[74chevy454]

I agree with all the above statements and I have assumed that the machine shop new what they were doing never again will i let someone else assemlbe my motors, and after getting the 468 running it felt like it was a vibrateing bed shook like crazy after taking it apart and being smarter this time went thru family business and they balanced everything for me come to find out the scat crank needed to be balanced before installation hhmmmmmm doesnt sound right but thank god my family is in the business cuz my cousin just swapped parts out for me and now its a sweet dream.

But i also think the rod wasnt in the lifter cup if there are no piston to vavle marks.


Hope u find out soon.

[T-bucket23]

As someone above stated, if it was just that one cylinder with an issue it still should have started and ran. Did you have compression in any cylinders. If not and it were me I would pull the front off and check the gears at least .

If it wasnt in the cup and you went to zero lash and then another 1/2 turn you may have partially broken it while tightening it. Think about it if it was on the lip of the lifter after there was no lash and you continued to tighten something had to give.

[j.d.brown.042964]

UPDATE: Well, as it turns out, upon closer inspection and begin of teardown-ALL 8 intake pushrods bent. Only #1 was immediately visible due to jammed-thru-guideplate condition. Others looked fine until disassembly which proved them bent as well. Can't believe I didn't feel this during lash setup while turning over by hand, but-for whatever reason I did not . Anyways...Got as far as both valvetrains and upper rad.shroud,throttle and TV linkages,fuelline,waterpump & accesories detached before the rainstorms set in.(No garage or carport-must work out in the yard) . Will pull intake and heads tomorrow to evaluate damage. Probably then I will drop front of oilpan enough for walking-out the timing cover for inspect of cam-to-crank gears relationship. Spoke again with shortblock builder who assures me I'll find them set properly-but I guess WE WILL FIND OUT SOON ENOUGH. Learned a valuable lesson about "taking for granted that interference wouldn't be an issue" on smaller/milder cam. (Shortblock builder thinks possibly cam is not ground to correct spec's, but I wonder about this-as he stated that he's only seen that happen once or twice before in 30+ years of engine builds). I suppose anything's possible, but just have to wait and see. For right now, I'm only hoping for "least amount of collateral damage", but with my luck (OR apparent lack thereof), I might as well brace for the worst. Really sucks because I have only myself to blame for not doing a modeling clay run-thru check for clearance(s) myself. : Worst of it is not having a covered area to work in or even smooth ground to roll the cherry-picker on. (Makes it a real pain in the rear to do these things by myself with no assistance, but I guess that's price I pay for living "out in the boondocks"). If nothing else I'm getting really good at improvising when needed! For now I can only hope that any valve to piston contact was limited in scope and severity, and possibly may have occured AFTER TDC when piston already moving away on downstroke, so as to minimize impact and damage. {Still thinking at this point that coil-bind was not a factor, as less lift in this setup than previous}. If it turns out that pistons are only nicked slightly, I may have some leeway as to my options. Overall, I still can't believe this is happening, as it's like something from "GroundHog Day", except for each new day's findings bring a bit worse news than the day before... Hope it starts getting better soon before I lose all my marbles and determination to see this through to fruition! I'll keep y'all posted. In the meantime maybe you all can send in a few days of cooler/overcast weather that would be nice to work outdoors in, as today's humidity and heat was like working in a dang sauna. -Jim.

[n-gin]

Every intake valve . Man I would be pssd off. I think he is full of it when he said the cam was ground wrong but I supose any thing is posisble. I wonder were the timing marks are lined up at? Take some pics if you can. I'll try to send cooler temps but right now looks like t-storms a-headin your way, and 91* day temp. If I were you I'd get a trouble light and work at night when it will be cooler.

[MadmanMark]

Every intake bent means the valve-to-piston kiss was violent enough to bend the pushrods. The pistons might be scarred but OK, but you will likely need a set of intake valves and half a valve job on the heads.

Whatever you do, remember shortcuts now will have you in the same predicament a month from now and you'll be blowing more $$s.

[j.d.brown.042964]

I'll know more as soon as I finish getting it torn down, but I'm going to look it all over very closely. Probably won't be able to give pictures as only digital photo ability I have is wife's cellphone-which I am unfamiliar with as far as how to upload or "post images". May do some work @ night if the afternoon and evening T-storms stop making it a wet and muggy proposition. Otherwise doing most work in the morning hours, before it gets miserably oppresive to work in. I will keep you all posted on the (slow) progress of teardown and inspect. -Jim

[ScoTFrenzel]

Originally Posted by 74chevy454

But i also think the rod wasnt in the lifter cup if there are no piston to vavle marks.


.

If the pushrod was not in the lifter cup, then the valve to piston strike would be even worse, since the lifter edge is higher and cannot compress.

If the pushrod missed the lifter completely, then it probably would not align enough to get through the head passage.

[n-gin]

If the pushrod was not in the lifter the valve wouldnt even lift off the seat. It is more likly that the cam timing was off and bent the rods, then pushrods fell to the side as the one was under psi and wedged in the guideplate.

If it was off to the side of the lifter cup it would be the same lift. I believe that if the pushrod was not in the cup it would have moved the clip and forced its way to the cup.
The idea of all the Intake valves bent would assume cam timing. The thought of all the intake not being in the cup and bending, and not any of the exhaust would be malice on the builders part as he would only set all the intakes like that and non of the exhaust.

[Stroke]

Rest assured, you have indeed learned a valuable lesson. I can safely assume you will always check everything from here on out. It's not something you'll forget anytime soon.

[j.d.brown.042964]

Well folks, it's beginning to look a bit brighter- as I've just pulled all lifters and surprisingly the intakes look no different than the exhausts-No unusual pattern or signs of debris seen, which would lead me to believe (so far) that impact was immediate and may have caused less than "worst case scenario" damage level. I'm thinking that all bent intake pushrods occured completely on 1st revolution or two- thus explaining why I couldn't get it to fire. All valve stem tips appear (to naked eye) to be at same level, so far nothing SEVERE observed. Gotta get back at it and try to beat the heat. 8:30 am and already 80* w/high humidity.-YUCK. Will add info of further findings/observations later today or tonight. Keep your fingers crossed for me,eh? -Jim

[j.d.brown.042964]

Well; Finally got time and energy to finish teardown, and the good news is-pistons and valves look fine (thank goodness for the big valve reliefs on the H400CP pistons), also the cam looks fine, as do all the lifters. Cam timing is definitely way off, but marks on sprockets line up 6/12,12/12-just not happening at #1 or #6 TDC. Evidently cam sprocket or crank sprocket is indexed wrong. With cam and crank punchmark dots at either 6/12 or 12/12, the #1 piston is NOT at TDC. Much closer to BDC, but not quite there. Soooooo.... Will start fresh in the a.m. and try to find out what is mis-marked or mis-indexed. Just ran out of time tonite, and hadn't eaten all day. For what it's worth, the crank keyway is at 9:30-10 o'clock position when alignment dots are 6/12 or 12/12, instead of the normal 2 o'clock position. Anyways, I'm sure we'll get it figured out, and it looks as if I'll get out of this with 8 new pushrods + misc. gaskets, at least as it stands right now. Will certainly give everything the "twice-over" anyways. More info.will be posted tomorrow, as soon as I get this figured out as to exactly what is mis-indexed. -Jim

[bluesman2333]

I would put some diesel fuel in the combustion chambers to check for bent valves. With the heads upside down add fuel to the top of the deck then see if it drains down into the intake or exhaust ports.

[j.d.brown.042964]

I did still plan to check for seat(s) sealing properly, at least on the one head (1-3-5-7) that I pulled. Really, I was amazed upon inspect that everything except the 8 intake pushrods looks to be in perfect condition with no signs of any damage. Hope it turns out to be the case! -Jim

[ericnova72]

Sound like maybe someone put the crank gear wrong side up in the machine when they broached the keyway, manufacturing error? If this is the case go after the company and see if they will deal with you.

[SSedan64]

I saw that happen to a friend. Bent the pushrods cranking but got lucky and didn't bend any valves. Hope your as lucky as he was Jim. I'd check for bent valves on both heads for sure.