moparmat2000
Well-Known Member
hi y"all
i know i posted a thread about using the magnum cylinder heads on the older LA engines, its a good design from the chambers and flow standpoint, but as members of the site have said in numbers the casting doesnt hold up very well due to cracking in the water jackets. well i was surfing on my smart phone last night looking for "new" magnum heads since i still want to do this conversion. what i found was a company called enginequest or A&A specialty midwest. they make circle track parts including a new iron cast magnum head. they improved the port design a bit for better flow over the stock magnum heads, beefed up the casting where they have a tendency to crack, and come fully machined and ready for your valves.
i am sure you could also port them, but in an article they have linked to their site popular hot rodding built an engine quest magnum headed older LA 318 and made it all bolt on with no port matching or any other gee whiz machining, and it made 402HP and 341 FT LBS of torque at 6,200 RPM.
pop hot rodding also ported a different set of these same aftermarket heads, and installed larger than stock 1.92 valves to a 2.03 diameter intake sized valve with the ported heads and oversized intake valves and nothing else changed the same engine made 425 HP and 360 FT LBS of torque at 6,200 RPM.
if the stock dodge cast magnums are junque from the cracking standpoint, they can at least give up their rockers and pedestals and misc pieces to a set of these engine quest heads.
engine quest sells these heads in 2 different types for those of you who are interested
the CH318A $399 each cylinder head is machined with a standard magnum intake bolt thread pattern and angle so you will have to use a magnum compatible 4BBl intake
the CH318B $399 each same casting but is machined with the early pre magnum intake manifold bolt pattern and angle, so if you have an earlier aluminum intake it will work on these.
i have found on ebay a magnum 4 BBL aluminum dual plane intake designed for the magnum heads called a crosswind. i dunno how good it is, but i personally think the way the magnum intakes bolt to the heads seals better than the earlier design as it forces the intake down to wedge against the heads causing the gasket to seal tighter. i dont think chrysler would have went this direction on the magnums for bolting the intakes on if it wasnt a better idea. the 3rd gen chevy 350s pre vortec went this direction in the 80s, and i believe fords windsor series of engines also had their intakes bolted this way from the 1960s.
several people have also confirmed what i also thought which was your original 5 bolt valve covers will fit the 10 bolt magnum heads. chrysler kept the same shape on the heads for the valve covers, and left the 5 original bolt holes/ bosses in the pre magnum stock locations, but added 5 more equally spaced holes/ bosses for a later style magnum 10 bolt valve. use 5 bolt valve cover gaskets, and your original valve covers.
you will need to use the magnum head bolts, but standard LA pre magnum headgaskets can be used. you will have to use flat tappets, and hollow pushrods for the rocker arm oiling, with the stock non adjustable magnum rockers the comp cam hollow pushrods (#7960)will work according to the PHR article.
this is about all i got on this. hope this helps someone out looking to update their LA V8 now i gotta wonder with an essentially blueprinted and balanced bottom end and KB popups on the rodney daingerfield of mopar V8s can make 402 as a bolt together setup what if care was taken by port matching, porting etc, and making the 318 into a 390 stroker. how much power then?
i will prob just go with the 402 HPcombination for my cuda as its light enough, and i will be making it into a handling car and not a drag stripper.
i know i posted a thread about using the magnum cylinder heads on the older LA engines, its a good design from the chambers and flow standpoint, but as members of the site have said in numbers the casting doesnt hold up very well due to cracking in the water jackets. well i was surfing on my smart phone last night looking for "new" magnum heads since i still want to do this conversion. what i found was a company called enginequest or A&A specialty midwest. they make circle track parts including a new iron cast magnum head. they improved the port design a bit for better flow over the stock magnum heads, beefed up the casting where they have a tendency to crack, and come fully machined and ready for your valves.
i am sure you could also port them, but in an article they have linked to their site popular hot rodding built an engine quest magnum headed older LA 318 and made it all bolt on with no port matching or any other gee whiz machining, and it made 402HP and 341 FT LBS of torque at 6,200 RPM.
pop hot rodding also ported a different set of these same aftermarket heads, and installed larger than stock 1.92 valves to a 2.03 diameter intake sized valve with the ported heads and oversized intake valves and nothing else changed the same engine made 425 HP and 360 FT LBS of torque at 6,200 RPM.
if the stock dodge cast magnums are junque from the cracking standpoint, they can at least give up their rockers and pedestals and misc pieces to a set of these engine quest heads.
engine quest sells these heads in 2 different types for those of you who are interested
the CH318A $399 each cylinder head is machined with a standard magnum intake bolt thread pattern and angle so you will have to use a magnum compatible 4BBl intake
the CH318B $399 each same casting but is machined with the early pre magnum intake manifold bolt pattern and angle, so if you have an earlier aluminum intake it will work on these.
i have found on ebay a magnum 4 BBL aluminum dual plane intake designed for the magnum heads called a crosswind. i dunno how good it is, but i personally think the way the magnum intakes bolt to the heads seals better than the earlier design as it forces the intake down to wedge against the heads causing the gasket to seal tighter. i dont think chrysler would have went this direction on the magnums for bolting the intakes on if it wasnt a better idea. the 3rd gen chevy 350s pre vortec went this direction in the 80s, and i believe fords windsor series of engines also had their intakes bolted this way from the 1960s.
several people have also confirmed what i also thought which was your original 5 bolt valve covers will fit the 10 bolt magnum heads. chrysler kept the same shape on the heads for the valve covers, and left the 5 original bolt holes/ bosses in the pre magnum stock locations, but added 5 more equally spaced holes/ bosses for a later style magnum 10 bolt valve. use 5 bolt valve cover gaskets, and your original valve covers.
you will need to use the magnum head bolts, but standard LA pre magnum headgaskets can be used. you will have to use flat tappets, and hollow pushrods for the rocker arm oiling, with the stock non adjustable magnum rockers the comp cam hollow pushrods (#7960)will work according to the PHR article.
this is about all i got on this. hope this helps someone out looking to update their LA V8 now i gotta wonder with an essentially blueprinted and balanced bottom end and KB popups on the rodney daingerfield of mopar V8s can make 402 as a bolt together setup what if care was taken by port matching, porting etc, and making the 318 into a 390 stroker. how much power then?
i will prob just go with the 402 HPcombination for my cuda as its light enough, and i will be making it into a handling car and not a drag stripper.
ops:
