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Discussion Starter · #1 ·
have a 318 30 over with 360 heads and a perty decent cam need to know what the demensions are for the valve springs are so i can get new ones .it has brend new springs but wen running u can hear a slight tick on the exhaust valve.
 

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Most often the ticking is an exhaust leak. Could also be coolant water killing combustion because of a bad seal on the head gasket. Use springs that are matched to the cam by the cam manufacturer.
 

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Discussion Starter · #3 ·
i would like tono if there the differance between mag 360 heads and regular 360. and i also was wonderin if any one had any recomendations on high volume oil pumps only have a stock and dosnt keep up at hight rpms
 

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The 360LA and Magnum heads have the same port size. The Magnum is the last evolution of the 360 LA head. The Magnum has a different rocker setup, oils rockers via pushrods (LA oils through block and heads). Intake mounts differently. No exhaust crossovers in Magnum heads. Despite the differences, if certain parts are swapped, the heads will interchange.
Melling oil pump. Meantime step up to 10W40, 20W50 in summer.
 

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The 360LA and Magnum heads have the same port size. The Magnum is the last evolution of the 360 LA head. The Magnum has a different rocker setup, oils rockers via pushrods (LA oils through block and heads). Intake mounts differently. No exhaust crossovers in Magnum heads. Despite the differences, if certain parts are swapped, the heads will interchange.
Melling oil pump. Meantime step up to 10W40, 20W50 in summer.
No, that's not true. The Magnum heads have 1.92/1.65 ports, the LA heads have 1.88/1.60 or 2.02/1.60 ports. "Out of the box" the Magnum heads flow better than the LA heads, I've heard of people putting Magnum heads on LA engines but never the other way around. Like you said, the Magnum heads need different rockers, pushrods and intakes but and also lifters. The bolt pattern is different so an LA intake won't work on Magnum heads and vice-versa. You can modify an LA intake so it will work but that's not an easy thing to do unless you know exactly what you're doing. I think that you'd also need to open up the oil passages on the Magnum to allow the shaft mount rockers to oil properly.

I'm not clear on if 89dodgekid was looking to use Magnum heads on an LA engine or vice-versa... if he's looking to use Magnum heads on an LA you can ignore a lot of what I said. ;-)
 

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I said port size, not valve size. Before you say something I've posted is not true, be sure you know the difference.
 

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Let's address a few things here.

Magnum heads outflow LA's. Well they should since they incorporated everything Mopar head grinders had been doing ever since 1968. Actual Mopar tests showed the 340 "X" head and Magnum within 5hp at 6,000 rpm. The Magnum does manage to accomplish this with an intake VALVE smaller than the 2.02" VALVE in the old 340 "X" head. So, as stated, the extensive revisions done internally helped improve flow, and more importantly flow balance between intake and exhaust ports. The 273/318 LA have small ports. The 340/360 LA and 318/360 Magnum share the same large port dimensions. I did not mention valve sizes because the Magnum does not flow better due to having a smaller valve head diameter. The improved flow capability is primarily due to the re-contouring of the PORTS. The smaller valve stem on the Magnum also helps flow as it's an 8mm stem (about .315 inches) as opposed to .375 inches on the LA. Oh, and I believe the exhaust valve on the Magnum is 1.625 inches, not 1.65.

So you've never heard of anyone using LA heads on a Magnum block? Guess that means nobody ever did it, huh? So let's say you have a set of heavily massaged LA heads for racing and you need a new block. Why not a Magnum block for a few hundred bucks? Or, maybe the Magnum heads haven't been approved by the sanctioning body yet. Nahhh, I'd much rather throw away the $5 grand I have in these LA heads, or just not race while the committee drags around on approving the new heads. Yeah, right. While it wasn't a common swap, it was done early on in the Magnum's day. Add to that the fact that there were no traditional carburetor-style wet intakes available for the first couple years, and yeah, you had people figuring out how to use LA parts on Magnum blocks.

The Magnum heads can be drilled to allow use of an LA intake, they even sell them pre-drilled for the application. This is a situation where one has Magnum heads on an LA block. You cannot just take an LA intake and have it fit in place of the Magnum intake on a Magnum block, the spacing is wider on the Magnum. An LA intake won't even touch the heads on the full Magnum engine.

You DO NOT have to open the oil passages for a Magnum block/LA head conversion. Oiling lifters with hollow pushrods will serve the purpose as long as the LA rockers have an oil hole in the rocker pushrod cup. Believe it or not, some early units didn't have them.

Different lifters for Magnum heads? Depends. Is this a pre-roller LA block? The roller LA's lifters had oil holes in the pushrod cups, but the block oiling method was retained on all LA's. Swap in hollow pushrods and it's a done deal. No need to replace the lifters. Stock Magnums did have lifters with smaller oil holes to restrict topside oil flow with the stud-mount rockers, but it's not necessary. On a flat tappet unit, over 90% of the aftermarket lifters also have the oil hole in the pushrod cup. The engine may already have them. Again, use hollow oiling pushrods and you're good. As I already said, "if certain parts are swapped, the heads will interchange."
 
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