Engine problem with 63 L84

[Clem Z.]

Re: Engine problem with 63 L84

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?

those engines would have to have some type of push rod guides installed to use the old style rocker arms.

[Duke W.]

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.

We're talking about small blocks, not W or Mark IV big blocks. The OE small block valve spring that was used from '57 to '66 was replaced with a new design that went into production for 1967. This spring has marginally higher seat force and rate than the earlier spings and remained in production through at least 1979. It's currently available as Sealed Power VS677, costs about a buck a piece, and I recommend it for ALL SB engine restorations, assuming an OE cam or OE cam lobes are used on a custom design.

When exhaust valve rotators were added in the seventies the exhaust spring design changed to accomodate the rotators, but the seat force and rate remained the same.

BTW these springs were used on ALL small blocks of the era - from 2-bbl. 283s to the mechanical lifter SHP engines.

High strength bolts will do absolutely nothing to correct the inherent weakness at the bolt seat of pre-'66 small block rods. They are paper weights! Those little humps of material added adjacent to the bolt seats on the second design 327 rods beginning circa 1966 make a HUGE difference in fatigue resistance which adds considerable durability.

For hydraulic lifter engines up to 6000 RPM I recommend reusing them as is with only a dimensional conformity check - no Magnaflux, resizing/new rod bolts are necessary. Of course the owner also has the option of spending $250 on a set of Eagle SIR rods for insurance and peace of mind, and the late 327 rods can be sold or donated to an early 327 or 283 owner and reused in those engines.

Duke

[Duke W.]

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?

What Clem said, but I also have to ask, why were the rocker arms replaced?

It's rare to find excessively worn rocker arms/balls. My advice has always been to bag them along with the pushrods as matched sets on disassembly, and at some point they should be cleaned and inspected. If the wear surfaces are just burnished and show no ridges, galling, or other evidence of excess wear they are perfectly okay to reuse.

Where the rules allow, roller trunnion rockers will improve durability in applications where revs are continously at 5000 and above, which means racing engines. Back in the late sixties, the OE rocker arm system worked okay on Trans-Am engines, but lobe dynamics had to remain relatively mild. Contemporaneous F5000 engines were allowed to use roller trunnion rockers, which allowed more aggressive lobe dynamics; and with IR fuel injection systems they were able to rev to about 8000 and made about 10 percent more average power in the upper 20 percent of the rev range than Trans-Am engines.

Duke

[Clem Z.]

Re: Engine problem with 63 L84

the LT-4 engines used crane full roller rockers BUT i think it was used to lower the engine oil temp. there have been tests run that show about 15 degree reduction in oil temp over rocker ball type rocker arms. with full roller rockers you need the top of the studs to be machined flat so the lock set screw gets a good bite. the way you adjust them is to set the lash .003 loose lock the set screw and than just tighten down in the adjustment nut to the lash spec. with hyd lifters you set set the amount of preload lock the set screw and then crank the adjustment nut down 1/8 of a turn

[Michael H.]

Re: Engine problem with 63 L84

the LT-4 engines used crane full roller rockers BUT i think it was used to lower the engine oil temp. n

Clem,

The roller rocker arms were used to reduce oil volume requirement. Not oil temp. Although it may have reduced temp a bit, that was not the original goal.

[Joe C.]

Re: Engine problem with 63 L84

LT4 was using 1.6:1 rockers, which increased force, thus friction at the pivots.

[Clem Z.]

Re: Engine problem with 63 L84

Clem,

The roller rocker arms were used to reduce oil volume requirement. Not oil temp. Although it may have reduced temp a bit, that was not the original goal.

did GM put a reducing orifice in the oil passages to cut back on the oil flow ??? that is what we did on race engines but you also wanted to make sure you had enough oil to cool the springs

[Clem Z.]

Re: Engine problem with 63 L84

here is a tool that makes the setting of roller rockers a lot easier

[Duke W.]

Re: Engine problem with 63 L84

The LT4 was a limited production "technology demonstrator" precusor to the LS1, although some of it like Opti-Spark and reverse flow cooling didn't make the cut.

In a high-revving racing engine roller trunnion rockers do decrease friction and oil temperatures. It's also true for a road engilne although to much lesser effect due to the much lower average revs.

Roller trunnion rockers is one of many techniques applied to reduce internal engine friction to help meet CAFE requirements, but that doesn't mean that adding roller trunnion rockers will yield a measureable improvement in fuel economy for typical vintage Corvette driving conditions.

Notwithstanding the fact that most will not fit under the OE valve covers, you would be unlikely to ever recover the cost in fuel savings.

Note that the above ONLY applies to ROLLER TRUNNION rocker arms. - NOT those PoS aftermarket roller tip rockers.

Duke

[Michael H.]

Re: Engine problem with 63 L84

did GM put a reducing orifice in the oil passages to cut back on the oil flow ??? that is what we did on race engines but you also wanted to make sure you had enough oil to cool the springs

Clem,

Here's a post from a while back about the real reason why engineering started using roller rocker arms. I know this to be true.

https://www.forums.ncrs.org/showthre...leage&uid=5460

And another from 2008

https://www.forums.ncrs.org/showthread.php?65893-Roller-Cams&highlight=friction

From one of the discussions....

As you know, if there was actually enough friction at the lifter/lobe to cause any substantial drag, the lobe and lifter would quickly grind itself away, so we know that this isn't the case. A constant high volume flow of oil prevents damage and wear.

Here's the story. One of the reasons why mfg's have switched to rollers is because they require a LOT less lubrication. What's that got to do with it? Well, more lubrication means that the oil pump has to work a lot harder and this is consuming energy. (HP and fuel) Believe it or not, most of this is a result of the EPA regs on fuel mileage. This is one of the reasons why newer cars have/require less oil pressure.

If we reduce the oil pressure/volume, the amount of energy lost in driving the oil pump is less, but we eventually get to a point where the reduced amount of oil isn't enough to properly lubricate the lifter. Rollers cure this problem.

There's an incredible amount of energy lost in any engine that produces 60-70 lbs of oil pressure at 2500+ RPM. That's why engineering wanted to reduce this pressure and volume requirement. Lifters and rocker arm oiling was consuming a large part of the volume so efforts were made to reduce this requirement.

In racing engines, some builders are actually switching to roller cam bearings for this same reason. There's no HP gain from reduced friction but there is gain in not having to pump as much oil to these bearings.

Internal engine oil requirements and leaks are responsible for a lot of energy loss. Another example would be the oil that leaks by the distributor lower housing. Some new distributors for comp now have "O" ring grooves to seal the housing to the block to prevent these leaks.

If folks don't thinkk the oil pump consumes a lot of energy, think again. In a drag race motor, the distributor drive gear can be completely worn out in 50 passes. (thus, the invention of the bronze driven gear) I've never known the actual numbers on this but I'm sure it would be interesting to learn just how much HP is required to drive an oil pump at 7000 engine RPM with 40W or 50W racing oil.

[Clem Z.]

Re: Engine problem with 63 L84

i know GM reduced the oil pressure in a lot of engines like my 88 350 silverado as it runs a about 30#/35# at cruising speed BUT i still want to know how they reduced the oil flow volume to the rockers,thru the lifters ??? they still had to maintain enough oil flow to cool the valve springs. i remember the chevy stock block engine project at indy when the valve springs were going away in just one lap. they found out that the G forces in the turns was causing the oil not to get to the springs. GM ran a test with clear see thru rocker cover on a engine that the oil flow to the lifters could be shut off. in about 30 seconds of no oil flow to the valve springs they turned cherry red. this is where the spring oilers in the valve covers you see on most race engines came from

[Joe C.]

Re: Engine problem with 63 L84

i know GM reduced the oil pressure in a lot of engines like my 88 350 silverado as it runs a about 30#/35# at cruising speed BUT i still want to know how they reduced the oil flow volume to the rockers,thru the lifters ??? they still had to maintain enough oil flow to cool the valve springs. i remember the chevy stock block engine project at indy when the valve springs were going away in just one lap. they found out that the G forces in the turns was causing the oil not to get to the springs. GM ran a test with clear see thru rocker cover on a engine that the oil flow to the lifters could be shut off. in about 30 seconds of no oil flow to the valve springs they turned cherry red. this is where the spring oilers in the valve covers you see on most race engines came from

Beehive springs, which are made of ovoid cross sectional wire run cooler than conventional springs. They are progressive rate, lighter and therefore less prone to resonance. They require less oiling and need less pressure (force) to maintain the same control as that of a conventional spring. Beehives for higher lift cams don't require inner springs or dampers. Not sure when they came into use on GM engines (LS1 ?).

The LS9 uses 1.7:1 rockers for valve lifts of .558/.552 and the LS7 uses 1.8:1 rockers for valve lifts of .591/.591. My 327 uses 1.6:1 rockers for valve lifts of .608/.610 when lashed at .016/.018.

[Clem Z.]

Re: Engine problem with 63 L84

Beehive springs, which are made of ovoid cross sectional wire run cooler than conventional springs. They are progressive rate, lighter and therefore less prone to resonance. They require less oiling and need less pressure to maintain the same control as that of a conventional spring. Beehives for higher lift cams don't require inner springs or dampers. Not sure when they came into use on GM engines (LS1 ?).

The LS9 uses 1.7:1 rockers for valve lifts of .558/.552 and the LS7 uses 1.8:1 rockers for valve lifts of .591/.591. My 327 uses 1.6:1 rockers for valve lifts of .608/.610 when lashed at .016/.018.

not till the LS series engines. now the aftermarket has copied GM. the big help was the smaller retainer,less weight

[Joe C.]

Re: Engine problem with 63 L84

not till the LS series engines. now the aftermarket has copied GM. the big help was the smaller retainer,less weight

True. And if you use titanium retainers, that saves even more inertial weight.

Back to the OP and/or all old school people who believe that the zenith of engine design was way back in 1970: none of this applies if you use olde fashioned flat tappet camshafts with cripplingly slow ramp action and meager lift. These anemic cams will not overwork the olde fashioned marshmallow springs that they were designed to mate with.

The "secret" to modern engines' very high specific power output, besides the obvious precise fuel metering and very well designed ignition systems is:

1. Advanced head design.
A.) Compact chambers
B.) Valve placement permitting very little shrouding.
C.) High swirl chambers for more efficient burn.
D.) Last and certainly not least, increasingly higher flows at higher valve lift up to .600 and better.

2. Updated camshaft design philosophy:
A.) Use of valve lifts approaching .600 on stock engines
B.) Faster ramps enabling faster opening/closing events, thereby lowering bleed-off of cylinder pressure.
C.) Abandonment of high duration/overlap as a means of increasing cylinder charge at high RPM's.

Most of this design philosophy can be applied to old, Gen I SBC engines, retaining reliability while increasing broadband torque as well as horsepower.