valve springs
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From: Hico
valve springs
I was wondering if anyone could tell me the specs on the stock valve springs for a '79 300. I'm building one up right now and i know that they like to start floating valves around 3500 rpms. It has an Offenhauser four barrel intake, EFI manifolds, Cam Research cr266 camshaft, the engine has been bored 40 over and the heads been shave at least 40 thousandths. I just want to get a bit more rpms out of the build to make it all worth it. I know the cast bottom end can only handle so much, but i'm not going to be racing it or anything and i know when to stop before it explodes lol. Thanks in advance!
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Senior User
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From: Hico
at .050 intake duration is 200 and the exhaust is 205 valve lift is .410 on both intake and exhaust.
More Turbo
Joined: Nov 2015
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The Comp 903 spring is the stock replacement spring and fits the stock intake retainer.
Seat pressure at 1.700" installed height is 80 lbs with a 293 spring rate.
Next higher spring:
Crane 99833 spring, 98 lbs seat pressure at 1.700" with a 328 spring rate.
Use with a Comp 768 retainer.
Fleet Mechanic
Joined: Nov 2002
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I was wondering if anyone could tell me the specs on the stock valve springs for a '79 300. I'm building one up right now and i know that they like to start floating valves around 3500 rpms. It has an Offenhauser four barrel intake, EFI manifolds, Cam Research cr266 camshaft, the engine has been bored 40 over and the heads been shave at least 40 thousandths. I just want to get a bit more rpms out of the build to make it all worth it. I know the cast bottom end can only handle so much, but i'm not going to be racing it or anything and i know when to stop before it explodes lol. Thanks in advance!
I don't have records for a '79, but here are the specs for an '82:
INTAKE SPRING INSTALLED HEIGHT: 1.70"
INTAKE SPRING INSTALLED LOAD: 80#
(197# @ 1.30#; SPRING RATE 293 #/in)
COIL BIND @ 1.14"
EXHAUST SPRING INSTALLED HEIGHT: 1.58"
EXHAUST SPRING INSTALLED LOAD: 81#
(192# @ 1.18"; SPRING RATE 278#/in)
COIL BIND @ 1.01"
NOTE: Spring rates vary slightly from year-to-year. My guess is that the spring itself did not change but statistical quality control measurement methodology maybe did.
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