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I haven't heard anything about needed longer valves or springs but the machine of the guides is requires around the .510 lift range b/c of the guide to retainer clearance or lack of.

The springs will have to be changed out must likly has the stock ones are not that great. they are must likely not going to have enough spring pressure. As for the roller lifts it depends on the year block last few years of the LA family block has the provison to use "factory sytle" roller lifters . This cuts the cost down.



Everything I have read its .525" that is the limit but its certainly prudent to check on anything over .5"

I have magnum heads on an LA block with a .509/.512" lift cam and there was clearance between the bottom of the retainer and the top of the valve seal when I checked. I used retainers from a 2.2 mopar 4cyl and it may be different with other retainers.

If you are going to have a valve job on the heads it wouldn't be a bad idea to just cut the guides down so you aren't so limited on lift. But, the head flow numbers I have seen on magnum heads you don't gain anything above .5" with a stock head anyway.



is the 509/512 lift base on 1.5 rockers or 1.6

Another thing to remeber when picking a cam magnums have 1.6 rockers stock.