Technical Loose rocker

Just installed this 327 bored 40 over. Edelbrock aluminum heads. Local race shop built this engine for me. Since I installed the engine it has a miss to it. Pulled valve cover on right side and number 6 roller rocker is really loose compared to the others. I cranked the engine over and that roller rocker barely moves. What would cause this on a new engine.

 

the engine guru's will be on here shortly so i'll just "whup this out". The cam is a flat tappet i assume, lobe pushing on a correct hyd. or solid lifter, pushing on a correct sized pushrod that operates a rocker arm-clearance to be either 0 lash if hydraulic or whatever is spec'd if solid lifter. Cam lobe flat-loosey goosey. Wrong size pushrod-goosey again. Clearance wrong-duh. Won't comment on valve spring since they are supposed to be new. If hyd..consider collapsed lifter.

 

Assuming it didn't lose its adjustment, and was properly adjusted in the first place, a wiped out cam lobe?

 

Hopefully it just needs to be adjusted. What is the cam?

 

Readjust it and see if it runs more smoothly.

 

Bent push rod? It looks like the heads of the rocker studs are hitting the slot in the rocker. Very small area of contact, doesn't look right to me.

 

Here is the cam card and what the race shop ticket on how they built the engine

 

Disable the ignition, put your thumb down on the push rod end of the rocker and have someone bump the engine over. Got a feeling you're not going to like what that tells you.

 

Or......call engine builder guy and have him come take a look. Lippy

 

Damm Right!
U spent big bucks for this thing, got it back and now this. Its their baby, if the cam is flat its their problem (assuming they broke it in)--if they gave it to you new and told you to break it in then you might have a fight on your hands. Anything else, they ought to take care of it.

 

Flat cam. Pretty common with aftermarket parts, ie, stiff springs, aggressive lift curves, in particular.

Time to pony up for a hydraulic roller. Going to rollers pretty much eliminated cam lobe failures on Detroit production engines. They allow faster lift curves with lower tension springs, and lower hertz stress on the lobe.

 

pretty mild cam. Id try adjusting it as others have said and see it gains lash....hopefully not.

 

The exhaust rocker to the right looks like it is riding offcenter to the valve stem, as if the rocker stud isn't in the right place. I'd be looking at all the rockers, a roller rocker will not live if it isn't in the middle of the valve.
'Speedmaster' & other chyna heads had/have that problem and a roller rocker won't stay tight, I know these are Edelbrock and it may well be that it is just a photographic angle suggesting it is offcenter, but this is something I have seen before and worth mentioning.

 

Was the engine broken in by the engine builder or did you do it?

If you broke it in, please explain how you did so and what oil you used.

My guess is the cam lost a lobe (went flat). If you're lucky, the phone rang and the engine builder missed setting that final rocker but my money is on a failed cam.

 

David -

I hope you mean .040" (or .04") overbore...NOT 40 overbore !?
I doubt a small Chevy (or any other!) will go, 40 overbore.

Mike

 

Well, I'm going with the old adage, if you haven't got something good to say, don't say anything.



But that being said, sorry for you loss.
Now, I'm going to express what these guys are thinking as they're quietly reading the bill.
Boy oh boy, you're not getting any satisfaction from those guys. NFW. To much time has passed and well, did ya see the bill. I'm sure they are good ol boys and everything under one roof like a multi process welder but seriously, everything rounded up to even numbers.

No harm no foul, you're going to need a paddle cause you sir are up the creek.

 

I had a buddy squeeze a .060.lol, cracked a main after drill out for 4 bolt caps.

Is .060 over too much on a 283? | The H.A.M.B. (jalopyjournal.com)

 

This head should be using a guide plate to center the rocker arms. Something must be really amiss
for that intake rocker to be so cockeyed. Maybe the push rod is broken from binding or a guide
plate issue. If you remove the rocker arm I am sure there are several of us wanting to see what lies
underneath ! Thanks CP

 

Looks like a guide plate under the next cylinder but not the one in question. I would also check under each adjuster nut to see it the rocker arm shaft is upside down.

 

I think the shop owns the problem. Last two charges say “assemble” and “dyno”. Means they fired it up, right?

 

I see break in oil and two changes on the bill. Call them, I would cause if you go messing with it they are gonna wash they're hands of it for sure.

 

It’s a hydraulic flat tappet comp cam

 

Yea I called them, it’s had a miss since day 1. I never touched anything on the rockers

 

Yea I paid them to break it in and dyno it. . I’m hoping it’s something simple. Btw have you guys heard of tge faulty cams and lifters going around

 

Sorry about that yea it’s bored .40 over

 

What am I going to have to do to fix this problem? Go to a roller cam ? What size cam should I buy

 

Any good suggestions on a good roller cam that’s not too expensive

 

I posted some better pictures, I tried to upload a video of me cranking the engine while my son recorded. It wouldn’t go through