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View Full Version : Pontiac-Bent pushrods



firebob
10-23-2006, 06:24 PM
One broke a couple of days ago and when I pulled th intake and val pan off I had 8 more that were bent. I had a day long event with NASA at Infineon a couple of weeks ago and haven't driven the car much since. I'm wondering if an oil starvation issue could cause damage like this? I never saw the pressure drop but I couldn't watch the gauge every second.
It's a Pontiac 400 with about .522 lift with 1.65 rockers and hyd lifters. About 400hp. Do I need stronger pushrods?

Robert

camcojb
10-23-2006, 06:35 PM
One broke a couple of days ago and when I pulled th intake and val pan off I had 8 more that were bent. I had a day long event with NASA at Infineon a couple of weeks ago and haven't driven the car much since. I'm wondering if an oil starvation issue could cause damage like this? I never saw the pressure drop but I couldn't watch the gauge every second.
It's a Pontiac 400 with about .522 lift with 1.65 rockers and hyd lifters. About 400hp. Do I need stronger pushrods?

Robert


I would say you have a mechanical interference issue. Coil springs binding, retainer hitting the valve guide area, valve hitting piston, etc.

Jody

OHCbird
10-23-2006, 09:31 PM
Ditto- have you scoped the bores to see if there is any damage? My guess is coil bind. Are you using 16 heads?

firebob
10-24-2006, 08:36 PM
Which bores? Lifter bores are fine. Yes, the heads are 16s. What difference?

Robert

Zee
10-25-2006, 02:02 AM
Were the push rod holes in the cylinder heads elongated for the 1.65 rockers you are running? If they were not, I believe that is your problem and there are only two solutions. Either pull the heads and have the holes elongated or lower the rocker ratio.

PT Goat
10-25-2006, 05:04 AM
Paul Spotts makes an excellent push rod hole elongation tool. That does indeed sound like your problem.

www.spottsperformance.com

PT Goat
10-25-2006, 05:04 AM
Found the actual link: http://www.spottsperformance.com/headtool

firebob
10-25-2006, 05:12 AM
Holes are elongated for the rockers. No timing chain(gears) so that's not it. These pushrods are longer than most at stock being 9.17" long. Makes it easier for them to bend I would think.

Robert

camcojb
10-25-2006, 07:31 AM
Holes are elongated for the rockers. No timing chain(gears) so that's not it. These pushrods are longer than most at stock being 9.17" long. Makes it easier for them to bend I would think.

Robert

Big blocks are longer still, they don't bend without reason. I'd keep looking for an interference issue, somethings binding/hitting to force the pushrod to bend.

Jody