leaky 360

dan58

It's time to finally put an end to the leaky bastage that is my 360. I think the culprit is pressure, not the seal itself. Now that the motor sees higher RPM and temps for longer periods, it's rather evident that the crankcase is building too much pressure and blowing out seals. When running at high speed for a while, I'll see the dipstick covered in oil, and the rear oil pan seal and back of the block covered in oil.
The info:
360 on propane, Edelbrock performer cam & intake, shorty headers
When I get to the garage tonight, the first thing I'm going to check is the PCV.

To the best of my knowledge, the black grommet at the back of the intake is the PCV. That needs to see a vac, correct?

Where else should I be looking on this beast?

fuzz401

try a breather in each valve cover and bigger one on the oil tube

dan58

Thanks, Fuzz. I guess that means drilling/tapping the valve covers?

fuzz401

try a set of steel covers first - my K&N breathers
4 screw holes and 1 big hole

dan58

I'll have to dig up a set. Would stockers fit the bill? Would that fix help the pressure with the oil pan leaking?

ironman_gq

If nothing else works you can always hook up a vacuum pump like some racers do. THey say it helps ring seal as well as keeps blowby under control

fuzz401

it should help I was shooting oil out my breather/oil fill tube it slowed it down other then that new rings

dan58

I just need to get through two more races and one trail ride this year. It looks like the fancy cast Edelbrock valve covers have no vent on them at all? Odd. And I don't recall what the 90 degree brass fitting is for on the intake???

fuzz401

power breaks?

msalaba

dan58 wrote
I just need to get through two more races and one trail ride this year. It looks like the fancy cast Edelbrock valve covers have no vent on them at all? Odd.

And I don't recall what the 90 degree brass fitting is for on the intake???

The valve covers do not have a vent cause AMC vented through the intake manifold. Vented valve covers are a Chev thing....

The 90 deg fitting is a manifold vacuum source. From the size of the barb i'd say brake booster or PCV.

I don't understand how you can be getting R's that high with an Edelbrock cam. Should fall on it's face shortly after 4500 RPM. With my Summit K8600 power starts to fade ~ 5200ish...

Sounds more like your PCV valve took a dump. I'd also check that you oil filer/breather is not plugged.

I wouldn't think you'd need more breathing capacity untill 6500+

Old Rugged Crosser

Dan, In your other post concerning the need of more low end power for those short burst of speed. I was looking at the pic you have here on your oil leaking problem I saw your intake manifold and have a suggestion for you that could help you in your desire for more low end torque and hp. I think you are using the wrong manifold for what you are trying to achieve. Here is my suggestion from Edelbrock : Performer #2131 (Idle - 5500 RPM) Patented Dual-plane, low-rise design with a 180º firing order greatly improves torque over a wide rpm range for excellent throttle response from off-idle through 5500rpm. Performers are ideal for passenger cars, trucks, 4x4s and RV's. While you are torn down this mite be the time to swap. :sa: :sa: :sa: p.s. I would think that that 90* fitting on your intake would be for your vacuum to your power brake booster. Your pvc valve should go below your carb.

dan58

Larry, that's the manifold that I have. :?: I did find something interesting tonight. It has no PCV valve.... 111!!!

dan58

Pictures speak a thousand words (or so I hope).

fuzz401

what does the hose with the yellow cap on it go to?

dan58

fuzz401 wrote
what does the hose with the yellow cap on it go to?

That runs from the hole (assuming PCV) on the back of the intake manifold to the propane mixer. I pulled it apart last night while running. It's making vacuum at idle, and it stumbled when disconnected.

fuzz401

there is a yellow cap on the base of the mixer that is not used could the pvc valve be hooked there with a bigger hose to pull more vacumn?

dan58

I can give that a whirl tonight when I get back up to the garage. Would I still want to try the valve covers?

fuzz401

if you can get more vac pull you should be able to not use the valve cover breathers

msalaba

fuzz401 wrote
there is a yellow cap on the base of the mixer that is not used could the pvc valve be hooked there with a bigger hose to pull more vacumn?

The yellow cap you are seeing is covering a stud. That Impco uses a Holly vac. secondary base plate rigged to run primary and secondary butterflies together. (Same one on mine)

Dan:

There is a 1/8" NPTF fitting in the middle of the rear of the baseplate. Screw a barb fitting into it for your PVC vac. Makes for a clean install...

The vac ports on the mixer body in the front are for the old fuel controller that was a POS. There is only one of value and that is the ported vac (draws from above the throttle plates) for the vac advance on the dist. Can't remember which one, I run manifold vac to the advance. There is one vac port on teh front of the baseplate too, it's full manifold.

The PCV valve is a small metal can with a barb on one end for the vac line and pushes into the grommet on the manifold (can be a PITA). Make sure it is not plugged.

Hope this helps.... 111!!!

msalaba

Boy was I off.... #-o That's an OMG - 450 mixer.... :t: Same Holly baseplate, different vac lines. IIRC, There is only one vac port on the mixerbody (Ported). All ports in the baseplate are full manifold vac. It looks like you are not running vac advance on your dist. It's generally a good idea... Another idea to help w/ torque would be to heat up your ign. Propane likes a hot spark. Best thing I did to mine since propane was a CDI box and 12v coil. (MSD 6AL + Blaster coil) Pick your brand... They're all the same.