OT Small Block Chevy crew: advice needed

My car developed a miss and a valvetrain noise awhile ago. I parked the car because I didn't have time to look at it. I drove the car a little bit today and under light throttle the car drove and pulled great but under heavy throttle there was a lot of popping and skipping so I knew there was a problem that amounted to more than "needs a tune up".

I pulled the valve cover and noticed the number 7 exhaust valve rocker arm wasn't moving hardly at all, so I removed it. I then saw the retainer had broken and was kind of cockeyed on/in the spring. The pushrod isn't bent.

Its an LT4 retainer so I'm going to go to my dealer today and order one. I really HOPE that I can replace the retainer and call it good. What do you think the chances are I could have a broke spring or bent valve?

If I have a bent valve do you think I can get away with just rebuilding that one head since I dont have a ton of miles on the motor?

 

Little better picture of the valve stem...it doesn't look worn on the edges at all, only on the center


The rocker arm body got a little beat up by the spring but the rest of it looks fine. The spring *looks* fine but I'll check it better when I remove it.

 

not SBC crew, but I'd say pull that spring and another exhaust spring to compare to. If they look fine and the rocker looks mechanically fine, I don't see a reason why you would have to replace more than the retainer. I don't *think* that you would have bent the valve with that kind of problem.

 

Just called my engine builder and they said the same. I hope u guys are right.

 

I kind of look at it this way: nothing that you can do at this point will fuck up the valve any more than it is (or is not) fucked up already. If it's bent, well, nothing you can do will change that, and the only way you'll know is if when you replace the retainer, if it still doesn't run quite right.

Come to think of it, are you running a head/piston/cam/rocker combo that would make it an interference engine? Because if not, then there basically isn't anything to worry about at all re: valves and pistons.

 

after retainer replacement, the #7 exhaust valve wont open all the way, as shown by the rocker arm movement, and the popping in the exhaust/hesitation of the motor. Also, at a certain RPM there is a fluttering noise when you rev the motor a little.

I dont see any metal in the oil that would lead me to think the cam went bad. I did switch from synthetic to dino oil after I resealed the intake, and I hadn't got around to putting synthetic back in, even though the car wasn't driven much.

Not sure why I didn't put new lifters in, but I felt it should be mentioned.

Could I bad lifter cause the retainer to break like that?

 

No idea. If it's still running bad though, you might as well pull the head and check the valve

 

i'm going to measdure the lobe lift on #7 and compare the 2 lobes to see if one is wiped out

 

sounds like a bent valve to me... and yes, you can bend a valve with a retainer that went bad like yours did.

 

its not bent though.

 

I see guideplates in that picture. Are you sure you didn't bend a stud? Are they 3/8th or 7/16th?

Take the stud out and check. If you are sure you didn't bend a valve then pull the lifter out and post pix.

 

this is gonna sound dumb, but whats with the offset rocker studs? What kind of small block heads are those? I thought only the big blocks run an offset like that?

 

Offset rocker studs?!

 

in the first pic it looks like the studs are offset, or is it just a funny angle? Looks to me like they dont fall in line with one another? I guess it could just be my eyes fucking with me

 

TFS cylinder heads.................

 

Well, a compression test last night shows between 195 and 200 psi in each cylinder. This leads me to believe that the cylinder head is fine and that the valve isn't bent and it did not nick the valve seat. This is good! But it means its definitely a bad cam or lifter. I'm putting the car away for the winter and I'll get back to messing with it once the weather is warmer

 

Did you leak it down?!

 

I'm betting you collapsed a lifter.

Maybe Dex will chime in here with his thoughts from his extensive experience?

 

I know for a fact I have a bent valve but mine still hit 190's across the board

 

Couldn't you bend a valve and still have the head seat properly??

 

the valve moved perfectly fine up ad down by hand and spun freely. It was leaked down too and was fine.

I've never seen a collapsed lifter cause this type of problem but anything is possible with this car lol

edit: oil still seems to be flowing through that lifter just fine. Could it still be bad?

 

FUCKIN THING SUCKS!!


I took advantage of Ebays Live search 30% off deal, stacked with a 10% off coupon, and I got a total of $325 off a set of new 195cc AFR Eliminator heads. I've sold my old heads already so I theoretically only paid like $200 out of pocket. I would have spent at least that much to upgrade the heads I had.

Now I have to choose a cam. What would you recommend for a 9.5:1 355 with 195cc AFR Eliminators, and a TPiS MiniRam intake? I'm looking for peak power around 6000rpms. Anyone have any luck with those XFI cams? They seem pretty good, but I would like a lope to my cam, and those XFI cams are all about smoothness.

 

did you check the flux capacitor? check the flux capacitor.

 

Call a cam grinder

 

yup I've talked to a few and their suggestions vary pretty wildly