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#1
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LA to Magnum Heads
I'm thinking of converting to magnum heads on my 340 if I can find everything cheap enough. I'd like to know what parts can be found and used from the junk yard. Here are the things I need to change as far as I know:
Heads lifters pushrods rockers Intake (or weld and redrill holes) What about springs? Are the springs on these really beefy roller cam springs? I'm running a MP .474" hydrolic which I plan to keep for now. Are all magnum head rockers rollers? I understand from a recent post that the 97 and later heads are less prone to cracking, so I should find heads off a 97 and later 318 or 360. Are the 318 and 360 heads identical? Are they identical to the MP magnum crate motor heads? What are the actual combustion chamber sizes? These are closed chamber? These should give a slight compression increase over stock x or j heads? It would be nice if we could work out a default low-buck method of conversion. Thanks for all your future input. Keith |
#2
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Get AMC Style lifters and pushrods!
The rockers out of the magnum will not work with your hydraulic! If you got the money get the Magnum R/T Heads from the dealer! They flow 230-240 out of the box. Have potential to be good bracket race head! They got 2.02 valve cuts in them too! You might have trouble with the alternator lining up, but shouldn't be a hard task to do! Here's some specs Combustion Chamber 60CC 2.02/1.625 or 1.92/1.625 Int Port Vol: 180CC (high flowers here!) 52 lbs each I think they are an awesome head myself (don't have them personally I got the 340HP heads so I wouldn't have to convert over all that stuff!) Choosing a head to, is based on what you plan to do with the car. You racing it? or is it a street cruiser? anyways, hope this helps moparmac! |
#3
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moparmac,
What are the AMC lifters and pushrods? Where do I get them? Do you have a approximate idea for cost of the heads from a dealer? Do these come assembled or bare? Is that 60cc chamber for both R/T and normal heads? What rockers can I use with the hydraulic? My car is a street cruiser, but not really a daily driver. I don't race just cause its so far to the nearest track I've never gotten into it. I do like to drive with my foot down. How do you like the 340HP head? They are often overlooked I think. Keith |
#4
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Mopar has the right push rods for the swap the rt heads are a better chose amc lifters you can get any place the stock stamped steel rockers off amag will work your cam. I put aset on a 318 with a comp cams 265 and it sounds nice and runs good .The mag heads have a1.6 rocker so you will get more lift out of your cam Jerry
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#5
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Ok, here is what I've got so far
Aquire heads (preferably r/t) and stock magnum rockers Use these (from mancini) pushrods: Hyd. - Magnum Head on Standard "A" Block - Set (7.625") Designed to allow the use of Magnum heads and standard Magnum rockers on standard (1967-91) "A" short block/engines. Requires the use of Magnum cylinder heads, Jeep tappets P4529220 and Magnum rocker arms P4876050 to oil rocker arms through tappet and pushrod. MOPP5007477 $32.95 These lifters: Jeep engine (V8, I6, & I4) - Hydraulic Tappet Sets Sold individually MOPP4529220 $6.95 Total cost so far is: 32.95 + 6.95*16 = $144.15 + heads + manifold swap Could you find a set of junk yard heads, take valves, locks, rockers and use them in an R/T head? What about springs? This is starting to look possible... |
#6
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Keith,
I'm not 100% sure, but doesn't the LA head have less bolts holding it in place than Magnum heads? That could be one reason why LA heads seem more likely to crack. |
#7
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Magnum heads bolt on just like LA heads...You will need magnum specific head bolts so save them from the junky....I HAVE BEEN RUNNING THESE HEADS ON MY 74 360 FOR NEARLY 3 YEARS AND THEY WORK GREAT!!!!! I run 13.50 @107mph with a 2.2 60 ft...
360 4-sp....I wish I could hook it up!!!... I am running the M1 single plane and 1.6 chevy style crane energizer rockers.. they work great and are cheep!!! my pushrods measured out to be 7.550 for my application... TPA |
#8
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What pistons are you running in your 340? The R/T heads are closed chamber and the stock 340 pistons will hit the heads. The 340X heads have the pent dome to match the pistons.
One other thing to remember is that the exhaust ports are a little different shape and will not exactly match with your LA headers/manifolds. The stock rocker set up on the Magnum head isn't very strong. You should seriously consider a set of the rockers that Hughes sells. They also upgrade the studs for the rockers on the R/T heads. For the added cost of converting to the Magnum heads you should consider a set of the LA Edelbrock cylinder heads. They will bolt up to your existing combo and will flow 250 CFM in the intake side right out of the box. You wouldn't have to change anything else. Compression is the issue here though. If your compressioin is low, you don't want to go Edelbrock. The cost of the heads, intake, lifters, rockers, exhaust mis-match, push rods, valve covers is certainly more than a set of NEW Edelbrock heads ($1270 From Summit + $80 for the bolts). Unless you were Magnum to begin with, I personally don't think it is worth it. It seems to be a bit of a mis-match from the get go. |
#9
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$1,493 Hughes Stage 1 R/T heads (complete)
$40 Lifters $80 Pushrods $200 Intake (M1) $279 Rockers $75 Valve Covers $2,167 $1,270 Edelbrock Heads $80 Bolt Kit $1,350 |
#10
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So is the A engine the one with the eight bolt pattern vs the current 10 bolt on the magnum or the LA as you mentioned?
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#11
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Keith,
The AMC lifters are available at any chain parts store (AUTO ZONE HAS THEM IN STOCK) Just go to auto zone ask for a set of lifters for a amc javelin or somethin like that, or as a matter of fact just ask for a set fro your car (for the 340). They are the same part number in their computer (i know this because I work there!!) And you'll notice there is an oiling hole in the center of the lifter where the pushrod sits. Then the pushrods are same length (I think, I'll take a look into it when I go to work today) and they have an oiling hole through the middle of the pushrod. I haven't put on the 340HP heads yet (cause I have no block to put them on) but I know I am gonna like them because they have the best flowing exhaust port made from chrysler as a stock production head. Ditto with the intake. The 340HP's are based off the 308 casting so they are swirlport heads! Anyways once I get completed with the short block and run it, I'll let you know what it does and how I like them! Moparmac! |
#12
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Magnum heads use the SAME # of head bolts as LA engine....you may be confusing the VALVE COVER bolts as they use 10 instead of the normal 5!!!! TPA
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#13
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The edelbrock heads are what I was trying to beat for cost/performance. If you start out buying a set of head assemblies for $1400 then you are beat already by the edelbrocks. This would only be worth it if most of the parts could be found for cheap.
Dart, Thanks for pointing out the cost of the valve covers. I had forgotten about them. Hmm, I seem to remember that the magnum covers have the same pattern as the LA's but with 5 extra holes. Can anyone verify this? About the rockers not being very strong, would I have to worry about them on my <.5" cam going less than 6000 rpm? tpaflyer, Did you have to do anything special to run the chevy rockers? Could you run a set of chevy roller rockers? Keith |
#14
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I have the stock rockers, pivots, bolts and pushrods from my 380 crate motor that I want to sell. They are new and never run. If you want them let me know.
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#15
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Hey Kieth.. I would buy hammers rockers and FYI.. stock valve covers will work just fine on the Mag heads...you can use only 5 of the 10 holes but the stockers work O.K. with 5???... as far as the crane energizer roller rockers.. the application for SBC and magnum heads is the same...stock rockers are also 1.6 ratio and seem to be a pretty nice design... TPA
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#16
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Hammer,
Let me look around for some heads and come up with a total price. What are you running instead of the stock valve train? When you can go to roller rockers for so cheap its very tempting to do that. How much HP from just a swap to roller rockers? How much should I expect to pay for a set of good junkyard magnum heads? Keith |
#17
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I went with then Crane Gold rockers and pushrods. At the time they were the only ones besides MP that sold them. MP was more expensive and I think that they are even Crane's. As far as HP gains I am not sure. A true roller rocker is always less friction. Maybe 10 HP more. Most junkyards have a set price for parts or should be able to tell you over the phone. Also I have heard that the crate Magnums heads are different than the stock ones but they looked identical to my trucks heads. I should take the valve cover off of my truck and get some casting numbers. Did you ever look at the assembled heads in the MP catalog. I seem to remember them being cheap. I will check later tonight.
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#18
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From mancini:
Head Assembly MOPP5007086 $295.00 x 2 Pushrod conversion set MOPP5007477 $32.95 Jeep lifters MOPP4529220 $6.95 x 16 Rockers+hardware MOPP4876050 $6.50 x 8 Intake bolts MOPP4876772 $4.95 Head bolt kit MOPP4876759 $11.95 Total: $803.05 This is with re-using valve covers and swapping intakes for no cost. The rest is buying new! Am I missing anything? They should package this as a kit and knock off $100. Advantages of magnum swap over edelbrock: Better flowing exhaust port smaller combustion chamber 1.6:1 rockers cheaper easy upgrade to r/t heads cheap upgrade to roller rockers Advantages of edelbrock: weight (maybe 25# total?) easy bolt on better intake flow more manifold selection tpaflyer- how is the single plane? Is it a street car? I think I would use the DP M1. On the exhaust, does the exhaust bolt up at a different location or the are the ports shaped differently than the stock manifolds? I'd assume anyone doing this swap probably has headers. |
#19
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My understanding is that if you go with Magnum heads you must use a magnum intake
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#20
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The exhaust bolts on the same and seems to be in the same location when I did my swap. The ports look the same also. I am waiting for MP or Edelbrock to come up with some different Magnum intake manifolds.
$803 sound like a deal to me. |
#21
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Hey everyone, this is my first post but here's my 2cents,
I converted to the magnum heads the day afterthe first p5249816($169 dealer cost then, now i think $209), mpi singal plane arrived in my parts dept.( 2 years ago.) There wasn't as much info as there is now on the swap. All i wanted the heads for wasa for the manifold. Which was already drilled for injectors, used the factory tb and fuel rail, and was cheap! No custom manifold milling/welding/drilling or fuel rail fabricating.Sweet deal. Anyways I agree with every thing said so far but here's some extra tips. My biggest problems were the pushrod length and more importantly PUSHROD TO HEAD CLEARENCE!!! Did anyone else have this problem? It was my bigest of the swap. After alot of dickin around to find the proper length to work with the factory rockers(i settled on 7.66" crowers) i chucked em a got the mp's.($220 dealer cost) Yes they are crane energizers. Tip 1: get adjustable rollers and heavy .080 propper legth pushrods period! With flat tappets being so much shorter than the rollers, the pushrod angle was so severe that they rubbed on the casting. At startup i could here the pushrods making all kinds of racket as they flexed and were forced out of the lifter cup. One lifter took the lickin but didn't stay tickin. The CHEAP autozone lifter's wire retainer broke and took my oil preasure with it. End result is a bunch of wiped bearings Tip 2: Don't be too cheap. spend the extra few bucks on good hp lifters(prob extra $30-40). ie a true snap ring retianer. Tip 3: test fit the pushrods through the head. You need to grind enough of the casting flash away so there won't be any interference. It a hell of a lot easier before the heads are on the car. Dave |
#22
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Yes Duster.. I had to grind a little on the heads due to pushrod clearance...about 10 minutes work with a dremel grinder...I used the crane lifters and have had no probs....I use the M1 single plane intake and it's a little soft down low but really get with the program above 3,000rpm... I am using 3.91 gear with a 4-speed....I would recommened the dual plane... my car would probably be faster if I had the dual plane... TPA
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#23
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well i took me about an hour of grinding on my heads('95s). I think this clearence is still an important caveat.
ditto TPA on the single plane. with a carb it sucks down low. Its best have steeper gears and a high stall. Admittedly i left my duster half done. ie hp manifolds and crapy stock pipes but big cam and intake. so my no torque is mostly my falt. I got old injectors plugin the holes up now with a 750 afb, but i really believe ounce i get the MPI up and running and fix the exhaust, most of my torque(+more?) will come back. Dave |
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