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A 5/16 .080 wall pushrod isn’t going to bend from driving around the block at low rpm from too much spring. I don’t possibly see how the lifters could bend a pushrod either…maybe I’m wrong. Only time I’ve ever seen a pushrod bend was from either interference in the valvetrain somewhere, or at high rpm with a pushrod that was too small diameter. Your not running a lot of valvespring here, at least not enough to bend a pushrod at low rpm. I still say there is interference somewhere. Check PTV and make sure cam is installed correctly. Wrong installation or a cam that’s cut wrong, can cause too little PTV.
My thoughts as well. Start with PTV, if possible, at least check degree on cam as installed as well.
pistons in the right direction? if relieved/domed,, and flipped front to rear,,, might be hitting..
Stock LQ9 flat tops
Originally Posted by LilJayV10
It will interesting to see what the cause was. There's no way that cam is big enough to have PTV issues unless the cam was installed way off.
I'd get a bore scope and look at the top of the pistons, it should be very noticeable if there was contact.
The pushrods that were bent, where they all intake or exhaust or both?
Since the passenger side was the noisy side Ive only been looking at it but so far I've found both I/E bent.
Got my new bore scope last night and got a pretty good look. All passenger cylinders looked good. To check max lift I tried to get measurements off the rocker and then straight off the PR but I think the lifter bled down because I the readings kept dropping. Max I saw was in the beginning at only had around .550 and this was after turning the motor over a few times to check for PTV damage. From there it kept dropping to .300 when I gave up.
With no damage to the pistons I'm sorta leaning back to spring binding from too long PR. I wonder if theres something funky about the lifters thats not letting me measure accurately. Although the last time I measured for PR distance the motor was run the night before, not turned over and I measured on a rocker that didn't have pressure so I wouldnt think it leaked down with no pressure on it.
I'm still lost as to what this is. I think my next step is leak down test and go from there. If no good then I'll pull the heads and see whats up. If it passes....idk..maybe swap to shorter PR and cross my fingers. This is a pretty budget build but obviously I'm not looking to waste money on an avoidable issue.
Could very well be that the PR's were too long and when the rocker arms maxed out it ended up bending them. I'd be going thorugh the cylinder heads and checking them for damage as well.
Totally in the camp of timing chain wasn't installed right. Was the cam degreed when installed?
It was not degreed and I wouldnt disagree with you but after seeing no damage on the pistons I'm not sure its an interference issue.
Originally Posted by 01CamaroSSTx
Could very well be that the PR's were too long and when the rocker arms maxed out it ended up bending them. I'd be going thorugh the cylinder heads and checking them for damage as well.
Thats the plan at the moment. Hopefully I'll get to do a leak down on it today and then go from there.
how does 1 bend a pushrod, assuming it's in the lifter cup, if the valve didn't hit a piston?
Valve spring coil bind. Basically compresses the spring until it cant compress any more but the cam stil keeps going. Somethings got to give and if you're lucky its just a PR.
I typically dont have that kinds luck but you never know. Even a married man gets lucky every now and then
Valve spring coil bind. Basically compresses the spring until it cant compress any more but the cam stil keeps going. Somethings got to give and if you're lucky its just a PR.
I typically dont have that kinds luck but you never know. Even a married man gets lucky every now and then
Can't say I've ever encountered that. Would be super random.
I'm starting to wonder if only one of the PR is bent. I put a new one up against a straight edge to comapre, both same brand. This is rudimentary but its close to what I see holding it by hand and lets me take a picture. One PR is brand new, never installed. The other is one pulled from motor. And yes I compared different sides, not much difference. Outside of the one obvious bent one (not pictured) they all look more or less like this.
Yup. First thing I did and it rolls good but you can hesr some variation in noise when it rolls. Did it on dinning table (wood), counters and concrete. Not sure if its the uneven surface or the pushrod causingthe noise variation. Its a good test but not is 100% level. Honestly I've never put a new pushrod up against a straight edge. Maybe they all look like this. I did compare to some old sbc PR I have and they looked the same. They are used too though
One is definitely bent. I pulled several others with it and checked against a straight edge. From what I saw it looked like they were bent also. Today when I compared them to new ones they dont look that different so I'm lost as well.
That said I've also never sat down and checked straightness for new PR on a straight edge so I'm not sure what they are supposed to look like
If the push rods are correct for the intended purpose and the springs aren't coil binding then the only thing left is the lifters.
Yes the Morel lifters have hi failure rates here in Australia and has been shown on many different build platforms here..
This seems to be the case, my shop didn't want to touch Morel lifters when I asked about them for my combo. They supplied LS7 lifters instead.
12-09-2022 | 12:06 PM
