Some 360 magnum questions

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Abodysrule

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So, I finally fired up my 360 magnum, set the timing, took it for a short test drive ('67 dart 2 door hardtop). I have a few questions and and an issue (the thing I dread most, an oil leak). It runs cool, no issue there, great response, kickdown is working perfectly (A904), very smooth and gobs of power.

First, I set the timing according to spec, 32 degrees mechanical advance at 2800 rpm, 50 total with vacuum. It runs fantastic, but I did notice when it's warmed up it was starting a bit more slowly, i.e. cranking a bit slow as an engine does when the timing is too far advanced. I don't hear any detonation or anything, the AFR is 14.5 at idle and cruise, but lower under throttle, like 12.5-13. It wasn't overheated or anything, at least the coolant temp was 200 degrees. I'm just wondering if the hot slow cranking is indicative of the timing being too far advanced. Should I retard the timing a bit, thoughts on that? It's a Mopar Performance distributor and I'm using FiTech 30003 TBI four barrel.

Second, when I start it cold, the oil pressure is 50-60 psi, but after it warms up it goes down to a bit less than 20 psi at idle and just under 40 psi at highway speeds (2800 rpm). That seems a bit low to me, but tell me if it's normal.

Third, ugh, I stopped to check everything after a few miles and the rear main seal is leaking oil. OMG, I HATE rear seal leaks. I've had many engines not leak a drop, even junk yard pulls, and only a few with rear seal leaks. Are 360 magnums more prone than not, or did my builder just not do a good job.....ugh, I dread the thought of having to pull it after all that work. Anyway, if there are super triple lip seals or any special advice there, let me know as I'm pretty sure I'll be pulling it out and redoing that rear seal in a short time.

Thanks all.

Brian

P.S. the 360 magnum is a BEAST! My TTi shorty headers/2.5" dual exhaust is a bit loud, I'm gonna have to modify it to tone it down a bit, but man does that engine have power.
 
If engine is a fresh rebuild, needs time to break in. Usually more heat is produced when engine is new. The headers could be heat soaking the starter if the shorty TTI's are close to it causing slow start. Make sure valve covers aren't leaking at the rear giving you false rear main leak. Also oil pressure sender could be leaking. Hopefully not the rear main seal.
 
Preliminary check shows oil pressure sensor not leaking, I'll check the valve covers but I'm not hopeful there. The mini starter seems pretty clear of the TTi shorty headers, lots of room when installing it. I pulled her into the garage, rechecked the tranny fluid while still warm, shut her off (disgusted), and after she cools off I'll check and report back.
 
Yes, well the check ball was moving freely, pretty new, not gummed up or anything. Other than checking to see that the PCV valve's ball is freely moving, how might I check that?
 
Update: Now that it's cooled off, I crawled under to see where the oil was. See pics. Green arrows indicate No Oil and red arrows indicate oil found here. Sorry, I wiped it up before realizing it would be good to see where it was.

1. no oil coming from 90 degree oil filter adapter, not the bolt or the main gasket on the block.
2. no oil on the curved pan rail at the rear (good sign), but definitely oil between the inspection plate and the bell housing.
3. oil all over the pan, steering linkage and drain plug (no, the drain plug was not leaking)
4. oil on the bell housing and transmission pan
5. oil near the distributor clamp, but I didn't see any around the oil pressure sending unit base, it was running down the passenger side of the engine near the bell housing from that area though, could be distributor isn't sealed properly.
6. oil on the bottom passenger side of the block where it mates the bell housing, consistent with leak seen at distributor clamp.

NOTE: the valve covers are not leaking, definitely bone dry all the way around.

So, the distributor had an o-ring seal, do these leak commonly? What about the intake gasket at the rear where the dizzy is, maybe that's leaking?

Brian

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Ah, so upon further inspection, I note (see pics) that there is no oil at the base of the oil pressure sending unit, there is no oil at the base of the distributor, but I do see oil between the intake and the block at the rear. The paint is new and shiny, you'll have to take my word for it if the pictures (taken of the reflection from a small mirror) aren't clear. And, I also found this discussion on exactly the same issue: Can't stop oil leak at base of distributor

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Also check the back of the intake manifold where it joins the block as i had a gasket fail there and thought it was a rear main gone on the return of a 1000 klm round trip and was just topping up fuel at first stop and was checking fluids and found the oil a bit low so looked under the car and saw the oil
 
Since you pretty much ruled out the easy leak fixes, then probably intake manifold at the China wall as it is called. Many of us just use silicon at the manifold at the front and rear and not use the gaskets.
 
Thanks all, yes, there was also some advice in that link to this forum I found (posted above). Any tricks of the trade like that are helpful. I'll buy some gaskets today, best silicone? Some suggest red RTV, but I'd prefer specific brand if anyone has a silicone they prefer.
 
I don't know, but I think it's a standard volume pump, Melling. That's a good rule of thumb you gave, so it has about 10 psi / 1k.

What about intake gasket recommendations? This is a 360 magnum but I have a naturally aspirated air gap intake on there, the Professional Products model.

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And before I go too deep, is there any chance this can be sealed without removing the intake? I'm guessing the answer is no, but I thought I'd ask.
 
good chance it's coming from the rear of the intake like mentioned above. With the aluminum intake, on the ends (china wall) just use a 3/8 bead of Permatex RTV MAX OIL Resistance Black Silicone. And but an extra bead in each of the corners. Give it a couple hours to settle up before starting. Then use the intake to head gaskets as you normally would, obviously. I also put a thin coat of rtv around the water jackets on each end of the heads, both sides of the gaskets
 
Yeah, this morning I felt with dry finger around the oil sending unit and dizzy and no oil, but clearly it was running from the intake rear and down the passenger side of the block. Checked the intake bolts they were firm, not loose.

OK, so you use a 3/8" bead of that RTV, little extra where the head gaskets meet it, let it set, then put on the head gaskets with just a thin coat around the water jacket ports, but nowhere else, right? I've also seen the silicone with steel core gaskets for the front and back ends, people use a dab of silicone where those meet the head gaskets as well.

Great stuff.

Brian
 
Abodysrule said:
Oh yeah, just thought of that, these are stock cast iron magnum heads.
Click to expand...
I like the Felpro 1213 or Edelbrock #7276 on my LA builds, I’m trying the Mr Gasket ultra seal(I think?) next. I’ve never done a magnum based SB so I’m no good on a part number recommendation.
 
Abodysrule said:
Yeah, this morning I felt with dry finger around the oil sending unit and dizzy and no oil, but clearly it was running from the intake rear and down the passenger side of the block. Checked the intake bolts they were firm, not loose.

OK, so you use a 3/8" bead of that RTV, little extra where the head gaskets meet it, let it set, then put on the head gaskets with just a thin coat around the water jacket ports, but nowhere else, right? I've also seen the silicone with steel core gaskets for the front and back ends, people use a dab of silicone where those meet the head gaskets as well.

Great stuff.

Brian
Click to expand...
For sake of explaining, if the china wall runs east and west, i run a short bead north and south on the corners under the water jackets to seal the corner, kind of use my finger to "build a dam".
 
Abodysrule said:
And before I go too deep, is there any chance this can be sealed without removing the intake? I'm guessing the answer is no, but I thought I'd ask.
Click to expand...
FWIW, I've "fixed" one before by cleaning thoroughly with brake cleaner and applying a fillet of ultra black to the entire rear of the intake to block interface. 2 years later it is still not leaking.
 
There is a trick to aligning the manifold when installing. Use a threaded rod screwed into the heads, at least 2, which will bring head straight down. I don't remember thread size that you need for the rod and probably 4" long rod will do the trick. Maybe someone here knows what the thread size is or take a manifold bolt to Home Depot and match it up. This is only done with the vertical bolts on the manifold.
 
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