...If I launched that hard I would probably break something. 
Hydraulic Roller vs Solid Roller...
Melting Slicks
Joined: Oct 2003
Posts: 2,951
Likes: 3
From: Mount Vernon OH
Originally Posted by Kwik88
I was told that a hydraulic roller, lets say measuring 235@.050 will act similar to a solid roller measuring about 250@.050. If so, why?
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
its more like a hydraulic roller, lets say measuring 235@.050 will act similar to a solid roller measuring about 239@.050. A hydraulic roller has no valve lash. A solid roller has any where from .016 to .028 of valve lash that takes away from the duration and lift of the cam.
Thread Starter
Racer
Joined: Oct 2001
Posts: 262
Likes: 0
From: Palos Hills IL
So it will 'act' just slightly larger? I've been looking at some port work on the 190's and some more cam, just not sure how much more. I've seen a few cars break into the tens with as little as 224@.050 with about .600 lift.
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Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Good stuff. With my mph I should be running quicker. But for street tires I think its respectful. I have been launching pretty easy, I dont want to burn up the clutch. I plan on getting so BFG drag radials and going larger with the cam to put me deep into the 11's. My goal is 124-125mph.
Last edited by chriswtx; Jan 4, 2005 at 02:09 AM.
Melting Slicks
Joined: Apr 2000
Posts: 3,490
Likes: 2
From: Oviedo FL
Originally Posted by Kwik88
So it will 'act' just slightly larger? I've been looking at some port work on the 190's and some more cam, just not sure how much more. I've seen a few cars break into the tens with as little as 224@.050 with about .600 lift.
It's putting down 415 rwhp/417 rwtq
No 1/4 mile times yet but I'm really only interested in the mph anyways. My car is setup to road race only (that's where all the fun is
)Will let you know what she runs when I get her out there in the next month or so.
Mike
Race Director
Joined: Dec 2002
Posts: 13,348
Likes: 233
From: SCMR Rat Pack'r Charter Member..Great Bend KS
Originally Posted by chriswtx
A solid roller has any where from .016 to .028 of valve lash that takes away from the duration and lift of the cam.
The lash you speak of is designed to close up to near zero at operating temperatures. So, you can pretty much disregard it when you are measuring lift/duration.
Larry
code5coupe
Burning Brakes
Joined: Nov 2001
Posts: 1,241
Likes: 9
From: Houston TX
lash on solid cams gets looser with higher temps, not tighter. when you set lash on a cold engine, you have to set it tighter than the advertised (hot lash). for a sbc, this means .004" tighter with iron heads, and .007" tighter with Al heads, as a general rule.
as to the original question, if you intended "drivability," then it actually is true. the total overlap and duration set drivability and idle characteristics more than anything else. a solid has such fast ramp rates that a 250 at .050" cam might only be 280 overall, then subtract some for lash.
as an example, a friend of mine with a 347 ford went from a 248 at .050" solid roller, to a 232 at .050" hy-roller, and the drivability was about the same, with the hy-roller actually having a bit more surging below 1500rpm.
something else to consider, because of ramp rate differences and the lash, a lobe separation angle on solid vs hydraulic acts differently. (this makes sense, since the lsa really just determines overlap for a given duration.)
-michael
as to the original question, if you intended "drivability," then it actually is true. the total overlap and duration set drivability and idle characteristics more than anything else. a solid has such fast ramp rates that a 250 at .050" cam might only be 280 overall, then subtract some for lash.
as an example, a friend of mine with a 347 ford went from a 248 at .050" solid roller, to a 232 at .050" hy-roller, and the drivability was about the same, with the hy-roller actually having a bit more surging below 1500rpm.
something else to consider, because of ramp rate differences and the lash, a lobe separation angle on solid vs hydraulic acts differently. (this makes sense, since the lsa really just determines overlap for a given duration.)
-michael
Le Mans Master
Joined: Feb 1999
Posts: 6,172
Likes: 11
From: somers, ny
As a rule of thumb i have used 8 deg for a hyd to solid compare. Could be more or less depending on lash and ramp rates, so 15 is not out of the question.
Can you tell me more about the combos going 10s with 224 duration cams?
Can you tell me more about the combos going 10s with 224 duration cams?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by rocco16
Not entirely true.
The lash you speak of is designed to close up to near zero at operating temperatures. So, you can pretty much disregard it when you are measuring lift/duration.
Larry
code5coupe
The lash you speak of is designed to close up to near zero at operating temperatures. So, you can pretty much disregard it when you are measuring lift/duration.
Larry
code5coupe
Have you never heard of "hot lashing" the valves? Adjusting the valve lash with the engine hot? No way the lash gets close to zero, hot and running. One BIG difference in solid and hydraulic cams, flat or roller, is the lash take up ramps ground into the solid lifter camshaft. THAT is the main reason the duration of a solid and a hydraulic, can't be directly compared. Besides, the lash itself is a non factor in the duration numbers. The durations are measured at the specified LIFTER height, not valve height. Just trying to prevent the spread of some mis-information.
RACE ON!!!
