Valve spring suggestions

Pronto

Pronto

Believe nothing you hear and half of what you see.
Joined
Dec 9, 2002
We suspect the currently installed valve springs are not up to the task. The engine is experiencing knock at about 5100 rpm. No tune, octane, mechanical problems can be found. Smooth power comes on strong though the rpms with no skips, pops, hesitation or audible noises. Power seems to taper off soon after the knock fades and rpms go higher. We expected to have power still being made to at least 5800.
The single wind springs tested 130lbs @ 1.70" install height. We do not know the brand or complete specs. These springs are in nicely ported/polished iron heads, larger intake valves and clearanced for roller rockers. Lifters are Morel regular style roller.
Billet roller cam specs according to paperwork: duration 270/264, 214/210 at .340 lift, lobe sep 113, lift x 1.6 ratio .544/.544. Currently has 1.65 roller rockers. We do not want to switch to bee hives. What valve springs would work correctly with this setup? Thanks.
 
There are 3 pulls on this log. I just added a dual nozzle to the Alky Control. I have leaned it out some since.
I'm going to pull a valve cover and measure the coil bind space at full lift. Haven't measured that yet.
 

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  • first dual nozzle run.dat
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Do you have the lobe numbers so I can verify exactly what type of lobes they are. Chances are you need more seat pressure.


BPE2013@hotmail.com
 
Not sure what you mean by lobe numbers. Other than what was listed I have the open and close degrees, is that what you need? The cam is from TA. The number is TA270-64RH. Grind 53385
 
I run 135lb singles on a 222@0.050" cam pull 6800 rpm before floating on 18psi with an 0.82 turbine housing.

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Dunno about knock my sensor gets turned off after 3600rpm due to noise

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I mean the actual 4 digit lobe numbers that were selected out of the lobe catalog. I just skimmed through and didn't see any lobes that have the numbers you listed in your op. Some were close but no direct hits. I just browsed quickly so it's possible I overlooked. If they are XFI lobes they will need a lot of seat pressure. Even if XER id still want at least another 25-30 on the seat with 1.65 rockers. Id call TA performance for more info. They should have more accurate info. Without knowing the lobe numbers or actuall measured cam numbers you won't get accurate spring info. I'd measure the lobe lift with an indicator and use that info to determine a closer valve lift number and work backward from coil bind to determine a spring that will get you about 160 on the seat if you are staying with the 1.65 rocker. 1201 is a good spring that will likely go on with no problem but you should still get the actual lift data so you can see how much room you have


BPE2013@hotmail.com
 
Last edited:
Would reducing the rocker ration to 1.6 or 1.55 be a better choice?
 
Pronto said:
Would reducing the rocker ration to 1.6 or 1.55 be a better choice?
Click to expand...
It would definitely increase the rpm potential with a given spring but I'd still want to know what lobes you have before I could say x amount of seat pressure will definitely work with them. The magnum roller lobes will work with 130 seat with 1.55 rockers and rev to about 6000. Xer and up will need more spring unless you are keeping rpm low


BPE2013@hotmail.com
 
Pronto said:
We suspect the currently installed valve springs are not up to the task. The engine is experiencing knock at about 5100 rpm. No tune, octane, mechanical problems can be found. Smooth power comes on strong though the rpms with no skips, pops, hesitation or audible noises. Power seems to taper off soon after the knock fades and rpms go higher. We expected to have power still being made to at least 5800.
The single wind springs tested 130lbs @ 1.70" install height. We do not know the brand or complete specs. These springs are in nicely ported/polished iron heads, larger intake valves and clearanced for roller rockers. Lifters are Morel regular style roller.
Billet roller cam specs according to paperwork: duration 270/264, 214/210 at .340 lift, lobe sep 113, lift x 1.6 ratio .544/.544. Currently has 1.65 roller rockers. We do not want to switch to bee hives. What valve springs would work correctly with this setup? Thanks.
Click to expand...

And this issue is occurring at different psi levels, correct?
 
Talked to TA.
Bison, I tried to explain the lobe numbers you wanted but the person I talked to didn't know what I was talking about. I probably didn't explain it well enough. He did had a sheet with the recommended closed and open seat pressures. He said 155 closed and 370 open. He also said that should be good for 6000rpm.
Looking at the PAC catalog there is the 1201x that bumps up the closed to 150 vs 140 and open to 460 vs 437. Would that be enough with the 1.65 rockers? I really don't want to have to get a new set of rockers too...
 
1201X is a great spring, have them on my car. added benefit is they typically don't require valve guide machining. It would get the job done for you IMO, we usually try to keep a set on the shelf
Mike
 
Pronto said:
Talked to TA.
Bison, I tried to explain the lobe numbers you wanted but the person I talked to didn't know what I was talking about. I probably didn't explain it well enough. He did had a sheet with the recommended closed and open seat pressures. He said 155 closed and 370 open. He also said that should be good for 6000rpm.
Looking at the PAC catalog there is the 1201x that bumps up the closed to 150 vs 140 and open to 460 vs 437. Would that be enough with the 1.65 rockers? I really don't want to have to get a new set of rockers too...
Click to expand...
Haha. http://www.compcams.com/Technical/Catalogs/LC2007/2007LobeCatalog.pdf

This isn't a complete listing but has most of what you ever see talked about on this board. Most of what's typically used/discussed here is on pages 13-16. Keep in mind the catalog info usually doesn't match the actual info because most of those are S master lobes that are designed for small block Chevy cam journal. Fwiw XFI lobes are ok with 170 seat pressure and 1.65 rockers up to at least 6000rpm. I ran PAC 1203 for this but they aren't drop ons and be sure you run a quality timing set with them. No Rolon chains!


BPE2013@hotmail.com
 
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