save my intake valves!and my sanity

[DR BOOST]

on a fresh rebuild, i smacked all 6 brand new ferrea intake valves right when i started it. it stayed running for 5 minutes on 3 cylinders and then died. i did a compression check and i had 3 dead cylinders that would not respond to oil squirted in the cyl.( to rule out bad rings). i pulled the heads to see the signs of valves smacking the piston tops. took the heads to the machine shop and found out all the intakes were bent. at first i suspected the double roller timing chain so i replaced it. i mocked up the head with an old gasket with clay on the piston tops. i rotated the crank and there was a point of resistance so i stopped. i removed everything and saw that the valves are again contacting the pistons. the cam is a new comp cam 212/212. when the valves are closed i can rotate the pushrods in the usual manner.

i think i may have a misground cam...anyone else have problems like this?

i invite all suggestions.


thank you

surej

 

[Nick Micale]

Does your roller timing set have multiple keyways?

 

[blackbuick87]

The cam may be severely advanced or retarded. Do you have the stock rocker arm ratio? I cant believe it ran for 5 minutes on 3 cylinders
Be sure there is no debris elsewhere in the engine

 

[DR BOOST]

just for clarification....

1. when the timing chain sprockets are lined up the key on the crank is at 12 o'clock.

2. when the cylinder is at TDC the key is at about 2 o'clock

Nick there is a +4 and a -4 but i used 0

black buick 87, yes i have stock arms, and it did run for 5 minutes but was irresponsive to throttle input

keep the ideas coming...


thank you
surej

 

[Chuck Leeper]

Cam timing?

Cam is advanced a bunch...
You must set the engine to TDC, #1, then install the chain so the marks are matched..
What you described, put the cam out of time, thus the bent valves.

 

[DR BOOST]

thanks chuck...problem solved.

the firs two timing chains were missing the straight up dot. the third one has it.

thanks to all who helped

surej