has anyone ran the PRC heads and factory rockers? i have a set of prc as cast 225's on my car with manton 5/16 pushrods in it. The Pushrod is extreamly close to hitting the casting on one side. its this way on a couple of cylinders. not all of the. We just finished my brothers TBSS as well with the 235 castings and his were the same way. Not sure if this is a flaw in the PRC casting or if this is normal and nothing to worry about. any help would be appreciated. Probably have like 25 thou between the two. thanks

 

Something's not right, I was looking at the same heads and TSP mentioned several times that those will clear 3/8th pushrods. With what you're seeing that doesn't seem to be true so I imagine there must be a fault somewhere. Hopefully TSP can chime in cuz this kinda puts the kibash on my PRC plan.

 

As long as you have clearance it'll be fine.

 

they would clear 3/8 without issue if they were centered. But my brother built his TBSS and we ran the 11/32 which we had the same issue with. Tons of clearance on certain pushrods because they were centered and others were extremely close to hitting. thats why i chose to run the 5/16. i am glad i did because the 11/32 would have hit. The boss or opening is large enough but it seems that they may not be centered or the factory rocker sits off center. i have heard people complain that factory rocker wipe patterns are off to the side of the tip but no one ever complain about it pushing the pushrod out of line. hopefully some of the Sr. guys can chime in. i would assume its okay as long as its not hitting but for 1800 bucks i expected it to be right. another thing i noticed is that the factory valve covers sit a little higher on the PRC head than they do the factory. Not enough to cause a leak but a noticeable visible difference.

 

That pushrod clearance is normal. When designing the cathedral ported head we opted to have a more straight design instead of leaving more room for larger pushrods. We basically chose extra power vs the larger pushrod. For those wanting a better pushrod you could always run the .105 wall 5/16. While we haven't tried ourselves I've heard of a few guys getting the 3/8 to work but that was never the intention with the cathedrals. A lot of the Trickflow heads are the same way. Without an offset rocker you just can't get the port where you want it and still keep tons of pushrod room.

 

I had the same problem with my TFS heads. Had them clearanced for 3/8" PRs with brass tube inserts in the intake side.

 

He's talking about a 5/16 tho, not the 3/8.

 

Not sure what you're reading but I read him talking about 3/8" fitting in some applications.

 

The OP said his 5/16 was close, 11/32 would hit and 3/8 was no dice. The discussion around the 3/8 is moot - it'll probably hit from what TSP said. But should it be that close with 5/16? Aluminum expands when it gets hot...

 

Is there enough meat in the pushrod area to open it up for 3/8 pushrods?

 

Rubbing is not a issue. If they bind that is a issue but rub not hurt anything

Tim