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solid flat tappet to hydraulic flat tappet comparison
#1370309
01/15/13 03:03 PM
01/15/13 03:03 PM
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Joined: Sep 2006
Posts: 1,139
West Tennessee
rbstroker
OP
super stock
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OP
super stock
Joined: Sep 2006
Posts: 1,139
West Tennessee
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Trying to do a comparison between hydraulic and solid flat tappet cams. Looking at MP .528 solid cam for big blocks. I know that for effective lift, the .528 must have the valve lash of .028 and .032 subtracted, but what about duration of 241* at .050 and valve timing events (especially intake closing)? I need some accurate numbers in order to plug into a dynamic compression calculator and also to try finding a comparable hydraulic cam.
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: DaytonaTurbo]
#1370316
01/16/13 09:17 PM
01/16/13 09:17 PM
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Joined: Sep 2006
Posts: 1,139
West Tennessee
rbstroker
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Outstanding. Hopefully someone might be able to say what the valve timing events are. Thanks.
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: BSB67]
#1370318
01/16/13 10:07 PM
01/16/13 10:07 PM
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Joined: Sep 2006
Posts: 1,139
West Tennessee
rbstroker
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OP
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My fault for not being clear. Subtracting the .032 and .028 lash gives an effective lift of .496 and .500 with my 1.5 rockers. Daytona poins out that the comparable hydraulic cam duration at .050 is 230* when you take lash into consideration. Now I need for someone a lot smarter than me (that's almost everyone) to tell me what the valve timing events are when you take lash into consideration. Andy Finkbeiner strongly recomends the MP .528 cam for street driven 4 speed strokers with manifolds. I'd like to mimick that cam with a hydraulic unit. In order to check myself, I need the numbers to plug into a calculator.
This is the land of the free
because of the brave
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: rbstroker]
#1370319
01/16/13 10:25 PM
01/16/13 10:25 PM
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Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67
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Prospect, PA
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About 284. The problem is that unlike most other cam grinders/suppliers, Mopar does not tell you how they measured the published advertised duration.
Lew, (posted above) I think measured the .528" cam's 284 @ 0.015" lift. (Correct Lew?) If so, that means that if you set the lash at 0.022" (with a true 1.5 rocker) the actual seat timing would be 284. So it you go with more lash, like 0.028", it will have shorter duration. I'm guessing about 278 to 280.
Oh, and technically, that would not mimic a hydraulic, as most of them are measured at 0.006" lift. So for comparison sake, you would need to set the lash at 0.015" to make the 528's 284 to look like a hydraulics 284.
Last edited by BSB67; 01/16/13 10:32 PM.
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: CSK]
#1370321
01/16/13 10:31 PM
01/16/13 10:31 PM
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Joined: Aug 2011
Posts: 2,872
Pattison Texas
CSK
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that for 112 lsa,,108 intake center line
230 @ .050
Last edited by csk; 01/16/13 10:32 PM.
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: CSK]
#1370322
01/16/13 10:34 PM
01/16/13 10:34 PM
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Joined: Feb 2005
Posts: 4,321
Prospect, PA
BSB67
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Prospect, PA
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The LSA matters not, the cam has about 240 @ 0.050", and he is using actual seat timing  All said and done, I would plug in 68 degrees ABDC. It will probably be right withing one or two.
Last edited by BSB67; 01/16/13 10:39 PM.
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: CSK]
#1370325
01/16/13 10:45 PM
01/16/13 10:45 PM
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Joined: Aug 2011
Posts: 2,872
Pattison Texas
CSK
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master
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Pattison Texas
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ivo 28
ivc 64
evo 72
evc 20
272 advertized
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: rbstroker]
#1370326
01/16/13 11:03 PM
01/16/13 11:03 PM
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Joined: Jun 2012
Posts: 1,899
MYRTLE BEACH SOUTH CAROLINA
ek3
top fuel
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top fuel
Joined: Jun 2012
Posts: 1,899
MYRTLE BEACH SOUTH CAROLINA
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Quote:
My fault for not being clear. Subtracting the .032 and .028 lash gives an effective lift of .496 and .500 with my 1.5 rockers. Daytona poins out that the comparable hydraulic cam duration at .050 is 230* when you take lash into consideration. Now I need for someone a lot smarter than me (that's almost everyone) to tell me what the valve timing events are when you take lash into consideration. Andy Finkbeiner strongly recomends the MP .528 cam for street driven 4 speed strokers with manifolds. I'd like to mimick that cam with a hydraulic unit. In order to check myself, I need the numbers to plug into a calculator.
First off , subtracting lash does not change the lift - none - . that is a matter of the lobes max height x Rocker arm ratio. The valve timing events are only slightly changed by adding or subtracting lash. Generally speaking , you only shorten the ramp areas a little. If you want the solid cam in a a hyd. version , just have one ground , [if they dont make it]. the only real advantage to a solid lifter is that it wont pump up at hi rpms. ie; solid lifters can operate at higher rpms. some race style hyd. lifters can nearly get the same job done. if you really want to add power , add a hyd. "roller cam".
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Re: solid flat tappet to hydraulic flat tappet comparison
[Re: BSB67]
#1370327
01/16/13 11:52 PM
01/16/13 11:52 PM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
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Too Many Posts
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Manitoba, Canada
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I saved this post years ago. Someone much more experienced and skilled with cams than me posted this in the race section, but I forget who it was. Anyway I've referenced it periodically and to me it seems like good info. Quote:
Since I believe the DC/MP Solids all come from the same lobe "family"........
First the advertised duration is incorrect (for what we're all used to)
The seat to seat duration is given @ .015" not .020"
To find duartion @ .020", subtract 8º from what MP tells you.
To find duration @ .050", subtract 32º(intensity)from the answer you got from above.
So, a 296º-.557" is really 288º @ .020"/256º @ .050"
312º-.590.........304º @ .020"/272º @ .050" and so on.
Keep in mind when comparing duration at .050 on a hydraulic verses a solid, or two solids with different lash specs, that the lash must be taken into account. I have found that 1/2 degree per thousanth of lash is a decent rule of thumb.
Most of the solid cams I use have lash specs of .018 in. so I would subtract 9 degrees off the solid cam duration at .050 to compare to a hydraulic (with no lash). The mopar cams the lobes are designed with a .028 lash so I would subtract about 5 degrees at .050 to compare it to solid cam with a .018 lash.
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