Valve springs

Tom87GNX

Active Member
Joined
Nov 29, 2012
I'm looking for ideas on what valve springs I should install. I'm not modifying anything on the inside with the exception of timing chain, oil pump, and valve springs. I have bone stock engine, with 60# injectors, gutted cat, hooker cat back, TT v5.7 93 chip, stock trans and rear. No alky or anything like that.
 
Comp cam 979's work outstanding with stock cam. Imo the lt1 or 980's are overkill and simply put extra unneeded load on tappets
 
im not familiar with 979s but 980 comps have gone soft on some of us pretty quickly with aftermarket cams, the lt1 springs work well for that, in fact champion uses them on their aluminum heads for flat tappet cams, from what ive heard from them. about 100 lbs seat psi, can be set up a little less with +50 retainers, use zddp additive in every oil change to protect your cam lobes from wiping, also sealed power has one good enough for stock cam, about 85-90lbs, i have some new lt1 springs i dont need you can have cheap, lmk if you want them by pm, good luck
 
bison said:
When installed at the correct height and not expecting much over 5000rpm/25psi

Bison, since I'm running a stock cam an 18-20 psi of boost should I run 980 springs? Is there machining required to install these? And do you also recommend the matching retainers and locks? I'm looking for the best reliable combo without causing problems with lobe wear etc.
 
I measure the heights and shim to the pressures I want. 980 is plenty for what you're doing
 
Tom, I'm in very similar position as you right now with my engine. If you're replacing the timing gear and springs why not go ahead and swap out the cam, lifters, and pushrods as well? That's what I'd like to do, but like you I'm not sure of the latest recommendations, vendors who carry these items, etc.. Thanks for the thread.
 
bishir said:
Tom, I'm in very similar position as you right now with my engine. If you're replacing the timing gear and springs why not go ahead and swap out the cam, lifters, and pushrods as well? That's what I'd like to do, but like you I'm not sure of the latest recommendations, vendors who carry these items, etc.. Thanks for the thread.

I was considering doing all this but was later in formed that for what I'm looking for that's not necessary. I've been told that with all stock internals these can go into the 10's. it may or may not hold up long but none the less I'd rather just swap out the necessary items and invest my money in other beneficial areas. I'm only really looking to build a high 11 or low 12 second car so in my case a cam swap isn't necessary.
 
What about the 100lb springs Kirban sells? Any thoughts on springs from other vendors? I have read that the LT1 springs are great, but does anyone have a correct part number?
 
What about the 100lb springs Kirban sells? Any thoughts on springs from other vendors? I have read that the LT1 springs are great, but does anyone have a correct part number?

Bought these (Kirban's) back in about 2001, installed them in 2002, been running them ever since on my stock cam. Granted, I've only put maybe 10,000 miles on them, since my car is not a daily driver. I noticed a definite improvement in performance, especially above 4500 RPM. When I was drag racing the car, I ran 25 psi with no problems - pulled nice all the way up to 5500 RPM (not ideal, I know). Combo and times in my sig - 119 mph on a stock cam with stock heads is not bad. I just got done checking lobe lift with a dial indicator, and so far no cam lobe wiping (knock on wood). For most of that time, I was running Mobil-1 (which everyone now hates ;) ) and a half bottle of GM EOS per oil change.

Here's some fun - back then, I had access to a spring tester. Here is a comparison of the Kirban's springs (new) versus the stock springs (used, I removed them at about 33,000 miles). You can see that the Kirban's were a big step up in load. I imagine they've softened a bit by now (11 years and about 10,000 miles later).



GM Service Manual Specs: Free Length = 51.56mm, 74-82 lbs. @ 44mm, 175-195 lbs. @ 34mm

K I R B A N S || S T O C K
Free Length Load@44mm Load@34mm Engine Pos. Free Length Load@44mm Load@34mm
# mm lbs lbs Cyl/Valve mm lbs lbs
1 52 104 257 1 EXH 51 69 168
2 52 100 256 1 INT 51.5 68 170
3 51.5 99 253 3 EXH 51.5 66 169
4 51.5 100 249 3 INT 51.5 67 170
5 51.5 98 249 5 INT 51 65 172
6 51.5 103 254 5 EXH 51 64 169
7 51.5 104 259 2 EXH 51 68 168
8 52 105 256 2 INT 51.5 65 165
9 51.5 104 260 4 INT 51.5 66 166
10 51.5 103 255 4EXH 51.5 66 170
11 52 105 256 6 INT 51 65 172
12 51.5 103 254 6 EXH 51 69 172


I'm not sure if Kirban's has changed the design of their springs at all since 2001?

Might be interesting to get the specs for the Comp 979's and 980's (and LT1's) against these. Come to think of it, I'm guessing they've been posted some time in the past - do a search when that starts working.
 
OK, so the board destroyed my formatting in the above post. I tried to post the Excel data as a picture, but that's not working, either.

The new Kirban's springs had loads in the 99 ~ 105 lb. range at 44mm height, and 249 ~ 260 lb. at 34mm height. I expect that if I remeasured them after 10,000 miles, they are probably a bit softer.

The removed stock spring had loads in the 64 ~ 66 lb. range at 44mm height, and 165 ~ 172 lb. range at 34 mm height.

Sorry for the formatting problem above...
 
mgmshar said:
OK, so the board destroyed my formatting in the above post. I tried to post the Excel data as a picture, but that's not working, either.

The new Kirban's springs had loads in the 99 ~ 105 lb. range at 44mm height, and 249 ~ 260 lb. at 34mm height. I expect that if I remeasured them after 10,000 miles, they are probably a bit softer.

The removed stock spring had loads in the 64 ~ 66 lb. range at 44mm height, and 165 ~ 172 lb. range at 34 mm height.

Sorry for the formatting problem above...

Good data. I wouldn't expect the new springs to drop more than 5% after running them. Also
The 44mm installed height is tighter than most installs (some totally botched) I've seen over the years. Removing the factory damper and running the new spring without it and no shimming will net a taller installed height. Anyone who installs springs without measuring is leaving themselves open for problems that will be harder to diagnose
 
We have been selling the same 100lb springs since 1999. They are normally between 98 and 103 lbs on the ones we have measured over the years. We have sold several thousand sets without any problems. I put a set on my unopened 153k mile engine in 1999 before I worked at Kirbans and picked up 3mph in the quarter mile. I could feel the difference. We buy them from a local supplier.

Pete
Kirbans
 
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