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I'm putting some scorpion 1.6 roller rockers on my ported E7TE heads. I've looked on ARP's website and found some part numbers, but I want to make sure that they are the correct size studs.
No the stock pushrods should be fine. You could potentially gain some power using 1.7 ratio rockers but how much and if there is clearance for that depends what cam the motor has.
If you have 1.6 pedistal rockers then you're good but if they are stud mount then no you can't use them. My comment about the 1.7 rockers was based on a guess that they would produce quite a bit more than 0.500" lift but after actually running it through the calculator I see that they would only just exceed 0.500" lift on the exhaust and that's OK. The stock springs can only handle a little over 0.500" lift so that's why this is a concern.
Well I bought these ported E7's from as guy that works with my brother. The springs are not stock, he said they were softer than stock springs. The motor he was going to put the heads on had close to the same cam I'm runnning.
Rocker arm ratio is simply how much it multiplies cam lobe lift. Your cam has lobes that are 0.280/0.295" high, so multiply that by 1.6 or 1.7 to get the actual valve lift.