Valve lift and stock springs

[zaq123]

MM compressed spring height measurement of 1.040" (per his pdf) corresponds perfectly with the minimum recommended spring height to avoid the coil bind (1mm gap between coils per my cam card).
MM specifies installed spring height - 1.465" or 37.2mm
Spring installed height per my cam card - 37mm or 1.457"
compressed spring height - 1.040" or 26.4mm
Valve clearance is 0.25mm
Valve lift for this cam is listed as 11.5

Does anyone know if cam card's valve lift represents the actual valve lift (lobe lift x rocker ratio)?

If so, stock springs are no go or new oem springs would be able to handle this?

37-11.5=25.5mm when 26.4mm is min. to maintain 1mm coil clearances.
At 25.5mm, oem spring has about average gap of 0.77mm between coils

[digger]

often that is all they do is use some assumed rocker ratio x lobe lift. may or may not result in exactly the same lift when installed.

what lift do your OEM springs go solid in your head?

[zaq123]

what lift do your OEM springs go solid in your head?

on average 13.5mm of lift makes them solid. If cam is really 11.5 lift (will measure at some point for sure), will 2mm safe zone before total coil bind be acceptable?

[digger]

im surprised it is that much but yes 2mm is fine

catcams guideline is 1mm from coil bind, and 0.6mm retainer to stem seal

[zaq123]

im surprised it is that much but yes 2mm is fine

catcams guideline is 1mm from coil bind, and 0.6mm retainer to stem seal

Well, I measured it and this is what I came up with:

Dbilas 276/276 cam. Card calls for 0.25 valve gap. Advertised lift - 11.5; stem to retainer 1mm min, 1mm min from coil bind.

Didn't have 0.25 gauge so used .27mm. My dial indicator shows 0.63 stem to retainer. Lift - 11.9mm. Didn't check for coil bind yet.. using test springs.
Using HD rockers - I guess the same ratio as OEM?? Should I be concerned about that much lift? 37-11.9=25.1mm
I compressed old oem spring in my small vise till 25.1mm and I have about 0.8mm gap on average (spring doesn't compress evenly, some gaps are small, some smaller).

No go with stock springs?

[digger]

Compress the spring all the way until solid and measure what the length of the spring is. As long as you are 1mm from that solid position at max lift the coil bind is ok.

I’ve noticed the IE rockers give a little more lift, they seem to be optimized for regrinds (atleast the ones i have are) so you dont need oversized eccentrics. this means the pad profile is offset from OEM translating to different valve motion, might be way to "cheat" on some series where you must use stock cam….

If you install an OEM rocker onto a shaft next to a IE one and remove the bolt/eccentric and install a precision rod through the bore you can see what I mean.

Lift is ok as long as the pad is always in contact with the lobe, with some cams the cam lobe runs off the actual contact pad. this is why performance rockers have longer pads so you can run high velocity without the lobe running off the edge of the foot.

catcams will soon be offering billet steel rockers with such a feature

use a good oil though with nice amount of zinc and phos,

[zaq123]

Compress the spring all the way until solid and measure what the length of the spring is. As long as you are 1mm from that solid position at max lift the coil bind is ok.

Thank you for this info. Stock spring is dead solid at 23.1 mm so I have 2 mm of room. Pad looks like it contacts cam lobes ok, never at pad's sharp edge

[TobyB]

Are the pressures ok? I found OE to be a little low on seat pressure- used an Isky inner
for safety...

t

[zaq123]

I guess there is only so much one can do with test springs. I decided to replace soft test spring with OEM spring and my valve lift went down close to the advertised lift, 11.6mm. Test springs were showing 11.9mm. Just an observation. Moral of the story: if you want accurate measurements, bring all conditions close to their final state

[zaq123]

I'm having second thoughts about running new oem springs with that much lift. I mean 11.5mm is max for Schrick springs. Should I reconsider?

[digger]

if you want to use better springs for piece of mind just do it. what does dbilas recommend?

I have a mate that used mm beehive and crmo retainers with that cam

[TobyB]

Don't be afraid to go shopping in the roundy- round catalogs-
there are a LOT of valve springs out there, and the sizes, heights and rates are well documented.
For example, I use Isky inners and stock outers on the M10 race motor, and it's solid
at 7500 with stock rockers and 12mm of lift with a pretty aggressive '314' cam....

Agreed to see what numbers dBilas wants you to use.

Revs are everything- as they go up, spring rates have to go up faster...

t

[zaq123]

Dbilas cam card call for:


Valve spring set # 63.500.001 - $220 shipped to US
Double spring

No. of springs:24
No. of upper spring retainers: Standard
No. of lower retainers inlet: Standard
No. of lower retainers outlet: Standard

Installed high: 37
Valve lift: 13
Hardness kp: 122

Mill down spring bearing isn´t necessary

[digger]

what does the hardness of 122 kp mean?

eibach also do excellent valve springs (thats what im using now) i wouldnt hesitate to use them but you need to choose yourself from the EVS section at the back based on the installed height, seat and nose loads and max lift or email them to get a recommendation

http://eibach.com/sites/eibach.com.m-america/files/catalogs/evs-catalog.pdf

some relevant data from e30tech

[zaq123]

what does the hardness of 122 kp mean?

eibach also do excellent valve springs (thats what im using now) i wouldnt hesitate to use them but you need to choose yourself from the EVS section at the back based on the installed height, seat and nose loads and max lift or email them to get a recommendation

http://eibach.com/sites/eibach.com.m-america/files/catalogs/evs-catalog.pdf

some relevant data from e30tech

Eibach is a good idea. I bet you at least 60% springs on the market are rembrended eibach. Need to look into it