I built a 390 for a friend recently and it came back this week with bent pushrod. I need some help now finding replacements.

The motor is a mild 390 bored .040 over with flat top pistons, a Lunati Voodoo 62001 cam with matching valvesprings and new retainers and keepers. The motor was running great for about 200 miles, but it started a tap when he started it one morning. Turns out it bent the pushrod on the #1 intake valve, and the pushrod was hitting an intake bolt. I checked lifter clearance when I first put it together and I know it was within spec. I straightened the pushrod this time and put it back together and lifter clearance is less than 1/4", which again is within spec. I started it up with the straightened lifter and it runs perfect, no funny noises. I assume the reason it bend is because it is weak???

I tried to order new replacement rods with stronger bodies, but, even though they were advertised with 3/8" tips, the tips actually measured much smaller at .310". Summit says that I have to have pushrods custom made to my specifications. Really? Custom pushrods for a mild 390 with mostly stock internals???

 

with that cam (same as mine ) the stock replacement pushrods should be fine .

 

Looks like you have basically the same setup as I do. Only difference is that I'm running an old Edy Streetmaster intake with a 670 Holley.

Can I purchase NEW stock replacement pushrods? Summit doesn't seem to sell them.

 

yes
but the problem is what length and are the rockers adjustable or not ?
my block and heads came out of a 67 tbird and there was no machining done so my pick was easy .

 

if i remember right i got the sealed power 9.621

 

No, the rockers are not adjustable, and the heads are from a different motor than the current block.

Has anyone used the Crower Adjustable pushrods?

Crower Adjustable Pushrods 70000-16 - SummitRacing.com

 

an FYI, in case you hadnt seen this:
FE's That Bend Push-rods, A Dirty little Secret .: Articles

 

great article

thanks bamaf150 , now i have to check mine

 

Yes, I saw that article and ran through the step on this engine. My specs checked out well within range. Which makes me wonder why this rod bent. Like I said, I straightened the rod back out and put it back in and the motor runs perfect, so I don't think there's anything wrong with the valve (new guides in heads too).

 

Hitting an intake bolt ? Please explain.


All pushrods same length?
rotating while it's running ?
Did you check geometry ? Load the lifter, mark the valve stem tip with marker, rotate engine full cycle and load lifter and check for centerline scuffing.

 

The pushrod was hitting the intake bolt after it bent. It actually rubbed a notch into the pushrod where it was hitting the bolt. It does not hit the bolt when it is straight.

Yes, all of the pushrods are the same length, I checked them.

I started it up with the valve covers off and confirmed that all 16 are rotating when running.

I'm not sure exactly what you mean by checking the geometry. centerline scuffing?