TSP/PAC 660 springs limit?
Thread Starter
Teching In
Joined: Dec 2023
Posts: 46
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TSP/PAC 660 springs limit? I'm working with Brian Tooley racing on a custom cam for my endurance road racing application. I'm running TSP Brawler heads with their TSP/PAC 660 springs. They recommend higher seat pressure and adding steel lash caps on the valve tips. I couldn't really verify those recommendations based on internet searching, but I figured I'd take their word for it as experts who designs a lot of these valvetrains.
To accommodate the lash caps (and provide more seat pressure), they got me a set of 0.075 offset locks.
The TSP/PAC 660 specs are:
Thoughts? If the springs have plenty of coil bind clearance at 0.700, why are they marketed as 660 springs?
BTW, I e-mailed the guys at TSP but I figured I'd ask hear in the meantime to see what ya'll think
Thanks,
Sal
To accommodate the lash caps (and provide more seat pressure), they got me a set of 0.075 offset locks.
The TSP/PAC 660 specs are:
- 1.810 installed height
- 1.015 coil bind
- 0.135 coil bind clearance at 0.660 max lift
- 1.735 installed height
- 1.015 coil bind
- 0.091 coil bind clearance at 0.629 max lift
- I checked and I've got plenty of clearance (~0.085) between the retainer and the valve seal
Thoughts? If the springs have plenty of coil bind clearance at 0.700, why are they marketed as 660 springs?
BTW, I e-mailed the guys at TSP but I figured I'd ask hear in the meantime to see what ya'll think
Thanks,
Sal
Joined: Apr 2006
Posts: 3,909
Likes: 1,158
From: Grand Rapids, Michigan
My guess is, variances in installed height might cause coil bind issues in some applications and it's better to err on the safe side. The other possibility is that the spring design isn't set up for the aggressiveness that a .700+ lift cam would have.
Thread Starter
Teching In
Joined: Dec 2023
Posts: 46
Likes: 7
Thread Starter
Teching In
Joined: Dec 2023
Posts: 46
Likes: 7
TSP also confirmed that it's more of a marketing thing... for the mass market they advertise 660 to keep folks within the safe realm of usage whereas if they marked them as 700, more folks would push them to (or beyond) the safe limit
