C2 327 hydraulic lifters bleeding down

[William G.]

Sorry if this is a little long! Here's a questions for a better engine mechanic than me. In December I purchased a nice 66 roadster L79 350 hp 4 speed car with an original driveline. The motor was rebuilt a few years ago and currently has 3000 miles on it. I have no reason to disbelieve the former owner because he has become a friend and has been truthful about the car in all instances.

I bought the car in Texas and had it shipped to Massachusetts in January. After starting it up I noticed that several lifters were bleeding down overnight. They would pump up 5-15 seconds after starting the car, and the engine ran fine. I removed the intake manifold and valve covers and send them to Jerry McNeish for "reskinning." That was the perfect time to replace the lifters.

I called Crane Cams and asked for a recommendation and purchased a quality set of anti-pump-up lifters. They advised that I could use the new lifters with the broken in cam if I use the appropriate break-in grease on the cam surface and added GM EOS (engine oil supplement) to the crankcase. I broke-in the lifters at 2000 rpm for 20 minutes.I use Rotella 15-40 diesel oil.

I did a very careful static adjustment of the lifters using the #1 cylinder at TDC and then rotating around to #6 TDC ,adjusting the appropriate valves to 3/4 preload. The engine now runs well,will idle at 550 rpm if I ask it to, and I have a steady 17 inches Hg at 750 rpm idle. However, there are still a few of the new lifters that bleed down overnight and take 5-10 seconds to pump up and quiet down.


I called Crane and they asked if my oil was dirty ( it isn't). They suggested sending back the lifters for analysis. Here's my problem. Logically it seems that there must be another issue here with two sets of lifters doing the same thing. There might be one more factor. The car was running very rich when I got it because it had the wrong power valve in the Holley carb,and that has been corrected. I checked the oil to see if it was diluted with gas but it smells like motor oil with no gas present.

At this point I am going to do two things.

1) I will change to fresh oil assuming that the EOS has thinned the oil.

2) I am going to make a valve cover with a cutout so that I can adjust the lifters while the engine is running. I find it hard to believe that my adjustments weren't done properly because I am getting smooth idle with steady idle vacuum, and all lifters pump up after a few seconds.

I will welcome any advice from engine experts.
Could there be something else that I am missing?
Something caused by my engine. Any opinions? Thanks for your help.

[Duke W.]

Re: C2 327 hydraulic lifters bleeding down

It will help if you go back and edit your post - break it into more paragraphs with spaces between the paragraphs.

Half a screen of solid text is very difficult to read.

Duke

[Clem Z.]

Re: C2 327 hydraulic lifters bleeding down

the post looks OK to me duke. i would try the hot lash while running before taking things apart again. NEVER fill HYD lifters with oil before installing.

[William G.]

Re: C2 327 hydraulic lifters bleeding down

Clem, I did not fill the lifters before assembly. I am curious as to what that would do.When I installed them, the plungers could be depressd with only the spring resistance.

[Clem Z.]

Re: C2 327 hydraulic lifters bleeding down

Clem, I did not fill the lifters before assembly. I am curious as to what that would do.When I installed them, the plungers could be depressd with only the spring resistance.

if you fill them with oil you will have trouble depressing the push rod cups and not get the proper preload.

[Joe L.]

Re: C2 327 hydraulic lifters bleeding down

Sorry if this is a little long! Here's a questions for a better engine mechanic than me. In December I purchased a nice 66 roadster L79 350 hp 4 speed car with an original driveline. The motor was rebuilt a few years ago and currently has 3000 miles on it. I have no reason to disbelieve the former owner because he has become a friend and has been truthful about the car in all instances.

I bought the car in Texas and had it shipped to Massachusetts in January. After starting it up I noticed that several lifters were bleeding down overnight. They would pump up 5-15 seconds after starting the car, and the engine ran fine. I removed the intake manifold and valve covers and send them to Jerry McNeish for "reskinning." That was the perfect time to replace the lifters.

I called Crane Cams and asked for a recommendation and purchased a quality set of anti-pump-up lifters. They advised that I could use the new lifters with the broken in cam if I use the appropriate break-in grease on the cam surface and added GM EOS (engine oil supplement) to the crankcase. I broke-in the lifters at 2000 rpm for 20 minutes.I use Rotella 15-40 diesel oil.

I did a very careful static adjustment of the lifters using the #1 cylinder at TDC and then rotating around to #6 TDC ,adjusting the appropriate valves to 3/4 preload. The engine now runs well,will idle at 550 rpm if I ask it to, and I have a steady 17 inches Hg at 750 rpm idle. However, there are still a few of the new lifters that bleed down overnight and take 5-10 seconds to pump up and quiet down.


I called Crane and they asked if my oil was dirty ( it isn't). They suggested sending back the lifters for analysis. Here's my problem. Logically it seems that there must be another issue here with two sets of lifters doing the same thing. There might be one more factor. The car was running very rich when I got it because it had the wrong power valve in the Holley carb,and that has been corrected. I checked the oil to see if it was diluted with gas but it smells like motor oil with no gas present.

At this point I am going to do two things.

1) I will change to fresh oil assuming that the EOS has thinned the oil.

2) I am going to make a valve cover with a cutout so that I can adjust the lifters while the engine is running. I find it hard to believe that my adjustments weren't done properly because I am getting smooth idle with steady idle vacuum, and all lifters pump up after a few seconds.

I will welcome any advice from engine experts.
Could there be something else that I am missing?
Something caused by my engine. Any opinions? Thanks for your help.

William-----

I also find it strange that you would have the same problem with 2 different sets of lifters IF THE PROBLEM WAS RELATED TO THE LIFTERS. So, I really think it has to lie elsewhere. One possibility might be excessive wear-induced clearance in the lifter bores or, even, excessive clearance that has existed since the engine was new. In either case, this is kind of unusual for a small block Chevrolet but it can happen.

As far as being able to properly adjust the lifters in the static condition, keep in mind that EVERY small block and big block Chevrolet engine ever built had their lifters originally adjusted in this manner. As far as I know, there were very few problems with initial lifter adjustment over the millions of engines manufactured.

The EOS should not thin the oil. If anything, it will thicken it.

[Ray G.]

Re: C2 327 hydraulic lifters bleeding down

Hello;
First things that popped into my pea brain when reading your description.
Is it possible the rocker arms or push rod sockets are binding?
Or a cut rocker stud?
What's the oil pressure at start up and/or is the oil volume low?
You can have good pressure and low volume. Restriction?

Hope that helps.
Ray

[Larry M.]

Re: C2 327 hydraulic lifters bleeding down

William:

I would also check to make sure that one (or more) rocker arm studs are not beginning to pull out of the head. This can create lifter adjustment problems as well as more significant engine issues.

Larry

[William G.]

Re: C2 327 hydraulic lifters bleeding down

Thanks to my fellow board members for your comments. In answer to some of the comments, I also agree that it is strange that this would happen to two sets of lifters. When I took out the first set of lifters three were bled down to the point that I could take a philips screwdriver and put the plunger all the way down with only internal spring pressure resisting. The other 13 lifters are still pumped up hard to this day .Unfortunately I did not record which ones were bad.

The former owner installed a high pressure oil pump which I plan to change to a stock unit in the near future. My oil guage reads 55-60 lbs at idle or under load. I know that's unnecessary and counterproductive. When I installed the new lifters I used a drill powered primer for a couple of minutes until the lifters pumped up and I had good pressure and some oil flow under the valve cover.

The lifter bores did not appear worn or damaged. I was pretty careful about things when I reassembled the engine.

So far, I suspect that either I have a condition in the engine that is very quickly damaging the lifters (they only have one hour total running time on them, or I have some defective lifters out of the box, or lastly I screwed up the preload adjustment. I'm not 100% sure but it seems that since the two or three noisy lifters do pump up after a few seconds, it seems to me to be unlikely that the preload is the problem. If they were set too tight then I believe that would show up as erratic vacuum pressure. And if they were set too loose they would clack all the time and could not pump up enough to quiet down.Am I correct?

Can a hydraulic lifter bleed down as a result of screwing up the preload?

[Joe L.]

Re: C2 327 hydraulic lifters bleeding down

I also agree with what Ray and Larry mentioned. Those are definite possibilities. Another possibility is self-locking rocker nuts that have low pre-load (i.e. they're worn and they aren't "locking" like they're supposed to). I'd just replace all the rocker nuts to eliminate that possibility; they are not that expensive.

If you determine that you have the "pulling studs" problem as Larry suggested, my recommendation would be to have screw-in studs installed rather than going with oversize replacement studs. To maintain original appearance, you can even use "flangeless" type screw-in studs as available from Pioneer Products, Dorman and others. These don't require the milling down of the stud bosses and are installed after tapping of the stud holes by double-nutting.

[Joe L.]

Re: C2 327 hydraulic lifters bleeding down

Thanks to my fellow board members for your comments. In answer to some of the comments, I also agree that it is strange that this would happen to two sets of lifters. When I took out the first set of lifters three were bled down to the point that I could take a philips screwdriver and put the plunger all the way down with only internal spring pressure resisting. The other 13 lifters are still pumped up hard to this day .Unfortunately I did not record which ones were bad.

The former owner installed a high pressure oil pump which I plan to change to a stock unit in the near future. My oil guage reads 55-60 lbs at idle or under load. I know that's unnecessary and counterproductive. When I installed the new lifters I used a drill powered primer for a couple of minutes until the lifters pumped up and I had good pressure and some oil flow under the valve cover.

The lifter bores did not appear worn or damaged. I was pretty careful about things when I reassembled the engine.

So far, I suspect that either I have a condition in the engine that is very quickly damaging the lifters (they only have one hour total running time on them, or I have some defective lifters out of the box, or lastly I screwed up the preload adjustment. I'm not 100% sure but it seems that since the two or three noisy lifters do pump up after a few seconds, it seems to me to be unlikely that the preload is the problem. If they were set too tight then I believe that would show up as erratic vacuum pressure. And if they were set too loose they would clack all the time and could not pump up enough to quiet down.Am I correct?

Can a hydraulic lifter bleed down as a result of screwing up the preload?

William-----


Can an hydraulic lifter bleed down as a result of screwing up the pre-load? It's not likely, but I would not rule it out completely. As a matter of fact, with an hydraulic lifter, there is really quite a range of adjustment that should still yield satisfactory operation. Factory spec is one turn down from zero lash. This approximately centers the plunger in the lifter bore. However, folks adjust these things with as little as 1/4 turn down to 1-1/4 turns down and no lifter problems ensue. So, the point is, your pre-load adjustment would have to be WAY off to cause problems.

I would recommend changing to a standard pressure oil system. However, you don't necessarily have to change the oil pump to accomplish this. Assuming that your pump is fairly new AND IS A STANDARD VOLUME TYPE PUMP (1.3" long gears rather than 1.5" long gears), all you need to do is change the pressure relief spring in the pump. GM #3814903 is the spring you need. If you have a high pressure AND high volume pump, change the whole pump. However, I do not think the oil pump is the cause of your lifter problems.

It would be interesting to know if the lifters which were causing the problem in the original set occupied the same positions as the lifters that are causing the problems in the replacement set. If so, I'd say the problem for sure has something to do with something besides the lifters.

[Clem Z.]

Re: C2 327 hydraulic lifters bleeding down

i just reread the first post and it said you used anti pump up lifters and any anti pump up lifters i ever used needed "zero" lashed

[Timothy B.]

Re: C2 327 hydraulic lifters bleeding down

William,
My vote is for rocker arm studs pulling out. If it were mine I would remove the valve covers and find the loose rockers before start up and some how check the studs compared to the others. Do it the same way you adjusted the valves, #1 TDC then #6 and check them for looseness. 17" vacuum is high for L79 and this indicates to me either play in the valve train or not original cam. Keep with the simple things first.

[William G.]

Re: C2 327 hydraulic lifters bleeding down

Last night I pulled the valve covers off and the studs all look fine and with the same number of exposed threads. So I don't think that the nuts or studs are the problem.
I just talked to the Crane Cam technician and he advised me
that anti-pump-up lifters require the same preload of 1/4 to 1 turn depending on who you talk to.I used 3/4 turn preload.

He also asked me if I have changed the oil after using the EOS (Engine Oil Supplement). He was quite assertive that that is probably my problem since any break-in particles present would cause the bleeding down. The first time I called Crane they asked if my oil was dirty and I never thought about how long to keep using the EOS mixture in the oilpan....and he never mentioned that the oil should be changed after break-in. So first thing today I will warm up the engine and replace the oil.

Does that sound reasonable?

[Timothy B.]

Re: C2 327 hydraulic lifters bleeding down

William,
I have never heard of anything like problems with GM EOS and lifter bleed down. You may want to check the rockers before you start the engine as in my first post, at least this will let you know if it's only a few or all are loose. When you adjusted the valves did you roll the push rod with your fingers until it feels like everything is snug then tighten one additional turn? I am sure you did but maybe you did not put enough preload (tighten enough).
Other possibilities could be wore out rocker arms and I bet many people overlook this, I know I did.