Re: {Chrysler 300} Re: Valve spring specs 57c

agree totally — lifter and cam “ problems” come from guys who think they are smarter than the original 3 guys who designed that motor .Failures not due to “oil” —all of a sudden — after 60 (!) years of no problems . yes phosphate (ZDDP ) helps but quality of heat treat on lifters matters a lot more, and many of these experts were guilty of selling private labeled inferior chinese lifters , just follow $ for your answer , always.

Simply not possible , that someone knows more today about street driven hemi and why decisions on spring loading were made — and that includes comp cams , — than those three guys. . But a better cam , from comp , yes . Technology on cam profile does advance a lot as does QC .

I once had a factory drawing of a 300 cam , unbelievable detail , like maybe 50 toleranced numbers for QC including heat treat of materials , chemical constituents of alloy etc — why it worked . All pre cnc too . The drawing itself was a week of drafting work .

The 300 hemi motor went to 5800-6k , with original spring loads ; springs which are not ,in general, “tired” as they lasted 200 k ; going more than that rpm is totally pointless in a 300 , trans will shift anyway and ignition goes away . records and races were won with close to stock spec 300 valve gear , which is a little more load than NY er . And solids .

Related , unless you get into taller valve gear etc the basic geometry of the engine limits lift to 450-480 max . More , and the rocker will almost , or will, slide off the valve tip and puts side loads on the guides . Raise rocker arms , it slides off the other side .

They had one hell of a time in first few years with losing cams lifters etc , but we all know of 392 300’s topping 200k stock , Jerry Kocur went 3-400 k on a b block . Only 5 k miles on spring “ improvement “ says it all.

I learned about 50 years ago that listening to self proclaimed “ experts “ is bs , after one of them told me to shim the oil pump spring , — that idea later lifted oil filter can up off gasket at block , unknown to me all oil out in 20 seconds at high rpm = a lunched engine when I had no money . I still feel today like punching that guy out , ( a “ professional truck engine mechanic” ) which says little for my own humility . I believed him .

Along same lines , I wanted to go with beehive springs , a hands on skilled engine guy I really trust told me any single spring coil with a scratch will fail there , dropping the valve , engine is toast . dual springs don’t do that and internal steel tensile forces in a dual pack for same net total force at a fixed travel are always lower . And that cost a lot more , for 2 springs per valve , not a decision taken easily —- those three guys in 1948 knew all this .
all this imho . Great subject

john g

ps put the old ones back... if anywhere near constant and near spec

Sent from my iPhone not by choice

On 20 May 2021, at 2:22 pm, Larry Wood <larryjw7@xxxxxxxxx> wrote:

Michael Do not put the wrong springs to much pressure will destroy your cam! i have a specialist that give me some over pressure springs 190# at 1.7-16 inch. it would fly but you don not want to replace your cam and springs in 5800 miles!
chrysler 300C factory spects are 158# AT 1 and 7/32 inch height outer spring. hope this helps. larry

On Thursday, May 20, 2021 at 1:32:35 PM UTC-4 micke.sundbom wrote:

Hello
300 world, I have a delicate question regarding valve springs for my 57 300c engine. I am in full swing renovating cylinder heads. We put in all new guides and valves etc. A problem we feel after having measured the spring pressure on the new springs and compared to the tired originals. We find that the pressure is tremendously great with the ones we have had from Hot Heads,, they probably have others but these I have been recommended.
I absolutely do not want to kill my cam lobes. Therefore, I am looking for specification of lbs spring pressure and at what length of spring travel.
My new springs are the inner and outer type..Before we move on im glad for any input regarding specs , brand part nr with springs close to the originals.
Hope you understand my technical Donald Duck language .. input is welcome.

Thanks
Michael

Skickat från min Galaxy

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