Hi everyone this is my first post!

I have replaced the 403 in my 79TA with a 455 .060 over, forged pistons, Melling high volume Oil Pump, Lunati Voodoo 284/294 Cam, 11:1, Edelbrock RPM Air Gap, Edelbrock 800 CFM AVS Carb, 3000 stall, 3.73 gears. Engine makes tremendous power but has oil leaks at the top end after acceleration. I am prepared to pull the engine and go back into it but would like to have a really good game plan. I am considering going to go back to a stock pump and seal up everything including the intake ends to keep oil in the bottom end. What are y'alls thoughts on a way to proceed? Also, probably going to replace 3.73 with 3.23 to slow it down a bit too.

 

Where exactly is the oil leaking? "Top end" isn't very descriptive.

 

Thanks Fun71! I am running it without the hood and i get a burst of smoke off the headers right side when I let off after a hard acceleration. Since there is oil all over the front and back of the engine at the Intake Valleys and it is running down I assume it is in the top due to the high volume oil pump. Never had these issues with the 403 but it was mostly stock with a mild cam. Any thoughts would be appreciated.

 

Throughly clean everything.


Go to your nearest auto parts store, get a small bottle of A/C oil with the fluorescent dye. Add a little to the oil, take it for a long hard drive. Then look the engine over with a black light. The dye will highlight exactly where the leak is coming from.

I personally would want a plan before pulling the engine out. You might be able to save yourself a lot of labor.

 

It’s most likely not the pump.
Your crankcase has pressure in it, that is most likely coming out of the breathers. Try running 1 less qt of oil in it and see what happens.

 

Make sure your PCV valve is hooked up to manifold vacuum. Hopefully it's just the valve cover gaskets.

 

Thanks everyone!
PCV system was suspected early on and still may be part of the problem but is connected correctly. I also added a breather to the oil fill tower to allow an extra source. I am also going to add an oil catch can in the future. Right now I am just trying to resolve the major oil leak issue and the dye plan is a great idea that will be my next step. Back to the pcv system, early on I suspected the valve and replaced it. I am wondering if it was faulty during break-in and may have caused the intake valley RTV form-in-place gaskets to blow out?????? I do not want to pull the engine but could have it out in a few hours. If that's the necessary case, I want it one and done! Hopefully. Thanks again everyone for your help and I appreciate the thoughtful ideas without the snarky comments usually associated with forums, especially to new guys.

 

Here's an engine bay pic of the 455

 

IMHO, a newly rebuilt engine should not build a lot of crankcase pressure if any. I would clean the oil up and check the valve cover and intake gaskets.

 

The oil pump is not causing your leaks. I think you are on the right path with some die to find out exactly where it is leaking from

 

Die may be overkill - try the dye, instead.

 

BTW, did you use the turkey tray intake gasket? It is difficult to install. I always cut the sides off of the turkey tray and use Right Stuff gasket maker instead of the included end rails.

 

I used Edelbrock's Gasket and RTV in the valley's. I have been doing that for 30 years with good results. I did not mention that the engine is turning 3000 RPM at 55 with the 3.73 gear set. I am thinking that is adding to my oil leaks also and will go down to 3.23 at a later date. The 455 does not need the 3.73's but it did help wake up the 403 that was previous.

 

RTV Ultra Black instead of the End Gaskets to clarify.

 

Do you have low manifold vacuum? If so the stock PCV might not work properly, good discussion here:
https://www.chevytalk.org/fusionbb/s...php?tid/96564/

You need to figure out where the oil is coming from. If it's from your breathers, the performance PCV might help. If it's from the valve covers or the intake, there is no reason to pull the engine, just fix the leaks.

If you have concerns about too much oil pumping up to the heads, did you use restricted pushrods? That's what most people are doing to keep oil down to the bottom end.

Factory valve covers tend to get distorted from over tightening. I use a body hammer and dolly to flatten them out at the bolt holes. I use a straight edge to check if I did it right. You can also use thicker valve cover gaskets that are more forgiving than the thin rubber ones.

 

Update!

Removed the intake manifold and found the valley gaskets had blown out. Sanded both sides and reinstalled the intake manifold with Felpro Gaskets (Like them better than the Edelbrock the Air Gap recommended). Also added a K&N valve cover breather and an oil fill breather cap as well as a new PCV valve for the 455. The only remaining leak is a small drip out of the front main seal. I believe what cause all of this was a faulty PCV system from the 403 that just wasn't sufficient for an 11:1 455. It was fine during break in but the first time I stood on it, it pressurized the crankcase and blew out the aforementioned seals. I will pull the harmonic balancer and replace the front main seal at a later date. Its only a small leak that I can live with for the time being. Now it's on to replacing the electric fuel pump with an Aeroquip. The current can't keep up with the 800 CFM carb. Thanks everyone for your suggestions and help.

 

Glad you cured the oil leak.

 

A PCV system cannot pressurize an engine as it is a vacuum. I believe you had blowby due to some reason, perhaps not fully seated rings, that did pressurize the crank case and punch out the seals. I am glad that you have found the issue, repaired it, and it is not happening again. Bear in mind that the 455 is a monstrous engine and does not need a ton of hi-po performance parts to be a street brawler. If you're seriously drag racing, then lay on that aftermarket performance fun, but a lot of people add more than what they need for street fun, especially in a T/A. Make sure the rest of that fire chicken is up to snuff, turning and stopping and the rest of the powertrain is important.

 

The PCV is vacuum operated and with little to no vacuum at WOT, it has nothing to do with relieving crankcase pressure in that scenario.

 

If you are running an after market harmonic balancer measure the snout some times they can be out of spec, its not always a seal issue.