Oaker57

Ok Fellas, I need some help with my non original motor in my 64. The original fuelie, was long gone when I got the car, so I went the crate motor route, installing a 300hp 350. I wanted to maintain the original look, just because I really like it, but also made a few modifications for safety and or reliability. I then ran into the problem of no breather hole in the rear of the block, and thus, how to properly vent with the original Corvette finned valve covers still in place. The best solution at the time was to use a vented cap and PCV both on the oil fill tube. This seemed to work ok and had good oil pressure, except that oil would mist out of the breather cap and get spread around the engine, but it ran great with no other issues. After doing some research I found a company called "PLM" ( yourcovers.com ) that makes a nice reproduction valve cover with vent holes and grommets discretely located on the inboard sides, one with a breather and the other side set up for the PCV. They installed nicely and look great.

Thinking that these covers would solve my issue, I installed a proper oil fill cap, (temporarily left the old PCV in place and plugged it while I test the new setup) and new PCV to manifold vacume.

Now the main problem:

With this the new setup, I suddenly have very high oil pressure, it idols at a little over 40psi, which is ok, but when driving at around 45-50 mph it's pushing near 80psi. I am also developing leaks at the intake manifold-to-head gasket area, and also at the fuel pump, seemingly from the pivot pin. This must be due to excessive oil pressure, why would I suddenly have so much pressure? It also seems to want to idol higher until it's really warmed up, where as before I could get it to idol down relatively quickly. I'm running a Winters 461 intake with a 600 Holley. It runs and drives fine otherwise, but I'm really concerned about this excessive pressure and leakage, and I'm out of ideas on how to solve all this. I'm just trying to make a nice reliable driver. Any help or advice would be greatly appreciated.

I have posted some pictures of the setup below.

Thanks for reading.

Mark


https://www.corvetteforum.com/forums...1&d=1444617941

Oaker57

Anybody??

BD104X

I think your new PCV configuration is giving you pressure instead of vacuum for some reason. I would use the port that is going to your brake booster as a test (I assume your power brakes are working so we know you have good vacuum there) and see if that changes anything.

Tooth Doctor

I don't think you need two pcv valves. Leave the one on the oil fill tube and remove the second one from the passenger side valve cover, plug the vacuum fitting on the intake, and put in a filter inlet like you have on the driver's side. Nice looking engine by the way.

Oaker57

Thanks for the tip, I never would of thought that there could be pressure there, I will give it a try.

Oaker57

Thank you. I'm not really using two, the one in the oil fill is temporarily plugged while I'm testing this out, but thats not a bad idea to vent both covers and keep the original pcv valve. Appreciate the tip.

MikeM

Looks like you have your PVC plumbed into the #8 intake runner. Bad move as this makes for very lean fuel mixtures in this cylinder. Move the PVC vacuum source to the carb where the PB hose is and move the PB hose to the #8 intake runner where it's supposed to be.

I can't tell where/if you are getting fresh air into the crankcase. Can you run a hose from the air cleaner to the oil filler tube?

OR, you could screw the PVC into the oil fill tube and run the vacuum source from the back of the CARBURETOR and draw fresh air into the crank case from the valve cover to the air cleaner.

I don't see any way what you've done would affect oil pressure.

MasterDave

Put a breather cap on your oil fill tube, you need to not suck the gaskets into the intake valley.

rene-paul

I do not see a "clean air source"; On a typical 350 [post 68] the clean air source begins in the air filter routed to the valve cover,[right side]. The vacuum source begins at the carburetor routed to the left valve cover with a pcv valve installed there. You might consider this if your air cleaner has the ability to provide the clean air source. You do have the needed valve cover holes. You would have to remove and plug the pcv valve in the oil fill tube.
Let us know.
Brgds,
Rene

rene-paul

I forgot to mention to also plug the intake. Keep it simple.
Brgds,
Rene

JohnZ

Nothing you have done has any affect whatsoever on oil pressure, which has nothing to do with crankcase vacuum.

Oaker57

As I stated in the OP, that's where I started, and wanted to get away from the ugly looking breather cap. These vented valve covers are supposed to be the solution for that.

Faslane

Nothing you have done is wrong, looks great, absolutely nothing you did should cause higher oil pressure. try another sender first. then try to start it valve cover off and see if every push rod is pushing oil, if its not the gauge or sender its dead heading somewhere, did you put the cam bearing in?
BTW a lot of car flippers would like to know your secret. lol
Lane

Oaker57

Thanks for the reply Mike. A couple of questions :

Would the lean fuel mixture in #8 cause a miss by any chance?

The fresh air is getting in through the breather hole on the driver side valve cover, are you saying this may not be sufficient ? If not I can run air in from the air cleaner to that valve cover breather if that will help.

I am still stumped about the excessive oil pressure though.....

Oaker57

Thanks John, but can you think of any other reason that I would suddenly have this oil pressure issue? As I stated, I didn't have that issue until I made this change. It's getting very frustrating, and I don't want oil leaks on a nice clean motor.....

Oaker57

All good thoughts, but I don't think the sender or gauge is bad, as they were working perfectly right before this change, and the fact that the sudden leaks are appearing backs up the senders high pressure reading.

The cam bearing came already in, and I have been running the motor without any issues for about 9 mos. now

Faslane

Go back and configure it like you had it at first. See if it goes to normal.
Lane

MikeM

Yes to the possibility of causing a miss and high idle speed. If you hook up the PVC hose to the carb, that will distribute that calibrated vacuum leak to all cylinders instead of just one.

I couldn't see your fresh air intake on the other valve cover but I would run a hose to the air cleaner, INSIDE the air filter element.

I'd contact the engine supplier about the high oil pressure and the intake/head oil leak. This would not be related to your pressure either as would not the leak at the fuel pump pivot pin.

Check the pin on the fuel pump and see if it's starting to back out.

leif.anderson93

After doing all the work mentioned, did you change the oil? If so, did you go with a different viscosity of oil??

Oaker57

Mike, Thanks for all the advice. I will switch things around and see what happens. Sometimes it's nice to have a second set of eyes, and ideas.