse it has a triple pulley on the crank an a double on the water pump. thanks guys
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By lovefordgalaxie - 13 Years Ago
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Yes, looks like it can be a worn rocker.
A worn rocker will have a depression where it touches the valve, and the tool can't get inside the depression, so you end edjusting the valve "wrong". Mine were this way before I rebuilt the engine, and I swaped them by a remanufactured set that had being regrouded. It's possible to regound the contact surfaces, and while you are there, you can also check the rocker for excessive play on the shaft.
Another detail I just remembered, is that I do the valve adjusts after the engine is hot. had always good results this way.
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By sc63uni - 13 Years Ago
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what is "excessive play" rocker to shaft? if i pull rocker assembly am i more likely to see the rocker worn or shaft? my mechanic (Chevy guy, mostly alignment and frame but dropped motor in and doing other stucyural work for me) said it might be a grooved cam but is it more likely to be in the rocker assembly?
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By MoonShadow - 13 Years Ago
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Check this article by the late Walt Knuckles. Using his method allows for wear in the rocker tips. That should give you a true adjustment on the rockers. Chuck http://www.y-blocksforever.com/tech/html/valvelash.html
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By lovefordgalaxie - 13 Years Ago
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Well, excessive play needs to be measured and the lash between the rocker and shaft has to be between 0,002"-0,004" for both 1,5 and 1,4 ratio rockers. This is acording to my shop manual.
What I have seing is more wear on the shafts than on the actual rockers.
If you really have this problem, never just install a new shaft on old rockers without carefull measuring the lash. You can always take the rocker/shaft assemblys off and send them to be rebuilt by a professional, that is going to install bronze bushings inside the rockers to restore their diameter, and then instal a new shaft. They also reground the rockers to eliminate the wear on the contact area with the valve.
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By sc63uni - 13 Years Ago
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Thanks guys . ill give ole walts method a try in the morning. if the rockers are cupped and they go down over the top point of valve stem, i think its gunna be pretty hard to"see" when they just touch. think i may use a flexible "feeler gauge" like tyvek" (or a mattress tag) to slip under there, note its thickness and adjust accordingly. ill get back with results. have a good week yall boyd
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By MoonShadow - 13 Years Ago
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Using Walts method you dont have to see or feel a gap. Chuck
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By Hoosier Hurricane - 13 Years Ago
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If you twist the pushrod as you tighten the screws to 0 lash, you can feel when the rocker arm touches the valve stem. The pushrod will stop turning freely when conatct is made.
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By sc63uni - 13 Years Ago
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thanks guys. decided to leave the mattress tags on after i saw video of someone finding 0.00 with that method. so ive adjusted my valves on the noisey side this way and seems its still noisey and you can feel the tapping on the valve cover. again, i do not have this on the passenger side. what else could this be? thanks
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By MoonShadow - 13 Years Ago
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Its really quite easy. Do you know which rocker is noisy? You can find out with the engine running by pushing down on the rocker tip to see which one quiets it down. Sometimes you can get away with a worn shaft by turning it over. All of the wear is usually on the bottom side. Also how loud is it? May be normal solid lifter noise. Again I highly recommend Walt's method to adjust all of the valves. It will work. Chuck
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By Y block Billy - 13 Years Ago
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just remember at that high a readings you may have to go with a higher octane gas?
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By sc63uni - 13 Years Ago
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thanks again Chuck and i found Walts method not only an easier method but beneficial. i dont have a good way of explaining how load or noisey the lifters are and probably would not have started this post if both sides were the same. maybe i should open up other side of valve train, adjust using walts method, maybe then they will sound the same i ill quit whining. maybe ill should a higher octane. i do hear the valves clacking when i accelerate from a lower rpm. maybe this is normal ,dunno. maybe timing not just right. not ever had anyone look into it. seemed to run pretty good after install and other stuff to worry about so never pushed the issue. started this process to see if it makes sense to rebuild and install back up heads but if my compression readings are this high does that mean that the valves are seating fine. which was a major concern being that the valve seats were probably not hardened. are there other ways of sampling engine condition/wear without opening it up? or would it be a good idea go ahead with heads and have a look see when the top end is open? Rear main leaks pretty good, not as bad as ive read about but i would like to repair it. i think would involve oil pan removal and maybe tranny, but would this also allow me to check condition of lower end? if so, what should i be looking for, and at what point does it make sense to do complete rebuild? again this truck is my daily and only so I dont feel the need to have it up on the racks or my check book on the counter but also dont wanna overlook some maintainence/repair if it will allow me to keep rollin maybe some sound/heat shield on the floor and a bit of music turned up,and an anti rattle kit from DC and door seals and a new windshield and seat springs with a new towel and (dreaming here) maybe a 3.73 rear end from a '72 (4.56 in house)so i can cruise at 50. whatcha think? boyd
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By MoonShadow - 13 Years Ago
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It would be a good idea to set the other side too. Y-block solid lifters are not normally real noisy but if your used to hydraulics it could seem louder to you. If there is a problem you want to track it down and fix it. No sense wasting a good engine. As far as the hardened valve seats go I wouldn't worry about it much. When you have to have the heads done then the seats can be replaced but the old style seats should last quite a while without problems. I'm sure some of our more knowledgeable folks will chime in here on the subject. Chuck
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By Hoosier Hurricane - 13 Years Ago
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Is the valve cover bent or distorted? I wouldn't think you would feel the tapping on the cover unless something is hitting it. Are there tell tale marks inside the cover? With the cover off, do you still hear the same noise? Sometimes a fuel pump can make a tapping noise like a loose valve.
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