Hey there. I just installed a TFS stage 1 cam with gt40p heads. I put the stock pushrods in and they are scrubbing the top of the pushrod hole pretty good. I also have the trick flow springs on the heads. I made a pushrod checker and came to the conclusion that 7.600 length is about what I need to fix that problem. Anyone ever heard of that issue?

 

Generally, installing a cam with a higher lift than the highest lift stock cam (Mustang .444 or Explorer .448) will require longer than stock pushrods. This due to the smaller base circle of high lift cams. Considering a stock pushrod is 6.25" you might want to recheck your measurement.

 

I forgot to add that this engine is a 351. I just freshened up the top end and a cam.

 

Sorry. I saw GT40P and made an assumption.

Back to generalities, many modifications will change the required pushrod length. Cam base circle dimension to mind first. Machining deck or heads or going from flat tappet to roller are among others.

​​​​​​​Measuring as you have done is the best practice.

 

Yeah. I ordered 1 pushrod from oreillys the length I think I need. Be here Tuesday. Know more after that.

 

Update. Got a 7.600 PR and now it bottoms the lifter out. 1¼ turns to torque. I put a .035 shim under the rocker pedestal and it's back to .035 preload per dial indicator. ¾ turn to torque. I still can't figure out why the PR was rubbing the hole in the cyl head. The longer PR clears fine just needs a rocker shim.