LA 318 w/ Magnum Heads What Pushrods

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Commando66

Commando66

She's a beaut Clark!
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Like the title says, I’m wondering if there is an off the shelf pushrod that will work for this combo. It’s an LA 318 with a hydraulic cam, Magnum heads with roller rockers. I don’t have it assembled yet, just trying to see if I can order a set ahead of time.
 
I bought them for my project, but I was going to use the factory magnum rockers. If you think it might be the same, I can get you a number tomorrow.
 
Are those ball/ball ends? With roller rockers you should measure to be sure.
 
toolmanmike said:
Are those ball/ball ends? With roller rockers you should measure to be sure.
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yes, the factory uses ball ends. If he is using HS roller 1.7's, they are direct factory replacement and use the factory push rods. I put them on my truck. However, the swap he is doing needs a different push rod length. I bought them for my project.
 
Thanks guys. I think the rockers are from Hughes. There’s no markings on them but based on what I was told about the cam and springs they’re probably Hughes.
 
You can NOT and should NOT order pushrods based simply on what parts are on the engine. There are too many variables to just guess. Like cylinder head machining, block decking, head gasket thickness, etc. The correct way to do it is mock up the engine, buy a length checking pushrod and measure it. If you get lucky there will be an off the shelf pushrod in the correct length and you can order those. But save yourself the headache and do it right one time.
 
TT5.9mag said:
You can NOT and should NOT order pushrods based simply on what parts are on the engine. There are too many variables to just guess. Like cylinder head machining, block decking, head gasket thickness, etc. The correct way to do it is mock up the engine, buy a length checking pushrod and measure it. If you get lucky there will be an off the shelf pushrod in the correct length and you can order those. But save yourself the headache and do it right one time.
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Solid advice. I'm going to go this way. Probably measure and order from Smith Bros.
 
Magnum heads also require oil through pushrods and lifters. La heads oil the rockers through the head. Keep that in mind when you’re ordering parts
 
I ordered the MP conversion pushrods for the 1st one of these conversions I did, they were too short. OEM heads and stock Magnum valve gear. I think MP ones were 7.625 and I ordered 7.650. Ordered the 7.650 for the 2nd one we did as well, they worked fine. or what ever the MP ones were, I ordered 0.025" longer.
 
AMC lifters are exactly the same as what you're gonna get these days when you get lifters for a small block Mopar anyhow. Same PN.
 
Commando66 said:
Like the title says, I’m wondering if there is an off the shelf pushrod that will work for this combo. It’s an LA 318 with a hydraulic cam, Magnum heads with roller rockers. I don’t have it assembled yet, just trying to see if I can order a set ahead of time.
Click to expand...
I used a 7.625 from Mopar performance the first time. They were made for doing the conversion. I could not find those the second time so I used a 7.620 Trick flow. Since I used guides I had to have a hardened pushrod. After adjusting the valves using the 1 turn from 0 type adjustment I had plenty of travel. As said above every engine is different so what I used may not work for you. That said, just about every engine book out there lists the magnum head/LA block conversion part list uses the MP 7.625 part number.
Go for it, it will give seat of the pants results.
 
I had heard somewhere that 351W pushrods work for the magnum head conversion. Unsure what year(s) apply there. That might be where I got the 7.650 length? I remember searching thru a pushrod catalog when I did my 1st magnum head conversion and just went with what worked on the 1st engine when I did my 2nd.
I remember buying the MPs and them not working for me, I advertised them on one of the forums and it didn't take long for me to find a taker for them. Around that time i'd seen others on the forums that had done the conversion before my appointment that had said that they had to go with the same pushrods that worked for me
 
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