Rebuilding my 5.9 Magnum, suggested upgrades?
Champion
Joined: Jun 2012
Posts: 3,096
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From: Iowa
i like the comment about not using aluminum pistons with high power ignition LOL. have to say that ive never, ever, saw an engine with anything other than aluminum alloy pistons.
besides that, factory magnum heads are known for cracking, more commonly in the front/back cylinder exhaust bowls. when i rebuilt my engine, i ported the heads and found exactly where the cracks were in the bowls. didnt have new heads in the budget so they went on the new shortblock(dumb idea) but have held up for 40K miles and towing my other truck cross country. valve springs are weak on these engines, 1.7 rockers will cause float issues around 5K rpms. its a good idea to find some better springs/retainers/locks for cam and rocker upgrade. it may also be a good idea to take the back two pistons out and check the size. due to the poor coolant circulation on the back two cylinders, they tend to run a little hot. if the engine ever overheated, the piston skirts may have collapsed enough to cause piston slap. ive found it on a 360 mag with milage as low as 30K miles, and it was babied. if you need new pistons, keep in mind that summit lists LA pistons all the way up to 96 iirc. i bought that set and found they were wrong. LA heads had the open combustion chamber with little to no quench areas, among a couple of other differences. overall the magnum heads flow really well in stock form, if you can find a set with no cracks. iirc, intake flows ~240-250 cfm, exhaust needs a little help. eitherway, they are decent heads. to address the comment about too strong of an igniton system, ive never heard of that before. with higher compression, a stronger spark or smaller plug gaps help keep the spark from being blown out, same applies for boost/nitrous. also, you may be able to find a nice set of magnum R/T heads, last i heard they werent being produced anymore. iirc edelbrock had some decent OTS heads for the magnum. i may still have a flow sheet comparison somewhere if anyone cares.
besides that, factory magnum heads are known for cracking, more commonly in the front/back cylinder exhaust bowls. when i rebuilt my engine, i ported the heads and found exactly where the cracks were in the bowls. didnt have new heads in the budget so they went on the new shortblock(dumb idea) but have held up for 40K miles and towing my other truck cross country. valve springs are weak on these engines, 1.7 rockers will cause float issues around 5K rpms. its a good idea to find some better springs/retainers/locks for cam and rocker upgrade. it may also be a good idea to take the back two pistons out and check the size. due to the poor coolant circulation on the back two cylinders, they tend to run a little hot. if the engine ever overheated, the piston skirts may have collapsed enough to cause piston slap. ive found it on a 360 mag with milage as low as 30K miles, and it was babied. if you need new pistons, keep in mind that summit lists LA pistons all the way up to 96 iirc. i bought that set and found they were wrong. LA heads had the open combustion chamber with little to no quench areas, among a couple of other differences. overall the magnum heads flow really well in stock form, if you can find a set with no cracks. iirc, intake flows ~240-250 cfm, exhaust needs a little help. eitherway, they are decent heads. to address the comment about too strong of an igniton system, ive never heard of that before. with higher compression, a stronger spark or smaller plug gaps help keep the spark from being blown out, same applies for boost/nitrous. also, you may be able to find a nice set of magnum R/T heads, last i heard they werent being produced anymore. iirc edelbrock had some decent OTS heads for the magnum. i may still have a flow sheet comparison somewhere if anyone cares.
Banned Goober Smoocher
Joined: Jun 2010
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I have a Briggs 500 on my lawn mower and, it's 6 or 7 years old and runs like new.
Champion
Joined: Oct 2009
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From: N/A
There are Odessa/Clearwater and there is Cific then Eddy heads, Indy heads. R/T heads are not made any more but can be found used, Mopar dose still have a few of there aluminum Magnum heads left.
I have no idea if Hughes heads are any thicker than stock.
Link on steel pistons. http://www.mahle.com/MAHLE/en/Produc...OTHERM-pistons
I have no idea if Hughes heads are any thicker than stock.
Link on steel pistons. http://www.mahle.com/MAHLE/en/Produc...OTHERM-pistons
Rookie
Joined: Dec 2012
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From: Alamogordo
those are the RHS heads, supposedly cast thinker for angle milling and reenforced bowl areas
Record Breaker
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Last edited by Ugly1; Dec 27, 2012 at 09:22 PM.
Champion
Joined: Jun 2012
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From: Iowa