valve springs
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
valve springs
i was talking to a machine shop yesterday about going through my heads and checking them over, i know i need new valve seals,have a little smoke on initial start up but goes away in a few seconds. engine has good compression,good steady vacume,and runs great. told the guy the car had been in storage for the last 14 years,and i was suprised at how well it runs,ecspecialy after some major tunning up,and other small items,and doesnt leak any fluid. he said i should replace the valve springs because they will be weak, and at least 4 springs would have been compressed and probably no good now. does this sound right? should i just do a complete rebuild on the heads and replace everything? better plant another money tree.
btw its a 78 L82.
btw its a 78 L82.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
valve springs are cheap ...especially since they're coming off to replace seals. Many/most valves can be reconditioned & reused. Just have the guy seat the valves, new springs & seals. Don't go beyond that without also considering other heads ... 78 heads are not the greatest.
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
it sounded logical, but today you can never tell, some people just like to make a sale. what do you think aboul using some better rockers, like the COMP magnum rocker arms, and changing to the 1.6 instead of the 1.5. figure if im going to rebuild heads, rebuild it all. hate putting old parts on new.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I can't imagine that being in compression would significantly change any behavior of a valve spring. That's a few hundred pounds of force on metal with a modulus of many thousands of pounds.....don't think it has an effect. BUT....they could have gotten rusty and/or pitted just sitting there for that long (without oil), and that would weaken them. Plus, as the Bird said, they're cheap and used...and should be replaced.
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
well since i will rebuild the heads, and want to use some better rockers like the comps i asked about earlier, does anybody have any thoughts on springs, stock or upgrade, and what manufacture suggestions.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Choice of springs is dependent on what type of lifters, expected max. RPM, etc. If you go with a high-lift cam and solid lifters, you will need stronger springs to respond to those forces. Unless you get specific advice from accomplished engine builders, go with what the cam manufacturer recommends. Whatever springs you go with, if the vendor offers shot peening (or similar processing) for an extra charge...do it. This will put compressive stresses into the spring surface and likely prevent any spring fatigue failures.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
Choice of springs is dependent on what type of lifters, expected max. RPM, etc. If you go with a high-lift cam and solid lifters, you will need stronger springs to respond to those forces. Unless you get specific advice from accomplished engine builders, go with what the cam manufacturer recommends. Whatever springs you go with, if the vendor offers shot peening (or similar processing) for an extra charge...do it. This will put compressive stresses into the spring surface and likely prevent any spring fatigue failures.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Not really. There may be some microscopic "work hardening" at the surface, but that is of no real benefit by itself. Shot peening puts compressive stresses by "working" the surface with the peening shot. Doing that removes any [tensile] stress risers on the spring surface...which is where fatigue failures start.
Thread Starter
Racer
Joined: Feb 2007
Posts: 307
Likes: 0
From: liberty mo
aaaaahhhhhhhhhh i see. its kinda funny that you mentioned this,because im researching blast cabinet's, wanting to buy a bench top model so i can clean up parts and repaint them,you know to all that corosion off the aluminium parts and rust off the steel parts. while looking a came accross some of the big ones that do peening. wouldn.t happen to have any experince with the bench tops would you,or any suggestions? 
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
No experience in buying them. I would suggest that you find one that can shoot several mediums...sand, small shot, walnut hulls are the best to use. You can do so much with one. Sand can clean off surface corrosion/rust in a flash; small shot can peen a surface and make a cast aluminum look brand new; walnut hulls can clean "crap" off anything and leave it looking undamaged. Check 'Harbor Freight' to see if they sell one with those kind of capabilities. I'm not sure a small cabinet would have enough force to peen the surface of hardened steel (like valve springs)...best leave the 'critical' processes to good manufacturers.
i think we have harbor freight in town, will have to go check it out, thanks for the info, later