Engine problem with 63 L84

[John D.]

Re: Engine problem with 63 L84

Congratulations Michael. You are lucky. By the way you better carry your extra cranking signal valve as those valves do not take kindly to back fires.
JD

[Ken A.]

Re: Engine problem with 63 L84

How come GM always has recommended needle roller rockers for high performance applications?
However, they do offer the caveat that you need screw in studs or pinned studs as they are hard
on the studs. Could it be that their stamped steel rockers all vary from the published ratio?

[Jerry G.]

Re: Engine problem with 63 L84

Before you put in OE stamped rockers make sure your valve springs are close to original seat pressures, aftermarket or high performance spring rates will eat up stamped rockers.

[Michael G.]

Re: Engine problem with 63 L84

Interestingly, last time we visited this engine it was bending push rods and pulling rocker studs out of the heads. We rightly attributed this to "gorilla" type valve springs erroneously used in the rebuild, which I then replaced with springs with the correct load. Now, though, I'm not too sure that some of the original problem wasn't the rockers themselves. What was not discussed at that time is that both the rockers used in the rebuild, and the first replacements I substituted, were recently-made slotted parts. I'll find some correct ones, perhaps at Crane, before I switch out the roller tipped parts.Thanks,

[Monte M.]

Re: Engine problem with 63 L84

Mike,

Really glad to hear it turned out alright. You did the right thing by trying everything before givivg up and tearing it down. Hope your knuckles survive, but it was one of the steps taken for you to figure this out.


We all learn alittle each time something like this happens and you did a great job of going back to the basics and starting from there. That is what figured it out for you.


Once again, Congrats. Bet you enjoy it a little bit extra the next time you take it out for a ride. Enjoy

M

[Duke W.]

Re: Engine problem with 63 L84

Let me get this straight. You're saying that whoever rebuilt this engine used a set of late type slotted rocker arms with a Duntov mechanical lifter camshaft.

Who rebuilt this engine?

What happened to the original rocker arms/balls?

Duke

[Michael G.]

Re: Engine problem with 63 L84

Duke, and don't forget the wrong springs.. I tend to avoid criticizing people in print, so think I'll pass on posting the name here...Thanks,

[Duke W.]

Re: Engine problem with 63 L84

Oh, yeah. Gorilla valve springs for a Duntov cam, too because Duntov just didn't know what he was doing.

The TDB is full of "engine builder" horror stories. The incompetence out there is rampant.

Do everyone a favor and post the name and location of the shop that did the work. That, in and of itself is not critical, but everyone can draw their own conclusions based on the posts in this thread.

You might save another NCRS member from the same fate.

Duke

[Ken A.]

Re: Engine problem with 63 L84

ANY Chevrolet engine that's going to see regular high RPM usage needs pinned rocker arm studs or better yet, screw in studs.

[Duke W.]

Re: Engine problem with 63 L84

Not at all true. Plenty of early small blocks with OE valve trains saw lots of high rev service including my 340 HP, which suffered one memorable trip well beyond 7000 when I let the clutch out too fast on a 1-2 shift, and it hung in neutral as I got back on the throttle.

In almost every case of "pulled rocker studs" I've seen, the heads had higher than OE force valvesprings.

I don't recommend replacing pressed in studs on a small block restoration with any OE cam including mechanical lifter as long as OE replacement springs are used, and no OE cam needs more force that the OE springs offer to achieve 6500+ with hydraulic lifter cams and 7000+ with mechanical lifter cams.

Pinning is obsolete, but if heads are stripped for a rebuild it's neither difficult nor expensive to install threaded in studs, so it's up to the owner, but IMO the money is better spent elsewhere.

Duke

[Ken A.]

Re: Engine problem with 63 L84

Oh, but it is true. Chevy started pinning 409's in late 63, because screw in studs hadn't been developed as yet. Screw in studs & better rod bolts are the best investment for insuring the endurance of your classic Chevy engine. Chevy also continually developed improved valve springs as better wire became available in the late 60's and continues to this day to do so.
So, you are right, it is up to owner to choose, and hopefully make an informed decision based on facts-not opinions.

[Patrick B.]

Re: Engine problem with 63 L84

Let me get this straight. You're saying that whoever rebuilt this engine used a set of late type slotted rocker arms with a Duntov mechanical lifter camshaft.

Who rebuilt this engine?

What happened to the original rocker arms/balls?

Duke

Duke -- About 20 years ago, I rebuilt a 65 Fuelie engine for a friend whose car was being restored. I used all GM parts (including the LT-1 rather than the 30-30 cam) and TRW stock forged pistons. The only GM rocker arms available were ones with bumps on either side of the valve tip contact area. I had never seen them before and was annoyed that my usual feeler gages would be useless for setting valve lash. I assume that these are what you are calling slotted type rocker arms. I got some narrow feeler gages, set the valve lash cold, and delivered the engine to the out of state restorer. It took 6 more years before my friend got his car finished because he made the mistake of paying in advance for the restoration. However, all the reports to me were than the engine ran very well. Is there something more to be concerned about these GM rocker arms other than the impossibility of using standard width feeler gages with them?

[Joe C.]

Re: Engine problem with 63 L84

Duke -- About 20 years ago, I rebuilt a 65 Fuelie engine for a friend whose car was being restored. I used all GM parts (including the LT-1 rather than the 30-30 cam) and TRW stock forged pistons. The only GM rocker arms available were ones with bumps on either side of the valve tip contact area. I had never seen them before and was annoyed that my usual feeler gages would be useless for setting valve lash. I assume that these are what you are calling slotted type rocker arms. I got some narrow feeler gages, set the valve lash cold, and delivered the engine to the out of state restorer. It took 6 more years before my friend got his car finished because he made the mistake of paying in advance for the restoration. However, all the reports to me were than the engine ran very well. Is there something more to be concerned about these GM rocker arms other than the impossibility of using standard width feeler gages with them?

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ?????????????????????????????????

[Clem Z.]

Re: Engine problem with 63 L84

the main problem is you need to open up the double (D) shaped holes in the heads for push rod clearance . if you do not do this you are trying to line up 3 places in a straight line ,the double(D) hole for the push rod, the rocker arm stud and the groove in the rocker tip on the valve stem.

[Patrick B.]

Re: Engine problem with 63 L84

the main problem is you need to open up the double (D) shaped holes in the heads for push rod clearance . if you do not do this you are trying to line up 3 places in a straight line ,the double(D) hole for the push rod, the rocker arm stud and the groove in the rocker tip on the valve stem.

I see the issue. Maybe I was just lucky or maybe the holes in the heads were already sloppy. But this would be just as big an issue with a hydraulic cam as with a mechanical cam. Were the holes in 1980's and later small block heads larger, and will those engines have problems with ordinary rocker arms?