Magnum Adventure

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sledger46

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Hello all,

I decided to create a separate thread concerning the details of the Magnum engine I was planning to swap into a 67 Dart. The back story goes like this: The current LA 360 in my Dart is your typical junkyard 360 from the late 70s with low compression and 2bbl cam. I was originally planning to pull the 360 for a mild performance build. It just so happens a low mileage 360 pops up on Craigslist. It is a 320 HP, Magnum 360, crate engine with 20,000 miles. The price is only $400. The engine was only missing the valve covers and the oil pan. For another $100 I picked up a M1 dual plane to go on it.

engine%2520front01.jpg


I patted myself on the back for this lucky find and immediately began to order up parts for it. I ordered up the correct oil pan and pickup for my Dart. I also picked up a used flexplate for a Magnum that would allow me to run my zero balance torque converter. I even called up Comp Cams and had a custom roller cam ground.

I had originally planned to swap in the cam and use the springs on the Magnum heads as they are the "heavy duty" ones. Failing to find the specs on the "heavy duty" springs. I figured it would be a good idea to swap the springs and clean up the bowls in the heads. I might even mill the heads a bit and use the thinner gasket to gain some more compression.

Like many of my other projects that just started as an innocent cam swap and nothing more, I began my taking the engine apart. The first task was to remove the intake, which took less than 3 seconds due to my awesome mechanic skills. NOT...it wasn't even bolted down.
engine%2520valley02.jpg


The lifter valley was clean and free of debris. I began the job of removing the rockers and pushrods on the drivers side head. I then removed the head bolts and removed the head. What I found would be considered typical for an engine with 20K miles.

I pulled the rockers and pushrods from the passenger side head and then proceeded to remove the head bolts. When I pulled the passenger side head I was greeted by a strange alien life form....

WARNING: The following picture are not intended for persons with weak constitutions!

goo%2520on%2520piston02.jpg



goo%2520on%2520piston.jpg


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I removed the alien life form and placed it in a specimen bag for future investigation.
goo%2520in%2520bag.jpg
 
Yum! Blown headgasket muck! That is quite interesting that it is that built up in just one cylinder. Id wanna go get your heads checked at the machine shop
 
Wow. That's NASTY.

Still, you got a hell of a great deal on that motor...I suspect it will be well worth salvaging.

Keep us posted.
 
When I looked at the head gasket, it didn't show any signs of being blown. I am wondering if the intake gasket wasn't seeping allowing that cylinder to suck down some coolant. It was the rear most cylinder on the passenger side. The cylinder shows signs of something funky stuck to the walls.
bad%2520cylinder%2520wall02.jpg



Yum! Blown headgasket muck! That is quite interesting that it is that built up in just one cylinder. Id wanna go get your heads checked at the machine shop
 
that head might be cracked or water came in through an open intake, either way, you have more fun ahead of you. I lean towards cracked head.
 
It could be a crack in the head between the valves. I have seen Magnum heads do it before at the junkyard when I was trying to find a set. Id just take em to a shop to be safe. That's just my two cents. You still got a pretty good deal.
 
Considering it was in the junkyard sitting for who knows how long, the valves may have not been fully seated and allowed water to seep in. You all are so quick to trash the head as cracked.
 
Considering it was in the junkyard sitting for who knows how long, the valves may have not been fully seated and allowed water to seep in. You all are so quick to trash the head as cracked.


x2. That's "normal" crap that is left after water infiltrates. The biggest issue will be rust piting on the cylinder walls and the condition of the rings and piston in that hole. I've seen much worse cleaned off and run and that's not a blown head gasket.
 
So do the Magnum crate engines suffer the same cracked head issues as the production motors?
 
The crate engines used the same castings as the regular magnum heads until they made the change to the RT heads, which these are not.
 
Head cracking issues abound from every auto manufacturer there is at any given time on a y engine. Many peoe here love to trash the Magnim head as prone to cracking and offer nothing but repeated statements of the issue.

I have had J heads crack, '68 Ford 302 heads crack. Cooling the engine is what needs to be done effectively in order to avoid any head cracking issues.
Whe some heads are more prone to cracking, the crack can be of little issue or a catastrophe.
 
Head cracking issues abound from every auto manufacturer there is at any given time on a y engine. Many peoe here love to trash the Magnim head as prone to cracking and offer nothing but repeated statements of the issue.

I have had J heads crack, '68 Ford 302 heads crack. Cooling the engine is what needs to be done effectively in order to avoid any head cracking issues.
Whe some heads are more prone to cracking, the crack can be of little issue or a catastrophe.

You make a good point, Rob.

My 360 Magnum (regular heads) has been subjected to 10 pounds of boost from my Vortech supercharger on the strip and on the street for several years, now, and shows no signs of cracking. But, when I installed the blower, I bought a new 3-core heavy-duty radiator and it's never gotten very hot... 200 max.
On the other hand, I inadvertantly let my 1993 318 DAKOTA get too hot once and it cracked both heads.
 
Considering most of the engines I pulled the heads off had been in the yard less than a month (worked at this junkyard), doubtful. I didn't say either that no other engine suffers this issue. I was just staring at a pair of 4.6 heads at the machine shop that cracked in between the valves. I never said every set of Magnum heads cracks or any such thing. I just said, I have seen it happen. Sorry if it came off like I was trashing Magnum heads. I was just saying perhaps they have cracked. Jeez.
 
It's common for Magnum heads to crack. It's less common for those cracks to penetrate to the cooling jackets. there are thousands of Magnums out running perfectly that show visible cracks between the seats. But in this case I do not believe that's a cracked head.
 
If you have to punch it, Check out EngineQuest heads,or RHS heads.About 6 to 8 bills,buys you extra metal in the crack areas.Also gains you,better flowing intake/exhaust ports,hardened exh.seats.Lapped new valves in,decent valve job,for a runner.(my own stuff,I have one as well...).
 
I pulled the piston last night to check out the rest of the cylinder and the piston itself.

piston%2520pin%2520area01.jpg


piston%2520pin%2520area02.jpg


What a mess. I cleaned up the piston, but still need to get the rings out. The goo being compressed into the head pushed past the rings and packed into the ring lands. I will have a fun time getting the rings out due rings being compressed down with no gap showing. I am pretty sure this crap will be under the valves as well. I will pull the valves and take a look at that tonight.
 
Try soaking it in transmission fluid for a couple days. See if that loosens it up.

I pulled the piston last night to check out the rest of the cylinder and the piston itself.

piston%2520pin%2520area01.jpg


piston%2520pin%2520area02.jpg


What a mess. I cleaned up the piston, but still need to get the rings out. The goo being compressed into the head pushed past the rings and packed into the ring lands. I will have a fun time getting the rings out due rings being compressed down with no gap showing. I am pretty sure this crap will be under the valves as well. I will pull the valves and take a look at that tonight.
 
Considering it was in the junkyard sitting for who knows how long, the valves may have not been fully seated and allowed water to seep in. You all are so quick to trash the head as cracked.

from what I understood this is not a salvage yard engine, his old one was, this was suppost to be a 20,000 mile crate engine. so there shouldn't of been rain water in it

its was caused by either a intake gasket, head gasket or cracked head
 
Diesel fuel works wonders,let in soak for a while.(Stinky stuff, hide from the lady in your life....) Check it ,once in a while. Might take a few days.
 
I'm pretty sure the 360 Crate Engines were built using seasoned (used) blocks and overbored .020. If the cylinder for that slug is bad, then it's another bore job. Mopar Performance does not recommend overboring more than .020 over stock but it's done everyday. I guess they're worried about cylinder wall distortion.

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What does the cylinder wall look like?
__________________
1986 Mazda RX7
- 360 Magnum, Comp XR265HR, Air-Gap, QFT 650dp
- GM 200-4R, 3400 Stall
- Ford IRS 8.8, 3.73, Trac-Lok

Hey UOP, I just saw a picture of your RX7 in the March 2013 Hot Rod. One of the quickest 32 in the daily driver class at Drag Week. Threw them a curve with the Mopar Power. :finga:
 
I got my custom cam from Comp Cams last night.....yup...it was ground with the wrong lobe separation angle. Someone doesn't want me to build this motor.

What does the cylinder wall look like?
bad%2520cylinder%2520wall01.jpg


bad%2520cylinder%2520wall02.jpg


With piston and rod out of the way...
bad%2520cylinder%2520wall03.jpg


The rest of the cylinders look great. I didn't see any .020 stamped on the piston. I think this crate motor might pre-date the "seaoned block" series.
 
This whole thread seems to answer the question: "What do you get when you mix transmission fluid and a mud daubber nest."
 
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