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105's or not?

Z34Phoenix

Z34Phoenix

Florida Tuner
Ok im just about done porting my heads for the topswap and am looking to start assembling them soon. I have a set of 105 # springs but unsure if is should use them or the stock springs. here is what will be installed and total mods:

L36
Gen 3 with mild porting, 3.8"
High velocity TB
Ported heads. referenced photos of stage 3 heads while porting. port and valve diameter are stock. port shape nicely tweaked, chamber smoothed and clearanced for the valves.
Si Valves
SLP 1.8 aluminum roller rockers
Speed Daddy headers
3" high flow cat
2.5" cat back

I guess the main question is... are the 105's needed at all for my setup? i no longer think i will be revving the engine out high in the rpm band. the other factors in my head are that the member i purchased the springs from did not know the brand of them. i know there were bad batches of springs that were cracking... adding to that is the fact that all the Si valves that broke were due to heavier springs. now i have read that they are rated for 115 # springs or less and mentioned that 90# yellow springs caused failures due to the high ramp rate on them. my thinking is if the springs aren't needed for my setup then i will just go with stock springs which are more reliable and safer for the Si valves.

ok input/ advice time.
 


Agreed.. L76 springs would be perfect for that setup with 1.8 rockers. 90lb seat but a linear spring rate similar to the 105's. Will be easier on your chain/damper than yellow 90lb ls6 springs.
 
Im sure you can find them cheaper on the internet, but I just ordered some l76 springs and retainers from the dealer and they are more than that around here.
$4.26 for springs
$4.28 for the retainers

All in all still not too bad.
 


the l76 are the G8 springs right? I might swap to them... i noticed the stock springs are lighter then the 105's i have. hopefully the l76 are light or close to the stock wieght. i know its is very trivial... but attention to the little details adds up.
 
i had considered them before... but heard that they wear faster? not sure why they would but i remember hearing it. for the price too i dont think the weight savings was worth it. thats why i bought the Si Valves instead.

I guess if the stock springs are fine then i wont spend any more on the valve train. the only thing bouncing in my head is if i get the l76 springs down the road if i want a cam, maybe i can have ZZP custom cut something like a VS or GT2 to work with my SLP 1.8's
 


Performance reducing rockers require significantly more valve spring to keep them under control. I would either put LS6 springs in or switch to stock rockers. Stock rockers would probably make more power.
 
Yeah, run LS6's and enjoy yanking off the front cover every 40-50k since they are way harder on the timing chain than Crow 105's. Which will also work fine.
 
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