Help with pushrods
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Laughing Gas
Joined: Sep 2006
Posts: 791
Likes: 62
From: Backwoods of western Pa
Help with pushrods
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???
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???
Thread Starter
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Laughing Gas
Joined: Sep 2006
Posts: 791
Likes: 62
From: Backwoods of western Pa
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.
Can I purchase NEW stock replacement pushrods? Summit doesn't seem to sell them.
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Laughing Gas
Joined: Sep 2006
Posts: 791
Likes: 62
From: Backwoods of western Pa
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
Has anyone used the Crower Adjustable pushrods?
Crower Adjustable Pushrods 70000-16 - SummitRacing.com
Posting Guru
Joined: Dec 2009
Posts: 2,134
Likes: 1
From: Mississippi
an FYI, in case you hadnt seen this:
FE's That Bend Push-rods, A Dirty little Secret .: Articles
FE's That Bend Push-rods, A Dirty little Secret .: Articles
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Logistics Pro
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Laughing Gas
Joined: Sep 2006
Posts: 791
Likes: 62
From: Backwoods of western Pa
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).
Logistics Pro
Joined: Oct 2005
Posts: 3,785
Likes: 4
From: Mddl A MexCans
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.
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.
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Laughing Gas
Joined: Sep 2006
Posts: 791
Likes: 62
From: Backwoods of western Pa
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?
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?
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