Ok, here we go. 468 BB no decking stock 781 ovalports with no shaving done other than to true things up. 566 lift comp magnum hyd roller matched lift. 270 duration 110 centerline.1.7 pro magnum roller rockers, 1713 intake pushrods 1714 exh comp pushrods. Stock style headgaskets stock replacement flatops. rolled the motor during preoil and began to find top dead by removing # one plug. Heres where the shet starts to sour, discovered no compression, pulled valve cover to find all four intake pushrods were bent severly. The same senerio on the right bank also. All exhaust pushrods ok. Confirmed with comp that the pushrods were in fact the right ones for the app, and installed in the correct position. long ones for exh short for int. I havent pulled the thing down yet, just wanted some ideas beforehand. why the hell if valve clearance is an issue did it not bend int and exhaust pushrods, same ? if the installed height of the springs was off? And during assembley I checked roller tip position over valve tip and it was centered as its supposed to be.0 lift off center midlift on center full lift just past center.Flat tops with valve reliefs. Any more info needed just ask i think ive given about all that i know. I do know that this just cost me and damn near makes me want to go back to the small block chevy. As this is only my second BB and the first to be mildly built.

All input, opinions, welcome by all, Thanks ...VIC...

 

You say you checked the valve tip geometry while building it, why didn't the pushrods bend then ?

Well what I think is unless you were using light checking springs then when you fired it up the hydraulic lifters pumped up and now your geometry is all wrong and you bent pushrods, or you got into valve bind when it was fired up.

 

are you sure the pistons are flattops and they are installed correctly?....did you align the timing marks correctly? or are the pistons correct for the head chamber style?

 

Engine never fired,was rolling motor while priming engine,discovered no compression when i went to roll motor to # 1 to time it.when I checked goemetry only checked #1, assumed all was good which was a mistake on my part. Timing chain dot to dot Just like smallblock.

 

Did you check for clearance from the spring retainer to the valve guide? Might be an issue there. I built a big block for another car and had to get .100 longer valves to allow for the extra lift.

 

I think this could be the problem. I wont know untill tommorow. If the valves hasnt hit the pistons then its definatly a spring, retainer, valve issue.The thing with this senerio is that its only 566 lift, its a baby cam for a BB...

 

I dont think they bent then, because they werent pumped up. I really dont think this happened till I was priming and rolling motor 1/4 turn at a time while priming. I think the lifters primed then all this... So I guess whatever the problem is, its related to the preload depth of the lifters, because when they pumped up shet broke!!! I usually use a solid lifter for checking things, but all my mock up stuff is for smallblocks. Figured hell its a small cam open chambers flat tops with pockets,what could happen... Wellllllll. Murphys law is at it again. Im just glad it happened when it did.Learning about the good ole BB now...

 

UPDATE: Pulled heads this morning,all int valves bent.

 

No larger than that cam is I would not have expected you to have P to V clearance issues.
You might want to double check your cam timing. On multi-keway timing sets its not unusual for somebody to accidentally align the wrong marks.
Advancing a cam will move the intake valves closer to the pistons. If its overly advanced it could cause the intake valves to hit.

 

Well, here it is gentleman.The problem is too much cam lift, found out today that the stock style replacement flat tops have absolutely no tolerance for a decent cam. Was told by my machinest that this style piston will not accomodate much more than a 510 lift cam that has any kind of duration performance wise. Funny thing is the machinest new this was the cam i was going to run, woulda been nice to know then. Think I will be finding another one.

 

Got any pics of all these parts? Pistons mainly?

While there are definitely issues with 2.19" valves on many of the stock pistons (radial clearance....not depth) usually 2.06 valves do fine. I've used well over .600" lift 266-270** flat tappet cams with stock pistons.

Something isn't right overall here.

And when turning it by hand...you didn't feel it locking up? I mean that's a pretty solid hit to bend valves and pushrods 8 times??

JIM

 

I can post pics, thats not a prob, Also your the second person to tell me that this motor should accomodate this cam. Ill post pics and detailed cam specs within the hour.Thanks 427 I was hoping for a response from ya!

 

Heres the cam thats in the motor. http://www.compcams.com/Cam_Specs/Ca...?csid=434&sb=2
This thing didnt hit untill i primed the oil pump and built oil pressure,I guess this is the reason for not catching it untill i got ready to time the engine.

 

Wow, those pistons leave precious room for error! When I went through my 427 we decided to use a TRW forged piston (I want to say #L2300 but it was a long time ago) but with noticeably more relief area than you have. They were more of a pop-up design which we milled to achieve my 9.5 to 1 comp ratio. Even with that, when I later stepped up my cam/head choice, we found that radial clearance (as mentioned by 427Hotrod) was a problem and we had to remove material to make room for the larger valves. It looks like you'll either need to stay with a mild cam or change the piston and/or head combo to run a true performance cam. Good luck.

 

Wow, that looks like a mucho foopau.
Back in the day, we would set up one cylinder and use clay to establish a footprint and, hopefully, determine clearance on any new combination. Also, with only one cylinder set up, you could immediately feel an impending interference.
Sorry to hear of your problem, glad you diagnosed it successfully.
Regards,
Chuck

 

Got any pics of the timing chain setup? Is it a 3 position type deal? That cam is only 215*@.050". Even though it's on a 110 LSA and supposed to be at 106 ICL...it shouldn't bend up stuff like that. Looks like it's awful advanced.

Put it at TDC on compression (both lifters down) and see if you can tell if one lifter is much higher than the other. Sure looks awful advanced?


If you have to...you can use an ISKY piston notching tool or you can get it from:

http://www.etsupply.com/edgetools/index.html

They work slick!


JIM

 

Did the motor fire ? and if so was it running ? I can't see rolling the motor over by hand would do this ? Moreover you would / should feel the valve hitting the head.

More info would be helpful and there is always flycutting the pistons but you have metal in there now I think you are in for complete teardown. Sorry to see you trouble

 

The engine never fired,never. I did rol the motor by hand several times BUT the lifters werent pumped up tight with oil ,so when i turned it the valves hit but was just colapsing the lifter. The motor being tight camaflaged the interferance with the valves. This is why i didnt catch this sooner. Wish i did, so far im seeing about 600.00 in costs to get it back in the car. All this happened when i was getting ready to drop the distributor. Bumping engine over with starter to find #1.

 

[QUOTE=427Hotrod;1574662821]Got any pics of the timing chain setup? Is it a 3 position type deal? That cam is only 215*@.050". Even though it's on a 110 LSA and supposed to be at 106 ICL...it shouldn't bend up stuff like that. Looks like it's awful advanced.

Put it at TDC on compression (both lifters down) and see if you can tell if one lifter is much higher than the other. Sure looks awful advanced?


If you have to...you can use an ISKY piston notching tool or you can get it from:

http://www.etsupply.com/edgetools/index.html

They work slick!

427, let me go back out to the shop,ill pull the timing cover and get you a couple of shots, give me an hour.

 

Sorry to hear of your problems, but take a look at this:
http://www.iskycams.com/votc.php
It is a great primer for valve to piston clearance issues.

BTW, it is not the lift of the cam that causes interference, but the point near TDC (generally within 20 degrees) when the valves are closing (exhaust), or opening (intake). When intake valves open, they chase the piston down; when exhaust valves are closing, they are chased by the piston moving up. When a valve reaches maximum lift, the piston is very much lower in the cylinder such that interference at maximum lift is impossible.

When a cam is advanced too far, the intake comes closest or hits; when the cam is retarded, the exhaust comes closest or hits. I recommend that you check for a very advanced cam.