New cam instal, engine won't turn over

[Jason4x4]

Okay, I like the strait edge on the valve idea, and the coat hanger in the plug hole. I really think I was at the limit of valve/piston clearance. I am hoping the cam will work in the stock position. How obvious would piston damage be? Obvious enough for me to see when I pull the head?

It should be very obvious if there is piston damage, but I dought it cause it was never spinning very fast.

 

[az-k5]

It should be very obvious if there is piston damage, but I dought it cause it was never spinning very fast.

Just a couple of cranks with the starter. I got a better look at it tonight. The valves are wasted. Some stuck and bent a 1/4" below seated, some I can freely lift up a 1/4" but not remove. Not all of them are junk, but it only takes one. So new heads are the plan. I talked with summit about the cam, even with the 1.6 rockers it should clear fine since I am still under .500 gross lift. They did say to check for spring bind however. I think it was partially due to the advancing of the cam that took away from the slight clearance I already had. I am going to try it again with the stock setting.

Are the 1.6 arms worth that much power? This is on an 84 K20 I use as a tow rig for my truggy. It never really sees above 3500RPM. I am willing to put stock 1.5's back in just for safety.

Thanks for all of the help. You guys are keeping my sanity.

 

[pauly383]

I didn't see your post on advancing the cam in time to stop you , sorry about that

Closer to stock builds and less agressive cams ( I.E stock old school single grinds ) seem to work better with 1.6 on the exhaust , mimicking the effects of a dual pattern cam , stockISH motors with stock exhaust have better intake than exhaust . Your new cam is dual pattern , and favors the exhaust anyway , 1.5 sounds like a better/safer idea .

Use the 1.6 on the stroker your planning with a wicked but streetable dual pattern grind

 

[mosesburb]

Man, I don't think your cam is big enough to do any of the damage you sustained. Yeah, it's bigger than stock, but really not that impressive. I have run larger cams than that with stock valvetrain without problems for many tens of thousands of miles. In your description of your timing chain install, if I read (and understand correctly), you set the crank gear to a triangle then lined up the dots. This is where I am wondering if you might have created the issue. All of the multiple keyway timing sets I have used had (IIRC) a dot, a triangle and a square (not sure on the square as it is the cam retard keyway and I never have retarded a cam). Now, the ones I used had a corresponding dot, triangle and square to set the cam to (toward the outer diameter of the gear, near the teeth). For example, using the timing kit in "stock" form you install the gear on the crank using the dot keyway. Then you align the dot on the OD of the gear to the dot on the cam gear. Now, if you are using the triangle, you install the crank gear using the triangle keyway and there should be a triangle on the OD of the gear to align with the dot on the cam gear. Now, that being said, did you align the dot with the cam gear (while using the triangle keyway on the crank gear) or did you align the triangle with the dot on the cam gear?? If you aligned the dot while using the triangle keyway, this would be a very easy way to produce the damage you encountered.

 

[4X4HIGH]

This is what mosesburb was trying to explain.

 

[az-k5]

It looks just like the pic above. I lined up the dot just like that pic but did put the crank sprocket on the traingle key way. I am pretty sure this is where I went wrong as well. The gear teeth had no marks other than the factory dots. A moderately expensive mistake on my part. So If I put the dot key way on and go tooth dot to tooth dot with the gears all should be factory design.

I guess this is where the degree wheel would have come in. I wanted to scrap those 882 heads anyway

 

[mosesburb]

It is a real easy thing to do. My question is how the hell are you supposed to be able to time the cam with three keyways and only one alignment dot?? WTF?? As far as the heads go, valves are cheap and the '882 casting is not a terrible casting (other than being crack-prone). They flow similar numbers on the intake side compared to the '441 castings and only lose about 5cfm on the exhaust. SBC motors are not known for cracking guides while bending valves, so you might be able to pitch a few valves at them and get it going again.

 

[4X4HIGH]

If he has a 3 keyway crank gear like the one i posted there is (or should be) a dot, triangle, and a rectangal on the outer most part of the gear near the teeth that correlate to the keyway that you install it on. Each key way is 4* either side of "straight up" cam timing. Another words, once is straight timing, one is 4* advanced and the other is 4* retarded.

 

[pauly383]

I guess this is where the degree wheel would have come in. I wanted to scrap those 882 heads anyway

They are still sellable cores , drop them off at a machine shop for cash . They are all useful for stock builds .

The bad one can be machined down on all the stud bosses for screw in studs , since you messed up that area prior , willl work fine on an regular stock rebuild .

 

[wasted wages]

can you post up a few pictures of the tops of the pistons ?

how deep are the valve contact marks ?

now that you have the heads off,,dial in your cam how ever you want,,
advanced / retarded whatever....

get some modeling clay and put it on top of a piston.

bolt the head on with no head gasket.

set up the valvetrain,, ( pushrods,rockers and set lash ) on the piston with the clay.

roll the engine over several times by hand.

remove the head and using a set of dial calipers now you can clearly see how much clearance you now have in the valve depressions in the clay.

add the thickness of the compressed head gasket and you have your total valve clearance.

ahhhh,,,lessons learned the hard way,,,gotta love em'

 

[az-k5]

pulled the head tonight. One bent valve and one broken valve. There is a small gouge in the piston top. Doesn't look deep and is where the relief is machined into the piston for the valve. I just hope the piston isn't shot. Cant feel or see a crack in it.

 

[wasted wages]

BROKE A VALVE ???? Damn,,,Timing must have been way off....


get some pics of the damage and post em up,,,,

as long as the gouge is in the center of the piston,,your probably OK ,,,take a dremmel tool or die grinder and smooth down the high spots.

Around the edges of the piston where the rings are is where you need to be concerned. A smashed ring land is bad news....

 

[Thunder]

Your piston is most likely fine. I smoothed the valve contact gouges on more than one engine that lost a timing set, with no ill affects.. Clean the top of the piston good and inspect for cracks with a magnafing glass.
Doubt if your head is bad. Just replace the guides on the valves that are bent or broken.

You really need to get a degree wheel. Degreeing the cam is quick and easy, would have saved you all this.

 

[az-k5]

I am just running it in the stock setting now. I got a set of lightly used goodwrench heads for a decent price so I don't mind changing them. The scar is nowhere near the edge. I am just going to buff it down, and check it real good. I wanted the advance on the cam for low end, but I think I will be fine. The 1.6 rockers didn't help the situation any as far as clearance.

Thanks for all of the help and hints. Should be back up on the road tomorrow afternoon.

 

[reddog64]

Pics Damnit!!!!