Hey all, I've been searching for a couple of months both on FTE and FSP to find exactly what i need to do to upgrade my 1981 300 engine with Chevy 250 Rockers. I've seen people say its a direct bolt in and others say its not. I never seem to find any help on how to do this with specifics. Just a lot of it can or can't be done. If some one out there has done this, could you please give me instructions for my specific engine year and if there is more to it then just changing the rockers. Also any other things i should do while trying this would be nice. I am just building my first engines and this idea intrigued me. I appreciate all the help and knowledge in advance.

 

https://fordsix.com/viewtopic.php?t=33886

 

Awesome, you're the man! I appreciate the link!!! I am sorry I must really suck at searching these forums if I missed that one. It has everything I needed except the torque specs. Thanks

 

No prob I remembered reading that thread years ago and knew it was on the Ford six forum a quick search there turned it up.
And from my recollection no torque specs you use a locking nut instead and adjust the preload in the standard manner for hydraulic lifters.

 

Just remember, like they said in the article, if your rockers use bolts, you cannot do this mod without modifying the heads. I am assuming the cast hole in the six head is tight enough to hold the pushrods and the chevy rockers in alignment. That is the reason you cannot do something like this on the Ford v8's.

 

The on the pre 85 300's the pushrod holes in the heads are the push rod guides to align the rockers to the valve tip, they are not like the early small blocks that used rail rockers to align them to the valve tip. Ford went to pedestal rockers on the 300 in 85. So if the engine is original there are no worries. And really all you have to do is pop the oil cap to see what is installed.

This is actually a good mod it gives ya bit more lift and increases rocker life.

 

I am getting the pressed in studs removed and threaded to 7/16th while also getting the head worked on. The thread you pointed out was very helpful and says to use 7/16 to 3/8 studs but im not sure how long the studs should be for this mod. Any ideas on length and where a good place to get them at is?

Thanks,

 

With the cam half way through it's lift you want the rocker tip centered on the valve tip with the.rocker center line at 90° to the valve. You can just center the rocker on the valve tip at the cams zero base line for giving you an idea what you need for stud length.
Going with 7/16" studs and rocker are not only more stable.but will allow you to use a 7/16 bolt to help with figuring stud length as it can just go through the rocker and screw in to the head.. as you set up the geometry .An adjustable push rod makes the job easier also and it is easy enough to fab one up just take a new push rod cut it in half and tap the both sides where you cut it and use a threaded chunk from a bolt threaded in to each end and this will allow you adjust the length of the push rod
That is the short and sweet explanation.
I could go way in in depth on this but there are lots of videos on valve-train geometry on youtube that will explain it better than I could here in a write up.
ARP has a good selection of rocker studs.

Some videos that will help ya along.