318/360 magnum issues

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70Swinger510

70Swinger510

Bay Area Swinger
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!!! So I'm on my last nerve with this engine,
it's a 318 block 360 magnum heads,
I blew a head gasket car overheated changed them both, a few houndred miles later blew the other head gasket, not completley just had oil seeping out where it mates with the head, changed them both again doing everything right torqueing them to 100 ft lbs and I'm out driving today less then 100 miles since the new gaskets and oil is seeping out the passenger side head gasket ....

It has a large cam hydraulic lifters it doesnt over heat, it runs about 170 and in traffic was creeping to 190, i had the heads checked and surfaced there are a few passages on the block that were plugged i guess to acomedate the magnum heads...

anyone have any ideas? anything I should check to make sure that mysetup is working? i'm about ready to dump this setup and find a running 360 and just drop that in...


thanks !

Chris
 
Was the block super clean when you installed them?? Did you coat your gaskets with copper gasket spray prior to install to seal up the inperfections in the surfaces?? If you havent tried COMETIC head gaskets yet, try them. When installed correctly they seal fine as long as your surfaces are nice and clean....... call Don at FBO, he has many sizes and thicknesses in stock for your correct bore sizing etc, no messing around with a 4.170 bore size when you are a 318 with a 3.910 bore size.....

Check out his site at www.4secondsflat.com
Don is a good guy, give him a call and tell him what you got and he
will be more than willing to help you solve your problem.
 
hi, why do you torque them to 100 #?? I found that torquing them causes the block to pull up and creates a problem with head gaskets leaking.
where are you leakin oil from ?? at the maniflold /block juncture?? is it running down to bottom of block ? making it look like head gasket is leaking? just curious . what torque sequence steps do you use?
 
Torque spec for Magnum heads (on a magnum engine) is 105 ft lbs. Not sure if it should be any different when the heads are bolted onto an LA block. I used the thin Mopar gaskets on my 360, copper coated em, torqued to 105 ft lbs (way too much for an old fart like me) and haven't had an issue. Are you using bolts for the Magnum heads? Not sure if the LA bolts would even work. Maybe you're getting the torque value but not compressing the heads if you're using LA head bolts. Mopar or NAPA has the Magnum head bolts, NAPA was around $40.
 
Thanks for all the replies guys, first off, I'm using standard felpro gaskets, and used magnum head bolts, I cleaned the block as much as I could with some emery cloth, didn't try the copper spray. heads were sent to the machine shop for a surface mag and pressure test

And it's definatly leaking from where the block meets the head, I will try to take some photos, i thought it might have been running down from the front of the intake manifold, but doesn't seem like it.

I am going to give this thing one more shot, I'm gonna pull the motor this time and do it out of the car because it's a pain in the *** to torque inside the car. This way i can make sure its super clean and possibly send the block out as well and have it decked. Let me go take a few photos and I will post shortly!

You guys rock!

-Chris
 

fore sure check the deck out. it will never seal right if its not flat. also don't put anything on the fel-pro gaskets, install them dry like they say to.
 
yep, sounds like the deck's out of square, or you have a burr somewhere which isn't allowing a seal.
 
Purchase a bottoming tape and clean out all the head bolt holes.1,the bolts thread in easier and 2,it's possible they were not going all the way down to give you the proper clamping force.Also,try torqueing the heads in multiple steps and in the pattern shown in the service manual.Start at 25 ft.lbs. to snug everything down.then 50,next 75,then the final called for torque.May be a lot of extra work,but little details add up.Good luck!Bob
 
70Swinger510 said:
!!! So I'm on my last nerve with this engine,
it's a 318 block 360 magnum heads,
I blew a head gasket car overheated changed them both, a few houndred miles later blew the other head gasket, not completley just had oil seeping out where it mates with the head, changed them both again doing everything right torqueing them to 100 ft lbs and I'm out driving today less then 100 miles since the new gaskets and oil is seeping out the passenger side head gasket ....

It has a large cam hydraulic lifters it doesnt over heat, it runs about 170 and in traffic was creeping to 190, i had the heads checked and surfaced there are a few passages on the block that were plugged i guess to acomedate the magnum heads...

anyone have any ideas? anything I should check to make sure that mysetup is working? i'm about ready to dump this setup and find a running 360 and just drop that in...


thanks !

Chris
Click to expand...


Magnum heads means you are oiling thru the pushrods. The LA blocks had the passage that allowed oil to go up thru the pedistal for the LA rocker shafts. Did you tap and plug this passage? If not then thats where your oil is leaking from.... The passage is actually outside the cylinder torque area and it is prone to leak on magnum headed LA setups unless plugged.

Larry
 
I have not blocked my oil passage on my 77 360 with magnum heads and I have driven my car for over 500 miles with no issues whatsoever. If it did leak, i'd bet it would leak into the lifter valley.
 
I plugged mine on the stroker I am working on. They say that the head gasket is a good enough sealer but I didnt want to chance it.
 
Goldduster318 is probably correct on this subject. The hole is right near the lifter valley............trying to attach a picture with arrows on it, having issues will try later...........
 
With a Magnum engine, all sources I've said say to torque in sequence like an intake manifold (center first, moving outward on both sides). Start with 25 ftlb and move incrementally ten ftlb each time up to 105ftlb. I did this and no leaks.
 
Mad Dart said:
Goldduster318 is probably correct on this subject. The hole is right near the lifter valley............trying to attach a picture with arrows on it, having issues will try later...........
Click to expand...

Here is the picture, Look at cylinder #1 at about 1pm right at the lifter valley. There you will see the plug.

410 Stroker oil hole 007.jpg
 
after you check the deck to make sure it is level. get yourself some felpro 1008's they seem to seal up the best on the magnum blocks. Most of the dakota guys are running them with some 400-600 hp magnums. I would stay away from the cometic gaskets, almost everyone that I have heard use them leaked. usually they leak antifreeze near the back of the blocks.
 
When I built my 360LA with magnum heads I never heard anyone recommending that the LA oil feed hole be plugged and I didn't. I used Fel Pro LA head gaskets and now have 30,000 miles on my set up with no leak issues.

My block was decked but the magnum heads were low mileage units from a warranty failure of the bottom end of the egine they were on. I cleaned them up, checked them for flatness with a straight edge, installed new seals, springs and bolted them on.

If the heads have been surfaced then I would be looking at the block to make sure the surface is flat.
 
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