MS4 with GM HP lifters (caddy), need some help please
09-10-2007, 10:11 AM
#1
Staging Lane
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MS4 with GM HP lifters (caddy), need some help please Guys,
I'm installing the MS4 (111 LSA) with TSP stage 1 heads and the caddy lifters. I have the 7.400 length pushrods.
I have .75 preload on those lifters (1.5 turns on the lifter bolt, plus I measured this with a dial indicator). .80 is what I was told by the vendor to set preload, so i'm close enough. I've also used a pushrod length checker, just to verify the needed length. Came out to 7.400.
To check piston to valve clearance, I took the springs out of the caddy lifters and put bushings in there to make them solid lifters, setting the plunger right at the top. I put the heads on and start turning the crank to 20 degrees BTDC but can't get there because the piston is hitting the valve.
Are the caddy lifters that much taller? I did some rough measuring, their plunger seat seemed to be about .030 higher than stock, but I could be wrong. And I don't think .030 would cause my clearance issue. It would make it tighter, but not cause the psiton to contact the valve.
Should I go with a shorter pushrod, even though all measurements indicate 7.400? I'd rather not flycut right now, personally, I'd be fine with the advertised PtoV clearance of 75/80 (don't recall the exact clearances).
Any advice would be appreciated
I'm installing the MS4 (111 LSA) with TSP stage 1 heads and the caddy lifters. I have the 7.400 length pushrods.
I have .75 preload on those lifters (1.5 turns on the lifter bolt, plus I measured this with a dial indicator). .80 is what I was told by the vendor to set preload, so i'm close enough. I've also used a pushrod length checker, just to verify the needed length. Came out to 7.400.
To check piston to valve clearance, I took the springs out of the caddy lifters and put bushings in there to make them solid lifters, setting the plunger right at the top. I put the heads on and start turning the crank to 20 degrees BTDC but can't get there because the piston is hitting the valve.
Are the caddy lifters that much taller? I did some rough measuring, their plunger seat seemed to be about .030 higher than stock, but I could be wrong. And I don't think .030 would cause my clearance issue. It would make it tighter, but not cause the psiton to contact the valve.
Should I go with a shorter pushrod, even though all measurements indicate 7.400? I'd rather not flycut right now, personally, I'd be fine with the advertised PtoV clearance of 75/80 (don't recall the exact clearances).
Any advice would be appreciated
09-10-2007, 12:10 PM
#2
The MS4 clears by about 0.040(it was posted by TSP a while back). Add the extra lifter height and the fact that you shimmed the preload out of the lifter and you get contact. I ran stock unmilled heads, caddy lifters, 7.4 PR's, and the MS4 without PTV contact so you may be ok. Personally if I had the heads off I would flycut to be on the safe side.
09-10-2007, 12:38 PM
#3
TECH Senior Member
I would never run that cam without flycutting 1cc (.080) of intake. But that is me.
If you cannot clear a solid lifter 20* BTDC that should tell you something. P-rod length has nothing to do with PTV unless they are too long and keeping the valves open which is not the case here.
If you cannot clear a solid lifter 20* BTDC that should tell you something. P-rod length has nothing to do with PTV unless they are too long and keeping the valves open which is not the case here.
