454 Problems

[Jon87V20]

Alright, so this is a bit of a long story so bare with me. My brother has a 78' Chevy K10 with a 454. It has a Edelbrock Performer and a Holly 750. It has an HEI distributor with an Accel Super Coil. Every thing else is factory as far as I know. It was running okay last winter when it was parked untill recently. It has been occasionaly started and run for a while. Even before it was parked it had a slight ticking in the valve train on the passenger side. Well when he recently had it re-registered we started it let it warm up for a few minutes and went to leave. He romped on it for a second and it was pulling pretty well and all of the sudden it started missing and was having problems idling. The next time we ran it after that the valve noise was getting very bad. After removing the valve covers I saw that the number 6 exhaust rocker was so loose I could almost pick it up and shake it. Numbers 3 and 5 exhaust valves were nearly as bad. I adjusted the lash on all of the valves and ran it again. The noise was gone but it was still running horrible. It had an Edelbrock carburator at this point and when we turned the metering rod on the passenger side in all the way it didn't make any difference. A friend of ours suggested that the carburator was junk and that this had something to do with the poor idle. This is when we put the Holly on. No change in the way it was running. I should also add that for quite some time there has been alot of blow by coming up through the breather. After doing a compression test all of the cylinders were at 150 but 3 and 5 were at 30 and 0. I didn't think this could be right so I took off the valve cover again and saw that a few of a rockers on the driver side bank were a bit loose again and I proceeded to back of all of the valves for 3 and 5. I did another compression test on them and sure enough they both pumped up to 150 pounds. I re-adjusted the lash on them again thinking that I had messed up and they were too tight. Well when I went to put the extra half turn on them after removing the lash I saw that the valves were opening. So I backed them off untill they were closed. After running the truck again it seemed to be running very well. I will admit that I was stupid and didn't use a timing light but instead moved the timing around untill it seemed to be happy. I took it for a test run and it seemed to be doing well but then the radiator started boiling and sent a bunch of coolant out of the overflow. I'll also add that the vacuum advance was disconnected at this time. I figured that it had been too far advanced at that would explain the overheating although it wasn't pinging. I also noticed that the number one spark wire position was one spot over from where it should be counter clockwise. I tried putting number one where it was supposed to be and it refuses to start that way, no matter how you position the distributor. I put the wires back and set the timing at 8 degrees with the vacuum connected. (I had it at 8 with the vacuum disconnected but it jumped up to 12 when reconnected and I wanted to play it safe to see how it did.) It seemed to be idling well but once again after about 10 minutes or so it started overheating again. It's also falling on it's face and dying when you put it in gear. I can't figure out what is going on with it for the life of me! Is this a timing issue? Is the new carburator jetted too lean maybe? Radiator cap isn't sealing? I would like to get some input or advice from you before I do any more trial and error because I hate to keep overheating it. Thank you for your time, any advice would really help because I'm stuck on this one. 

[Russ130]

Replace your thermostat and make sure you radiator is filled. Is the fan working correctly? Do you have a fan shroud? The best way to set valve lash with hydraulic lifters is with it running. Back off each rocker arm adjusting screw until you hear it start to click then slowly tighten til clicking is gone. Do all the rockers on one side then tighten 1/2 to 1 full turn each after the engine is off. Make sure you turn them all the same amount whether it be 1/2 turn or a full turn or whatever. Repeat for the other side. Factory spec is 1 turn but I like to get as close to zero as possible myself. They make little clips that will block the oil from spitting out of the push rods but I use an old valve cover and cut the top off with a die grinder.

[VileZambonie]

Personally I would set the valve lash at tdcc in each cylinder with the engine cold and go one full turn additional from zero lash since the engine is mostly stock.

Flush the cooling system and replace the t-stat as Russ suggested.

Rebuild the edlebrock carb and put that back on.

Sounds like it's time to rebuild the distributor also or just get one of those ebay drop in's.

http://cgi.ebay.com/ebaymotors/HEI-DISTRIBUTOR--BBC-396-402-427-454-502-Chevy_W0QQitemZ150279303764QQcmdZViewItem

[Jon87V20]

It has a flex fan on it but no shroud. It hasn't had the shroud for quite some time and it wasn't a problem before. The problem with the lash is whenever I do any extra turns what so ever after zero lash the valves on the driver side stay open. I was thinking maybe a lifter problem with that? It almost sounds like the distributor is making a slight noise as well and maybe it is time to change that out. I do have an extra one around here. As far as the stalling when put in gear, any ideas on that? Thanks for the help.

[Russ130]

Stalling when you put it ingear could be a lot of things. However the most popular reason is a vacumn leak or really low vacumn.

The reason I do the the valve lash while its running is to increase the accuracy of my adjustment. Sometimes if a lifter is weak or has bled down it will go in quite a bit before you feel any drag. When its running more than likely the lifter will be pumped up to where it is going to run anyhow. Plus an audible click is a lot more distinguishable than the feel of a slight drag on the push rod. They don't make those clips because its Busch league they make them because a lot of us do it that way. Remember it is better to err on the side of noisy valves than adjusting them too far in. Too far in and you'll wind up with a bent valve, a little noisy just means slightly less lift but a better seal when closed. An old timer once told me noisy valves are happy valves due to the fact at least you know they are closing and won't be hitting the piston.

[VileZambonie]

ok fan with no shroud is pretty useless. It's better than nothing but you need a shroud.

Please detail how you are adjusting your valves.

Putting it in gear puts a load on the engine and will stall it if it is not running correctly.

Russ I have to disagree with your old timer. Think of a hammer smacking the tip of your valve. Can you say mushroom?

[Jon87V20]

I have been putting number one at TDC. I take the lash out of both of number one's valves and then do an extra half turn.  Then I go around and do all of the valves that are closed at that point, and then rotate the engine 360 degrees and adjust the rest of them. The thing is 3 and 5 exhaust are staying open with the half turn which I suppose could be due to the lifters already being compressed because they are stuck that way maybe? The other problem was a few of them were loose already the second time I went back in. Only on the driver side bank though. So would putting each individual clyinder on TDC for it's adjustment be a better way to go then? Right now it's the overheating out of the blue that has me confused. Don't thermostats usually slowly fail? One day it was fine and the next it's getting too hot. I guess he's planning on replacing the thermostat and the distributor on the first of the month when he gets paid. I'll try the valves again and pull the thermostat in the meantime to see what it does and give you an update.

[Russ130]

Vile - I think he was referring more to the light clicking noise as opposed to the clacking noise of a seriously misadjusted lifter. Think Rhodes lifters.

Jon - That is not the correct procedure to adjust the lifters while not running. Bring no. 1 up to tdc when it would be firing and adjust Ex. valves 1, 3, 4, 8 In. valves 1, 2, 5, 7 then you rotate engine one complete turn and do the others. Ex. 2, 5, 6, 7 In. 3, 4, 6, 8. First you back them out til you feel the pushrod spin freely then you adjust until push rod has slight amount of drag, then turn one full turn in to center the lifter plunger. You can tell when no 1 is in firing position by whether or not the valves are moving while bringing it up to tdc. If the valves are moving on no 1 then rotate a complete rotation or do the second set of valves first.

[VileZambonie]

With the engine cold put it on TDC compression #1 cylinder. Adjust the valves from zero lash 1 full turn. Don't try to find zero lash by rotating the pushrod. Do it by lifting it up and down until you feel the lash gone. once it's zero tighten an additional full turn. Do both intake and exhaust valve. Rotate the engine clockwise 90° and adjust #8 in the same manner. Rotate the crank another 90° following the firing order 1-8-4-3-6-5-7-2

Don't worry if other rockers feel loose as you go around. You're just feeling the lifter bleeding down.

[VileZambonie]

Either method is fine.

[Russ130]

For me since I've worked contruction all my life and never wore gloves I don't have the feel to do it either Vile's way or the way I stated which I pulled out of the GM shop manual. My hands are like leather and to be honest a lot of the nerve endings are probably dead so adjusting them while it is running is my only real option. A fan shroud is definately needed otherwise your fan will only be operating at 50% efficiancy at best and that number declines rapidly as the fan gets further and further from the radiator.  The fan should be no more than 2" from the radiator if it is, without a shroud, you might as well say you have no fan.

[MITOYZ]

You might want to check your timing chain,might be stretched making timing vary and could cause over heating,and I have also had this happen with cam lobes on the exhaust side worn to much and it kept overheating,and also cracked rockers are common on the exhaust side because of excessive heat from the valve,and would make it seem always loose.

[Russ130]

Good point MITOYZ