L78 Camshaft and springs

[Tommy]

I did a search and some of the links listed in old threads were no longer good but did find one that showed Crane PN 19038 (grind # 143 2A) as being the L78 cam. Is that correct ? I didn't see any information on which springs to purchase with the cam.

Tommy

[Keith Tedford]

If you plan of turning past 6K rpm, make sure that you use better springs than what GM used. They were the number one reason why L78 cars lost their engines. Not enought spring pressure to keep the valve in contact with the valve train. The valve would actually free fall shut eventually pounding the keepers through the retainer.

[Mr70]

As Keith mentioned,aim for the stronger valve springs,originally issued mid year in 1969,(late 69 production),as part #3989354 used on the new three prefix letter coded solid lifter engines for 1970 too.
The troublesome springs used before then were part #3859911,striped red/silver/purple & sometimes tan.

[3macs1]

I would not use the original GM retainer locks either. There are better ones available from the cam manufacturers.

[Chevy454]

Spring technology, mainly material/manufatcturing has come a long, long way...any spring, even a stock replacemtn, made within the last decade should be ok...you're not gonna need crazy spring pressures with that cam...most folks just run the springs that come with the blueprint cam from GM/Crane.

[WILMASBOYL78]

Call Eric jackson..he hooked me up with a great package of valvetrain parts when I "freshened" my 70 L78 th400 car last year. The valve stuff in those old motors is like "an accident waiting to happen"...kept Chevy busy building CE blocks

wilma

[VintageMusclecar]

Thanks Tom.

The other big potential issue is those factory 2-piece valves...they've been known to pop their heads off with alarming regularity, and weak spring-induced valve float/bounce only exacerbates the problem. If the heads ever have to come off, replacing those valves even with an economy set of aftermarket 1-piece stainless steel valves is a HUGE insurance benefit.

Eric