Is it common for the 390 and 429's to burn oil? Because just the other day while driving my 64, I notice upon start up the same lifter that was making noise a month ago, came back. So I decided to check the oil, and to my surprise there was no oil registered on the dipstick!!

I don't know how that is possible when I don't drive the car a whole lot and the car doesn't smoke, or really leak any oil. Thank god my instincts to check the oil came to light as I was down 2 1/2 quarts of it! 

After adding oil, the oil finally registered on the dipstick and once started up the lifter tap was gone.

I added a couple of gallons of 110 Leaded Octane race fuel in the tank, and took the car for a drive. The engine smoothed out so much that It really help in the idling department with the race gas. Well after 20 minutes of driving, all of sudden while at a stop light, the lifter tap came back, and the engine idled roughly. As I accelerated, I noticed a lack of power, and the tapping getting worse. 

So I pull into the nearest gas station, and suddenly the engine smoothed out and idled fine again. So I quickly drove home and the engine ran great, well as I pull into to park, the tapping came back and yet again the engine idled rough and was sorta shaking. 

I can't understand why this only happens after driving the car for say 20 minutes, and the tapping comes and goes. My first thought is low oil pressure, but the light has never came on. Or a clogged oil pick up screen starving the lifters of oil. I've used 10w40 and 20w50 oil just in case the pressure drops or is low.

The big concern that is shocking to me, is the high amount loss of oil. To lose almost 3 quarts is crazy. Someone told me to stay away from Synthetic as I used 0w40 Mobil 1 when I did the oil change a couple of months back, and stick to high mileage dino oil, or just use conventional oil. One of my co-workers owns a 70 Chevy pickup with a 350, and he was using full Syn oil at one point in time, but it leaked out badly from the seals. So he started using diesel oil, specifically Delvac, and the leaking stopped completely.

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When you said you replaced the valve covers gaskets ,that rang a bell for me
They do not seal as well as some other covers ,with more bolt holes ,only having four
As a rule i do not like to use a sealer on gaskets ,as they do not come apart as esily ,when required , but i would recommend it regarding the valve cover gaskets
The cork may be affected by the heat and most things on an engine SB checked for tight ,after the engine has come to operating temp a number of times
Good chance you found your leak
A slow leak might evaporate from the engines heat ,before it hits the ground but in most cases ,there will be some sign of oil under the engine ,or on it
The valve covers usually leak at the back of the engine ,close to the trans ,due to the angle the engine sits
That could look like a rear main seal ,but is a much easier fix than that
Hope the problem is solved

I think thats the case too. The oil leak isn't huge, but a slow seepage that took time. I will get the bottom of this fairly soon.

Thanks Tone! And Merry Christmas to everyone, and for the help you have all given me through my 64 ownership! It sure is a never ending learning process.

Hi Chris I replaced the valve cover gaskets on my 64 and they still leaked. When I took them off I noticed that the cover seemed to hit the head before the gasket did or was very close. I replaced them with Fel Pro gaskets and saw right away the gasket stuck down further than the cover. When everything was tightened and in place the covers were slightly off the head and made a tight seal. It's been 3 years and zero leaks. Also make sure your oil pressure indicator switch, located on the rear of the engine is tight. I am sure that is not your problem but it can drip down to where the rear seal is and give you a false indication of a rear seal leak.

Ok I didn't even know that was the oil pressure switch! Thanks!

Ron, good point about gasket thickness. Definitely avoid the thin cheap gaskets. The Felpro gaskets I use are very thick.
Looks like valve cover gaskets leaking on our year cars is more common than it SB
Need thick gaskets and some special attention to detail
Install the gasket to the valve cover ,with a sealent ,and let it dry ,so the gasket will not shift in the corners when you are seating it on the head
Do not overtighten ,but do recheck tightness after the engine has been run at its operating temperature a number of times
While keeping your eye out for a possible leak ,and checking your oil level and useage as well
Loosing oil is detramental to the health of our drive trains
Syn oils will leak out of some gaskets more easily ,as it appears to be thinner than conventional oil
I would recommend going back to the 10w- 30 oil that Cadillac suggests for the stock motors
My recent choice in oil is castrol 10w-30 oil ( back to conventional oil,last change ) ),with a Rislone zinc additive
I have run Mobile One - high mileage , 15,000 mile oil ,for years with a bit more seal leaking ,and higher cost ,as i only put about 600 miles a year on my car
I just wanted to increase the zinc in my oil ,over that of the Mobile
A side affect , is i think my engine is putting out more power with the conventional oil ,that i contribute to the lifters pumping up a bit more , from a different consistany oil and affecting the valve travel some
This is just my own best quest
Yes ,my oil seal leaks (all slight ) have decresed as well as the main crank seal ,that has reduced by 2/3rds the small leak i had ,and a nice improvement there
Most oils are good for X number of miles Or one year ,so using very expensive oil in a car used little does not make much sence
While my cars engine is protected to the max ,with the coventional oil i chose this time around

You know I used the thick Fel Pro cork gasket, so I didn't install some cheap off brand no name one. Yes I do believe conventional might suit this engine better, as the consistency is very different from a full syn 10w30 to a conventional 10w30.

Well the tapping went away guys! I had to add another bottle of the Rislone Zinc additive, and after about 15 minutes of driving, the tapping went away. 

Some engines are just very sensitive regarding zinc use, and this is the first classic car I have owned that has been so finicky with the kind of oil I have put in. The Zinc helped smooth the engine out as well. 

I'll definitely be keeping my eye on the oil level more closely now until the leakage is gone.

Hey guys I’m reviving my old thread because I have another issue that seems to always happen now when I am about to park the car after a quick cruise.

So when I come home and park the car, put it in reverse and then drive the idle will drop almost as if the engine wants to die, after a couple of times reversing then putting the car into drive, the engine will start running rough and start ticking again. It’s been doing more and more lately as well.

The car starts up great but with some slight ticking/tapping but then the noise will go away after the engine warms up. Nothing has changed since this post besides for using thicker oil like 20W50 which actually reduces the ticking and usually eliminates it. 

10W30 is too thin for some reason and the engine makes noise and runs rough with that kind of oil even when using a Zinc additive.

I want to install an oil pressure gauge, but I’m not sure what kind or what brand. Will any oil pressure gauge work or does it have to be specific?

i know I need to tackle the problem head on by removing the front timing cover and inspecting the oil pump itself, but I’ve been way too busy lately and it’s a job I’d rather have a shop do for me and get it done much faster at the same time they can replace the timing gears and tell me if something is seriously wrong.

Check your idle, it may be too low.  When was the last time the oil fill cap screen was cleaned, along with the PCV valve.

Hey Russ, the idle is fine when say I’m at a stop light. In drive, the RPMs are usually around 500-520, it’s only when I put the trans into R and back into D is when the idle drops really low and I get a bog.

The PCV is good, it’s not stuck. The oil cap is a closed system type, so it doesn’t have the breather screen.

If the oil filler cap is a sealed piece, then air needs to get in somewhere. If this is a Cali car, then the breather is in the air cleaner housing.



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