My motor brakes #1 cylinder exhaust pushrod on start-up , and only on start up. If I install a new pushrod after warm-up, it dosen't brake even if I rev over 5 grand; until it I shut it down for a bit, and try to start it again.
Has anybody had this problem before?

Thanks in advance,
Andy

first off is this a stock motor ? 5 grand on a stock motor is asking for something to happen....

This sounds like it could be a sticking valve, or worse yet vapour lock, is this a sold cam motor?

The motor is a 64 225 in a 64 Gt. It has a stock head and bottom end EXCEPT for: a clifford 260 cam, clifford intake/w a holley 390 vaccume sec 4bl carb, and clifford long tube headers.

I would pull the head to see what's going on. I once had the #1 exhaust valve sieze in the guide, bend the pushrod and smack the piston.

Mitch

I would pull-off the valvecover and lightly tap on the rocker arm tips with a hammer. Not real hard, just enough to over-ride the spring pressure for a moment. You can feel a stuck / sticky valve guide when you do this.

Also check for coil bind or look to see if the keeper is hitting the top of the valve guide at full lift.
DD

I pulled my rockers last night and checked/cleaned all the oil passages. I put it back together set the lash. Then I changed my oil and filter, but filled it with rotella! I ran it for 3 hours, rechecked the valve lash, and changed my oil and filter again, but filled it with Kendall. I've been running errands all day and so far so good.
Thanks for all your help

Andy

PS. DD thanks, I'm going to check it just to be sure.