Valve train woes

[Guest Anonymous]

Alright, my brother was helping me build up my engine,

and I let him put on the timing chain unsupervised.

Anyway, we got the motor ready to crank and turned it

over, it wouldn't crank and I didn't know why. So I pulled

the front end off the motor and sure enough my brother

had botched the timing chain install. I put it to OEM settings

and put the front end back together, set the distributer properly

and tried to crank...no go. Then I got to looking and my push

rods were bent. So I pulled off the heads and sure enough my

intake valves were all messed up. So I took them to the machine shop

where they are currently having new valves put in.

 

But I got to looking, and turned the motor over (with the heads off)

with a pull handle and watched. The intake lifter comes up on

every cylinder when the piston is at the top (not on the compression

stroke, but the other one).

 

Am I mistaken in thinking that this is a bad thing? I know that my cam is

timed right now.... I'm thinking that it is ok, but want to be sure as I

don't want to put in another set of valves.

 

The motor is a 350 with Sportsman II 64cc heads (with 2.02 valves),

flat top hypereutectic pistons, cloyes double roller timing chain, and

a Crane Energizer cam # 100072.

 

My first thought was that my brother's botched timing chain install (he didn't have the dots lined up, it was WAY off) was what bent the valves, but the fact that when manually turning the motor, my intake lifter is up when the piston is at the top makes me suspicious...should I worry??

[Guest greimann]

According to your cam card

 

http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=100072&B1=Display+Card

 

your intake valve is supposed to start its lift at 7 degrees before top dead center (@.050 tappet lift). It continues to open as the piston moves down. So starting to open as the piston reaches TDC is OK. Reaching max lift as the piston reaches TDC is very bad (but you know this now).

[Guest Anonymous]

Hmmm, its too dark to look at right now, but that is probably right when the rocker arms and push rods are installed.

 

Hmm, you reckon I should retard the timing a tad

to be sure that the sucker does right? Or should

I leave it as is... my brother had the timing advanced big time is what the problem was before (I think thats why the valves hit anyway).

 

So now that the timing is OEM, I shouldn't have

any probs, right? Anybody else with a similar

setup who can verify this?

[Guest greimann]

You should leave it "straight up", that is the timing with the dots aligned. Set up properly you will not have any problems because your lift and timing are not that extreme. You should not advance or retard a cam's timing without really knowing what you are doing. The more experienced engine builders use a degree wheel to check that the cam timing is correct.

[pparaska]

Two things come to mind:

 

1) the cam is timed correctly now (possibly). At TDC between exhaust and intake stroke (on crank revolution before/after TDC between the power and exhaust strokes) both the exhaust and intake valves will be open. The exhaust will be closing (but still open a bit) and the intake will be starting to open.

 

2) Be VERY careful to read the marks on the timing chain set. If it's one of those 3 or 9 way adjustable sets, its easy to have be looking at the wrong marks. For instance, you could be looking at a mark that's above a slot for the woodruf key and not the mark for aligning the chain sprockets. I know I've done that. It made the car run very retarded and burnt the valves.