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Old 07-09-2008, 01:39 AM
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bent pushrod during initial fireup

Well; I finally got around to the actual fireup of my 406 on Sunday, and encountered problem(s). Despite being EXTREMELY careful and double or triple checking everything I managed to have a serious issue that I need to find the cause of. The shortblock assy. is new 406 but basically same as my 412 was , flattop hypereutectics -.025 in the hole, same blockdeck height, very similar cam (slightly LESS lift and duration) and same heads and valvetrain components, with exception of course, to the lifters which were new with cam., but same brand (Elgin). Couldn't seem to get fire immediately,so checked multiple things, then finally decided to make sure I was not 180* out on distributor-although I was fairly certain I wasn't anyways. Pulled #1 plug to feel for compression and noticed "no pressure on the thumb". Pulled 1-3-5-7 valvecover and found #1 intake rollerrocker askew to the side and pushrod jammed/stuck at angle through the guideplate. Had went easy on the valvelash (only zerolash + 1/2 turn ) on initial setup to reduce pressure on lobes for breakin, and had tried to be VERY careful to doublecheck everything. Can't seem to think of a cause thus far, as I will need to pull 2-4-6-8 side and check, as well as repull the intake to view the lifters, but the ONLY thing I can surmise as possibility was combination of loose preload and slight misalignment of guideplate caused pushrod to jump out of the liftercup and jam (appeared to have "jumped" and lodged back against valley next to lifterbore,and thus held intake valve open-will know more when I have time to pull intake.) Parts are not mismatched, are Elgin (#PR577) +.100" hardened for guideplates, 1.6:1 stainless fullroller rockers-same exact setup from the 412 and all back in original positions and orientation. Cam is Crane #113801 with slightly less lift/duration than previous Z-Grind and shouldn't have required any geometry or spring changes. Must have happened almost immediately as I was not able to get it fired before discovering this. Anyone like to venture some possible scenarios as to what I might have overlooked or done wrong? I'm praying I didn't wipe the cam , and don't believe I had piston to valve contact, but further inspection will follow in next day or two.- Sure ruined my Sunday though -Jim

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Old 07-09-2008, 02:21 AM
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Sorry to here that Jim. Are you positive your timing gears are correct?
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Old 07-09-2008, 02:47 AM
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Can't be certain of anything I didn't assemble myself, but from what I could ascertain from my inspection and perusing prior to my putting the top-end on, I would feel that most likely yes. The man who built it (the shortblock assy.) has been doing them for 30+ years and I don't suspect any error on his part, at least not yet at this point in time. I'm thinking so far that the error is likely something on my part, or a "fluke". I have observed that so far (haven't pulled 2-4-6-8 vc yet) only #1 intake had this problem, (and yeah-it kinda sucks to have spent most of a week under the hot sun getting broiled, only to have this letdown.) I'm more concerned, however, with "what was the possible cause(s)"? I have a few ideas, but would like everyone's input as well, so as to know additional possibilities to check into.
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Old 07-09-2008, 05:47 AM
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Sorry to here you didnt get it running.
A couple of things come to mind. Did the assembler put the pushrods in with the intake allready on. If he did then posibly he did not have the pushrod in the lifter , but off to the side .
Other thing could be that when you adjusted maybe it had been knocked to the side off the lifter. Or if you removed the rocker maybe the oil on the rocker had created a suction on the pushrod causing the pushrod to come off its position on the lifter .
Having only one pushrod bend wont make 7 other cylinders not fire. There has to be somthing else wrong.

One more thing if there was dirt on the valve stem it is posible for the valve to get stuck causing bent pushrod, or even holding open and when the lifter and cam go to the low side it can cause the pushrod to "exit" the lifter. Check to see if the valves open and close without binding.
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Old 07-09-2008, 06:45 AM
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P to V clearance or something in the combustion chamber?
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Old 07-09-2008, 07:39 AM
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Quote:
don't believe I had piston to valve contact

The man who built it (the shortblock assy.)

shouldn't have required any geometry or spring changes
Well, these things tell me you did not check - P to V clearance, where cam is degreed, or valvetrain geometry. Assumptions will bite your *** every time. IMHO

What exactly do you have parts-wise? What heads? Any machining of block/heads? What lift cam? Cam specs??
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Old 07-09-2008, 08:46 AM
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I had the same thing happen to me a while back. The engine had been rebuilt by someone else and I just bought it from them. I assumed it had been assembled correctly.

Stroke said it right. Assumptions can come back to bite you. My bad.

When attempting to start the engine, other than a 'pop' or two there was nothing. I checked the lifter adjustment again. Initially found five bent pushrods. Finally pulled the harmonic balancer, water pump, etc, and removed the timing cover Here is what I found:

A three position crankshaft sprocket had been used. It had been installed as though the builder wanted to run the cam in the advanced position. However when he lined up the crank sprocket and the cam sprocket he used the '0' mark instead of the advanced mark on the crank sprocket. This causes the crank and cam to be way out of time and will cause several valves to hit the top of the pistons. I was lucky as no piston or valve damage occurred and I only had to replace the pushrods.

Check the position of the crank to cam timing!
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Old 07-09-2008, 09:09 AM
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x2 on the above statement

However,

Did you set the valve lash with the engine cold and no oil in the lifters? If you did then you may have overtightened the one with the bent pushrod. But it should have fired anyways.
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Old 07-09-2008, 10:44 AM
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I'll look into these other possibilities (cam/crank timing) as time permits, but as far as the lash adjustment-Yes-I made the adjustment cold after allowing several hours from time of priming the oil system for full bleed down. Followed Crane's instructions. As far as the combo of parts it's same topend I had on the 412: Patriot (Extreme Performance-the earlier series with CNC'd bowl blending-NOT the later "Freedom Series") heads w/ Manley valves,Elgin RV1943X springs, Elgin PR577 +.100 hardened pushrods, Elgin Hydr.Lifters,(forgot p/n, but same p/n as I was using with last setup), cam=Crane #113801 PowerMax- .467"/.494"-222*/234* (as compared to previous #113541 Z-Grind .491"/.497"-236*244*).Both were installed at 4* advanced. Rockers are ProMag Stainless Steel 1.6:1 full roller-(same set in same positions as last setup.) Same PR577 Pushrods (in same positions and orientation as before). Same FelPro gaskets, same blockdeck height (9.015") as before. Heads had .0015" skimmed for fresh surface -(they were well within square even without having this done-only done for fresh surface to ensure good sealing). ARP Headbolts properly torqued. THE ONLY REAL CHANGES from last setup are slightly milder cam, and having heads inspected and flymilled the .0015" for fresh surface, and the fact that this shortblock is using stock 400 (5.565") rods instead of 5.700". The pistons are Speedpro H400CP instead of H616CP. Both being flattops sitting -.025 in the hole, so no real difference there. The H400CP have 4 valve reliefs on the flattop,so .2 less c/r. Anyways... I conferred with shortblock builder before making cam choice and was assured that the milder cam was still well within the springs ratings, and no changes be neccesary in this area-and as you can see the change was minimal and to the "milder" side. Only other variable that came to mind was perhaps when I had Patriot go over the heads that IF they removed my studs and guideplates, that perhaps that guideplate (#1 cyl.) went back on a bit shifted and I didn't notice.-That's only thing I can think of-but I'll certainly look into the other possibilities. No matter what, I appreciate the information and will let you all know how it turns out. Slow process though, as I have little shade and it gets miserable working in this 94* heat for too long of stretch at a time! (Where's that extended cool-front when I need one?) -Almost forgot...The idea about suction on rocker pulling pushrod off lifter cup is intriguing, as there was assembly lube on the pushrod ends and in the cups of lifters and rockers, but I would think I would've needed an extreme amount of slop on that particular valve for such a thing to occur, but I suppose it's not out of the realm of possibility, especially if guideplate were a hair off to the side.

Last edited by j.d.brown.042964; 07-09-2008 at 11:03 AM. Reason: Forgot one thing
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Old 07-09-2008, 12:03 PM
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to bend the push rod, means major interferance somewhere in the valve train.

sam-missle
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Old 07-09-2008, 12:28 PM
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Make sure the valve spring not bottoming out....
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Old 07-09-2008, 11:01 PM
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Can't imagine how I'd be encountering coil-bind of valvesprings on this cam setup (which is less lift, gentler ramps,less duration and overall less agressive) when it didn't occur on previous setup that WAS more agressive and higher lift. (see previous posts on this thread) Also; wouldn't I be seeing it on more than 1 cylinder if that were the case? Just doesn't make sense to me at all, so I will have to wait and see what I encounter upon partial teardown. Anyways...Thanks for all of your input so far guys... It's definitely been "Food For Thought".-Jim
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Old 07-10-2008, 12:25 AM
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Hi Jim, sorry about your motor. I know how dis-heatening it is to have the whole thing go sour after the anticipation of firing it. Just sort of takes all the wind out of your sails. It has happened to me and I suspect most of the others on this board at one time or another.

For the pushrod to bend, one or more of three things had to have taken place. Valve kissed the piston, spring coil bound itself or the retainer hit the guide/seal. If the valve kissed the piston, it could have done some damage to the piston or could have bent the valve or both. If the spring coil bound itself, probably nothing hurt as far as the spring. If the retainer hit the seal/guide, it could have damaged the seal or guide, but I doubt there would be much damage to the retainer. I would inspect the locks and lock groove in the valve stem though, to make sure the locks still fit tightly.

Normally, when you have interference valve to piston, it will be the exhaust valve. But you said the cam is advanced 4 degrees, which will decrease the intake valve clearance. The Crane cam you're using was ground 5* advanced at the factory and you added 4*, so it is advanced 9*. That may have been enough to cause an intake valve kiss. (intake centerline 109* plus exhaust centerline 119* divided by 2 and subtract intake centerline 109*=5* advanced).

From what I've read, I doubt that you had any valve to piston interference and that it was just a fluke with the pushrod not being in the cup. However, if it were my motor, I'd be pulling the heads and doin' some inspectin'. Checking for a bent valve will be easy. Get some kerosene and a turkey baster. Lay the heads on the bench with the exhaust ports down and the valve heads facing out. Fill the intake ports about half full with the turkey baster and wait awhile. You'll be able to see any leakage of kerosene past the valve seat/s. Then suck out the kerosene and turn the heads over to do the exhaust valves. If the valves/seats are all valid, disassemble the spring/retainer on the valve that bent the pushrod and inspect the locks/retainer as well as the guide and seal. If good, reassemble.

Inspect the pistons for dents.

I don't know how the rest of the board members would proceed after that, but as for me, I'd be replacing the cam and one lifter. Visualizing the pressure that was exerted over the nose of that lobe in order to bend a pushrod is all the reason I would need. The lobe and lifter face had to take a severe scuffing (lifter probably couldn't rotate in its bore due to being jammed with the pushrod) and for a hundred bucks, I wouldn't take the chance. Not with my luck. But that's a call you'll have to make.
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Old 07-10-2008, 02:52 PM
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Have seen what you've had happen twice before in two different engines, and it turned out to be that the person adjusting the valve train didn't make sure that the pushrod was in the cup on the ROCKER ARM. Soon as the motor was rolled over with the starter it bent the pushrod and left it exactly like you found yours, wedged in the guide plate and out of the lifter cup. It left a nice impression of the pushrod tip in the aluminum of the rocker arm near the cup, looked like it got to about 3/4 lift and squirted out from under the rocker.
Just something to look for in your failure analysis, it always sucks when something goes wrong when it was supposed to be easy
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Old 07-10-2008, 03:18 PM
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I can't see what might make a pushrod jump up out of a lifter cup. The spring is always pushing down.
I too think that the pushrod was not in the cup initially.
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