Hi! I just joined the forum in search of some possible solutions.
I just finished rebuilding a chevy 250 engine in a 1966 Biscayne.
It had only 70,000 miles on it and I had to rebuild it with engine in car. It had one piston burned all the way down the side. Not much ridge in the cylinders. I replaced all the pistons rings and rods bearings, put a new head on it as old one was shot. I got it running ok but its running kinda rough. I have adjusted the valves 5 times. I turns out it will only run reasonably well with the valves set at right at about zero lash. It has hydraulic lifters and I took them all out and cleaned them and put them back in put new spring clips in them instead of the ones that it had as some of them were broke or near failure. If I adjust the vales according to manual where you give them a full turn after zero lash the engine runs really rough and shakes all over and two or three of the cylinders act like they are missing. I pull the plug wires to see which ones make a difference when running. So I suspect some valves are not closing all the way when I have a full turn on the lifter adjustment. At zero it runs pretty good but still a little rough. I tried half a turn also. So what is happening are the lifters pumping up too hard? air trapped or what. I put a high volume oil pump in it also. I would like it to run real smooth, but have not been able to get it to do that yet. I did put all the lifters back in the hole they came from. got two mixed up and bought two new ones to put in that hole. They all seem to be lifting fine, the cam was in OK shape. Got plenty of oil coming up through all the pushrods.
You did not say you primed the lifters or not.
How long has the engine been running?
H.V. oil pump is a no no. Causes premature wear on camshaft drive for the distributer & wears out the distributer gear.
I have seen lifters not pump up for a while,even when engine has been running for a while.
Are the lifters noisy?
MBHD
Well all I did was put a little oil in the top of each lifter with an oil can and pushed it up and down a fuw times. I read somewehre it not good to fill them up. I also turned the oilpump with a drill till oil came out the rocker arms. Engine seems to run quiet no lifter noise at any time. Reason I got high volume oil pump is because I didn't change the crank bearings. All rod old bearings looked in good shape and engine didn't have much wear on it, so I figured a high volume would just keep it about stock after losses. I have run engine about an hour or two total time so far. Drove car across town. seems to have plenty power and pep and response.
Where ever you read it is not good to fill them up,throw away that literature.
To fill lifters up,submerge them in a can filled with your engine oil & compress the center plunger until they fill up w/oil.
Or have them installed in the engine turn the oil pump with a drill motor & turn the crankshaft several times until you have good flow of oil coming out of the rocker arms.
HV,oil pump is still a no no,you will find out sooner or later.
It will ruin your camshaft,& distributer gear.
You can go a 1/4 turn also after you have zero lash.
Is it a stock cam?
MBHD
Well I did the second one, using the drill and turned the oilpump till the oil cam out of the rockers.
So can air still get trapped under the check valve inside the lifter? Seems like they would be soft if that happens. the way it behaves is that they don't bleed down good enough. Pump up solid and stay that way. Maybe running it for longer time will loosen them up.
I took each one completely apart and cleaned it very carefully and put them back together.
I will try the 1/4 turn and see what happens.
Yes it is a stock cam, I didn't remove it, just left it in there, don't have the cash to get a new one at this time.
I'll take my chances with the oil pump, with good lube you don't have to worry about things wearing out so easy. they have reduced wear additves in regular modern oil due to environmental reasons so one has to use an oil that is exempt from that and still has the wear additives. So I am not worried about the distributor gear, I'll have plenty of protection on that high pressure area then.
I know I will catch some flak for this but here goes...
If you have to change the lifters in a few weeks it aint too hard. You can fish them out thru the pushrod covers.
WHEN you do change the lifters get new pushrods too. I used a rubber gasket but it was only a dollar or so more. Oreillys had to order it and it took 3 days to get the rubber gasket.
When you put on the new pushrod cover gasket be sure to put some RTV on there to hold the gasket in place. I just changed my gasket this week and GRAVITY was winning until the RTV. Also it has to set on the motor perfect or it will leak. You can loosen the cover and scoot it back in place.
you don't need to replace the push rods, UNLESS there is something wrong with them. Clean them up be sure you can see through them. And there is no need for a HV pump espcaily on a stock motor.
Mike Kirby does not run a HV oil pump on his 10,000 rpm dragster engines. Just a regular one.
He states the same as I do, do not use a HV oil pump.
A regular volume oil pump is good enough.
I have worn out three distributer drives on the camshafts.
Had to replace them all,& 3 bronze distributer gears all because of a HV oil pump.
I later installed a standard volume oil pump, & the problem went away.
MBHD
And i guess i shoould have made the comment about mine That it seen 8000 manytimes and I'm sure this new motor will see that and then some??????
Hi guys thanks for all the good tips. I will keep the oil pump thing in mind. unfortunately its already in the engine and now I don't have the means to replace it. I had rebuilt the engine in somebodies yard and now that it runs I have it at my place and can not do any heavy work on it anymore. I plan on putting torco conventional diesel oil in the crank case once the rings are seated and then also add some torco MPZ additive, that should prevent any wear on the cam and distributor gear. This car will only be used to put around town mostly so its not going to see a lot of RPMs most of the time.
I did realize when I pumped up the oil pressure with a drill as suggested I forget to turn over the engine and do it some more so probably only some of the lifters got filled up. that could explain why it was missing on some of the cylinders. I am hoping it just works its way out once I run the engine long enough. The carburator is next for rebuild so that should help it at least start easier. Thanks again for all the pointers.
I think alot of people think the general rule is bigger is better (regarding the HV oil pump), but we all know that isn't always true considering we run Inline 6's in the first place
Well I rebuilt a slant 6 years ago and also a chevy 350 and always used a high volume pump in the rebuilds even though they were stock, never had a problem with them, just gave a few extra pounds of oil pressure as they wear out so you get more life out of the engine. I drove the slant 6 for 15 years and the chev has been going for over 10 and still going strong.
I compared it with the old pump and all you get is a slightly wider gear in it. Its a loose engine too so I don't think it will be a problem. The extra volume should do it fine. I prefer that than having low oil pressure. I expect the 250 to last 10 or 20 years or longer also.
The Slant 6 & SBC's are engines not known to having this type of problems with the distributer drives.,but Chevy inline 194,230,250,292's are known to having these problems when using a HV oil pump.
Does Leos book say not to use a HV pump,,,,I forgot?.
MBHD
If the problem with the inline 250 distributor gears has been happening for only the last 10 or 15 years then its probably due to the quality of the oil. there have been a lot of flat tappet Cam failures in the last decade especially on high performance engines and that is becaues of changes in the oil additives. Insuring that one has enough of the additives in the oil usually eliminates those kinds of problems in the high pressure points in the engines. A reduction in the Zinc and phosphorus additives mandated by the EPA due to "Environmmental Issues" in the oils makes less able to deal with the sliding pressure points like flat tappet lifters and thoes gears on the distributor. That causes metal to metal contact and wears them out. if you don't allow the metal to metal contact then they won't go bad. Simple solution. Most modern engines use roller lifters now so don't have a problem with the modern oils. so having problems with that cam and distributor gear could very well be the fault of the oil used. I guess I will be the test subject on that then, and we get to see how long it lasts with the right kind of oil in the engine. None of the crappy synthetic stuff.
When I had my problems with the camsahfts,it was an easy 15+ years ago with different makes of camshafts also & oils.
Goodluck!
MBHD
Vman, It sounds like your lifters are not working correctly. Can you get the engine to idle down by backing each one off, even to the point of being loose? If it does, then is just a lifter problem and another set should cure it. You should be able to go at least a full turn and half down with out any problem. You do have to go slow and wait while the engine catches up to each adjustment. It takes awhile to do so give it time.
With a 70,000 Mile set of worn bearings, I sure wouldn't worry about the oil pump, plus you already told me its a low rpm cruiser, not a high rpm racer. And about the oil, you don't need the heavy diesel oil if the cam and lifters already have 70K miles on them. Just pick up any brand of oil you like and add one can of Mellings or Crane oil additive if you want extra protection. The heavy oil is just extra work for the pump, gears, and distributor. I run Mobil 1 5W20 in my engine with out any problem and no additive. Once the cam is broke in, any of the new oils will work with our type of engine. Its the killer valve spring pressure and radical cam profiles that need the extra protection, not a stock 6 cylinder cam! Joe
Yeah I plan on putting some additive in there once the rings are seated. Found out about Torco MPZ also has extra zinc, phosphorus and moly in it.
Good website here about the oils etc.
http://www.brightgreen.us/lubedev/smartgas/ultra5.htmhttp://brightgreen.us/lubedev/smartgas/
A $3.00 bottle of STP has enough zinc for 4-5 quarts of oil. This is from STP customer service.
I think bananas may have that much zinc in them too, specially if they been sitting in the metal garbage can for a few months.
chuckle snort :-)
It's worth a try. Let us know how it works out for ya!
Well here it is almost 5 years later I originally posted in 10/13/08 . Just wanted to update you guys on the engine. Its still running great with the high volume oil pump. pressure goes up to 80 PSI when cold and runs around 60 psi during normal driving. idles hot around 30.
Great, have you pulled out the distributer & check the drive gear?
Take a pic & post it.
MBHD
OH yes actually I have it , I put a new HEI unit in there about a month ago and have the old distributor in the trunk. I will fetch it and take closeup photo of the drive gear. I have been using Torco MPZ Magnetic Friction Reducer in the engine all the time and also have aded Tungsten disulfide powder to the engine oil a few times so there should be no wear.
The main thing that contributes to distributor drive gear wear in these engines, and any other engine as well is excessive cam walk. Many people that have built these engines have never even checked that to see what it is when they are putting the engine together because they either don't know to check it or know how too, its just a part of engine blueprinting. It should never be more than the crank end play. A high volume pump has very little to do with it. If you or anyone has experienced failure from using a high volume pump, your problem was something other than the pump. What is going to happen if you have too much pinion backlash in a rear end? Headrick built several hundred of these engines for racers, other enthusiasts and Cotton and himself, this was never an issue for him.
I have said before in the past about gear wear.
I used to run a HV pump wore out 3 to 4 distributor gears before & switched to a standard volume oil pump, after that switch, no more problems.
In all camshaft changes, I used the same thrust washer. It was not worn.
Might have been just my bad luck, but not too sure.
Mike Kirby says a standard volume oil pump is fine to use, even for high RPM. My high RPM is 7500 @ 40 PSI of oil pressure.
Think my bearing clearances are loose.
Not like a typical SBC 10 PSi per 1000 RPM.
MBHD
There have been instances in the past where cam companies had hardness issues, so it could have been your bad luck as you said and that could have been the cause....soft cams. But too many hundreds of thousands of these have run fine with high volume pumps for the pumps to be the "cause". Thats how urban legends get started, and their usually found to have no foundation to support them.
Ok I have the photos of the distributor gear. a little dirt sorry. I looked close with a loupe magnifier and there is some scoring but no way to say it was from the high volume oil pump. Looks like misimal wear for an old beat up engine that was abused to the point of burning a piston all the way through by the previous owners. And then again I didn't put it under any stress, like racing or anything when I owned it. I posted the pics here on a web page.
http://www.photonmatrix.com/distributor/index.htm
Thats what it should look like. Looks good.