camshaft issues.

[NorwayCuda69]

Hello good ppl

i will now present the crushed valvetrain on my 340 engine look at the pictures..

i had solid lifters and a 242.246 dur 108 mec camshaft.. i think the exhaust valve that broke had .550 lift. heads are ported J with 2.02 and 1.60 ferrea stainless valves and mp springs/retainers.

Senario. i think that the chevy profile camshaft (i wont tel brand before i am sure this was the problem) was milled in the back side of the lobe to increase lift and duration. the notch in the solid lifters are bigger than hyd, this made the lifters go to far down in the bore and the support for the lifter became to short. in time it teared parts out of the bore, the finally grabbed the edge and ripped out the bore. For some reason the lifter broke in 2 and locked the valve open, the valve stem broke and dish fell on piston. the piston broke the cylinder wall and then the valve dish went trough the valve seat upraised (i haven't found it yet).

I didn't build this engine so im not that sure if its correct .. maybe the mechanical have bigger lobe radius that hyd? have anyone seen something like this before?:snakeman::snakeman:

 

[moper]

Nice assumption... but I think you're mistaken... Don't worry about "bashing"... You need aproblem solved and we need to know exactly what cam it was (part number?) to help solve the puzzle. Who did the head work? If you can post clea pics of the piston w/ the hole and the head with teh stem still stuck in it it might help...What was the valve guide clearance? Bronze or iron? New MP springs? What part number and installed height? Looks more to me like a guide or spring issue at first glance but need more info. I can tell you taht no solid lifter profiel with that duration at .050 comes anywhere close to grabbing the lifter edge.. Not in GM, Ford, or Chrysler sized profiles... And a smaller base circle cam is not needed for those lifts either, regardless of brand.

 

[NorwayCuda69]

i could find all part numbers over the weekend when im back home in the garage. it wasnt the cam lobe that grabbed.. i think the notch in the lifter where the oil passes trough the gallery is to big.. so when the lifter is on the base (no lift) only 2-3 mm are left of the lifter in the bore. the valve guides is bronze, clearance is still pretty good.. ( ehem btw all pistons had small notches from exhaust valves touching them) and the crank sprocket was 4deg advance..

i bought the engine from Sweden in 2003 it has been run hard ever since that so it held up pretty good actually.

i put in ilustrations.. i mean that hyd lifters have better guide in the bore?

 

[moper]

Id it clearances are good, have a few valve springs tested for pressure at your installed height an max lift height. If the valves all hit at some point, it was definately NOT the cam or lifter. More like dead springs and/or overrevving. But until you furnish the cam and spring numbers we wont know..

 

[Nitrous340Dart]

Those solid lifter dont look right... My Crower lifters if I remember right looked just like the hyd ones but were solid.

 

[clevengerw]

we have run these "barbell" type lifter on stock solid lift poly 318's, on my 340 i run the straight sided "solid" comp cams lifters w/solid cam. i could see how these lifters you used might rock in the bore if clearance was too much. sometimes cam companies cut the base circle of the cam so you get you lift but so it can still go thru the cam journal holes, that might of let the lifter go down to far in the bore ??? sorry for your loss. -w

 

[NorwayCuda69]

tnx for that tomorow when i get home i will check for the issues Moper mentioned, and get part numbers and pictures. i think maybe the valve train mostly came off a 273 with mech.. but im not sure.. i had the std adjust rockers when i bought it.. anyways tomorow we know some more

 

[rumblefish360]

WOW! That's some picture of the engine damage.