pwrcat4000 Posted January 8, 2016 Report Share Posted January 8, 2016 Drove the truck around town last week it has been running great. Warmed it up went about 2 miles, parked hung out for about 30 min. Left herd a lifter noise ticking figured maybe one of my rockers got loose was going to readjust when I got home made it about 4 blocks then lost power truck would not idle. I babied it home as it was still running just not at idle went about another mile to my house pulled the cover, and the intake on the #3 rocker was in place but the (I call it a guide Button) was laying in the head. I tried to put it back together and adjust I had to elevate the post a bunch. I realized the valve spring was compressed and the valve was half open. the valve will compress more but it will not return to regular hight. I was going to borrow a fiber-optic camera and look inside see if the seat came out bent the valve? I still have my L16 motor could I swap parts? Tech info 1971 521with 1979 L20B 1 Quote Link to comment
datzenmike Posted January 8, 2016 Report Share Posted January 8, 2016 Seat fell out and is jammed not allowing the valve to close. Get another W58 head for it. Keep that one and re-build as a spare. 3 Quote Link to comment
difrangia Posted January 9, 2016 Report Share Posted January 9, 2016 Bent valve stem ?? 1 Quote Link to comment
difrangia Posted January 9, 2016 Report Share Posted January 9, 2016 When I acquired our 78 620, it had no compression in #3. Rocker was off and laying in top of head. Valve stem was bent. The valve seats are bronze. That was a first for me. Had seats ground. Put new valves in, Runs like new. Probably 150K miles. Steve 2 Quote Link to comment
datzenmike Posted January 9, 2016 Report Share Posted January 9, 2016 Unlikely bent just from the seat loose. (if it IS the seat) I see the rocker arm was still in place so not from it being jammed momentarily under a cam lobe while falling out. The piston would have to hit the valve to bend it. Drove the truck around town last week it has been running great. Warmed it up went about 2 miles, parked hung out for about 30 min. Left herd a lifter noise ticking figured maybe one of my rockers got loose was going to readjust when I got home made it about 4 blocks then lost power truck would not idle. I babied it home as it was still running just not at idle went about another mile to my house pulled the cover, and the intake on the #3 rocker was in place but the (I call it a guide Button) was laying in the head. I tried to put it back together and adjust I had to elevate the post a bunch. I realized the valve spring was compressed and the valve was half open. the valve will compress more but it will not return to regular hight. I was going to borrow a fiber-optic camera and look inside see if the seat came out bent the valve? I still have my L16 motor could I swap parts? Tech info 1971 521with 1979 L20B Usually the seat falls out from over heating the engine. In fact the heads are heated between 300F and 400F and new frozen valve seats popped in. The seat swells from the warmth and the head shrinks as it cools to hold them in. 1 Quote Link to comment
pwrcat4000 Posted January 9, 2016 Author Report Share Posted January 9, 2016 Steve thanks for the info I am just dreading taking that thing apart it is not a push rod v8 the OHC frightens me. I just replaced the water pump so might be right mike! But I had been driving it for a week or two and since that so it has not over heated. ( some times I feel like I should just IM Mike with my problems LOL ) My buddies just laughed when I asked to borrow a camera. I charged one of those fancy cameras on the old mans parts account will take a look Sunday I will most likely have to take it back when he finds out. W58 head? Would my one off of the L16 work is it a W58 I think it said 210 on the casting but I did not look too closely? And it is too dark to look at the one in the car now. BTW I found a L20B head in Alabama for $50.00 with no cam what should I be asking the salvage guy? 1 Quote Link to comment
KoHeartsGPA Posted January 9, 2016 Report Share Posted January 9, 2016 Check it for cracked, if it's cracked you just threw away money's on scrap metal 1 Quote Link to comment
datzenmike Posted January 9, 2016 Report Share Posted January 9, 2016 Usually the cause is over heating. The '78-'80 L20Bs all used the W58 casting but it could have a different year engine in it. The210 'number' head is an L16 use only. It's too small for valves, ports and combustion chamber for use on an L20B. $50 is ok. I would put new valve seals on before swapping your cam and rockers onto it. Keep the rocker arms in order. If you have never pulled an L head before find out about the timing chain tensioner and how to block it from falling out when the cam sprocket is removed 3 Quote Link to comment
banzai510(hainz) Posted January 9, 2016 Report Share Posted January 9, 2016 521s are square port exhaust Quote Link to comment
datzenmike Posted January 9, 2016 Report Share Posted January 9, 2016 Drove the truck around town last week it has been running great. Warmed it up went about 2 miles, parked hung out for about 30 min. Left herd a lifter noise ticking figured maybe one of my rockers got loose was going to readjust when I got home made it about 4 blocks then lost power truck would not idle. I babied it home as it was still running just not at idle went about another mile to my house pulled the cover, and the intake on the #3 rocker was in place but the (I call it a guide Button) was laying in the head. I tried to put it back together and adjust I had to elevate the post a bunch. I realized the valve spring was compressed and the valve was half open. the valve will compress more but it will not return to regular hight. I was going to borrow a fiber-optic camera and look inside see if the seat came out bent the valve? I still have my L16 motor could I swap parts? Tech info 1971 521 with 1979 L20B 1 Quote Link to comment
banzai510(hainz) Posted January 9, 2016 Report Share Posted January 9, 2016 even with rebuilt head these seat mi still drop out if machinist did it wrong. Seen this on a GrassRoots Motorsport a Volyo P1800 motor totally redont only to have seats fall out as mentioned. If you still have a square exhaust port manifold a think a early head square port head would be better. Just my thoughts. More plentiful 1 Quote Link to comment
datzenmike Posted January 9, 2016 Report Share Posted January 9, 2016 Yes, what Hainz says. If running the 521 exhaust on that round port W58 head then look for an earlier L20B's U67 head. Same as the W58 but square port to match your manifold. 1 Quote Link to comment
difrangia Posted January 10, 2016 Report Share Posted January 10, 2016 Do take Mike's advice on the tensioner wedge. I tried to improvise when I took the head off our 78 Longbed and got into a mess when the tensioner piston popped out of it's cylinder. The tensioner is spring loaded with hydraulic supplement from the engine oil pressure when running. If the tensioner piston pops out, it's nearly certain that you'll be loosening the front of the oil pan, removing the distributor and oil pump, and pulling the timing cover to get it back together and timed. Seems the tensioner is about $5 from RockAuto, Amazon, Ebay, etc. and well worth it. Being the obstinate old bastard that I am, I squeezed a wooden stick down into the narrow area between the two sides of the timing chain, and, wonder-of-all-wonders, the tensioner popped out. I spent an hour or two digging through old Ratsun threads and every one but one said that I had to pull the above-listed parts but one. One guy told how he he'd fished the tensioner back in from above. I figured that I had nothing to loose, so gathered up a couple of long screwdrivers, a wire hook, and my LED headband light. With about ten minutes of finagaling, I got the tensioner back in and the chain pulled back up. Not for everyone, but worked for me. My sincere advice; GET THE WEDGE !!! Link to a thread with some good info on this: http://community.ratsun.net/topic/41595-timing-chain-wedge/ 1 Quote Link to comment
difrangia Posted January 10, 2016 Report Share Posted January 10, 2016 Previous post should have read: The tensioner wedge is about $5 from RockAuto, Amazon, Ebay, etc. 1 Quote Link to comment
Charlie69 Posted January 10, 2016 Report Share Posted January 10, 2016 U67 is in my opinion the best head for stock street use. Quote Link to comment
datzenmike Posted January 10, 2016 Report Share Posted January 10, 2016 U67 is in my opinion the best head for stock street use. Depends on what exhaust he is using and also if the coolant cooled intake is being used. If so then the U67 will need two 1/4" holes drilled for the coolant. Agree the U67 is a good head. The W-58 has the exhaust liners and though they don't affect anything much they would if any performance in planned. 1 Quote Link to comment
Charlie69 Posted January 11, 2016 Report Share Posted January 11, 2016 you are correct Mike In Phoenix I do not run coolant through my manifolds. Quote Link to comment
datzenmike Posted January 11, 2016 Report Share Posted January 11, 2016 Well the coolant flow intakes work both ways. Cooling the intake from radiated heat from the too near exhaust manifold and warming it in cold weather. This helps regulate the intake air temperature and like Goldilocks, the porridge isn't too or too cold... it's j-u-s-t right. With an air temperature that has fewer hot and cold swings the carb will be more in tune and the engine run more efficiently. The U67 used co-joined intake and exhaust manifolds, using the hot exhaust to warm the under side of the intake below the carb. There is a heat riser valve with a bi-metal coil, similar to the choke heater that closes off the exhaust when warm. The problem with this is it does nothing to cool the intake and the valve does need maintenance and they often just rust open or closed or in between. The liquid cooled intake works all the time. 1 Quote Link to comment
pwrcat4000 Posted January 18, 2016 Author Report Share Posted January 18, 2016 The head on it is a W58 I cant get them to call me back from the salvage yard I call and they say they cant find it but they will call me back when they find it. I am think I will just pull the head and machine it here locally but it is too cold even in the shop top do it now I will post when I get ready to pull the head I will look in to the tensioner block. that sounds like a good investment. Sorry for the long delay have been working alot and my son broke his arm Fucking hoverbords 1 Quote Link to comment
pwrcat4000 Posted January 31, 2016 Author Report Share Posted January 31, 2016 Well the salvage yard can't find the head. I am just going to pull the head and take it to the machine shop. datzenmike The rocker was off when I pulled the valve cover off it was wedged between the valve spring and the head so I am hoping it just bent the valve but while I have it off I might have them put in seats any way. I am dreading this job i have watched videos and think I have a good understanding of the process. I will probably get a The tensioner wedge as you and difrangia suggested. by the way I had a buddy weld my hood back together and i am debating wheter or not to put a Japanese Imperal flag design or the simpler Current Japanese flag just for shits and giggles here is a pic of where I am at now it is all white 1 Quote Link to comment
banzai510(hainz) Posted January 31, 2016 Report Share Posted January 31, 2016 The rocker was off when I pulled the valve cover off it was wedged between the valve spring and the head maybe that's the only proplem. fix it and see if runs. I had mine fall off a couple times ove rthe 20years. never fucked up a valve. flat black the hood 1 Quote Link to comment
pwrcat4000 Posted February 1, 2016 Author Report Share Posted February 1, 2016 The rocker was off when I pulled the valve cover off it was wedged between the valve spring and the head maybe that's the only proplem. fix it and see if runs. I had mine fall off a couple times ove rthe 20years. never fucked up a valve. flat black the hood as for the hood See other thread it may seem familiar to you LOL http://community.ratsun.net/topic/56464-just-bought-a-1971-521-for-5-large-500/?p=1346317 Not the only prob apparently. The damn spring guide was "clocked" a little off it kept coming so I took the gap tight to .03 or so. I even tried (somewhat gently) Using a claw hammer to pull it up to no avail. I think I am going to get an endoscope for my phone and see what is going on in the cylinder. 1 Quote Link to comment
datzenmike Posted February 1, 2016 Report Share Posted February 1, 2016 If the rocker was properly jamed it could hold the valve open as the piston passed TDC and hit it causing a bend. 1 Quote Link to comment
Charlie69 Posted February 2, 2016 Report Share Posted February 2, 2016 Well the coolant flow intakes work both ways. Cooling the intake from radiated heat from the too near exhaust manifold and warming it in cold weather. This helps regulate the intake air temperature and like Goldilocks, the porridge isn't too or too cold... it's j-u-s-t right. With an air temperature that has fewer hot and cold swings the carb will be more in tune and the engine run more efficiently. The U67 used co-joined intake and exhaust manifolds, using the hot exhaust to warm the under side of the intake below the carb. There is a heat riser valve with a bi-metal coil, similar to the choke heater that closes off the exhaust when warm. The problem with this is it does nothing to cool the intake and the valve does need maintenance and they often just rust open or closed or in between. The liquid cooled intake works all the time. Mike to me it is worth sourcing a Canon intake and a square port unmarried exhaust manifold or a shorty header rather than run a smog head. Just my opinion. Quote Link to comment
datzenmike Posted February 2, 2016 Report Share Posted February 2, 2016 The head doesn't really matter too much. The U67 isn't what I would call a smog head it just has that poor co-joined intake/exhaust set up. Throw the manifolds away and drill two coolant holes and you can run the U67 with a later '78/'79 intake (has larger ports that the L16/18 intake) and an earlier L16/18 square port 4 into 2 exhaust. Quote Link to comment
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