De-tune 360 mag

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sireland67

sireland67

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I have a 94 360 magnum that is fresh.
I built it for my duster, but may put it in my truck 78 W-150 SWB standard cab 435 4-speed 3.55 gear 28" tires
I need to make a truck motor out of what I already have.
As the motor sets right now:
Std bore, Std stroke, KB 107 pistons bottom end balanced, I do not want do anything to the block, crank, rods.
OTB Eldebrock mag heads.
If I put everything right in the compression caculator I have 11.37 static and 10.17 dynaimic.
This is with a Comp XR280HR-10 cam.
.039 head gaskets.
This truck will be used for pulling trailers and heavy loads.
Low usage only about a tank of gas a month.
How can I get the compression down?
Or am I better off building another motor with about 9.1 static and just leaving this one alone.
RPM requirements are 600 rpm to 5000.
Would like to run on pump gas.
 
I have a Crower 34116 hyd roller grind. 284@,[email protected] on a 114 lobe center. Had 21" at idle vacuum, @ 800 in drive.(carbed,16 initial).
 
Abodybomber said:
I have a Crower 34116 hyd roller grind. 284@,[email protected] on a 114 lobe center. Had 21" at idle vacuum, @ 800 in drive.(carbed,16 initial).
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What is the lift on that?
And what compression are you running.
Sorry did not look up the specs on the cam.
How does it pull down low 1000 -2500 rpm.
 
.491 lift.stock Magnum heads,gaskets, bottom end..Never drove it. Power band,2-6 k. A loose converter, behind it. A air gap,750 d.p. on top.BTW heads were shot.
 
What is your head gasket bore size? Did you measure your deck clearance? And that camshft intake closing point?
 
Abodybomber said:
.491 lift.stock Magnum heads,gaskets, bottom end..Never drove it. Power band,2-6 k. A loose converter, behind it. A air gap,750 d.p. on top.BTW heads were shot.
Click to expand...

The cam looks to have less lift but more duration, it my help lower cylinder pressure.
 
Coolness.,good luck. I have the cam,if interested.Went bigger.
 
Could always go with the Felpro 8553 gasket which has a compressed thickness of .045. That may help drop compression some too
 
I think you either need to build another one or change pistons in the one you have.
 
RustyRatRod said:
I think you either need to build another one or change pistons in the one you have.
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+1 11.37 static compression and "pulling trailers and heavy loads" don't go well together... sounds like a recipe for meltdown

You could go with a dished-quench piston to keep the quench with your closed-chamber heads but IDK if it would still lower your compression enough to be reliable and safe without overheating.
 
For $500 Sno performance does a plate inbetween the carb & intake that puts out methanol injection. Often people claim to be using windshield wiper fluid..?
David Vizard built a 17 to 1 motor and used kerosine as fuel with water injection with out detonation but everyone here will shoot that down. Vizard writes countess articles, was the engineer that debunked paper air filter effeciency compared to the stuff K&N & others now have, and has all the credentials.

The methanol injection is the easiest, more expensive fix.
 
greymouser7 said:
For $500 Sno performance does a plate inbetween the carb & intake that puts out methanol injection. Often people claim to be using windshield wiper fluid..?
David Vizard built a 17 to 1 motor and used kerosine as fuel with water injection with out detonation but everyone here will shoot that down. Vizard writes countess articles, was the engineer that debunked paper air filter effeciency compared to the stuff K&N & others now have, and has all the credentials.

The methanol injection is the easiest, more expensive fix.
Click to expand...

I would agree if this was a street/strip car but we're talking about a truck where the engine will be under constant heavy load for long periods of time... he'd need a 20-gal water tank to tow a trailer lol
 
I would just find a stock 360 mag from a JY to throw in the truck and keep the one you have for some other project. It would cost more to make that motor happy in a tow truck than just picking up a used motor for it.
 
I pretty much knew the answer when I asked the question.
I also have a fresh 340 .030 x heads that has 8.06 dynamic.
Shame to waste it in an old truck.
Might look around for another 360 mag they are cheap.
 
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